diff --git a/third_party/nix/.clang-tidy b/third_party/nix/.clang-tidy
index 5b22be767..ca2de1083 100644
--- a/third_party/nix/.clang-tidy
+++ b/third_party/nix/.clang-tidy
@@ -1,4 +1,4 @@
 ---
-Checks: 'abseil-c*,clang-analyzer-security-*,bugprone-*,google-*,modernize-*,cppcoreguidelines-*,misc-*,-modernize-use-trailing-return-type'
+Checks: 'abseil-c*,clang-analyzer-security-*,bugprone-*,google-*,modernize-*,cppcoreguidelines-*,misc-*'
 WarningsAsErrors: 'abseil-*,clang-analyzer-security*'
 ...
diff --git a/third_party/nix/src/build-remote/build-remote.cc b/third_party/nix/src/build-remote/build-remote.cc
index abf1270b7..0aeadd051 100644
--- a/third_party/nix/src/build-remote/build-remote.cc
+++ b/third_party/nix/src/build-remote/build-remote.cc
@@ -22,6 +22,7 @@
 #include "nix/legacy.hh"
 
 using namespace nix;
+using std::cin;
 
 static void handleAlarm(int sig) {}
 
diff --git a/third_party/nix/src/libexpr/attr-path.cc b/third_party/nix/src/libexpr/attr-path.cc
index 07ffebff1..a267e82b6 100644
--- a/third_party/nix/src/libexpr/attr-path.cc
+++ b/third_party/nix/src/libexpr/attr-path.cc
@@ -51,7 +51,7 @@ Value* findAlongAttrPath(EvalState& state, const std::string& attrPath,
   for (auto& attr : tokens) {
     /* Is i an index (integer) or a normal attribute name? */
     enum { apAttr, apIndex } apType = apAttr;
-    unsigned int attrIndex = 0;
+    unsigned int attrIndex;
     if (absl::SimpleAtoi(attr, &attrIndex)) {
       apType = apIndex;
     }
diff --git a/third_party/nix/src/libexpr/eval.cc b/third_party/nix/src/libexpr/eval.cc
index 6195b30be..0afa7567b 100644
--- a/third_party/nix/src/libexpr/eval.cc
+++ b/third_party/nix/src/libexpr/eval.cc
@@ -36,7 +36,7 @@
 namespace nix {
 
 static char* dupString(const char* s) {
-  char* t = nullptr;
+  char* t;
   t = GC_STRDUP(s);
   if (t == nullptr) {
     throw std::bad_alloc();
@@ -199,7 +199,7 @@ static Symbol getName(const AttrName& name, EvalState& state, Env& env) {
   return std::visit(
       util::overloaded{[&](const Symbol& name) -> Symbol { return name; },
                        [&](Expr* expr) -> Symbol {
-                         Value nameValue{};
+                         Value nameValue;
                          expr->eval(state, env, nameValue);
                          state.forceStringNoCtx(nameValue);
                          return state.symbols.Create(nameValue.string.s);
@@ -478,7 +478,7 @@ Value* EvalState::addConstant(const std::string& name, Value& v) {
 Value* EvalState::addPrimOp(const std::string& name, size_t arity,
                             PrimOpFun primOp) {
   if (arity == 0) {
-    Value v{};
+    Value v;
     primOp(*this, noPos, nullptr, v);
     return addConstant(name, v);
   }
@@ -577,8 +577,8 @@ Value& mkString(Value& v, const std::string& s, const PathSet& context) {
   mkString(v, s.c_str());
   if (!context.empty()) {
     size_t n = 0;
-    v.string.context = static_cast<const char**>(
-        allocBytes((context.size() + 1) * sizeof(char*)));
+    v.string.context =
+        (const char**)allocBytes((context.size() + 1) * sizeof(char*));
     for (auto& i : context) {
       v.string.context[n++] = dupString(i.c_str());
     }
@@ -772,7 +772,7 @@ void EvalState::resetFileCache() {
 void EvalState::eval(Expr* e, Value& v) { e->eval(*this, baseEnv, v); }
 
 inline bool EvalState::evalBool(Env& env, Expr* e) {
-  Value v{};
+  Value v;
   e->eval(*this, env, v);
   if (v.type != tBool) {
     throwTypeError("value is %1% while a Boolean was expected", v);
@@ -781,7 +781,7 @@ inline bool EvalState::evalBool(Env& env, Expr* e) {
 }
 
 inline bool EvalState::evalBool(Env& env, Expr* e, const Pos& pos) {
-  Value v{};
+  Value v;
   e->eval(*this, env, v);
   if (v.type != tBool) {
     throwTypeError("value is %1% while a Boolean was expected, at %2%", v, pos);
@@ -822,7 +822,7 @@ void ExprAttrs::eval(EvalState& state, Env& env, Value& value) {
        in the original environment. */
     size_t displ = 0;
     for (auto& attr : attrs) {
-      Value* vAttr = nullptr;
+      Value* vAttr;
       vAttr =
           attr.second.e->maybeThunk(state, attr.second.inherited ? env : env2);
       env2.values[displ++] = vAttr;
@@ -838,7 +838,7 @@ void ExprAttrs::eval(EvalState& state, Env& env, Value& value) {
 
   /* Dynamic attrs apply *after* rec. */
   for (auto& i : dynamicAttrs) {
-    Value nameVal{};
+    Value nameVal;
     i.nameExpr->eval(state, *dynamicEnv, nameVal);
     state.forceValue(nameVal, i.pos);
     if (nameVal.type == tNull) {
@@ -906,7 +906,7 @@ static std::string showAttrPath(EvalState& state, Env& env,
 unsigned long nrLookups = 0;
 
 void ExprSelect::eval(EvalState& state, Env& env, Value& v) {
-  Value vTmp{};
+  Value vTmp;
   Pos* pos2 = nullptr;
   Value* vAttrs = &vTmp;
 
@@ -957,7 +957,7 @@ void ExprSelect::eval(EvalState& state, Env& env, Value& v) {
 }
 
 void ExprOpHasAttr::eval(EvalState& state, Env& env, Value& v) {
-  Value vTmp{};
+  Value vTmp;
   Value* vAttrs = &vTmp;
 
   e->eval(state, env, vTmp);
@@ -985,7 +985,7 @@ void ExprLambda::eval(EvalState& state, Env& env, Value& v) {
 
 void ExprApp::eval(EvalState& state, Env& env, Value& v) {
   /* FIXME: vFun prevents GCC from doing tail call optimisation. */
-  Value vFun{};
+  Value vFun;
   e1->eval(state, env, vFun);
   state.callFunction(vFun, *(e2->maybeThunk(state, env)), v, pos);
 }
@@ -1053,7 +1053,7 @@ void EvalState::callFunction(Value& fun, Value& arg, Value& v, const Pos& pos) {
       auto& fun2 = *allocValue();
       fun2 = fun;
       /* !!! Should we use the attr pos here? */
-      Value v2{};
+      Value v2;
       // functors are called with the element itself as the first
       // parameter, which is partially applied here
       callFunction(*found->second.value, fun2, v2, pos);
@@ -1210,17 +1210,17 @@ void ExprOpNot::eval(EvalState& state, Env& env, Value& v) {
 }
 
 void ExprOpEq::eval(EvalState& state, Env& env, Value& v) {
-  Value v1{};
+  Value v1;
   e1->eval(state, env, v1);
-  Value v2{};
+  Value v2;
   e2->eval(state, env, v2);
   mkBool(v, state.eqValues(v1, v2));
 }
 
 void ExprOpNEq::eval(EvalState& state, Env& env, Value& v) {
-  Value v1{};
+  Value v1;
   e1->eval(state, env, v1);
-  Value v2{};
+  Value v2;
   e2->eval(state, env, v2);
   mkBool(v, !state.eqValues(v1, v2));
 }
@@ -1238,8 +1238,8 @@ void ExprOpImpl::eval(EvalState& state, Env& env, Value& v) {
 }
 
 void ExprOpUpdate::eval(EvalState& state, Env& env, Value& dest) {
-  Value v1{};
-  Value v2{};
+  Value v1;
+  Value v2;
   state.evalAttrs(env, e1, v1);
   state.evalAttrs(env, e2, v2);
 
@@ -1251,9 +1251,9 @@ void ExprOpUpdate::eval(EvalState& state, Env& env, Value& dest) {
 }
 
 void ExprOpConcatLists::eval(EvalState& state, Env& env, Value& v) {
-  Value v1{};
+  Value v1;
   e1->eval(state, env, v1);
-  Value v2{};
+  Value v2;
   e2->eval(state, env, v2);
   state.concatLists(v, {&v1, &v2}, pos);
 }
@@ -1281,7 +1281,7 @@ void ExprConcatStrings::eval(EvalState& state, Env& env, Value& v) {
   ValueType firstType = tString;
 
   for (auto& i : *es) {
-    Value vTmp{};
+    Value vTmp;
     i->eval(state, env, vTmp);
 
     /* If the first element is a path, then the result will also
@@ -1488,7 +1488,7 @@ std::optional<std::string> EvalState::tryAttrsToString(const Pos& pos, Value& v,
                                                        bool copyToStore) {
   auto i = v.attrs->find(sToString);
   if (i != v.attrs->end()) {
-    Value v1{};
+    Value v1;
     callFunction(*i->second.value, v, v1, pos);
     return coerceToString(pos, v1, context, coerceMore, copyToStore);
   }
@@ -1701,10 +1701,9 @@ bool EvalState::eqValues(Value& v1, Value& v2) {
 void EvalState::printStats() {
   bool showStats = getEnv("NIX_SHOW_STATS", "0") != "0";
 
-  struct rusage buf {};
+  struct rusage buf;
   getrusage(RUSAGE_SELF, &buf);
-  float cpuTime = buf.ru_utime.tv_sec +
-                  (static_cast<float>(buf.ru_utime.tv_usec) / 1000000);
+  float cpuTime = buf.ru_utime.tv_sec + ((float)buf.ru_utime.tv_usec / 1000000);
 
   uint64_t bEnvs = nrEnvs * sizeof(Env) + nrValuesInEnvs * sizeof(Value*);
   uint64_t bLists = nrListElems * sizeof(Value*);
@@ -1713,8 +1712,8 @@ void EvalState::printStats() {
       nrAttrsets * sizeof(Bindings) + nrAttrsInAttrsets * sizeof(Attr);
 
 #if HAVE_BOEHMGC
-  GC_word heapSize = 0;
-  GC_word totalBytes = 0;
+  GC_word heapSize;
+  GC_word totalBytes;
   GC_get_heap_usage_safe(&heapSize, nullptr, nullptr, nullptr, &totalBytes);
 #endif
   if (showStats) {
diff --git a/third_party/nix/src/libexpr/get-drvs.cc b/third_party/nix/src/libexpr/get-drvs.cc
index fb5ada54c..02ddae1f8 100644
--- a/third_party/nix/src/libexpr/get-drvs.cc
+++ b/third_party/nix/src/libexpr/get-drvs.cc
@@ -6,7 +6,6 @@
 
 #include <absl/strings/numbers.h>
 #include <glog/logging.h>
-#include <math.h>
 
 #include "libexpr/eval-inline.hh"
 #include "libstore/derivations.hh"
@@ -244,7 +243,7 @@ NixInt DrvInfo::queryMetaInt(const std::string& name, NixInt def) {
   if (v->type == tString) {
     /* Backwards compatibility with before we had support for
        integer meta fields. */
-    NixInt n = 0;
+    NixInt n;
     if (absl::SimpleAtoi(v->string.s, &n)) {
       return n;
     }
@@ -263,7 +262,7 @@ NixFloat DrvInfo::queryMetaFloat(const std::string& name, NixFloat def) {
   if (v->type == tString) {
     /* Backwards compatibility with before we had support for
        float meta fields. */
-    NixFloat n = NAN;
+    NixFloat n;
     if (string2Float(v->string.s, n)) {
       return n;
     }
@@ -368,7 +367,7 @@ static void getDerivations(EvalState& state, Value& vIn,
                            const std::string& pathPrefix, Bindings& autoArgs,
                            DrvInfos& drvs, Done& done,
                            bool ignoreAssertionFailures) {
-  Value v{};
+  Value v;
   state.autoCallFunction(autoArgs, vIn, v);
 
   /* Process the expression. */
diff --git a/third_party/nix/src/libexpr/names.cc b/third_party/nix/src/libexpr/names.cc
index 84329d7c0..1e9c2f2f4 100644
--- a/third_party/nix/src/libexpr/names.cc
+++ b/third_party/nix/src/libexpr/names.cc
@@ -68,8 +68,8 @@ std::string nextComponent(std::string::const_iterator& p,
 }
 
 static bool componentsLT(const std::string& c1, const std::string& c2) {
-  int n1 = 0;
-  int n2 = 0;
+  int n1;
+  int n2;
   bool c1Num = absl::SimpleAtoi(c1, &n1);
   bool c2Num = absl::SimpleAtoi(c2, &n2);
 
diff --git a/third_party/nix/src/libexpr/names.hh b/third_party/nix/src/libexpr/names.hh
index e820995b8..061388d51 100644
--- a/third_party/nix/src/libexpr/names.hh
+++ b/third_party/nix/src/libexpr/names.hh
@@ -11,7 +11,7 @@ struct DrvName {
   std::string fullName;
   std::string name;
   std::string version;
-  unsigned int hits{};
+  unsigned int hits;
 
   DrvName();
   DrvName(const std::string& s);
diff --git a/third_party/nix/src/libexpr/nixexpr.cc b/third_party/nix/src/libexpr/nixexpr.cc
index faf1020f8..94e7d335c 100644
--- a/third_party/nix/src/libexpr/nixexpr.cc
+++ b/third_party/nix/src/libexpr/nixexpr.cc
@@ -18,7 +18,7 @@ std::ostream& operator<<(std::ostream& str, const Expr& e) {
 
 static void showString(std::ostream& str, const std::string& s) {
   str << '"';
-  for (auto c : std::string(s)) {
+  for (auto c : (std::string)s) {
     if (c == '"' || c == '\\' || c == '$') {
       str << "\\" << c;
     } else if (c == '\n') {
@@ -191,7 +191,7 @@ std::ostream& operator<<(std::ostream& str, const Pos& pos) {
     str << "undefined position";
   } else {
     str << (format(ANSI_BOLD "%1%" ANSI_NORMAL ":%2%:%3%") %
-            std::string(pos.file.value()) % pos.line % pos.column)
+            (std::string)pos.file.value() % pos.line % pos.column)
                .str();
   }
   return str;
@@ -232,8 +232,8 @@ void ExprPath::bindVars(const StaticEnv& env) {}
 void ExprVar::bindVars(const StaticEnv& env) {
   /* Check whether the variable appears in the environment.  If so,
      set its level and displacement. */
-  const StaticEnv* curEnv = nullptr;
-  unsigned int level = 0;
+  const StaticEnv* curEnv;
+  unsigned int level;
   int withLevel = -1;
   for (curEnv = &env, level = 0; curEnv != nullptr;
        curEnv = curEnv->up, level++) {
@@ -363,8 +363,8 @@ void ExprWith::bindVars(const StaticEnv& env) {
   /* Does this `with' have an enclosing `with'?  If so, record its
      level so that `lookupVar' can look up variables in the previous
      `with' if this one doesn't contain the desired attribute. */
-  const StaticEnv* curEnv = nullptr;
-  unsigned int level = 0;
+  const StaticEnv* curEnv;
+  unsigned int level;
   prevWith = 0;
   for (curEnv = &env, level = 1; curEnv != nullptr;
        curEnv = curEnv->up, level++) {
@@ -405,7 +405,7 @@ void ExprLambda::setName(Symbol& name) { this->name = name; }
 
 std::string ExprLambda::showNamePos() const {
   return (format("%1% at %2%") %
-          (name.has_value() ? "'" + std::string(name.value()) + "'"
+          (name.has_value() ? "'" + (std::string)name.value() + "'"
                             : "anonymous function") %
           pos)
       .str();
diff --git a/third_party/nix/src/libexpr/parser.cc b/third_party/nix/src/libexpr/parser.cc
index 7b477f3ea..a96d345cc 100644
--- a/third_party/nix/src/libexpr/parser.cc
+++ b/third_party/nix/src/libexpr/parser.cc
@@ -85,10 +85,9 @@ void addAttr(ExprAttrs* attrs, AttrPath& attrPath, Expr* e, const Pos& pos) {
 }
 
 void addFormal(const Pos& pos, Formals* formals, const Formal& formal) {
-  if (formals->argNames.find(formal.name) != formals->argNames.end()) {
+  if (formals->argNames.find(formal.name) != formals->argNames.end())
     throw ParseError(format("duplicate formal function argument '%1%' at %2%") %
                      formal.name % pos);
-  }
   formals->formals.push_front(formal);
   formals->argNames.insert(formal.name);
 }
@@ -119,9 +118,9 @@ Expr* stripIndentation(const Pos& pos, SymbolTable& symbols,
     }
     for (size_t j = 0; j < e->s.size(); ++j) {
       if (atStartOfLine) {
-        if (e->s[j] == ' ') {
+        if (e->s[j] == ' ')
           curIndent++;
-        } else if (e->s[j] == '\n') {
+        else if (e->s[j] == '\n') {
           /* Empty line, doesn't influence minimum
              indentation. */
           curIndent = 0;
@@ -197,11 +196,10 @@ Path resolveExprPath(Path path) {
 
   /* If `path' is a symlink, follow it.  This is so that relative
      path references work. */
-  struct stat st {};
+  struct stat st;
   while (true) {
-    if (lstat(path.c_str(), &st)) {
+    if (lstat(path.c_str(), &st))
       throw SysError(format("getting status of '%1%'") % path);
-    }
     if (!S_ISLNK(st.st_mode)) {
       break;
     }
@@ -262,14 +260,13 @@ Path EvalState::findFile(SearchPath& searchPath, const std::string& path,
                          const Pos& pos) {
   for (auto& i : searchPath) {
     std::string suffix;
-    if (i.first.empty()) {
+    if (i.first.empty())
       suffix = "/" + path;
-    } else {
+    else {
       auto s = i.first.size();
       if (path.compare(0, s, i.first) != 0 ||
-          (path.size() > s && path[s] != '/')) {
+          (path.size() > s && path[s] != '/'))
         continue;
-      }
       suffix = path.size() == s ? "" : "/" + std::string(path, s);
     }
     auto r = resolveSearchPathElem(i);
diff --git a/third_party/nix/src/libexpr/primops.cc b/third_party/nix/src/libexpr/primops.cc
index 053565f48..a1c1f2517 100644
--- a/third_party/nix/src/libexpr/primops.cc
+++ b/third_party/nix/src/libexpr/primops.cc
@@ -86,8 +86,8 @@ void EvalState::realiseContext(const PathSet& context) {
   PathSet willBuild;
   PathSet willSubstitute;
   PathSet unknown;
-  unsigned long long downloadSize = 0;
-  unsigned long long narSize = 0;
+  unsigned long long downloadSize;
+  unsigned long long narSize;
   store->queryMissing(drvs, willBuild, willSubstitute, unknown, downloadSize,
                       narSize);
   store->buildPaths(drvs);
@@ -130,7 +130,7 @@ static void prim_scopedImport(EvalState& state, const Pos& pos, Value** args,
       mkString(*((*outputsVal->list)[outputs_index++]), o.first);
     }
 
-    Value fun{};
+    Value fun;
     state.evalFile(
         settings.nixDataDir + "/nix/corepkgs/imported-drv-to-derivation.nix",
         fun);
@@ -213,7 +213,7 @@ static void prim_isNull(EvalState& state, const Pos& pos, Value** args,
 static void prim_isFunction(EvalState& state, const Pos& pos, Value** args,
                             Value& v) {
   state.forceValue(*args[0]);
-  bool res = 0;
+  bool res;
   switch (args[0]->type) {
     case tLambda:
     case tPrimOp:
@@ -347,7 +347,7 @@ static void prim_genericClosure(EvalState& state, const Pos& pos, Value** args,
     res.push_back(e);
 
     /* Call the `operator' function with `e' as argument. */
-    Value call{};
+    Value call;
     mkApp(call, *op->second.value, *e);
     state.forceList(call, pos);
 
@@ -875,7 +875,7 @@ static void prim_readFile(EvalState& state, const Pos& pos, Value** args,
   }
   std::string s =
       readFile(state.checkSourcePath(state.toRealPath(path, context)));
-  if (s.find('\0') != std::string::npos) {
+  if (s.find((char)0) != std::string::npos) {
     throw Error(format("the contents of the file '%1%' cannot be represented "
                        "as a Nix string") %
                 path);
@@ -1048,13 +1048,13 @@ static void addPath(EvalState& state, const Pos& pos, const std::string& name,
 
     /* Call the filter function.  The first argument is the path,
        the second is a string indicating the type of the file. */
-    Value arg1{};
+    Value arg1;
     mkString(arg1, path);
 
-    Value fun2{};
+    Value fun2;
     state.callFunction(*filterFun, arg1, fun2, noPos);
 
-    Value arg2{};
+    Value arg2;
     mkString(arg2, S_ISREG(st.st_mode)
                        ? "regular"
                        : S_ISDIR(st.st_mode)
@@ -1063,7 +1063,7 @@ static void addPath(EvalState& state, const Pos& pos, const std::string& name,
                                    ? "symlink"
                                    : "unknown" /* not supported, will fail! */);
 
-    Value res{};
+    Value res;
     state.callFunction(fun2, arg2, res, noPos);
 
     return state.forceBool(res, pos);
@@ -1420,7 +1420,7 @@ static void prim_isList(EvalState& state, const Pos& pos, Value** args,
 static void elemAt(EvalState& state, const Pos& pos, Value& list, int n,
                    Value& v) {
   state.forceList(list, pos);
-  if (n < 0 || static_cast<unsigned int>(n) >= list.listSize()) {
+  if (n < 0 || (unsigned int)n >= list.listSize()) {
     throw Error(format("list index %1% is out of bounds, at %2%") % n % pos);
   }
   state.forceValue(*(*list.list)[n]);
@@ -1479,7 +1479,7 @@ static void prim_filter(EvalState& state, const Pos& pos, Value** args,
 
   bool same = true;
   for (unsigned int n = 0; n < args[1]->listSize(); ++n) {
-    Value res{};
+    Value res;
     state.callFunction(*args[0], *(*args[1]->list)[n], res, noPos);
     if (state.forceBool(res, pos)) {
       vs[k++] = (*args[1]->list)[n];
@@ -1537,7 +1537,7 @@ static void prim_foldlStrict(EvalState& state, const Pos& pos, Value** args,
     Value* vCur = args[1];
 
     for (unsigned int n = 0; n < args[2]->listSize(); ++n) {
-      Value vTmp{};
+      Value vTmp;
       state.callFunction(*args[0], *vCur, vTmp, pos);
       vCur = n == args[2]->listSize() - 1 ? &v : state.allocValue();
       state.callFunction(vTmp, *(*args[2]->list)[n], *vCur, pos);
@@ -1554,7 +1554,7 @@ static void anyOrAll(bool any, EvalState& state, const Pos& pos, Value** args,
   state.forceFunction(*args[0], pos);
   state.forceList(*args[1], pos);
 
-  Value vTmp{};
+  Value vTmp;
   for (unsigned int n = 0; n < args[1]->listSize(); ++n) {
     state.callFunction(*args[0], *(*args[1]->list)[n], vTmp, pos);
     bool res = state.forceBool(vTmp, pos);
@@ -1586,7 +1586,7 @@ static void prim_genList(EvalState& state, const Pos& pos, Value** args,
 
   state.mkList(v, len);
 
-  for (unsigned int n = 0; n < static_cast<unsigned int>(len); ++n) {
+  for (unsigned int n = 0; n < (unsigned int)len; ++n) {
     Value* arg = state.allocValue();
     mkInt(*arg, n);
     mkApp(*((*v.list)[n] = state.allocValue()), *args[0], *arg);
@@ -1614,8 +1614,8 @@ static void prim_sort(EvalState& state, const Pos& pos, Value** args,
       return CompareValues()(a, b);
     }
 
-    Value vTmp1{};
-    Value vTmp2{};
+    Value vTmp1;
+    Value vTmp2;
     state.callFunction(*args[0], *a, vTmp1, pos);
     state.callFunction(vTmp1, *b, vTmp2, pos);
     return state.forceBool(vTmp2, pos);
@@ -1638,7 +1638,7 @@ static void prim_partition(EvalState& state, const Pos& pos, Value** args,
   for (Value* elem : *args[1]->list) {
     state.forceValue(*elem, pos);
 
-    Value res{};
+    Value res;
     state.callFunction(*args[0], *elem, res, pos);
     if (state.forceBool(res, pos)) {
       right->push_back(elem);
@@ -1789,10 +1789,7 @@ static void prim_substring(EvalState& state, const Pos& pos, Value** args,
                     pos);
   }
 
-  mkString(v,
-           static_cast<unsigned int>(start) >= s.size()
-               ? ""
-               : std::string(s, start, len),
+  mkString(v, (unsigned int)start >= s.size() ? "" : std::string(s, start, len),
            context);
 }
 
@@ -1877,7 +1874,7 @@ static void prim_split(EvalState& state, const Pos& pos, Value** args,
     const size_t len = std::distance(begin, end);
     state.mkList(v, 2 * len + 1);
     size_t idx = 0;
-    Value* elem = nullptr;
+    Value* elem;
 
     if (len == 0) {
       (*v.list)[idx++] = args[1];
@@ -2141,7 +2138,7 @@ void EvalState::createBaseEnv() {
   baseEnv.up = nullptr;
 
   /* Add global constants such as `true' to the base environment. */
-  Value v{};
+  Value v;
 
   /* `builtins' must be first! */
   mkAttrs(v, 128);
diff --git a/third_party/nix/src/libexpr/primops/context.cc b/third_party/nix/src/libexpr/primops/context.cc
index fb8879ead..841a45c61 100644
--- a/third_party/nix/src/libexpr/primops/context.cc
+++ b/third_party/nix/src/libexpr/primops/context.cc
@@ -97,13 +97,12 @@ static void prim_getContext(EvalState& state, const Pos& pos, Value** args,
           ContextInfo{isPath, isAllOutputs,
                       output.empty() ? Strings{} : Strings{std::move(output)}});
     } else {
-      if (isPath) {
+      if (isPath)
         iter->second.path = true;
-      } else if (isAllOutputs) {
+      else if (isAllOutputs)
         iter->second.allOutputs = true;
-      } else {
+      else
         iter->second.outputs.emplace_back(std::move(output));
-      }
     }
   }
 
@@ -117,9 +116,8 @@ static void prim_getContext(EvalState& state, const Pos& pos, Value** args,
     if (info.second.path) {
       mkBool(*state.allocAttr(infoVal, sPath), true);
     }
-    if (info.second.allOutputs) {
+    if (info.second.allOutputs)
       mkBool(*state.allocAttr(infoVal, sAllOutputs), true);
-    }
     if (!info.second.outputs.empty()) {
       auto& outputsVal = *state.allocAttr(infoVal, state.sOutputs);
       state.mkList(outputsVal, info.second.outputs.size());
@@ -149,10 +147,9 @@ static void prim_appendContext(EvalState& state, const Pos& pos, Value** args,
   auto sAllOutputs = state.symbols.Create("allOutputs");
   for (const auto& attr_iter : *args[1]->attrs) {
     const Attr* i = &attr_iter.second;  // TODO(tazjin): get rid of this
-    if (!state.store->isStorePath(i->name)) {
+    if (!state.store->isStorePath(i->name))
       throw EvalError("Context key '%s' is not a store path, at %s", i->name,
                       i->pos);
-    }
     if (!settings.readOnlyMode) {
       state.store->ensurePath(i->name);
     }
diff --git a/third_party/nix/src/libexpr/primops/fetchGit.cc b/third_party/nix/src/libexpr/primops/fetchGit.cc
index 839094b72..7262a2915 100644
--- a/third_party/nix/src/libexpr/primops/fetchGit.cc
+++ b/third_party/nix/src/libexpr/primops/fetchGit.cc
@@ -30,9 +30,8 @@ std::regex revRegex("^[0-9a-fA-F]{40}$");
 GitInfo exportGit(ref<Store> store, const std::string& uri,
                   std::optional<std::string> ref, std::string rev,
                   const std::string& name) {
-  if (evalSettings.pureEval && rev == "") {
+  if (evalSettings.pureEval && rev == "")
     throw Error("in pure evaluation mode, 'fetchGit' requires a Git revision");
-  }
 
   if (!ref && rev == "" && absl::StartsWith(uri, "/") &&
       pathExists(uri + "/.git")) {
@@ -91,9 +90,8 @@ GitInfo exportGit(ref<Store> store, const std::string& uri,
     ref = "HEAD"s;
   }
 
-  if (rev != "" && !std::regex_match(rev, revRegex)) {
+  if (rev != "" && !std::regex_match(rev, revRegex))
     throw Error("invalid Git revision '%s'", rev);
-  }
 
   deletePath(getCacheDir() + "/nix/git");
 
@@ -106,13 +104,12 @@ GitInfo exportGit(ref<Store> store, const std::string& uri,
   }
 
   Path localRefFile;
-  if (ref->compare(0, 5, "refs/") == 0) {
+  if (ref->compare(0, 5, "refs/") == 0)
     localRefFile = cacheDir + "/" + *ref;
-  } else {
+  else
     localRefFile = cacheDir + "/refs/heads/" + *ref;
-  }
 
-  bool doFetch = 0;
+  bool doFetch;
   time_t now = time(0);
   /* If a rev was specified, we need to fetch if it's not in the
      repo. */
@@ -130,10 +127,9 @@ GitInfo exportGit(ref<Store> store, const std::string& uri,
   } else {
     /* If the local ref is older than ‘tarball-ttl’ seconds, do a
        git fetch to update the local ref to the remote ref. */
-    struct stat st {};
+    struct stat st;
     doFetch = stat(localRefFile.c_str(), &st) != 0 ||
-              static_cast<uint64_t>(st.st_mtime) + settings.tarballTtl <=
-                  static_cast<uint64_t>(now);
+              (uint64_t)st.st_mtime + settings.tarballTtl <= (uint64_t)now;
   }
   if (doFetch) {
     DLOG(INFO) << "fetching Git repository '" << uri << "'";
@@ -229,24 +225,22 @@ static void prim_fetchGit(EvalState& state, const Pos& pos, Value** args,
     for (auto& attr_iter : *args[0]->attrs) {
       auto& attr = attr_iter.second;
       std::string n(attr.name);
-      if (n == "url") {
+      if (n == "url")
         url =
             state.coerceToString(*attr.pos, *attr.value, context, false, false);
-      } else if (n == "ref") {
+      else if (n == "ref")
         ref = state.forceStringNoCtx(*attr.value, *attr.pos);
-      } else if (n == "rev") {
+      else if (n == "rev")
         rev = state.forceStringNoCtx(*attr.value, *attr.pos);
-      } else if (n == "name") {
+      else if (n == "name")
         name = state.forceStringNoCtx(*attr.value, *attr.pos);
-      } else {
+      else
         throw EvalError("unsupported argument '%s' to 'fetchGit', at %s",
                         attr.name, *attr.pos);
-      }
     }
 
-    if (url.empty()) {
+    if (url.empty())
       throw EvalError(format("'url' argument required, at %1%") % pos);
-    }
 
   } else {
     url = state.coerceToString(pos, *args[0], context, false, false);
diff --git a/third_party/nix/src/libexpr/primops/fetchMercurial.cc b/third_party/nix/src/libexpr/primops/fetchMercurial.cc
index 05a3d66ae..3ece094e6 100644
--- a/third_party/nix/src/libexpr/primops/fetchMercurial.cc
+++ b/third_party/nix/src/libexpr/primops/fetchMercurial.cc
@@ -28,11 +28,10 @@ std::regex commitHashRegex("^[0-9a-fA-F]{40}$");
 
 HgInfo exportMercurial(ref<Store> store, const std::string& uri,
                        std::string rev, const std::string& name) {
-  if (evalSettings.pureEval && rev == "") {
+  if (evalSettings.pureEval && rev == "")
     throw Error(
         "in pure evaluation mode, 'fetchMercurial' requires a Mercurial "
         "revision");
-  }
 
   if (rev == "" && absl::StartsWith(uri, "/") && pathExists(uri + "/.hg")) {
     bool clean = runProgram("hg", true,
@@ -91,10 +90,9 @@ HgInfo exportMercurial(ref<Store> store, const std::string& uri,
   /* If we haven't pulled this repo less than ‘tarball-ttl’ seconds,
      do so now. */
   time_t now = time(0);
-  struct stat st {};
+  struct stat st;
   if (stat(stampFile.c_str(), &st) != 0 ||
-      static_cast<uint64_t>(st.st_mtime) + settings.tarballTtl <=
-          static_cast<uint64_t>(now)) {
+      (uint64_t)st.st_mtime + settings.tarballTtl <= (uint64_t)now) {
     /* Except that if this is a commit hash that we already have,
        we don't have to pull again. */
     if (!(std::regex_match(rev, commitHashRegex) && pathExists(cacheDir) &&
@@ -200,22 +198,20 @@ static void prim_fetchMercurial(EvalState& state, const Pos& pos, Value** args,
     for (auto& attr_iter : *args[0]->attrs) {
       auto& attr = attr_iter.second;
       std::string n(attr.name);
-      if (n == "url") {
+      if (n == "url")
         url =
             state.coerceToString(*attr.pos, *attr.value, context, false, false);
-      } else if (n == "rev") {
+      else if (n == "rev")
         rev = state.forceStringNoCtx(*attr.value, *attr.pos);
-      } else if (n == "name") {
+      else if (n == "name")
         name = state.forceStringNoCtx(*attr.value, *attr.pos);
-      } else {
+      else
         throw EvalError("unsupported argument '%s' to 'fetchMercurial', at %s",
                         attr.name, *attr.pos);
-      }
     }
 
-    if (url.empty()) {
+    if (url.empty())
       throw EvalError(format("'url' argument required, at %1%") % pos);
-    }
 
   } else {
     url = state.coerceToString(pos, *args[0], context, false, false);
diff --git a/third_party/nix/src/libexpr/primops/fromTOML.cc b/third_party/nix/src/libexpr/primops/fromTOML.cc
index e3d2a4940..389ac0806 100644
--- a/third_party/nix/src/libexpr/primops/fromTOML.cc
+++ b/third_party/nix/src/libexpr/primops/fromTOML.cc
@@ -30,12 +30,10 @@ static void prim_fromTOML(EvalState& state, const Pos& pos, Value** args,
         if (auto i2 = i.second->as_table_array()) {
           size_t size2 = i2->get().size();
           state.mkList(v2, size2);
-          for (size_t j = 0; j < size2; ++j) {
+          for (size_t j = 0; j < size2; ++j)
             visit(*((*v2.list)[j] = state.allocValue()), i2->get()[j]);
-          }
-        } else {
+        } else
           visit(v2, i.second);
-        }
       }
     }
 
@@ -44,9 +42,8 @@ static void prim_fromTOML(EvalState& state, const Pos& pos, Value** args,
 
       state.mkList(v, size);
 
-      for (size_t i = 0; i < size; ++i) {
+      for (size_t i = 0; i < size; ++i)
         visit(*((*v.list)[i] = state.allocValue()), t2->get()[i]);
-      }
     }
 
     // Handle cases like 'a = [[{ a = true }]]', which IMHO should be
@@ -58,28 +55,25 @@ static void prim_fromTOML(EvalState& state, const Pos& pos, Value** args,
 
       state.mkList(v, size);
 
-      for (size_t j = 0; j < size; ++j) {
+      for (size_t j = 0; j < size; ++j)
         visit(*((*v.list)[j] = state.allocValue()), t2->get()[j]);
-      }
     }
 
     else if (t->is_value()) {
-      if (auto val = t->as<int64_t>()) {
+      if (auto val = t->as<int64_t>())
         mkInt(v, val->get());
-      } else if (auto val = t->as<NixFloat>()) {
+      else if (auto val = t->as<NixFloat>())
         mkFloat(v, val->get());
-      } else if (auto val = t->as<bool>()) {
+      else if (auto val = t->as<bool>())
         mkBool(v, val->get());
-      } else if (auto val = t->as<std::string>()) {
+      else if (auto val = t->as<std::string>())
         mkString(v, val->get());
-      } else {
+      else
         throw EvalError("unsupported value type in TOML");
-      }
     }
 
-    else {
+    else
       abort();
-    }
   };
 
   try {
diff --git a/third_party/nix/src/libmain/shared.cc b/third_party/nix/src/libmain/shared.cc
index 8b1b96140..b04bd279b 100644
--- a/third_party/nix/src/libmain/shared.cc
+++ b/third_party/nix/src/libmain/shared.cc
@@ -37,8 +37,8 @@ void printGCWarning() {
 }
 
 void printMissing(const ref<Store>& store, const PathSet& paths) {
-  unsigned long long downloadSize = 0;
-  unsigned long long narSize = 0;
+  unsigned long long downloadSize;
+  unsigned long long narSize;
   PathSet willBuild;
   PathSet willSubstitute;
   PathSet unknown;
@@ -128,7 +128,7 @@ void initNix() {
   startSignalHandlerThread();
 
   /* Reset SIGCHLD to its default. */
-  struct sigaction act {};
+  struct sigaction act;
   sigemptyset(&act.sa_mask);
   act.sa_handler = SIG_DFL;
   act.sa_flags = 0;
@@ -151,7 +151,7 @@ void initNix() {
   umask(0022);
 
   /* Initialise the PRNG. */
-  struct timeval tv {};
+  struct timeval tv;
   gettimeofday(&tv, nullptr);
   srandom(tv.tv_usec);
 }
@@ -327,7 +327,7 @@ RunPager::RunPager() {
   if (pager == nullptr) {
     pager = getenv("PAGER");
   }
-  if (pager && (std::string(pager) == "" || std::string(pager) == "cat")) {
+  if (pager && ((std::string)pager == "" || (std::string)pager == "cat")) {
     return;
   }
 
diff --git a/third_party/nix/src/libmain/stack.cc b/third_party/nix/src/libmain/stack.cc
index c60a53968..c7744f69c 100644
--- a/third_party/nix/src/libmain/stack.cc
+++ b/third_party/nix/src/libmain/stack.cc
@@ -9,14 +9,14 @@
 
 namespace nix {
 
-static void sigsegvHandler(int _signo, siginfo_t* info, void* ctx) {
+static void sigsegvHandler(int signo, siginfo_t* info, void* ctx) {
   /* Detect stack overflows by comparing the faulting address with
      the stack pointer.  Unfortunately, getting the stack pointer is
      not portable. */
   bool haveSP = true;
   char* sp = nullptr;
 #if defined(__x86_64__) && defined(REG_RSP)
-  sp = (char*)(static_cast<ucontext_t*>(ctx))->uc_mcontext.gregs[REG_RSP];
+  sp = (char*)((ucontext_t*)ctx)->uc_mcontext.gregs[REG_RSP];
 #elif defined(REG_ESP)
   sp = (char*)((ucontext_t*)ctx)->uc_mcontext.gregs[REG_ESP];
 #else
@@ -24,7 +24,7 @@ static void sigsegvHandler(int _signo, siginfo_t* info, void* ctx) {
 #endif
 
   if (haveSP) {
-    ptrdiff_t diff = static_cast<char*>(info->si_addr) - sp;
+    ptrdiff_t diff = (char*)info->si_addr - sp;
     if (diff < 0) {
       diff = -diff;
     }
@@ -36,7 +36,7 @@ static void sigsegvHandler(int _signo, siginfo_t* info, void* ctx) {
   }
 
   /* Restore default behaviour (i.e. segfault and dump core). */
-  struct sigaction act {};
+  struct sigaction act;
   sigfillset(&act.sa_mask);
   act.sa_handler = SIG_DFL;
   act.sa_flags = 0;
@@ -62,7 +62,7 @@ void detectStackOverflow() {
     throw SysError("cannot set alternative stack");
   }
 
-  struct sigaction act {};
+  struct sigaction act;
   sigfillset(&act.sa_mask);
   act.sa_sigaction = sigsegvHandler;
   act.sa_flags = SA_SIGINFO | SA_ONSTACK;
diff --git a/third_party/nix/src/libstore/binary-cache-store.cc b/third_party/nix/src/libstore/binary-cache-store.cc
index 677500a01..b862ea005 100644
--- a/third_party/nix/src/libstore/binary-cache-store.cc
+++ b/third_party/nix/src/libstore/binary-cache-store.cc
@@ -87,7 +87,7 @@ void BinaryCacheStore::getFile(const std::string& path, Sink& sink) {
             }
           }});
   auto data = promise.get_future().get();
-  sink(reinterpret_cast<unsigned char*>(data->data()), data->size());
+  sink((unsigned char*)data->data(), data->size());
 }
 
 std::shared_ptr<std::string> BinaryCacheStore::getFile(
@@ -205,9 +205,7 @@ void BinaryCacheStore::addToStore(const ValidPathInfo& info,
           .count();
   DLOG(INFO) << "copying path '" << narInfo->path << "' (" << narInfo->narSize
              << " bytes, compressed "
-             << ((1.0 -
-                  static_cast<double>(narCompressed->size()) / nar->size()) *
-                 100.0)
+             << ((1.0 - (double)narCompressed->size() / nar->size()) * 100.0)
              << "% in " << duration << "ms) to binary cache";
 
   /* Atomically write the NAR file. */
@@ -289,8 +287,9 @@ void BinaryCacheStore::queryPathInfoUncached(
 
               stats.narInfoRead++;
 
-              (*callbackPtr)(std::shared_ptr<ValidPathInfo>(
-                  std::make_shared<NarInfo>(*this, *data, narInfoFile)));
+              (*callbackPtr)(
+                  (std::shared_ptr<ValidPathInfo>)std::make_shared<NarInfo>(
+                      *this, *data, narInfoFile));
 
             } catch (...) {
               callbackPtr->rethrow();
@@ -354,9 +353,7 @@ void BinaryCacheStore::addSignatures(const Path& storePath,
      when addSignatures() is called sequentially on a path, because
      S3 might return an outdated cached version. */
 
-  // TODO(kanepyork): what is going on here
-  auto narInfo = make_ref<NarInfo>(const_cast<NarInfo&>(
-      dynamic_cast<const NarInfo&>(*queryPathInfo(storePath))));
+  auto narInfo = make_ref<NarInfo>((NarInfo&)*queryPathInfo(storePath));
 
   narInfo->sigs.insert(sigs.begin(), sigs.end());
 
diff --git a/third_party/nix/src/libstore/build.cc b/third_party/nix/src/libstore/build.cc
index 13a8b21dd..74db67e86 100644
--- a/third_party/nix/src/libstore/build.cc
+++ b/third_party/nix/src/libstore/build.cc
@@ -185,10 +185,10 @@ using steady_time_point = std::chrono::time_point<std::chrono::steady_clock>;
    path creation commands. */
 struct Child {
   WeakGoalPtr goal;
-  Goal* goal2{};  // ugly hackery
+  Goal* goal2;  // ugly hackery
   std::set<int> fds;
-  bool respectTimeouts = false;
-  bool inBuildSlot = false;
+  bool respectTimeouts;
+  bool inBuildSlot;
   steady_time_point lastOutput; /* time we last got output on stdout/stderr */
   steady_time_point timeStarted;
 };
@@ -732,7 +732,7 @@ class SubstitutionGoal;
 class DerivationGoal : public Goal {
  private:
   /* Whether to use an on-disk .drv file. */
-  bool useDerivation = false;
+  bool useDerivation;
 
   /* The path of the derivation. */
   Path drvPath;
@@ -746,7 +746,7 @@ class DerivationGoal : public Goal {
 
   /* Whether to retry substituting the outputs after building the
      inputs. */
-  bool retrySubstitution = false;
+  bool retrySubstitution;
 
   /* The derivation stored at drvPath. */
   std::unique_ptr<BasicDerivation> drv;
@@ -789,7 +789,7 @@ class DerivationGoal : public Goal {
   std::shared_ptr<BufferedSink> logFileSink, logSink;
 
   /* Number of bytes received from the builder's stdout/stderr. */
-  unsigned long logSize = 0;
+  unsigned long logSize;
 
   /* The most recent log lines. */
   std::list<std::string> logTail;
@@ -817,7 +817,7 @@ class DerivationGoal : public Goal {
   std::shared_ptr<AutoDelete> autoDelChroot;
 
   /* Whether this is a fixed-output derivation. */
-  bool fixedOutput = false;
+  bool fixedOutput;
 
   /* Whether to run the build in a private network namespace. */
   bool privateNetwork = false;
@@ -856,7 +856,7 @@ class DerivationGoal : public Goal {
   /* The current round, if we're building multiple times. */
   size_t curRound = 1;
 
-  size_t nrRounds = 0;
+  size_t nrRounds;
 
   /* Path registration info from the previous round, if we're
      building multiple times. Since this contains the hash, it
@@ -1585,15 +1585,13 @@ MakeError(NotDeterministic, BuildError)
 #if HAVE_STATVFS
       unsigned long long required =
           8ULL * 1024 * 1024;  // FIXME: make configurable
-      struct statvfs st {};
+      struct statvfs st;
       if (statvfs(worker.store.realStoreDir.c_str(), &st) == 0 &&
-          static_cast<unsigned long long>(st.f_bavail) * st.f_bsize <
-              required) {
+          (unsigned long long)st.f_bavail * st.f_bsize < required) {
         diskFull = true;
       }
       if (statvfs(tmpDir.c_str(), &st) == 0 &&
-          static_cast<unsigned long long>(st.f_bavail) * st.f_bsize <
-              required) {
+          (unsigned long long)st.f_bavail * st.f_bsize < required) {
         diskFull = true;
       }
 #endif
@@ -1832,7 +1830,7 @@ void chmod_(const Path& path, mode_t mode) {
 }
 
 int childEntry(void* arg) {
-  (static_cast<DerivationGoal*>(arg))->runChild();
+  ((DerivationGoal*)arg)->runChild();
   return 1;
 }
 
@@ -2137,7 +2135,7 @@ void DerivationGoal::startBuilder() {
 
     for (auto& i : inputPaths) {
       Path r = worker.store.toRealPath(i);
-      struct stat st {};
+      struct stat st;
       if (lstat(r.c_str(), &st) != 0) {
         throw SysError(format("getting attributes of path '%1%'") % i);
       }
@@ -2286,7 +2284,7 @@ void DerivationGoal::startBuilder() {
   }
 
   // Put the pt into raw mode to prevent \n -> \r\n translation.
-  struct termios term {};
+  struct termios term;
   if (tcgetattr(builderOut.writeSide.get(), &term) != 0) {
     throw SysError("getting pseudoterminal attributes");
   }
@@ -2359,9 +2357,9 @@ void DerivationGoal::startBuilder() {
           }
 
           size_t stackSize = 1 * 1024 * 1024;
-          char* stack = static_cast<char*>(
-              mmap(nullptr, stackSize, PROT_WRITE | PROT_READ,
-                   MAP_PRIVATE | MAP_ANONYMOUS | MAP_STACK, -1, 0));
+          char* stack =
+              (char*)mmap(nullptr, stackSize, PROT_WRITE | PROT_READ,
+                          MAP_PRIVATE | MAP_ANONYMOUS | MAP_STACK, -1, 0);
           if (stack == MAP_FAILED) {
             throw SysError("allocating stack");
           }
@@ -2414,7 +2412,7 @@ void DerivationGoal::startBuilder() {
 
     userNamespaceSync.readSide = -1;
 
-    pid_t tmp = 0;
+    pid_t tmp;
     if (!absl::SimpleAtoi(readLine(builderOut.readSide.get()), &tmp)) {
       abort();
     }
@@ -2711,7 +2709,7 @@ void setupSeccomp() {
     return;
   }
 #if HAVE_SECCOMP
-  scmp_filter_ctx ctx = nullptr;
+  scmp_filter_ctx ctx;
 
   if ((ctx = seccomp_init(SCMP_ACT_ALLOW)) == nullptr) {
     throw SysError("unable to initialize seccomp mode 2");
@@ -2831,7 +2829,7 @@ void DerivationGoal::runChild() {
           throw SysError("cannot open IP socket");
         }
 
-        struct ifreq ifr {};
+        struct ifreq ifr;
         strncpy(ifr.ifr_name, "lo", sizeof("lo"));
         ifr.ifr_flags = IFF_UP | IFF_LOOPBACK | IFF_RUNNING;
         if (ioctl(fd.get(), SIOCSIFFLAGS, &ifr) == -1) {
@@ -2920,7 +2918,7 @@ void DerivationGoal::runChild() {
       auto doBind = [&](const Path& source, const Path& target,
                         bool optional = false) {
         DLOG(INFO) << "bind mounting '" << source << "' to '" << target << "'";
-        struct stat st {};
+        struct stat st;
         if (stat(source.c_str(), &st) == -1) {
           if (optional && errno == ENOENT) {
             return;
@@ -3037,7 +3035,7 @@ void DerivationGoal::runChild() {
 #if __linux__
     /* Change the personality to 32-bit if we're doing an
        i686-linux build on an x86_64-linux machine. */
-    struct utsname utsbuf {};
+    struct utsname utsbuf;
     uname(&utsbuf);
     if (drv->platform == "i686-linux" &&
         (settings.thisSystem == "x86_64-linux" ||
@@ -3249,7 +3247,7 @@ void DerivationGoal::registerOutputs() {
       }
     }
 
-    struct stat st {};
+    struct stat st;
     if (lstat(actualPath.c_str(), &st) == -1) {
       if (errno == ENOENT) {
         throw BuildError(
@@ -3298,7 +3296,7 @@ void DerivationGoal::registerOutputs() {
        outputs (i.e., the content hash should match the specified
        hash). */
     if (fixedOutput) {
-      bool recursive = 0;
+      bool recursive;
       Hash h;
       i.second.parseHashInfo(recursive, h);
 
@@ -4453,7 +4451,7 @@ void Worker::waitForInput() {
      terminated. */
 
   bool useTimeout = false;
-  struct timeval timeout {};
+  struct timeval timeout;
   timeout.tv_usec = 0;
   auto before = steady_time_point::clock::now();
 
@@ -4480,9 +4478,9 @@ void Worker::waitForInput() {
   }
   if (nearest != steady_time_point::max()) {
     timeout.tv_sec = std::max(
-        1L, static_cast<long>(std::chrono::duration_cast<std::chrono::seconds>(
-                                  nearest - before)
-                                  .count()));
+        1L,
+        (long)std::chrono::duration_cast<std::chrono::seconds>(nearest - before)
+            .count());
     useTimeout = true;
   }
 
@@ -4497,11 +4495,10 @@ void Worker::waitForInput() {
       lastWokenUp = before;
     }
     timeout.tv_sec = std::max(
-        1L, static_cast<long>(std::chrono::duration_cast<std::chrono::seconds>(
-                                  lastWokenUp +
-                                  std::chrono::seconds(settings.pollInterval) -
-                                  before)
-                                  .count()));
+        1L,
+        (long)std::chrono::duration_cast<std::chrono::seconds>(
+            lastWokenUp + std::chrono::seconds(settings.pollInterval) - before)
+            .count());
   } else {
     lastWokenUp = steady_time_point::min();
   }
@@ -4566,7 +4563,7 @@ void Worker::waitForInput() {
           }
         } else {
           DLOG(INFO) << goal->getName() << ": read " << rd << " bytes";
-          std::string data(reinterpret_cast<char*>(buffer.data()), rd);
+          std::string data((char*)buffer.data(), rd);
           j->lastOutput = after;
           goal->handleChildOutput(k, data);
         }
@@ -4641,7 +4638,7 @@ bool Worker::pathContentsGood(const Path& path) {
   }
   LOG(INFO) << "checking path '" << path << "'...";
   auto info = store.queryPathInfo(path);
-  bool res = 0;
+  bool res;
   if (!pathExists(path)) {
     res = false;
   } else {
@@ -4666,8 +4663,8 @@ static void primeCache(Store& store, const PathSet& paths) {
   PathSet willBuild;
   PathSet willSubstitute;
   PathSet unknown;
-  unsigned long long downloadSize = 0;
-  unsigned long long narSize = 0;
+  unsigned long long downloadSize;
+  unsigned long long narSize;
   store.queryMissing(paths, willBuild, willSubstitute, unknown, downloadSize,
                      narSize);
 
diff --git a/third_party/nix/src/libstore/builtins/buildenv.cc b/third_party/nix/src/libstore/builtins/buildenv.cc
index 9413c4b03..95f915227 100644
--- a/third_party/nix/src/libstore/builtins/buildenv.cc
+++ b/third_party/nix/src/libstore/builtins/buildenv.cc
@@ -35,17 +35,15 @@ static void createLinks(const Path& srcDir, const Path& dstDir, int priority) {
   }
 
   for (const auto& ent : srcFiles) {
-    if (ent.name[0] == '.') { /* not matched by glob */
+    if (ent.name[0] == '.') /* not matched by glob */
       continue;
-    }
     auto srcFile = srcDir + "/" + ent.name;
     auto dstFile = dstDir + "/" + ent.name;
 
-    struct stat srcSt {};
+    struct stat srcSt;
     try {
-      if (stat(srcFile.c_str(), &srcSt) == -1) {
+      if (stat(srcFile.c_str(), &srcSt) == -1)
         throw SysError("getting status of '%1%'", srcFile);
-      }
     } catch (SysError& e) {
       if (e.errNo == ENOENT || e.errNo == ENOTDIR) {
         LOG(ERROR) << "warning: skipping dangling symlink '" << dstFile << "'";
@@ -63,12 +61,11 @@ static void createLinks(const Path& srcDir, const Path& dstDir, int priority) {
     if (absl::EndsWith(srcFile, "/propagated-build-inputs") ||
         absl::EndsWith(srcFile, "/nix-support") ||
         absl::EndsWith(srcFile, "/perllocal.pod") ||
-        absl::EndsWith(srcFile, "/info/dir") ||
-        absl::EndsWith(srcFile, "/log")) {
+        absl::EndsWith(srcFile, "/info/dir") || absl::EndsWith(srcFile, "/log"))
       continue;
 
-    } else if (S_ISDIR(srcSt.st_mode)) {
-      struct stat dstSt {};
+    else if (S_ISDIR(srcSt.st_mode)) {
+      struct stat dstSt;
       auto res = lstat(dstFile.c_str(), &dstSt);
       if (res == 0) {
         if (S_ISDIR(dstSt.st_mode)) {
@@ -76,53 +73,45 @@ static void createLinks(const Path& srcDir, const Path& dstDir, int priority) {
           continue;
         } else if (S_ISLNK(dstSt.st_mode)) {
           auto target = canonPath(dstFile, true);
-          if (!S_ISDIR(lstat(target).st_mode)) {
+          if (!S_ISDIR(lstat(target).st_mode))
             throw Error("collision between '%1%' and non-directory '%2%'",
                         srcFile, target);
-          }
-          if (unlink(dstFile.c_str()) == -1) {
+          if (unlink(dstFile.c_str()) == -1)
             throw SysError(format("unlinking '%1%'") % dstFile);
-          }
-          if (mkdir(dstFile.c_str(), 0755) == -1) {
+          if (mkdir(dstFile.c_str(), 0755) == -1)
             throw SysError(format("creating directory '%1%'"));
-          }
           createLinks(target, dstFile, priorities[dstFile]);
           createLinks(srcFile, dstFile, priority);
           continue;
         }
-      } else if (errno != ENOENT) {
+      } else if (errno != ENOENT)
         throw SysError(format("getting status of '%1%'") % dstFile);
-      }
     }
 
     else {
-      struct stat dstSt {};
+      struct stat dstSt;
       auto res = lstat(dstFile.c_str(), &dstSt);
       if (res == 0) {
         if (S_ISLNK(dstSt.st_mode)) {
           auto prevPriority = priorities[dstFile];
-          if (prevPriority == priority) {
+          if (prevPriority == priority)
             throw Error(
                 "packages '%1%' and '%2%' have the same priority %3%; "
                 "use 'nix-env --set-flag priority NUMBER INSTALLED_PKGNAME' "
                 "to change the priority of one of the conflicting packages"
                 " (0 being the highest priority)",
                 srcFile, readLink(dstFile), priority);
-          }
           if (prevPriority < priority) {
             continue;
           }
-          if (unlink(dstFile.c_str()) == -1) {
+          if (unlink(dstFile.c_str()) == -1)
             throw SysError(format("unlinking '%1%'") % dstFile);
-          }
-        } else if (S_ISDIR(dstSt.st_mode)) {
+        } else if (S_ISDIR(dstSt.st_mode))
           throw Error(
               "collision between non-directory '%1%' and directory '%2%'",
               srcFile, dstFile);
-        }
-      } else if (errno != ENOENT) {
+      } else if (errno != ENOENT)
         throw SysError(format("getting status of '%1%'") % dstFile);
-      }
     }
 
     createSymlink(srcFile, dstFile);
@@ -212,11 +201,10 @@ void builtinBuildenv(const BasicDerivation& drv) {
     return a.priority < b.priority ||
            (a.priority == b.priority && a.path < b.path);
   });
-  for (const auto& pkg : pkgs) {
+  for (const auto& pkg : pkgs)
     if (pkg.active) {
       addPkg(pkg.path, pkg.priority);
     }
-  }
 
   /* Symlink to the packages that have been "propagated" by packages
    * installed by the user (i.e., package X declares that it wants Y
diff --git a/third_party/nix/src/libstore/builtins/fetchurl.cc b/third_party/nix/src/libstore/builtins/fetchurl.cc
index 961d08142..b9c6ffc3f 100644
--- a/third_party/nix/src/libstore/builtins/fetchurl.cc
+++ b/third_party/nix/src/libstore/builtins/fetchurl.cc
@@ -20,9 +20,8 @@ void builtinFetchurl(const BasicDerivation& drv, const std::string& netrcData) {
 
   auto getAttr = [&](const std::string& name) {
     auto i = drv.env.find(name);
-    if (i == drv.env.end()) {
+    if (i == drv.env.end())
       throw Error(format("attribute '%s' missing") % name);
-    }
     return i->second;
   };
 
@@ -48,17 +47,15 @@ void builtinFetchurl(const BasicDerivation& drv, const std::string& netrcData) {
       decompressor->finish();
     });
 
-    if (unpack) {
+    if (unpack)
       restorePath(storePath, *source);
-    } else {
+    else
       writeFile(storePath, *source);
-    }
 
     auto executable = drv.env.find("executable");
     if (executable != drv.env.end() && executable->second == "1") {
-      if (chmod(storePath.c_str(), 0755) == -1) {
+      if (chmod(storePath.c_str(), 0755) == -1)
         throw SysError(format("making '%1%' executable") % storePath);
-      }
     }
   };
 
diff --git a/third_party/nix/src/libstore/crypto.cc b/third_party/nix/src/libstore/crypto.cc
index 2a03f825a..bec0b08c6 100644
--- a/third_party/nix/src/libstore/crypto.cc
+++ b/third_party/nix/src/libstore/crypto.cc
@@ -54,11 +54,10 @@ SecretKey::SecretKey(const std::string& s) : Key(s) {
 std::string SecretKey::signDetached(const std::string& data) const {
 #if HAVE_SODIUM
   unsigned char sig[crypto_sign_BYTES];
-  unsigned long long sigLen = 0;
+  unsigned long long sigLen;
   crypto_sign_detached(sig, &sigLen, (unsigned char*)data.data(), data.size(),
                        (unsigned char*)key.data());
-  return name + ":" +
-         absl::Base64Escape(std::string(reinterpret_cast<char*>(sig), sigLen));
+  return name + ":" + absl::Base64Escape(std::string((char*)sig, sigLen));
 #else
   noSodium();
 #endif
@@ -68,8 +67,7 @@ PublicKey SecretKey::toPublicKey() const {
 #if HAVE_SODIUM
   unsigned char pk[crypto_sign_PUBLICKEYBYTES];
   crypto_sign_ed25519_sk_to_pk(pk, (unsigned char*)key.data());
-  return PublicKey(name, std::string(reinterpret_cast<char*>(pk),
-                                     crypto_sign_PUBLICKEYBYTES));
+  return PublicKey(name, std::string((char*)pk, crypto_sign_PUBLICKEYBYTES));
 #else
   noSodium();
 #endif
@@ -103,9 +101,8 @@ bool verifyDetached(const std::string& data, const std::string& sig,
   }
 
   return crypto_sign_verify_detached(
-             reinterpret_cast<unsigned char*>(sig2.data()),
-             (unsigned char*)data.data(), data.size(),
-             (unsigned char*)key->second.key.data()) == 0;
+             (unsigned char*)sig2.data(), (unsigned char*)data.data(),
+             data.size(), (unsigned char*)key->second.key.data()) == 0;
 #else
   noSodium();
 #endif
diff --git a/third_party/nix/src/libstore/derivations.cc b/third_party/nix/src/libstore/derivations.cc
index 243aa0a24..29f929270 100644
--- a/third_party/nix/src/libstore/derivations.cc
+++ b/third_party/nix/src/libstore/derivations.cc
@@ -96,7 +96,7 @@ static void expect(std::istream& str, const std::string& s) {
 static std::string parseString(std::istream& str) {
   std::string res;
   expect(str, "\"");
-  int c = 0;
+  int c;
   while ((c = str.get()) != '"') {
     if (c == '\\') {
       c = str.get();
@@ -107,10 +107,10 @@ static std::string parseString(std::istream& str) {
       } else if (c == 't') {
         res += '\t';
       } else {
-        res += std::to_string(c);
+        res += c;
       }
     } else {
-      res += std::to_string(c);
+      res += c;
     }
   }
   return res;
diff --git a/third_party/nix/src/libstore/download.cc b/third_party/nix/src/libstore/download.cc
index dfa72e3eb..e73181e73 100644
--- a/third_party/nix/src/libstore/download.cc
+++ b/third_party/nix/src/libstore/download.cc
@@ -160,7 +160,7 @@ struct CurlDownloader : public Downloader {
           decompressionSink = makeDecompressionSink(encoding, finalSink);
         }
 
-        (*decompressionSink)(static_cast<unsigned char*>(contents), realSize);
+        (*decompressionSink)((unsigned char*)contents, realSize);
 
         return realSize;
       } catch (...) {
@@ -171,13 +171,12 @@ struct CurlDownloader : public Downloader {
 
     static size_t writeCallbackWrapper(void* contents, size_t size,
                                        size_t nmemb, void* userp) {
-      return (static_cast<DownloadItem*>(userp))
-          ->writeCallback(contents, size, nmemb);
+      return ((DownloadItem*)userp)->writeCallback(contents, size, nmemb);
     }
 
     size_t headerCallback(void* contents, size_t size, size_t nmemb) {
       size_t realSize = size * nmemb;
-      std::string line(static_cast<char*>(contents), realSize);
+      std::string line((char*)contents, realSize);
       DLOG(INFO) << "got header for '" << request.uri
                  << "': " << absl::StripAsciiWhitespace(line);
       if (line.compare(0, 5, "HTTP/") == 0) {  // new response starts
@@ -219,8 +218,7 @@ struct CurlDownloader : public Downloader {
 
     static size_t headerCallbackWrapper(void* contents, size_t size,
                                         size_t nmemb, void* userp) {
-      return (static_cast<DownloadItem*>(userp))
-          ->headerCallback(contents, size, nmemb);
+      return ((DownloadItem*)userp)->headerCallback(contents, size, nmemb);
     }
 
     static int debugCallback(CURL* handle, curl_infotype type, char* data,
@@ -247,8 +245,7 @@ struct CurlDownloader : public Downloader {
 
     static size_t readCallbackWrapper(char* buffer, size_t size, size_t nitems,
                                       void* userp) {
-      return (static_cast<DownloadItem*>(userp))
-          ->readCallback(buffer, size, nitems);
+      return ((DownloadItem*)userp)->readCallback(buffer, size, nitems);
     }
 
     void init() {
@@ -340,7 +337,7 @@ struct CurlDownloader : public Downloader {
       long httpStatus = 0;
       curl_easy_getinfo(req, CURLINFO_RESPONSE_CODE, &httpStatus);
 
-      char* effectiveUriCStr = nullptr;
+      char* effectiveUriCStr;
       curl_easy_getinfo(req, CURLINFO_EFFECTIVE_URL, &effectiveUriCStr);
       if (effectiveUriCStr != nullptr) {
         result.effectiveUri = effectiveUriCStr;
@@ -549,7 +546,7 @@ struct CurlDownloader : public Downloader {
       checkInterrupt();
 
       /* Let curl do its thing. */
-      int running = 0;
+      int running;
       CURLMcode mc = curl_multi_perform(curlm, &running);
       if (mc != CURLM_OK) {
         throw nix::Error(
@@ -558,8 +555,8 @@ struct CurlDownloader : public Downloader {
       }
 
       /* Set the promises of any finished requests. */
-      CURLMsg* msg = nullptr;
-      int left = 0;
+      CURLMsg* msg;
+      int left;
       while ((msg = curl_multi_info_read(curlm, &left)) != nullptr) {
         if (msg->msg == CURLMSG_DONE) {
           auto i = items.find(msg->easy_handle);
@@ -582,10 +579,9 @@ struct CurlDownloader : public Downloader {
           nextWakeup != std::chrono::steady_clock::time_point()
               ? std::max(
                     0,
-                    static_cast<int>(
-                        std::chrono::duration_cast<std::chrono::milliseconds>(
-                            nextWakeup - std::chrono::steady_clock::now())
-                            .count()))
+                    (int)std::chrono::duration_cast<std::chrono::milliseconds>(
+                        nextWakeup - std::chrono::steady_clock::now())
+                        .count())
               : maxSleepTimeMs;
       DLOG(INFO) << "download thread waiting for " << sleepTimeMs << " ms";
       mc = curl_multi_wait(curlm, extraFDs, 1, sleepTimeMs, &numfds);
@@ -848,7 +844,7 @@ void Downloader::download(DownloadRequest&& request, Sink& sink) {
        if it's blocked on a full buffer. We don't hold the state
        lock while doing this to prevent blocking the download
        thread if sink() takes a long time. */
-    sink(reinterpret_cast<unsigned char*>(chunk.data()), chunk.size());
+    sink((unsigned char*)chunk.data(), chunk.size());
   }
 }
 
@@ -902,10 +898,9 @@ CachedDownloadResult Downloader::downloadCached(
       std::vector<std::string> ss =
           absl::StrSplit(readFile(dataFile), absl::ByChar('\n'));
       if (ss.size() >= 3 && ss[0] == url) {
-        time_t lastChecked = 0;
+        time_t lastChecked;
         if (absl::SimpleAtoi(ss[2], &lastChecked) &&
-            static_cast<uint64_t>(lastChecked) + request.ttl >=
-                static_cast<uint64_t>(time(nullptr))) {
+            (uint64_t)lastChecked + request.ttl >= (uint64_t)time(nullptr)) {
           skip = true;
           result.effectiveUri = request.uri;
           result.etag = ss[1];
diff --git a/third_party/nix/src/libstore/gc.cc b/third_party/nix/src/libstore/gc.cc
index 85f7f1dba..9a6d97eb7 100644
--- a/third_party/nix/src/libstore/gc.cc
+++ b/third_party/nix/src/libstore/gc.cc
@@ -167,7 +167,7 @@ void LocalStore::addTempRoot(const Path& path) {
 
       /* Check whether the garbage collector didn't get in our
          way. */
-      struct stat st {};
+      struct stat st;
       if (fstat(state->fdTempRoots.get(), &st) == -1) {
         throw SysError(format("statting '%1%'") % fnTempRoots);
       }
@@ -239,10 +239,9 @@ void LocalStore::findTempRoots(FDs& fds, Roots& tempRoots, bool censor) {
 
     /* Extract the roots. */
     std::string::size_type pos = 0;
-    std::string::size_type end = 0;
+    std::string::size_type end;
 
-    while ((end = contents.find(static_cast<char>(0), pos)) !=
-           std::string::npos) {
+    while ((end = contents.find((char)0, pos)) != std::string::npos) {
       Path root(contents, pos, end - pos);
       DLOG(INFO) << "got temporary root " << root;
       assertStorePath(root);
@@ -388,7 +387,7 @@ void LocalStore::findRuntimeRoots(Roots& roots, bool censor) {
 
   auto procDir = AutoCloseDir{opendir("/proc")};
   if (procDir) {
-    struct dirent* ent = nullptr;
+    struct dirent* ent;
     auto digitsRegex = std::regex(R"(^\d+$)");
     auto mapRegex =
         std::regex(R"(^\s*\S+\s+\S+\s+\S+\s+\S+\s+\S+\s+(/\S+)\s*$)");
@@ -408,7 +407,7 @@ void LocalStore::findRuntimeRoots(Roots& roots, bool censor) {
           }
           throw SysError(format("opening %1%") % fdStr);
         }
-        struct dirent* fd_ent = nullptr;
+        struct dirent* fd_ent;
         while (errno = 0, fd_ent = readdir(fdDir.get())) {
           if (fd_ent->d_name[0] != '.') {
             readProcLink(fmt("%s/%s", fdStr, fd_ent->d_name), unchecked);
@@ -482,11 +481,11 @@ struct LocalStore::GCState {
   PathSet tempRoots;
   PathSet dead;
   PathSet alive;
-  bool gcKeepOutputs{};
-  bool gcKeepDerivations{};
+  bool gcKeepOutputs;
+  bool gcKeepDerivations;
   unsigned long long bytesInvalidated;
   bool moveToTrash = true;
-  bool shouldDelete{};
+  bool shouldDelete;
   explicit GCState(GCResults& results_)
       : results(results_), bytesInvalidated(0) {}
 };
@@ -499,7 +498,7 @@ bool LocalStore::isActiveTempFile(const GCState& state, const Path& path,
 }
 
 void LocalStore::deleteGarbage(GCState& state, const Path& path) {
-  unsigned long long bytesFreed = 0;
+  unsigned long long bytesFreed;
   deletePath(path, bytesFreed);
   state.results.bytesFreed += bytesFreed;
 }
@@ -523,7 +522,7 @@ void LocalStore::deletePathRecursive(GCState& state, const Path& path) {
 
   Path realPath = realStoreDir + "/" + baseNameOf(path);
 
-  struct stat st {};
+  struct stat st;
   if (lstat(realPath.c_str(), &st) != 0) {
     if (errno == ENOENT) {
       return;
@@ -698,7 +697,7 @@ void LocalStore::removeUnusedLinks(const GCState& state) {
   long long actualSize = 0;
   long long unsharedSize = 0;
 
-  struct dirent* dirent = nullptr;
+  struct dirent* dirent;
   while (errno = 0, dirent = readdir(dir.get())) {
     checkInterrupt();
     std::string name = dirent->d_name;
@@ -707,7 +706,7 @@ void LocalStore::removeUnusedLinks(const GCState& state) {
     }
     Path path = linksDir + "/" + name;
 
-    struct stat st {};
+    struct stat st;
     if (lstat(path.c_str(), &st) == -1) {
       throw SysError(format("statting '%1%'") % path);
     }
@@ -727,7 +726,7 @@ void LocalStore::removeUnusedLinks(const GCState& state) {
     state.results.bytesFreed += st.st_size;
   }
 
-  struct stat st {};
+  struct stat st;
   if (stat(linksDir.c_str(), &st) == -1) {
     throw SysError(format("statting '%1%'") % linksDir);
   }
@@ -841,7 +840,7 @@ void LocalStore::collectGarbage(const GCOptions& options, GCResults& results) {
          again.  We don't use readDirectory() here so that GCing
          can start faster. */
       Paths entries;
-      struct dirent* dirent = nullptr;
+      struct dirent* dirent;
       while (errno = 0, dirent = readdir(dir.get())) {
         checkInterrupt();
         std::string name = dirent->d_name;
@@ -912,12 +911,12 @@ void LocalStore::autoGC(bool sync) {
       return std::stoll(readFile(fakeFreeSpaceFile));
     }
 
-    struct statvfs st {};
+    struct statvfs st;
     if (statvfs(realStoreDir.c_str(), &st) != 0) {
       throw SysError("getting filesystem info about '%s'", realStoreDir);
     }
 
-    return static_cast<uint64_t>(st.f_bavail) * st.f_bsize;
+    return (uint64_t)st.f_bavail * st.f_bsize;
   };
 
   std::shared_future<void> future;
diff --git a/third_party/nix/src/libstore/legacy-ssh-store.cc b/third_party/nix/src/libstore/legacy-ssh-store.cc
index 8ae40d0da..02231aabc 100644
--- a/third_party/nix/src/libstore/legacy-ssh-store.cc
+++ b/third_party/nix/src/libstore/legacy-ssh-store.cc
@@ -34,7 +34,7 @@ struct LegacySSHStore : public Store {
     std::unique_ptr<SSHMaster::Connection> sshConn;
     FdSink to;
     FdSource from;
-    int remoteVersion{};
+    int remoteVersion;
     bool good = true;
   };
 
@@ -214,7 +214,7 @@ struct LegacySSHStore : public Store {
     conn->to.flush();
 
     BuildResult status;
-    status.status = static_cast<BuildResult::Status>(readInt(conn->from));
+    status.status = (BuildResult::Status)readInt(conn->from);
     conn->from >> status.errorMsg;
 
     if (GET_PROTOCOL_MINOR(conn->remoteVersion) >= 3) {
diff --git a/third_party/nix/src/libstore/local-fs-store.cc b/third_party/nix/src/libstore/local-fs-store.cc
index 8e5d3e211..2dd09093d 100644
--- a/third_party/nix/src/libstore/local-fs-store.cc
+++ b/third_party/nix/src/libstore/local-fs-store.cc
@@ -26,7 +26,7 @@ struct LocalStoreAccessor : public FSAccessor {
   FSAccessor::Stat stat(const Path& path) override {
     auto realPath = toRealPath(path);
 
-    struct stat st {};
+    struct stat st;
     if (lstat(realPath.c_str(), &st) != 0) {
       if (errno == ENOENT || errno == ENOTDIR) {
         return {Type::tMissing, 0, false};
@@ -41,7 +41,7 @@ struct LocalStoreAccessor : public FSAccessor {
     return {S_ISREG(st.st_mode)
                 ? Type::tRegular
                 : S_ISLNK(st.st_mode) ? Type::tSymlink : Type::tDirectory,
-            S_ISREG(st.st_mode) ? static_cast<uint64_t>(st.st_size) : 0,
+            S_ISREG(st.st_mode) ? (uint64_t)st.st_size : 0,
             S_ISREG(st.st_mode) && ((st.st_mode & S_IXUSR) != 0u)};
   }
 
diff --git a/third_party/nix/src/libstore/local-store.cc b/third_party/nix/src/libstore/local-store.cc
index 14ba58065..3ad574186 100644
--- a/third_party/nix/src/libstore/local-store.cc
+++ b/third_party/nix/src/libstore/local-store.cc
@@ -89,7 +89,7 @@ LocalStore::LocalStore(const Params& params)
       LOG(ERROR) << "warning: the group '" << settings.buildUsersGroup
                  << "' specified in 'build-users-group' does not exist";
     } else {
-      struct stat st {};
+      struct stat st;
       if (stat(realStoreDir.c_str(), &st) != 0) {
         throw SysError(format("getting attributes of path '%1%'") %
                        realStoreDir);
@@ -112,7 +112,7 @@ LocalStore::LocalStore(const Params& params)
   /* Ensure that the store and its parents are not symlinks. */
   if (getEnv("NIX_IGNORE_SYMLINK_STORE") != "1") {
     Path path = realStoreDir;
-    struct stat st {};
+    struct stat st;
     while (path != "/") {
       if (lstat(path.c_str(), &st) != 0) {
         throw SysError(format("getting status of '%1%'") % path);
@@ -132,7 +132,7 @@ LocalStore::LocalStore(const Params& params)
      needed, we reserve some dummy space that we can free just
      before doing a garbage collection. */
   try {
-    struct stat st {};
+    struct stat st;
     if (stat(reservedPath.c_str(), &st) == -1 ||
         st.st_size != settings.reservedSize) {
       AutoCloseFD fd =
@@ -350,8 +350,7 @@ void LocalStore::openDB(State& state, bool create) {
     if (sqlite3_step(stmt) != SQLITE_ROW) {
       throwSQLiteError(db, "querying journal mode");
     }
-    prevMode = std::string(
-        reinterpret_cast<const char*>(sqlite3_column_text(stmt, 0)));
+    prevMode = std::string((const char*)sqlite3_column_text(stmt, 0));
   }
   if (prevMode != mode &&
       sqlite3_exec(db, ("pragma main.journal_mode = " + mode + ";").c_str(),
@@ -380,7 +379,7 @@ void LocalStore::makeStoreWritable() {
     return;
   }
   /* Check if /nix/store is on a read-only mount. */
-  struct statvfs stat {};
+  struct statvfs stat;
   if (statvfs(realStoreDir.c_str(), &stat) != 0) {
     throw SysError("getting info about the Nix store mount point");
   }
@@ -434,7 +433,7 @@ static void canonicaliseTimestampAndPermissions(const Path& path,
 }  // namespace nix
 
 void canonicaliseTimestampAndPermissions(const Path& path) {
-  struct stat st {};
+  struct stat st;
   if (lstat(path.c_str(), &st) != 0) {
     throw SysError(format("getting attributes of path '%1%'") % path);
   }
@@ -445,7 +444,7 @@ static void canonicalisePathMetaData_(const Path& path, uid_t fromUid,
                                       InodesSeen& inodesSeen) {
   checkInterrupt();
 
-  struct stat st {};
+  struct stat st;
   if (lstat(path.c_str(), &st) != 0) {
     throw SysError(format("getting attributes of path '%1%'") % path);
   }
@@ -490,7 +489,7 @@ static void canonicalisePathMetaData_(const Path& path, uid_t fromUid,
      However, ignore files that we chown'ed ourselves previously to
      ensure that we don't fail on hard links within the same build
      (i.e. "touch $out/foo; ln $out/foo $out/bar"). */
-  if (fromUid != static_cast<uid_t>(-1) && st.st_uid != fromUid) {
+  if (fromUid != (uid_t)-1 && st.st_uid != fromUid) {
     if (S_ISDIR(st.st_mode)) {
       throw BuildError(format("invalid file '%1%': is a directory") % path);
     }
@@ -545,7 +544,7 @@ void canonicalisePathMetaData(const Path& path, uid_t fromUid,
 
   /* On platforms that don't have lchown(), the top-level path can't
      be a symlink, since we can't change its ownership. */
-  struct stat st {};
+  struct stat st;
   if (lstat(path.c_str(), &st) != 0) {
     throw SysError(format("getting attributes of path '%1%'") % path);
   }
@@ -575,7 +574,7 @@ void LocalStore::checkDerivationOutputs(const Path& drvPath,
           drvPath);
     }
 
-    bool recursive = 0;
+    bool recursive;
     Hash h;
     out->second.parseHashInfo(recursive, h);
     Path outPath = makeFixedOutputPath(recursive, h, drvName);
@@ -691,8 +690,7 @@ void LocalStore::queryPathInfoUncached(
 
       info->registrationTime = useQueryPathInfo.getInt(2);
 
-      auto s = reinterpret_cast<const char*>(
-          sqlite3_column_text(state->stmtQueryPathInfo, 3));
+      auto s = (const char*)sqlite3_column_text(state->stmtQueryPathInfo, 3);
       if (s != nullptr) {
         info->deriver = s;
       }
@@ -702,14 +700,12 @@ void LocalStore::queryPathInfoUncached(
 
       info->ultimate = useQueryPathInfo.getInt(5) == 1;
 
-      s = reinterpret_cast<const char*>(
-          sqlite3_column_text(state->stmtQueryPathInfo, 6));
+      s = (const char*)sqlite3_column_text(state->stmtQueryPathInfo, 6);
       if (s != nullptr) {
         info->sigs = absl::StrSplit(s, absl::ByChar(' '));
       }
 
-      s = reinterpret_cast<const char*>(
-          sqlite3_column_text(state->stmtQueryPathInfo, 7));
+      s = (const char*)sqlite3_column_text(state->stmtQueryPathInfo, 7);
       if (s != nullptr) {
         info->ca = s;
       }
@@ -864,8 +860,8 @@ Path LocalStore::queryPathFromHashPart(const std::string& hashPart) {
       return "";
     }
 
-    const char* s = reinterpret_cast<const char*>(
-        sqlite3_column_text(state->stmtQueryPathFromHashPart, 0));
+    const char* s =
+        (const char*)sqlite3_column_text(state->stmtQueryPathFromHashPart, 0);
     return (s != nullptr) &&
                    prefix.compare(0, prefix.size(), s, prefix.size()) == 0
                ? s
diff --git a/third_party/nix/src/libstore/nar-accessor.cc b/third_party/nix/src/libstore/nar-accessor.cc
index cfd3d50b3..49fa1bd1d 100644
--- a/third_party/nix/src/libstore/nar-accessor.cc
+++ b/third_party/nix/src/libstore/nar-accessor.cc
@@ -76,7 +76,7 @@ struct NarAccessor : public FSAccessor {
     void preallocateContents(unsigned long long size) override {
       currentStart = std::string(s, pos, 16);
       assert(size <= std::numeric_limits<size_t>::max());
-      parents.top()->size = static_cast<size_t>(size);
+      parents.top()->size = (size_t)size;
       parents.top()->start = pos;
     }
 
diff --git a/third_party/nix/src/libstore/nar-info-disk-cache.cc b/third_party/nix/src/libstore/nar-info-disk-cache.cc
index e4c4dc882..a09ed3c0b 100644
--- a/third_party/nix/src/libstore/nar-info-disk-cache.cc
+++ b/third_party/nix/src/libstore/nar-info-disk-cache.cc
@@ -55,10 +55,10 @@ class NarInfoDiskCacheImpl final : public NarInfoDiskCache {
   const int purgeInterval = 24 * 3600;
 
   struct Cache {
-    int id{};
+    int id;
     Path storeDir;
-    bool wantMassQuery{};
-    int priority{};
+    bool wantMassQuery;
+    int priority;
   };
 
   struct State {
@@ -164,9 +164,8 @@ class NarInfoDiskCacheImpl final : public NarInfoDiskCache {
               static_cast<int64_t>(wantMassQuery))(priority)
           .exec();
       assert(sqlite3_changes(state->db) == 1);
-      state->caches[uri] =
-          Cache{static_cast<int>(sqlite3_last_insert_rowid(state->db)),
-                storeDir, wantMassQuery, priority};
+      state->caches[uri] = Cache{(int)sqlite3_last_insert_rowid(state->db),
+                                 storeDir, wantMassQuery, priority};
     });
   }
 
@@ -182,9 +181,8 @@ class NarInfoDiskCacheImpl final : public NarInfoDiskCache {
           return false;
         }
         state->caches.emplace(
-            uri, Cache{static_cast<int>(queryCache.getInt(0)),
-                       queryCache.getStr(1), queryCache.getInt(2) != 0,
-                       static_cast<int>(queryCache.getInt(3))});
+            uri, Cache{(int)queryCache.getInt(0), queryCache.getStr(1),
+                       queryCache.getInt(2) != 0, (int)queryCache.getInt(3)});
       }
 
       auto& cache(getCache(*state, uri));
diff --git a/third_party/nix/src/libstore/optimise-store.cc b/third_party/nix/src/libstore/optimise-store.cc
index af67d5e19..eb24633c1 100644
--- a/third_party/nix/src/libstore/optimise-store.cc
+++ b/third_party/nix/src/libstore/optimise-store.cc
@@ -17,7 +17,7 @@
 namespace nix {
 
 static void makeWritable(const Path& path) {
-  struct stat st {};
+  struct stat st;
   if (lstat(path.c_str(), &st) != 0) {
     throw SysError(format("getting attributes of path '%1%'") % path);
   }
@@ -50,7 +50,7 @@ LocalStore::InodeHash LocalStore::loadInodeHash() {
     throw SysError(format("opening directory '%1%'") % linksDir);
   }
 
-  struct dirent* dirent = nullptr;
+  struct dirent* dirent;
   while (errno = 0, dirent = readdir(dir.get())) { /* sic */
     checkInterrupt();
     // We don't care if we hit non-hash files, anything goes
@@ -74,7 +74,7 @@ Strings LocalStore::readDirectoryIgnoringInodes(const Path& path,
     throw SysError(format("opening directory '%1%'") % path);
   }
 
-  struct dirent* dirent = nullptr;
+  struct dirent* dirent;
   while (errno = 0, dirent = readdir(dir.get())) { /* sic */
     checkInterrupt();
 
@@ -100,7 +100,7 @@ void LocalStore::optimisePath_(OptimiseStats& stats, const Path& path,
                                InodeHash& inodeHash) {
   checkInterrupt();
 
-  struct stat st {};
+  struct stat st;
   if (lstat(path.c_str(), &st) != 0) {
     throw SysError(format("getting attributes of path '%1%'") % path);
   }
@@ -183,7 +183,7 @@ retry:
 
   /* Yes!  We've seen a file with the same contents.  Replace the
      current file with a hard link to that file. */
-  struct stat stLink {};
+  struct stat stLink;
   if (lstat(linkPath.c_str(), &stLink) != 0) {
     throw SysError(format("getting attributes of path '%1%'") % linkPath);
   }
diff --git a/third_party/nix/src/libstore/pathlocks.cc b/third_party/nix/src/libstore/pathlocks.cc
index 7c528e876..4b153856d 100644
--- a/third_party/nix/src/libstore/pathlocks.cc
+++ b/third_party/nix/src/libstore/pathlocks.cc
@@ -37,7 +37,7 @@ void deleteLockFile(const Path& path, int fd) {
 }
 
 bool lockFile(int fd, LockType lockType, bool wait) {
-  int type = 0;
+  int type;
   if (lockType == ltRead) {
     type = LOCK_SH;
   } else if (lockType == ltWrite) {
@@ -119,7 +119,7 @@ bool PathLocks::lockPaths(const PathSet& paths, const std::string& waitMsg,
 
       /* Check that the lock file hasn't become stale (i.e.,
          hasn't been unlinked). */
-      struct stat st {};
+      struct stat st;
       if (fstat(fd.get(), &st) == -1) {
         throw SysError(format("statting lock file '%1%'") % lockPath);
       }
diff --git a/third_party/nix/src/libstore/profiles.cc b/third_party/nix/src/libstore/profiles.cc
index c2a965e2e..0d44c60cc 100644
--- a/third_party/nix/src/libstore/profiles.cc
+++ b/third_party/nix/src/libstore/profiles.cc
@@ -30,7 +30,7 @@ static int parseName(absl::string_view profileName, absl::string_view name) {
     return -1;
   }
 
-  int n = 0;
+  int n;
   if (!absl::SimpleAtoi(name, &n) || n < 0) {
     return -1;
   }
@@ -45,12 +45,12 @@ Generations findGenerations(const Path& profile, int& curGen) {
   std::string profileName = baseNameOf(profile);
 
   for (auto& i : readDirectory(profileDir)) {
-    int n = 0;
+    int n;
     if ((n = parseName(profileName, i.name)) != -1) {
       Generation gen;
       gen.path = profileDir + "/" + i.name;
       gen.number = n;
-      struct stat st {};
+      struct stat st;
       if (lstat(gen.path.c_str(), &st) != 0) {
         throw SysError(format("statting '%1%'") % gen.path);
       }
@@ -75,10 +75,10 @@ Path createGeneration(const ref<LocalFSStore>& store, const Path& profile,
                       const Path& outPath) {
   /* The new generation number should be higher than old the
      previous ones. */
-  int dummy = 0;
+  int dummy;
   Generations gens = findGenerations(profile, dummy);
 
-  unsigned int num = 0;
+  unsigned int num;
   if (!gens.empty()) {
     Generation last = gens.back();
 
@@ -138,7 +138,7 @@ void deleteGenerations(const Path& profile,
   PathLocks lock;
   lockProfile(lock, profile);
 
-  int curGen = 0;
+  int curGen;
   Generations gens = findGenerations(profile, curGen);
 
   if (gensToDelete.find(curGen) != gensToDelete.end()) {
@@ -158,7 +158,7 @@ void deleteGenerationsGreaterThan(const Path& profile, int max, bool dryRun) {
   PathLocks lock;
   lockProfile(lock, profile);
 
-  int curGen = 0;
+  int curGen;
   bool fromCurGen = false;
   Generations gens = findGenerations(profile, curGen);
   for (auto i = gens.rbegin(); i != gens.rend(); ++i) {
@@ -181,7 +181,7 @@ void deleteOldGenerations(const Path& profile, bool dryRun) {
   PathLocks lock;
   lockProfile(lock, profile);
 
-  int curGen = 0;
+  int curGen;
   Generations gens = findGenerations(profile, curGen);
 
   for (auto& i : gens) {
@@ -195,7 +195,7 @@ void deleteGenerationsOlderThan(const Path& profile, time_t t, bool dryRun) {
   PathLocks lock;
   lockProfile(lock, profile);
 
-  int curGen = 0;
+  int curGen;
   Generations gens = findGenerations(profile, curGen);
 
   bool canDelete = false;
@@ -219,7 +219,7 @@ void deleteGenerationsOlderThan(const Path& profile,
                                 const std::string& timeSpec, bool dryRun) {
   time_t curTime = time(nullptr);
   std::string strDays = std::string(timeSpec, 0, timeSpec.size() - 1);
-  int days = 0;
+  int days;
 
   if (!absl::SimpleAtoi(strDays, &days) || days < 1) {
     throw Error(format("invalid number of days specifier '%1%'") % timeSpec);
diff --git a/third_party/nix/src/libstore/remote-fs-accessor.cc b/third_party/nix/src/libstore/remote-fs-accessor.cc
index d5b202884..2917f01f7 100644
--- a/third_party/nix/src/libstore/remote-fs-accessor.cc
+++ b/third_party/nix/src/libstore/remote-fs-accessor.cc
@@ -75,14 +75,12 @@ std::pair<ref<FSAccessor>, Path> RemoteFSAccessor::fetch(const Path& path_) {
               throw SysError("opening NAR cache file '%s'", cacheFile);
             }
 
-            if (lseek(fd.get(), offset, SEEK_SET) !=
-                static_cast<off_t>(offset)) {
+            if (lseek(fd.get(), offset, SEEK_SET) != (off_t)offset) {
               throw SysError("seeking in '%s'", cacheFile);
             }
 
             std::string buf(length, 0);
-            readFull(fd.get(), reinterpret_cast<unsigned char*>(buf.data()),
-                     length);
+            readFull(fd.get(), (unsigned char*)buf.data(), length);
 
             return buf;
           });
diff --git a/third_party/nix/src/libstore/remote-store.cc b/third_party/nix/src/libstore/remote-store.cc
index 8d278d500..7c45c5ff5 100644
--- a/third_party/nix/src/libstore/remote-store.cc
+++ b/third_party/nix/src/libstore/remote-store.cc
@@ -97,7 +97,7 @@ ref<RemoteStore::Connection> UDSRemoteStore::openConnection() {
 
   std::string socketPath = path ? *path : settings.nixDaemonSocketFile;
 
-  struct sockaddr_un addr {};
+  struct sockaddr_un addr;
   addr.sun_family = AF_UNIX;
   strncpy(addr.sun_path, socketPath.c_str(), sizeof(addr.sun_path));
   if (addr.sun_path[sizeof(addr.sun_path) - 1] != '\0') {
@@ -347,7 +347,7 @@ void RemoteStore::queryPathInfoUncached(
         throw;
       }
       if (GET_PROTOCOL_MINOR(conn->daemonVersion) >= 17) {
-        bool valid = 0;
+        bool valid;
         conn->from >> valid;
         if (!valid) {
           throw InvalidPath(format("path '%s' is not valid") % path);
@@ -544,9 +544,9 @@ BuildResult RemoteStore::buildDerivation(const Path& drvPath,
   conn->to << wopBuildDerivation << drvPath << drv << buildMode;
   conn.processStderr();
   BuildResult res;
-  unsigned int status = 0;
+  unsigned int status;
   conn->from >> status >> res.errorMsg;
-  res.status = static_cast<BuildResult::Status>(status);
+  res.status = (BuildResult::Status)status;
   return res;
 }
 
diff --git a/third_party/nix/src/libstore/sqlite.cc b/third_party/nix/src/libstore/sqlite.cc
index 0ed77a51b..b6ecfce92 100644
--- a/third_party/nix/src/libstore/sqlite.cc
+++ b/third_party/nix/src/libstore/sqlite.cc
@@ -133,7 +133,7 @@ bool SQLiteStmt::Use::next() {
 }
 
 std::string SQLiteStmt::Use::getStr(int col) {
-  auto s = reinterpret_cast<const char*>(sqlite3_column_text(stmt, col));
+  auto s = (const char*)sqlite3_column_text(stmt, col);
   assert(s);
   return s;
 }
@@ -186,7 +186,7 @@ void handleSQLiteBusy(const SQLiteBusy& e) {
   /* Sleep for a while since retrying the transaction right away
      is likely to fail again. */
   checkInterrupt();
-  struct timespec t {};
+  struct timespec t;
   t.tv_sec = 0;
   t.tv_nsec = (random() % 100) * 1000 * 1000; /* <= 0.1s */
   nanosleep(&t, nullptr);
diff --git a/third_party/nix/src/libstore/ssh.cc b/third_party/nix/src/libstore/ssh.cc
index d28e44e13..e84944c4c 100644
--- a/third_party/nix/src/libstore/ssh.cc
+++ b/third_party/nix/src/libstore/ssh.cc
@@ -110,7 +110,7 @@ Path SSHMaster::startMaster() {
   state->tmpDir =
       std::make_unique<AutoDelete>(createTempDir("", "nix", true, true, 0700));
 
-  state->socketPath = Path(*state->tmpDir) + "/ssh.sock";
+  state->socketPath = (Path)*state->tmpDir + "/ssh.sock";
 
   Pipe out;
   out.create();
diff --git a/third_party/nix/src/libstore/store-api.cc b/third_party/nix/src/libstore/store-api.cc
index a68e6e8fc..96c6f9341 100644
--- a/third_party/nix/src/libstore/store-api.cc
+++ b/third_party/nix/src/libstore/store-api.cc
@@ -262,7 +262,7 @@ Path Store::makeFixedOutputPath(bool recursive, const Hash& hash,
                    "output:out",
                    hashString(
                        htSHA256,
-                       "fixed:out:" + (recursive ? std::string("r:") : "") +
+                       "fixed:out:" + (recursive ? (std::string) "r:" : "") +
                            hash.to_string(Base16) + ":"),
                    name);
 }
@@ -783,7 +783,7 @@ ValidPathInfo decodeValidPathInfo(std::istream& str, bool hashGiven) {
   }
   getline(str, info.deriver);
   std::string s;
-  int n = 0;
+  int n;
   getline(str, s);
   if (!absl::SimpleAtoi(s, &n)) {
     throw Error("number expected");
@@ -884,7 +884,7 @@ Strings ValidPathInfo::shortRefs() const {
 }
 
 std::string makeFixedOutputCA(bool recursive, const Hash& hash) {
-  return "fixed:" + (recursive ? std::string("r:") : "") + hash.to_string();
+  return "fixed:" + (recursive ? (std::string) "r:" : "") + hash.to_string();
 }
 
 void Store::addToStore(const ValidPathInfo& info, Source& narSource,
@@ -930,8 +930,7 @@ std::pair<std::string, Store::Params> splitUriAndParams(
               throw Error("invalid URI parameter '%s'", value);
             }
             try {
-              decoded += std::to_string(
-                  std::stoul(std::string(value, i + 1, 2), nullptr, 16));
+              decoded += std::stoul(std::string(value, i + 1, 2), nullptr, 16);
               i += 3;
             } catch (...) {
               throw Error("invalid URI parameter '%s'", value);
diff --git a/third_party/nix/src/libutil/archive.cc b/third_party/nix/src/libutil/archive.cc
index c26bf8257..408980932 100644
--- a/third_party/nix/src/libutil/archive.cc
+++ b/third_party/nix/src/libutil/archive.cc
@@ -66,7 +66,7 @@ static void dumpContents(const Path& path, size_t size, Sink& sink) {
 static void dump(const Path& path, Sink& sink, PathFilter& filter) {
   checkInterrupt();
 
-  struct stat st {};
+  struct stat st;
   if (lstat(path.c_str(), &st) != 0) {
     throw SysError(format("getting attributes of path '%1%'") % path);
   }
@@ -80,7 +80,7 @@ static void dump(const Path& path, Sink& sink, PathFilter& filter) {
       sink << "executable"
            << "";
     }
-    dumpContents(path, static_cast<size_t>(st.st_size), sink);
+    dumpContents(path, (size_t)st.st_size, sink);
   }
 
   else if (S_ISDIR(st.st_mode)) {
@@ -159,7 +159,7 @@ static void skipGeneric(Source & source)
 }
 #endif
 
-static void parseContents(ParseSink& sink, Source& source) {
+static void parseContents(ParseSink& sink, Source& source, const Path& path) {
   unsigned long long size = readLongLong(source);
 
   sink.preallocateContents(size);
@@ -170,7 +170,7 @@ static void parseContents(ParseSink& sink, Source& source) {
   while (left != 0u) {
     checkInterrupt();
     auto n = buf.size();
-    if (static_cast<unsigned long long>(n) > left) {
+    if ((unsigned long long)n > left) {
       n = left;
     }
     source(buf.data(), n);
@@ -235,7 +235,7 @@ static void parse(ParseSink& sink, Source& source, const Path& path) {
     }
 
     else if (s == "contents" && type == tpRegular) {
-      parseContents(sink, source);
+      parseContents(sink, source, path);
     }
 
     else if (s == "executable" && type == tpRegular) {
@@ -267,7 +267,7 @@ static void parse(ParseSink& sink, Source& source, const Path& path) {
           name = readString(source);
           if (name.empty() || name == "." || name == ".." ||
               name.find('/') != std::string::npos ||
-              name.find('\0') != std::string::npos) {
+              name.find((char)0) != std::string::npos) {
             throw Error(format("NAR contains invalid file name '%1%'") % name);
           }
           if (name <= prevName) {
@@ -341,7 +341,7 @@ struct RestoreSink : ParseSink {
   }
 
   void isExecutable() override {
-    struct stat st {};
+    struct stat st;
     if (fstat(fd.get(), &st) == -1) {
       throw SysError("fstat");
     }
diff --git a/third_party/nix/src/libutil/args.cc b/third_party/nix/src/libutil/args.cc
index 2be8a1b0c..c56383ef8 100644
--- a/third_party/nix/src/libutil/args.cc
+++ b/third_party/nix/src/libutil/args.cc
@@ -27,12 +27,12 @@ void Args::parseCmdline(const Strings& _cmdline) {
        `-j3` -> `-j 3`). */
     if (!dashDash && arg.length() > 2 && arg[0] == '-' && arg[1] != '-' &&
         (isalpha(arg[1]) != 0)) {
-      *pos = std::string("-") + arg[1];
+      *pos = (std::string) "-" + arg[1];
       auto next = pos;
       ++next;
       for (unsigned int j = 2; j < arg.length(); j++) {
         if (isalpha(arg[j]) != 0) {
-          cmdline.insert(next, std::string("-") + arg[j]);
+          cmdline.insert(next, (std::string) "-" + arg[j]);
         } else {
           cmdline.insert(next, std::string(arg, j));
           break;
diff --git a/third_party/nix/src/libutil/compression.cc b/third_party/nix/src/libutil/compression.cc
index b598927c8..779d326eb 100644
--- a/third_party/nix/src/libutil/compression.cc
+++ b/third_party/nix/src/libutil/compression.cc
@@ -17,7 +17,7 @@ namespace nix {
 
 // Don't feed brotli too much at once.
 struct ChunkedCompressionSink : CompressionSink {
-  uint8_t outbuf[32 * 1024]{};
+  uint8_t outbuf[32 * 1024];
 
   void write(const unsigned char* data, size_t len) override {
     const size_t CHUNK_SIZE = sizeof(outbuf) << 2;
@@ -43,7 +43,7 @@ struct NoneSink : CompressionSink {
 
 struct XzDecompressionSink : CompressionSink {
   Sink& nextSink;
-  uint8_t outbuf[BUFSIZ]{};
+  uint8_t outbuf[BUFSIZ];
   lzma_stream strm = LZMA_STREAM_INIT;
   bool finished = false;
 
@@ -89,7 +89,7 @@ struct XzDecompressionSink : CompressionSink {
 
 struct BzipDecompressionSink : ChunkedCompressionSink {
   Sink& nextSink;
-  bz_stream strm{};
+  bz_stream strm;
   bool finished = false;
 
   explicit BzipDecompressionSink(Sink& nextSink) : nextSink(nextSink) {
@@ -99,7 +99,7 @@ struct BzipDecompressionSink : ChunkedCompressionSink {
       throw CompressionError("unable to initialise bzip2 decoder");
     }
 
-    strm.next_out = reinterpret_cast<char*>(outbuf);
+    strm.next_out = (char*)outbuf;
     strm.avail_out = sizeof(outbuf);
   }
 
@@ -128,7 +128,7 @@ struct BzipDecompressionSink : ChunkedCompressionSink {
 
       if (strm.avail_out < sizeof(outbuf) || strm.avail_in == 0) {
         nextSink(outbuf, sizeof(outbuf) - strm.avail_out);
-        strm.next_out = reinterpret_cast<char*>(outbuf);
+        strm.next_out = (char*)outbuf;
         strm.avail_out = sizeof(outbuf);
       }
     }
@@ -205,12 +205,12 @@ ref<CompressionSink> makeDecompressionSink(const std::string& method,
 
 struct XzCompressionSink : CompressionSink {
   Sink& nextSink;
-  uint8_t outbuf[BUFSIZ]{};
+  uint8_t outbuf[BUFSIZ];
   lzma_stream strm = LZMA_STREAM_INIT;
   bool finished = false;
 
   XzCompressionSink(Sink& nextSink, bool parallel) : nextSink(nextSink) {
-    lzma_ret ret{};
+    lzma_ret ret;
     bool done = false;
 
     if (parallel) {
@@ -277,7 +277,7 @@ struct XzCompressionSink : CompressionSink {
 
 struct BzipCompressionSink : ChunkedCompressionSink {
   Sink& nextSink;
-  bz_stream strm{};
+  bz_stream strm;
   bool finished = false;
 
   explicit BzipCompressionSink(Sink& nextSink) : nextSink(nextSink) {
@@ -287,7 +287,7 @@ struct BzipCompressionSink : ChunkedCompressionSink {
       throw CompressionError("unable to initialise bzip2 encoder");
     }
 
-    strm.next_out = reinterpret_cast<char*>(outbuf);
+    strm.next_out = (char*)outbuf;
     strm.avail_out = sizeof(outbuf);
   }
 
@@ -316,7 +316,7 @@ struct BzipCompressionSink : ChunkedCompressionSink {
 
       if (strm.avail_out < sizeof(outbuf) || strm.avail_in == 0) {
         nextSink(outbuf, sizeof(outbuf) - strm.avail_out);
-        strm.next_out = reinterpret_cast<char*>(outbuf);
+        strm.next_out = (char*)outbuf;
         strm.avail_out = sizeof(outbuf);
       }
     }
@@ -325,7 +325,7 @@ struct BzipCompressionSink : ChunkedCompressionSink {
 
 struct BrotliCompressionSink : ChunkedCompressionSink {
   Sink& nextSink;
-  uint8_t outbuf[BUFSIZ]{};
+  uint8_t outbuf[BUFSIZ];
   BrotliEncoderState* state;
   bool finished = false;
 
diff --git a/third_party/nix/src/libutil/hash.cc b/third_party/nix/src/libutil/hash.cc
index 4a8904b4e..ac151201f 100644
--- a/third_party/nix/src/libutil/hash.cc
+++ b/third_party/nix/src/libutil/hash.cc
@@ -154,7 +154,7 @@ static std::string printHash32(const Hash& hash) {
   std::string s;
   s.reserve(len);
 
-  for (int n = static_cast<int>(len) - 1; n >= 0; n--) {
+  for (int n = (int)len - 1; n >= 0; n--) {
     unsigned int b = n * 5;
     unsigned int i = b / 8;
     unsigned int j = b % 8;
@@ -187,8 +187,7 @@ std::string Hash::to_string(Base base, bool includeType) const {
     case Base64:
     case SRI:
       std::string b64;
-      absl::Base64Escape(
-          std::string(reinterpret_cast<const char*>(hash), hashSize), &b64);
+      absl::Base64Escape(std::string((const char*)hash, hashSize), &b64);
       s += b64;
       break;
   }
@@ -355,7 +354,7 @@ Hash hashString(HashType ht, const std::string& s) {
   hash::Ctx ctx{};
   Hash hash(ht);
   start(ht, ctx);
-  update(ht, ctx, reinterpret_cast<const unsigned char*>(s.data()), s.length());
+  update(ht, ctx, (const unsigned char*)s.data(), s.length());
   finish(ht, ctx, hash.hash);
   return hash;
 }
@@ -371,7 +370,7 @@ Hash hashFile(HashType ht, const Path& path) {
   }
 
   std::vector<unsigned char> buf(8192);
-  ssize_t n = 0;
+  ssize_t n;
   while ((n = read(fd.get(), buf.data(), buf.size())) != 0) {
     checkInterrupt();
     if (n == -1) {
diff --git a/third_party/nix/src/libutil/json.cc b/third_party/nix/src/libutil/json.cc
index 59ff74f57..da636e7be 100644
--- a/third_party/nix/src/libutil/json.cc
+++ b/third_party/nix/src/libutil/json.cc
@@ -18,7 +18,7 @@ void toJSON(std::ostream& str, const char* start, const char* end) {
       str << "\\t";
     } else if (*i >= 0 && *i < 32) {
       str << "\\u" << std::setfill('0') << std::setw(4) << std::hex
-          << static_cast<uint16_t>(*i) << std::dec;
+          << (uint16_t)*i << std::dec;
     } else {
       str << *i;
     }
diff --git a/third_party/nix/src/libutil/serialise.cc b/third_party/nix/src/libutil/serialise.cc
index 26ab9be95..d02a0205a 100644
--- a/third_party/nix/src/libutil/serialise.cc
+++ b/third_party/nix/src/libutil/serialise.cc
@@ -93,10 +93,10 @@ std::string Source::drain() {
   std::string s;
   std::vector<unsigned char> buf(8192);
   while (true) {
-    size_t n = 0;
+    size_t n;
     try {
       n = read(buf.data(), buf.size());
-      s.append(reinterpret_cast<char*>(buf.data()), n);
+      s.append((char*)buf.data(), n);
     } catch (EndOfFile&) {
       break;
     }
@@ -126,10 +126,10 @@ size_t BufferedSource::read(unsigned char* data, size_t len) {
 bool BufferedSource::hasData() { return bufPosOut < bufPosIn; }
 
 size_t FdSource::readUnbuffered(unsigned char* data, size_t len) {
-  ssize_t n = 0;
+  ssize_t n;
   do {
     checkInterrupt();
-    n = ::read(fd, reinterpret_cast<char*>(data), len);
+    n = ::read(fd, (char*)data, len);
   } while (n == -1 && errno == EINTR);
   if (n == -1) {
     _good = false;
@@ -149,7 +149,7 @@ size_t StringSource::read(unsigned char* data, size_t len) {
   if (pos == s.size()) {
     throw EndOfFile("end of string reached");
   }
-  size_t n = s.copy(reinterpret_cast<char*>(data), len, pos);
+  size_t n = s.copy((char*)data, len, pos);
   pos += n;
   return n;
 }
@@ -179,7 +179,7 @@ std::unique_ptr<Source> sinkToSource(const std::function<void(Sink&)>& fun,
         coro = coro_t::pull_type([&](coro_t::push_type& yield) {
           LambdaSink sink([&](const unsigned char* data, size_t len) {
             if (len != 0u) {
-              yield(std::string(reinterpret_cast<const char*>(data), len));
+              yield(std::string((const char*)data, len));
             }
           });
           fun(sink);
@@ -200,7 +200,7 @@ std::unique_ptr<Source> sinkToSource(const std::function<void(Sink&)>& fun,
       }
 
       auto n = std::min(cur.size() - pos, len);
-      memcpy(data, reinterpret_cast<unsigned char*>(cur.data()) + pos, n);
+      memcpy(data, (unsigned char*)cur.data() + pos, n);
       pos += n;
 
       return n;
@@ -225,7 +225,7 @@ void writeString(const unsigned char* buf, size_t len, Sink& sink) {
 }
 
 Sink& operator<<(Sink& sink, const std::string& s) {
-  writeString(reinterpret_cast<const unsigned char*>(s.data()), s.size(), sink);
+  writeString((const unsigned char*)s.data(), s.size(), sink);
   return sink;
 }
 
@@ -276,7 +276,7 @@ std::string readString(Source& source, size_t max) {
     throw SerialisationError("string is too long");
   }
   std::string res(len, 0);
-  source(reinterpret_cast<unsigned char*>(res.data()), len);
+  source((unsigned char*)res.data(), len);
   readPadding(len, source);
   return res;
 }
@@ -305,7 +305,7 @@ void StringSink::operator()(const unsigned char* data, size_t len) {
     warnLargeDump();
     warned = true;
   }
-  s->append(reinterpret_cast<const char*>(data), len);
+  s->append((const char*)data, len);
 }
 
 }  // namespace nix
diff --git a/third_party/nix/src/libutil/util.cc b/third_party/nix/src/libutil/util.cc
index f2580f7b2..75a8e73ea 100644
--- a/third_party/nix/src/libutil/util.cc
+++ b/third_party/nix/src/libutil/util.cc
@@ -207,7 +207,7 @@ bool isDirOrInDir(const Path& path, const Path& dir) {
 }
 
 struct stat lstat(const Path& path) {
-  struct stat st {};
+  struct stat st;
   if (lstat(path.c_str(), &st) != 0) {
     throw SysError(format("getting status of '%1%'") % path);
   }
@@ -215,8 +215,8 @@ struct stat lstat(const Path& path) {
 }
 
 bool pathExists(const Path& path) {
-  int res = 0;
-  struct stat st {};
+  int res;
+  struct stat st;
   res = lstat(path.c_str(), &st);
   if (res == 0) {
     return true;
@@ -254,7 +254,7 @@ DirEntries readDirectory(DIR* dir, const Path& path) {
   DirEntries entries;
   entries.reserve(64);
 
-  struct dirent* dirent = nullptr;
+  struct dirent* dirent;
   while (errno = 0, dirent = readdir(dir)) { /* sic */
     checkInterrupt();
     std::string name = dirent->d_name;
@@ -300,7 +300,7 @@ unsigned char getFileType(const Path& path) {
 }
 
 std::string readFile(int fd) {
-  struct stat st {};
+  struct stat st;
   if (fstat(fd, &st) == -1) {
     throw SysError("statting file");
   }
@@ -308,7 +308,7 @@ std::string readFile(int fd) {
   std::vector<unsigned char> buf(st.st_size);
   readFull(fd, buf.data(), st.st_size);
 
-  return std::string(reinterpret_cast<char*>(buf.data()), st.st_size);
+  return std::string((char*)buf.data(), st.st_size);
 }
 
 std::string readFile(absl::string_view path, bool drain) {
@@ -349,7 +349,7 @@ void writeFile(const Path& path, Source& source, mode_t mode) {
   while (true) {
     try {
       auto n = source.read(buf.data(), buf.size());
-      writeFull(fd.get(), static_cast<unsigned char*>(buf.data()), n);
+      writeFull(fd.get(), (unsigned char*)buf.data(), n);
     } catch (EndOfFile&) {
       break;
     }
@@ -360,7 +360,7 @@ std::string readLine(int fd) {
   std::string s;
   while (true) {
     checkInterrupt();
-    char ch = 0;
+    char ch;
     // FIXME: inefficient
     ssize_t rd = read(fd, &ch, 1);
     if (rd == -1) {
@@ -389,7 +389,7 @@ static void _deletePath(int parentfd, const Path& path,
 
   std::string name(baseNameOf(path));
 
-  struct stat st {};
+  struct stat st;
   if (fstatat(parentfd, name.c_str(), &st, AT_SYMLINK_NOFOLLOW) == -1) {
     if (errno == ENOENT) {
       return;
@@ -449,7 +449,7 @@ static void _deletePath(const Path& path, unsigned long long& bytesFreed) {
 }
 
 void deletePath(const Path& path) {
-  unsigned long long dummy = 0;
+  unsigned long long dummy;
   deletePath(path, dummy);
 }
 
@@ -514,8 +514,8 @@ static Lazy<Path> getHome2([]() {
   Path homeDir = getEnv("HOME");
   if (homeDir.empty()) {
     std::vector<char> buf(16384);
-    struct passwd pwbuf {};
-    struct passwd* pw = nullptr;
+    struct passwd pwbuf;
+    struct passwd* pw;
     if (getpwuid_r(geteuid(), &pwbuf, buf.data(), buf.size(), &pw) != 0 ||
         (pw == nullptr) || (pw->pw_dir == nullptr) || (pw->pw_dir[0] == 0)) {
       throw Error("cannot determine user's home directory");
@@ -567,7 +567,7 @@ Paths createDirs(const Path& path) {
     return created;
   }
 
-  struct stat st {};
+  struct stat st;
   if (lstat(path.c_str(), &st) == -1) {
     created = createDirs(dirOf(path));
     if (mkdir(path.c_str(), 0777) == -1 && errno != EEXIST) {
@@ -619,7 +619,7 @@ void replaceSymlink(const Path& target, const Path& link) {
 void readFull(int fd, unsigned char* buf, size_t count) {
   while (count != 0u) {
     checkInterrupt();
-    ssize_t res = read(fd, reinterpret_cast<char*>(buf), count);
+    ssize_t res = read(fd, (char*)buf, count);
     if (res == -1) {
       if (errno == EINTR) {
         continue;
@@ -652,8 +652,7 @@ void writeFull(int fd, const unsigned char* buf, size_t count,
 }
 
 void writeFull(int fd, const std::string& s, bool allowInterrupts) {
-  writeFull(fd, reinterpret_cast<const unsigned char*>(s.data()), s.size(),
-            allowInterrupts);
+  writeFull(fd, (const unsigned char*)s.data(), s.size(), allowInterrupts);
 }
 
 std::string drainFD(int fd, bool block) {
@@ -663,7 +662,7 @@ std::string drainFD(int fd, bool block) {
 }
 
 void drainFD(int fd, Sink& sink, bool block) {
-  int saved = 0;
+  int saved;
 
   Finally finally([&]() {
     if (!block) {
@@ -830,7 +829,7 @@ int Pid::kill() {
 int Pid::wait() {
   assert(pid != -1);
   while (true) {
-    int status = 0;
+    int status;
     int res = waitpid(pid, &status, 0);
     if (res == pid) {
       pid = -1;
@@ -955,7 +954,7 @@ pid_t startProcess(std::function<void()> fun, const ProcessOptions& options) {
 std::vector<char*> stringsToCharPtrs(const Strings& ss) {
   std::vector<char*> res;
   for (auto& s : ss) {
-    res.push_back(const_cast<char*>(s.c_str()));
+    res.push_back((char*)s.c_str());
   }
   res.push_back(nullptr);
   return res;
@@ -1086,7 +1085,7 @@ void runProgram2(const RunOptions& options) {
       try {
         std::vector<unsigned char> buf(8 * 1024);
         while (true) {
-          size_t n = 0;
+          size_t n;
           try {
             n = source->read(buf.data(), buf.size());
           } catch (EndOfFile&) {
@@ -1145,7 +1144,7 @@ void closeMostFDs(const std::set<int>& exceptions) {
 }
 
 void closeOnExec(int fd) {
-  int prev = 0;
+  int prev;
   if ((prev = fcntl(fd, F_GETFD, 0)) == -1 ||
       fcntl(fd, F_SETFD, prev | FD_CLOEXEC) == -1) {
     throw SysError("setting close-on-exec flag");
@@ -1271,7 +1270,7 @@ std::string filterANSIEscapes(const std::string& s, bool filterAll,
   size_t w = 0;
   auto i = s.begin();
 
-  while (w < static_cast<size_t>(width) && i != s.end()) {
+  while (w < (size_t)width && i != s.end()) {
     if (*i == '\e') {
       std::string e;
       e += *i++;
@@ -1306,7 +1305,7 @@ std::string filterANSIEscapes(const std::string& s, bool filterAll,
       i++;
       t += ' ';
       w++;
-      while (w < static_cast<size_t>(width) && ((w % 8) != 0u)) {
+      while (w < (size_t)width && ((w % 8) != 0u)) {
         t += ' ';
         w++;
       }
@@ -1338,7 +1337,7 @@ void callFailure(const std::function<void(std::exception_ptr exc)>& failure,
 static Sync<std::pair<unsigned short, unsigned short>> windowSize{{0, 0}};
 
 static void updateWindowSize() {
-  struct winsize ws {};
+  struct winsize ws;
   if (ioctl(2, TIOCGWINSZ, &ws) == 0) {
     auto windowSize_(windowSize.lock());
     windowSize_->first = ws.ws_row;
diff --git a/third_party/nix/src/libutil/util.hh b/third_party/nix/src/libutil/util.hh
index 09f237060..d9fc1a27b 100644
--- a/third_party/nix/src/libutil/util.hh
+++ b/third_party/nix/src/libutil/util.hh
@@ -163,7 +163,7 @@ void drainFD(int fd, Sink& sink, bool block = true);
 class AutoDelete {
   Path path;
   bool del;
-  bool recursive{};
+  bool recursive;
 
  public:
   AutoDelete();
diff --git a/third_party/nix/src/nix-build/nix-build.cc b/third_party/nix/src/nix-build/nix-build.cc
index d2a4a23cc..7ebb14e1f 100644
--- a/third_party/nix/src/nix-build/nix-build.cc
+++ b/third_party/nix/src/nix-build/nix-build.cc
@@ -155,7 +155,7 @@ static void _main(int argc, char** argv) {
           ;  // obsolete
 
         } else if (*arg == "--no-out-link" || *arg == "--no-link") {
-          outLink = Path(tmpDir) + "/result";
+          outLink = (Path)tmpDir + "/result";
 
         } else if (*arg == "--attr" || *arg == "-A") {
           attrPaths.push_back(getArg(*arg, arg, end));
@@ -328,7 +328,7 @@ static void _main(int argc, char** argv) {
   }
 
   for (auto e : exprs) {
-    Value vRoot{};
+    Value vRoot;
     state->eval(e, vRoot);
 
     for (auto& i : attrPaths) {
@@ -343,8 +343,8 @@ static void _main(int argc, char** argv) {
   auto buildPaths = [&](const PathSet& paths) {
     /* Note: we do this even when !printMissing to efficiently
        fetch binary cache data. */
-    unsigned long long downloadSize = 0;
-    unsigned long long narSize = 0;
+    unsigned long long downloadSize;
+    unsigned long long narSize;
     PathSet willBuild;
     PathSet willSubstitute;
     PathSet unknown;
@@ -381,7 +381,7 @@ static void _main(int argc, char** argv) {
         auto expr = state->parseExprFromString(
             "(import <nixpkgs> {}).bashInteractive", absPath("."));
 
-        Value v{};
+        Value v;
         state->eval(expr, v);
 
         auto drv = getDerivation(*state, v, false);
@@ -453,7 +453,7 @@ static void _main(int argc, char** argv) {
       if (passAsFile.count(var.first) != 0u) {
         keepTmp = true;
         std::string fn = ".attr-" + std::to_string(fileNr++);
-        Path p = Path(tmpDir) + "/" + fn;
+        Path p = (Path)tmpDir + "/" + fn;
         writeFile(p, var.second);
         env[var.first + "Path"] = p;
       } else {
@@ -467,7 +467,7 @@ static void _main(int argc, char** argv) {
        convenience, source $stdenv/setup to setup additional
        environment variables and shell functions.  Also don't
        lose the current $PATH directories. */
-    auto rcfile = Path(tmpDir) + "/rc";
+    auto rcfile = (Path)tmpDir + "/rc";
     writeFile(
         rcfile,
         fmt((keepTmp ? "" : "rm -rf '%1%'; "s) +
@@ -486,7 +486,7 @@ static void _main(int argc, char** argv) {
                 "shopt -u nullglob; "
                 "unset TZ; %6%"
                 "%7%",
-            Path(tmpDir), (pure ? "" : "p=$PATH; "),
+            (Path)tmpDir, (pure ? "" : "p=$PATH; "),
             (pure ? "" : "PATH=$PATH:$p; unset p; "), dirOf(shell), shell,
             (getenv("TZ") != nullptr
                  ? (std::string("export TZ='") + getenv("TZ") + "'; ")
diff --git a/third_party/nix/src/nix-channel/nix-channel.cc b/third_party/nix/src/nix-channel/nix-channel.cc
index 7d60752e3..837fb861d 100644
--- a/third_party/nix/src/nix-channel/nix-channel.cc
+++ b/third_party/nix/src/nix-channel/nix-channel.cc
@@ -112,7 +112,7 @@ static void update(const StringSet& channelNames) {
     std::smatch match;
     auto urlBase = baseNameOf(url);
     if (std::regex_search(urlBase, match, std::regex("(-\\d.*)$"))) {
-      cname = cname + std::string(match[1]);
+      cname = cname + (std::string)match[1];
     }
 
     std::string extraAttrs;
@@ -163,7 +163,7 @@ static void update(const StringSet& channelNames) {
   runProgram(settings.nixBinDir + "/nix-env", false, envArgs);
 
   // Make the channels appear in nix-env.
-  struct stat st {};
+  struct stat st;
   if (lstat(nixDefExpr.c_str(), &st) == 0) {
     if (S_ISLNK(st.st_mode)) {
       // old-skool ~/.nix-defexpr
@@ -193,7 +193,7 @@ static int _main(int argc, char** argv) {
     enum { cNone, cAdd, cRemove, cList, cUpdate, cRollback } cmd = cNone;
     std::vector<std::string> args;
     parseCmdLine(argc, argv,
-                 [&](Strings::iterator& arg, const Strings::iterator& _end) {
+                 [&](Strings::iterator& arg, const Strings::iterator& end) {
                    if (*arg == "--help") {
                      showManPage("nix-channel");
                    } else if (*arg == "--version") {
diff --git a/third_party/nix/src/nix-copy-closure/nix-copy-closure.cc b/third_party/nix/src/nix-copy-closure/nix-copy-closure.cc
index 75768d313..3dbe29f22 100644
--- a/third_party/nix/src/nix-copy-closure/nix-copy-closure.cc
+++ b/third_party/nix/src/nix-copy-closure/nix-copy-closure.cc
@@ -17,7 +17,7 @@ static int _main(int argc, char** argv) {
     PathSet storePaths;
 
     parseCmdLine(
-        argc, argv, [&](Strings::iterator& arg, const Strings::iterator& _end) {
+        argc, argv, [&](Strings::iterator& arg, const Strings::iterator& end) {
           if (*arg == "--help") {
             showManPage("nix-copy-closure");
           } else if (*arg == "--version") {
diff --git a/third_party/nix/src/nix-daemon/nix-daemon-proto.cc b/third_party/nix/src/nix-daemon/nix-daemon-proto.cc
index 58f775438..63c68ed1e 100644
--- a/third_party/nix/src/nix-daemon/nix-daemon-proto.cc
+++ b/third_party/nix/src/nix-daemon/nix-daemon-proto.cc
@@ -22,6 +22,7 @@
 namespace nix::daemon {
 
 using ::grpc::Status;
+using ::nix::proto::BuildStatus;
 using ::nix::proto::PathInfo;
 using ::nix::proto::StorePath;
 using ::nix::proto::StorePaths;
@@ -84,7 +85,7 @@ struct RetrieveRegularNARSink : ParseSink {
 
 class WorkerServiceImpl final : public WorkerService::Service {
  public:
-  explicit WorkerServiceImpl(nix::Store& store) : store_(&store) {}
+  WorkerServiceImpl(nix::Store& store) : store_(&store) {}
 
   Status IsValidPath(grpc::ServerContext* context, const StorePath* request,
                      nix::proto::IsValidPathResponse* response) override {
@@ -394,8 +395,8 @@ class WorkerServiceImpl final : public WorkerService::Service {
     PathSet will_substitute;
     PathSet unknown;
     // TODO(grfn): Switch to concrete size type
-    unsigned long long download_size = 0;
-    unsigned long long nar_size = 0;
+    unsigned long long download_size;
+    unsigned long long nar_size;
 
     store_->queryMissing(targets, will_build, will_substitute, unknown,
                          download_size, nar_size);
diff --git a/third_party/nix/src/nix-daemon/nix-daemon.cc b/third_party/nix/src/nix-daemon/nix-daemon.cc
index fdb539d66..b36f9733c 100644
--- a/third_party/nix/src/nix-daemon/nix-daemon.cc
+++ b/third_party/nix/src/nix-daemon/nix-daemon.cc
@@ -183,7 +183,7 @@ struct RetrieveRegularNARSink : ParseSink {
   void createDirectory(const Path& path) override { regular = false; }
 
   void receiveContents(unsigned char* data, unsigned int len) override {
-    s.append(reinterpret_cast<const char*>(data), len);
+    s.append((const char*)data, len);
   }
 
   void createSymlink(const Path& path, const std::string& target) override {
@@ -296,8 +296,8 @@ static void performOp(TunnelLogger* logger, const ref<Store>& store,
     }
 
     case wopAddToStore: {
-      bool fixed = 0;
-      bool recursive = 0;
+      bool fixed = false;
+      bool recursive = false;
       std::string hashType;
       std::string baseName;
       from >> baseName >> fixed /* obsolete */ >> recursive >> hashType;
@@ -376,7 +376,7 @@ static void performOp(TunnelLogger* logger, const ref<Store>& store,
       auto drvs = readStorePaths<PathSet>(*store, from);
       BuildMode mode = bmNormal;
       if (GET_PROTOCOL_MINOR(clientVersion) >= 15) {
-        mode = static_cast<BuildMode>(readInt(from));
+        mode = (BuildMode)readInt(from);
 
         /* Repairing is not atomic, so disallowed for "untrusted"
            clients.  */
@@ -397,7 +397,7 @@ static void performOp(TunnelLogger* logger, const ref<Store>& store,
       Path drvPath = readStorePath(*store, from);
       BasicDerivation drv;
       readDerivation(from, *store, drv);
-      auto buildMode = static_cast<BuildMode>(readInt(from));
+      auto buildMode = (BuildMode)readInt(from);
       logger->startWork();
       if (!trusted) {
         throw Error("you are not privileged to build derivations");
@@ -466,7 +466,7 @@ static void performOp(TunnelLogger* logger, const ref<Store>& store,
 
     case wopCollectGarbage: {
       GCOptions options;
-      options.action = static_cast<GCOptions::GCAction>(readInt(from));
+      options.action = (GCOptions::GCAction)readInt(from);
       options.pathsToDelete = readStorePaths<PathSet>(*store, from);
       from >> options.ignoreLiveness >> options.maxFreed;
       // obsolete fields
@@ -639,15 +639,14 @@ static void performOp(TunnelLogger* logger, const ref<Store>& store,
     }
 
     case wopVerifyStore: {
-      bool checkContents = 0;
-      bool repair = 0;
+      bool checkContents;
+      bool repair;
       from >> checkContents >> repair;
       logger->startWork();
       if (repair && !trusted) {
         throw Error("you are not privileged to repair paths");
       }
-      bool errors =
-          store->verifyStore(checkContents, static_cast<RepairFlag>(repair));
+      bool errors = store->verifyStore(checkContents, (RepairFlag)repair);
       logger->stopWork();
       to << static_cast<uint64_t>(errors);
       break;
@@ -675,8 +674,8 @@ static void performOp(TunnelLogger* logger, const ref<Store>& store,
     }
 
     case wopAddToStoreNar: {
-      bool repair = 0;
-      bool dontCheckSigs = 0;
+      bool repair;
+      bool dontCheckSigs;
       ValidPathInfo info;
       info.path = readStorePath(*store, from);
       from >> info.deriver;
@@ -709,7 +708,7 @@ static void performOp(TunnelLogger* logger, const ref<Store>& store,
       logger->startWork();
 
       // FIXME: race if addToStore doesn't read source?
-      store->addToStore(info, *source, static_cast<RepairFlag>(repair),
+      store->addToStore(info, *source, (RepairFlag)repair,
                         dontCheckSigs ? NoCheckSigs : CheckSigs, nullptr);
 
       logger->stopWork();
@@ -722,8 +721,8 @@ static void performOp(TunnelLogger* logger, const ref<Store>& store,
       PathSet willBuild;
       PathSet willSubstitute;
       PathSet unknown;
-      unsigned long long downloadSize = 0;
-      unsigned long long narSize = 0;
+      unsigned long long downloadSize;
+      unsigned long long narSize;
       store->queryMissing(targets, willBuild, willSubstitute, unknown,
                           downloadSize, narSize);
       logger->stopWork();
@@ -796,9 +795,9 @@ static void processConnection(bool trusted, const std::string& userName,
 
     /* Process client requests. */
     while (true) {
-      WorkerOp op{};
+      WorkerOp op;
       try {
-        op = static_cast<WorkerOp>(readInt(from));
+        op = (WorkerOp)readInt(from);
       } catch (Interrupted& e) {
         break;
       } catch (EndOfFile& e) {
@@ -848,8 +847,8 @@ static void sigChldHandler(int sigNo) {
 }
 
 static void setSigChldAction(bool autoReap) {
-  struct sigaction act {};
-  struct sigaction oact {};
+  struct sigaction act;
+  struct sigaction oact;
   act.sa_handler = autoReap ? sigChldHandler : SIG_DFL;
   sigfillset(&act.sa_mask);
   act.sa_flags = 0;
@@ -903,7 +902,7 @@ static PeerInfo getPeerInfo(int remote) {
 
 #if defined(SO_PEERCRED)
 
-  ucred cred{};
+  ucred cred;
   socklen_t credLen = sizeof(cred);
   if (getsockopt(remote, SOL_SOCKET, SO_PEERCRED, &cred, &credLen) == -1) {
     throw SysError("getting peer credentials");
@@ -969,7 +968,7 @@ static void daemonLoop(char** argv) {
     }
     Path socketPathRel = "./" + baseNameOf(socketPath);
 
-    struct sockaddr_un addr {};
+    struct sockaddr_un addr;
     addr.sun_family = AF_UNIX;
     strncpy(addr.sun_path, socketPathRel.c_str(), sizeof(addr.sun_path));
     if (addr.sun_path[sizeof(addr.sun_path) - 1] != '\0') {
@@ -982,8 +981,7 @@ static void daemonLoop(char** argv) {
        (everybody can connect --- provided they have access to the
        directory containing the socket). */
     mode_t oldMode = umask(0111);
-    int res = bind(fdSocket.get(), reinterpret_cast<struct sockaddr*>(&addr),
-                   sizeof(addr));
+    int res = bind(fdSocket.get(), (struct sockaddr*)&addr, sizeof(addr));
     umask(oldMode);
     if (res == -1) {
       throw SysError(format("cannot bind to socket '%1%'") % socketPath);
@@ -1004,12 +1002,11 @@ static void daemonLoop(char** argv) {
   while (true) {
     try {
       /* Accept a connection. */
-      struct sockaddr_un remoteAddr {};
+      struct sockaddr_un remoteAddr;
       socklen_t remoteAddrLen = sizeof(remoteAddr);
 
-      AutoCloseFD remote = accept(
-          fdSocket.get(), reinterpret_cast<struct sockaddr*>(&remoteAddr),
-          &remoteAddrLen);
+      AutoCloseFD remote =
+          accept(fdSocket.get(), (struct sockaddr*)&remoteAddr, &remoteAddrLen);
       checkInterrupt();
       if (!remote) {
         if (errno == EINTR) {
@@ -1094,7 +1091,7 @@ static int _main(int argc, char** argv) {
     auto stdio = false;
 
     parseCmdLine(argc, argv,
-                 [&](Strings::iterator& arg, const Strings::iterator& _end) {
+                 [&](Strings::iterator& arg, const Strings::iterator& end) {
                    if (*arg == "--daemon") {
                      ; /* ignored for backwards compatibility */
                    } else if (*arg == "--help") {
@@ -1132,8 +1129,7 @@ static int _main(int argc, char** argv) {
           throw Error(format("socket name %1% is too long") % socketName);
         }
 
-        if (connect(s, reinterpret_cast<struct sockaddr*>(&addr),
-                    sizeof(addr)) == -1) {
+        if (connect(s, (struct sockaddr*)&addr, sizeof(addr)) == -1) {
           throw SysError(format("cannot connect to daemon at %1%") %
                          socketPath);
         }
diff --git a/third_party/nix/src/nix-env/nix-env.cc b/third_party/nix/src/nix-env/nix-env.cc
index e01ae0297..585cfbe3f 100644
--- a/third_party/nix/src/nix-env/nix-env.cc
+++ b/third_party/nix/src/nix-env/nix-env.cc
@@ -45,18 +45,18 @@ struct InstallSourceInfo {
   Path nixExprPath;         /* for srcNixExprDrvs, srcNixExprs */
   Path profile;             /* for srcProfile */
   std::string systemFilter; /* for srcNixExprDrvs */
-  Bindings* autoArgs{};
+  Bindings* autoArgs;
 };
 
 struct Globals : public gc {
   InstallSourceInfo instSource;
   Path profile;
   std::shared_ptr<EvalState> state;
-  bool dryRun{};
-  bool preserveInstalled{};
-  bool removeAll{};
+  bool dryRun;
+  bool preserveInstalled;
+  bool removeAll;
   std::string forceName;
-  bool prebuiltOnly{};
+  bool prebuiltOnly;
 };
 
 using Operation = void (*)(Globals&, Strings, Strings);
@@ -106,7 +106,7 @@ static void getAllExprs(EvalState& state, const Path& path, StringSet& attrs,
 
     Path path2 = path + "/" + i;
 
-    struct stat st {};
+    struct stat st;
     if (stat(path2.c_str(), &st) == -1) {
       continue;  // ignore dangling symlinks in ~/.nix-defexpr
     }
@@ -141,7 +141,7 @@ static void getAllExprs(EvalState& state, const Path& path, StringSet& attrs,
 }
 
 static void loadSourceExpr(EvalState& state, const Path& path, Value& v) {
-  struct stat st {};
+  struct stat st;
   if (stat(path.c_str(), &st) == -1) {
     throw SysError(format("getting information about '%1%'") % path);
   }
@@ -171,7 +171,7 @@ static void loadSourceExpr(EvalState& state, const Path& path, Value& v) {
 static void loadDerivations(EvalState& state, const Path& nixExprPath,
                             const std::string& systemFilter, Bindings& autoArgs,
                             const std::string& pathPrefix, DrvInfos& elems) {
-  Value vRoot{};
+  Value vRoot;
   loadSourceExpr(state, nixExprPath, vRoot);
 
   Value& v(*findAlongAttrPath(state, pathPrefix, autoArgs, vRoot));
@@ -189,12 +189,12 @@ static void loadDerivations(EvalState& state, const Path& nixExprPath,
   }
 }
 
-static long getPriority(DrvInfo& drv) {
+static long getPriority(EvalState& state, DrvInfo& drv) {
   return drv.queryMetaInt("priority", 0);
 }
 
 static long comparePriorities(EvalState& state, DrvInfo& drv1, DrvInfo& drv2) {
-  return getPriority(drv2) - getPriority(drv1);
+  return getPriority(state, drv2) - getPriority(state, drv1);
 }
 
 // FIXME: this function is rather slow since it checks a single path
@@ -346,13 +346,13 @@ static void queryInstSources(EvalState& state, InstallSourceInfo& instSource,
        argument `x: x.bar' is equivalent to `(x: x.bar)
        (import ./foo.nix)' = `(import ./foo.nix).bar'. */
     case srcNixExprs: {
-      Value vArg{};
+      Value vArg;
       loadSourceExpr(state, instSource.nixExprPath, vArg);
 
       for (auto& i : args) {
         Expr* eFun = state.parseExprFromString(i, absPath("."));
-        Value vFun{};
-        Value vTmp{};
+        Value vFun;
+        Value vTmp;
         state.eval(eFun, vFun);
         mkApp(vTmp, vFun, vArg);
         getDerivations(state, vTmp, "", *instSource.autoArgs, elems, true);
@@ -406,7 +406,7 @@ static void queryInstSources(EvalState& state, InstallSourceInfo& instSource,
     }
 
     case srcAttrPath: {
-      Value vRoot{};
+      Value vRoot;
       loadSourceExpr(state, instSource.nixExprPath, vRoot);
       for (auto& i : args) {
         Value& v(*findAlongAttrPath(state, i, *instSource.autoArgs, vRoot));
@@ -802,7 +802,7 @@ void printTable(Table& table) {
   for (auto& i : table) {
     assert(i.size() == nrColumns);
     Strings::iterator j;
-    size_t column = 0;
+    size_t column;
     for (j = i.begin(), column = 0; j != i.end(); ++j, ++column) {
       if (j->size() > widths[column]) {
         widths[column] = j->size();
@@ -812,7 +812,7 @@ void printTable(Table& table) {
 
   for (auto& i : table) {
     Strings::iterator j;
-    size_t column = 0;
+    size_t column;
     for (j = i.begin(), column = 0; j != i.end(); ++j, ++column) {
       std::string s = *j;
       replace(s.begin(), s.end(), '\n', ' ');
@@ -1050,7 +1050,7 @@ static void opQuery(Globals& globals, Strings opFlags, Strings opArgs) {
           attrs["valid"] = isValid ? "1" : "0";
           attrs["substitutable"] = hasSubs ? "1" : "0";
         } else {
-          columns.push_back(std::string(isInstalled ? "I" : "-") +
+          columns.push_back((std::string)(isInstalled ? "I" : "-") +
                             (isValid ? "P" : "-") + (hasSubs ? "S" : "-"));
         }
       }
@@ -1078,7 +1078,7 @@ static void opQuery(Globals& globals, Strings opFlags, Strings opArgs) {
         std::string version;
         VersionDiff diff = compareVersionAgainstSet(i, otherElems, version);
 
-        char ch = 0;
+        char ch;
         switch (diff) {
           case cvLess:
             ch = '>';
@@ -1102,7 +1102,7 @@ static void opQuery(Globals& globals, Strings opFlags, Strings opArgs) {
             attrs["maxComparedVersion"] = version;
           }
         } else {
-          std::string column = std::string("") + ch + " " + version;
+          std::string column = (std::string) "" + ch + " " + version;
           if (diff == cvGreater && tty) {
             column = ANSI_RED + column + ANSI_NORMAL;
           }
@@ -1266,7 +1266,7 @@ static void switchGeneration(Globals& globals, int dstGen) {
   PathLocks lock;
   lockProfile(lock, globals.profile);
 
-  int curGen = 0;
+  int curGen;
   Generations gens = findGenerations(globals.profile, curGen);
 
   Generation dst;
@@ -1303,7 +1303,7 @@ static void opSwitchGeneration(Globals& globals, Strings opFlags,
     throw UsageError(format("exactly one argument expected"));
   }
 
-  int dstGen = 0;
+  int dstGen;
   if (!absl::SimpleAtoi(opArgs.front(), &dstGen)) {
     throw UsageError(format("expected a generation number"));
   }
@@ -1334,13 +1334,13 @@ static void opListGenerations(Globals& globals, Strings opFlags,
   PathLocks lock;
   lockProfile(lock, globals.profile);
 
-  int curGen = 0;
+  int curGen;
   Generations gens = findGenerations(globals.profile, curGen);
 
   RunPager pager;
 
   for (auto& i : gens) {
-    tm t{};
+    tm t;
     if (localtime_r(&i.creationTime, &t) == nullptr) {
       throw Error("cannot convert time");
     }
@@ -1369,7 +1369,7 @@ static void opDeleteGenerations(Globals& globals, Strings opFlags,
                   opArgs.front());
     }
     std::string str_max = std::string(opArgs.front(), 1, opArgs.front().size());
-    int max = 0;
+    int max;
     if (!absl::SimpleAtoi(str_max, &max) || max == 0) {
       throw Error(format("invalid number of generations to keep ‘%1%’") %
                   opArgs.front());
@@ -1378,7 +1378,7 @@ static void opDeleteGenerations(Globals& globals, Strings opFlags,
   } else {
     std::set<unsigned int> gens;
     for (auto& i : opArgs) {
-      unsigned int n = 0;
+      unsigned int n;
       if (!absl::SimpleAtoi(i, &n)) {
         throw UsageError(format("invalid generation number '%1%'") % i);
       }
diff --git a/third_party/nix/src/nix-env/user-env.cc b/third_party/nix/src/nix-env/user-env.cc
index 93dcde969..06329e74f 100644
--- a/third_party/nix/src/nix-env/user-env.cc
+++ b/third_party/nix/src/nix-env/user-env.cc
@@ -17,7 +17,7 @@ DrvInfos queryInstalled(EvalState& state, const Path& userEnv) {
   DrvInfos elems;
   Path manifestFile = userEnv + "/manifest.nix";
   if (pathExists(manifestFile)) {
-    Value v{};
+    Value v;
     state.evalFile(manifestFile, v);
     Bindings& bindings(*Bindings::NewGC());
     getDerivations(state, v, "", bindings, elems, false);
@@ -42,7 +42,7 @@ bool createUserEnv(EvalState& state, DrvInfos& elems, const Path& profile,
 
   /* Construct the whole top level derivation. */
   PathSet references;
-  Value manifest{};
+  Value manifest;
   state.mkList(manifest, elems.size());
   unsigned int n = 0;
   for (auto& i : elems) {
@@ -109,13 +109,13 @@ bool createUserEnv(EvalState& state, DrvInfos& elems, const Path& profile,
       "env-manifest.nix", (format("%1%") % manifest).str(), references);
 
   /* Get the environment builder expression. */
-  Value envBuilder{};
+  Value envBuilder;
   state.evalFile(state.findFile("nix/buildenv.nix"), envBuilder);
 
   /* Construct a Nix expression that calls the user environment
      builder with the manifest as argument. */
-  Value args{};
-  Value topLevel{};
+  Value args;
+  Value topLevel;
   state.mkAttrs(args, 3);
   mkString(*state.allocAttr(args, state.symbols.Create("manifest")),
            manifestFile, {manifestFile});
diff --git a/third_party/nix/src/nix-instantiate/nix-instantiate.cc b/third_party/nix/src/nix-instantiate/nix-instantiate.cc
index e963cc145..be96943b1 100644
--- a/third_party/nix/src/nix-instantiate/nix-instantiate.cc
+++ b/third_party/nix/src/nix-instantiate/nix-instantiate.cc
@@ -30,7 +30,7 @@ void processExpr(EvalState& state, const Strings& attrPaths, bool parseOnly,
     return;
   }
 
-  Value vRoot{};
+  Value vRoot;
   state.eval(e, vRoot);
 
   for (auto& i : attrPaths) {
@@ -39,7 +39,7 @@ void processExpr(EvalState& state, const Strings& attrPaths, bool parseOnly,
 
     PathSet context;
     if (evalOnly) {
-      Value vRes{};
+      Value vRes;
       if (autoArgs.empty()) {
         vRes = v;
       } else {
diff --git a/third_party/nix/src/nix-prefetch-url/nix-prefetch-url.cc b/third_party/nix/src/nix-prefetch-url/nix-prefetch-url.cc
index 644df1dba..839227c1b 100644
--- a/third_party/nix/src/nix-prefetch-url/nix-prefetch-url.cc
+++ b/third_party/nix/src/nix-prefetch-url/nix-prefetch-url.cc
@@ -33,7 +33,7 @@ std::string resolveMirrorUri(EvalState& state, std::string uri) {
   }
   std::string mirrorName(s, 0, p);
 
-  Value vMirrors{};
+  Value vMirrors;
   state.eval(
       state.parseExprFromString(
           "import <nixpkgs/pkgs/build-support/fetchurl/mirrors.nix>", "."),
@@ -120,7 +120,7 @@ static int _main(int argc, char** argv) {
     } else {
       Path path =
           resolveExprPath(lookupFileArg(*state, args.empty() ? "." : args[0]));
-      Value vRoot{};
+      Value vRoot;
       state->evalFile(path, vRoot);
       Value& v(*findAlongAttrPath(*state, attrPath, autoArgs, vRoot));
       state->forceAttrs(v);
@@ -181,7 +181,7 @@ static int _main(int argc, char** argv) {
       auto actualUri = resolveMirrorUri(*state, uri);
 
       AutoDelete tmpDir(createTempDir(), true);
-      Path tmpFile = Path(tmpDir) + "/tmp";
+      Path tmpFile = (Path)tmpDir + "/tmp";
 
       /* Download the file. */
       {
@@ -201,7 +201,7 @@ static int _main(int argc, char** argv) {
       /* Optionally unpack the file. */
       if (unpack) {
         LOG(INFO) << "unpacking...";
-        Path unpacked = Path(tmpDir) + "/unpacked";
+        Path unpacked = (Path)tmpDir + "/unpacked";
         createDirs(unpacked);
         if (absl::EndsWith(baseNameOf(uri), ".zip")) {
           runProgram("unzip", true, {"-qq", tmpFile, "-d", unpacked});
diff --git a/third_party/nix/src/nix-store/nix-store.cc b/third_party/nix/src/nix-store/nix-store.cc
index 9f37bfbca..df17e5644 100644
--- a/third_party/nix/src/nix-store/nix-store.cc
+++ b/third_party/nix/src/nix-store/nix-store.cc
@@ -155,8 +155,8 @@ static void opRealise(Strings opFlags, Strings opArgs) {
         store->followLinksToStorePath(p.first), p.second));
   }
 
-  unsigned long long downloadSize = 0;
-  unsigned long long narSize = 0;
+  unsigned long long downloadSize;
+  unsigned long long narSize;
   PathSet willBuild;
   PathSet willSubstitute;
   PathSet unknown;
@@ -962,9 +962,9 @@ static void opServe(Strings opFlags, Strings opArgs) {
   };
 
   while (true) {
-    ServeCommand cmd{};
+    ServeCommand cmd;
     try {
-      cmd = static_cast<ServeCommand>(readInt(in));
+      cmd = (ServeCommand)readInt(in);
     } catch (EndOfFile& e) {
       break;
     }
@@ -991,8 +991,8 @@ static void opServe(Strings opFlags, Strings opArgs) {
               paths2.insert(path);
             }
           }
-          unsigned long long downloadSize = 0;
-          unsigned long long narSize = 0;
+          unsigned long long downloadSize;
+          unsigned long long narSize;
           PathSet willBuild;
           PathSet willSubstitute;
           PathSet unknown;
@@ -1174,15 +1174,13 @@ static void opGenerateBinaryCacheKey(Strings opFlags, Strings opArgs) {
     throw Error("key generation failed");
   }
 
-  writeFile(publicKeyFile,
-            keyName + ":" +
-                absl::Base64Escape(std::string(reinterpret_cast<char*>(pk),
-                                               crypto_sign_PUBLICKEYBYTES)));
+  writeFile(publicKeyFile, keyName + ":" +
+                               absl::Base64Escape(std::string(
+                                   (char*)pk, crypto_sign_PUBLICKEYBYTES)));
   umask(0077);
-  writeFile(secretKeyFile,
-            keyName + ":" +
-                absl::Base64Escape(std::string(reinterpret_cast<char*>(sk),
-                                               crypto_sign_SECRETKEYBYTES)));
+  writeFile(secretKeyFile, keyName + ":" +
+                               absl::Base64Escape(std::string(
+                                   (char*)sk, crypto_sign_SECRETKEYBYTES)));
 #else
   throw Error(
       "Nix was not compiled with libsodium, required for signed binary cache "
diff --git a/third_party/nix/src/nix/edit.cc b/third_party/nix/src/nix/edit.cc
index 94a42abb7..958e8aec4 100644
--- a/third_party/nix/src/nix/edit.cc
+++ b/third_party/nix/src/nix/edit.cc
@@ -28,7 +28,7 @@ struct CmdEdit final : InstallableCommand {
 
     auto v = installable->toValue(*state);
 
-    Value* v2 = nullptr;
+    Value* v2;
     try {
       auto dummyArgs = Bindings::NewGC();
       v2 = findAlongAttrPath(*state, "meta.position", *dummyArgs, *v);
@@ -46,7 +46,7 @@ struct CmdEdit final : InstallableCommand {
     }
 
     std::string filename(pos, 0, colon);
-    int lineno = 0;
+    int lineno;
     try {
       lineno = std::stoi(std::string(pos, colon + 1));
     } catch (std::invalid_argument& e) {
diff --git a/third_party/nix/src/nix/main.cc b/third_party/nix/src/nix/main.cc
index fa9ebe374..5536aac53 100644
--- a/third_party/nix/src/nix/main.cc
+++ b/third_party/nix/src/nix/main.cc
@@ -25,7 +25,7 @@ namespace nix {
 
 /* Check if we have a non-loopback/link-local network interface. */
 static bool haveInternet() {
-  struct ifaddrs* addrs = nullptr;
+  struct ifaddrs* addrs;
 
   if (getifaddrs(&addrs) != 0) {
     return true;
@@ -38,8 +38,7 @@ static bool haveInternet() {
       continue;
     }
     if (i->ifa_addr->sa_family == AF_INET) {
-      if (ntohl(
-              (reinterpret_cast<sockaddr_in*>(i->ifa_addr))->sin_addr.s_addr) !=
+      if (ntohl(((sockaddr_in*)i->ifa_addr)->sin_addr.s_addr) !=
           INADDR_LOOPBACK) {
         return true;
       }
diff --git a/third_party/nix/src/nix/path-info.cc b/third_party/nix/src/nix/path-info.cc
index 300a588a2..dca08b06a 100644
--- a/third_party/nix/src/nix/path-info.cc
+++ b/third_party/nix/src/nix/path-info.cc
@@ -96,9 +96,7 @@ struct CmdPathInfo final : StorePathsCommand, MixJSON {
 
         if (showSize || showClosureSize || showSigs) {
           std::cout << std::string(
-              std::max(0, static_cast<int>(pathLen) -
-                              static_cast<int>(storePath.size())),
-              ' ');
+              std::max(0, (int)pathLen - (int)storePath.size()), ' ');
         }
 
         if (showSize) {
diff --git a/third_party/nix/src/nix/repl.cc b/third_party/nix/src/nix/repl.cc
index 91bf50089..7644b7b8c 100644
--- a/third_party/nix/src/nix/repl.cc
+++ b/third_party/nix/src/nix/repl.cc
@@ -38,14 +38,14 @@ namespace nix {
 struct NixRepl : gc {
   std::string curDir;
   EvalState state;
-  Bindings* autoArgs{};
+  Bindings* autoArgs;
 
   Strings loadedFiles;
 
   const static int envSize = 32768;
   StaticEnv staticEnv;
-  Env* env{};
-  int displ{};
+  Env* env;
+  int displ;
   StringSet varNames;
 
   const Path historyFile;
@@ -194,7 +194,7 @@ static int listPossibleCallback(char* s, char*** avp) {
     return p;
   };
 
-  vp = check(static_cast<char**>(malloc(possible.size() * sizeof(char*))));
+  vp = check((char**)malloc(possible.size() * sizeof(char*)));
 
   for (auto& p : possible) {
     vp[ac++] = check(strdup(p.c_str()));
@@ -272,8 +272,8 @@ void NixRepl::mainLoop(const std::vector<std::string>& files) {
 }
 
 bool NixRepl::getLine(std::string& input, const std::string& prompt) {
-  struct sigaction act {};
-  struct sigaction old {};
+  struct sigaction act;
+  struct sigaction old;
   sigset_t savedSignalMask;
   sigset_t set;
 
@@ -334,8 +334,8 @@ StringSet NixRepl::completePrefix(const std::string& prefix) {
     cur = std::string(prefix, start + 1);
   }
 
-  size_t slash = 0;
-  size_t dot = 0;
+  size_t slash;
+  size_t dot;
 
   if ((slash = cur.rfind('/')) != std::string::npos) {
     try {
@@ -367,7 +367,7 @@ StringSet NixRepl::completePrefix(const std::string& prefix) {
       std::string cur2 = std::string(cur, dot + 1);
 
       Expr* e = parseString(expr);
-      Value v{};
+      Value v;
       e->eval(state, *env, v);
       state.forceAttrs(v);
 
@@ -477,7 +477,7 @@ bool NixRepl::processLine(std::string line) {
   }
 
   else if (command == ":a" || command == ":add") {
-    Value v{};
+    Value v;
     evalString(arg, v);
     addAttrsToScope(v);
   }
@@ -493,14 +493,14 @@ bool NixRepl::processLine(std::string line) {
   }
 
   else if (command == ":t") {
-    Value v{};
+    Value v;
     evalString(arg, v);
     std::cout << showType(v) << std::endl;
 
   } else if (command == ":u") {
-    Value v{};
-    Value f{};
-    Value result{};
+    Value v;
+    Value f;
+    Value result;
     evalString(arg, v);
     evalString(
         "drv: (import <nixpkgs> {}).runCommand \"shell\" { buildInputs = [ drv "
@@ -513,7 +513,7 @@ bool NixRepl::processLine(std::string line) {
   }
 
   else if (command == ":b" || command == ":i" || command == ":s") {
-    Value v{};
+    Value v;
     evalString(arg, v);
     Path drvPath = getDerivationPath(v);
 
@@ -540,7 +540,7 @@ bool NixRepl::processLine(std::string line) {
   }
 
   else if (command == ":p" || command == ":print") {
-    Value v{};
+    Value v;
     evalString(arg, v);
     printValue(std::cout, v, 1000000000) << std::endl;
   }
@@ -563,7 +563,7 @@ bool NixRepl::processLine(std::string line) {
       v.thunk.expr = e;
       addVarToScope(state.symbols.Create(name), v);
     } else {
-      Value v{};
+      Value v;
       evalString(line, v);
       printValue(std::cout, v, 1) << std::endl;
     }
@@ -575,8 +575,8 @@ bool NixRepl::processLine(std::string line) {
 void NixRepl::loadFile(const Path& path) {
   loadedFiles.remove(path);
   loadedFiles.push_back(path);
-  Value v{};
-  Value v2{};
+  Value v;
+  Value v2;
   state.evalFile(lookupFileArg(state, path), v);
   state.autoCallFunction(*autoArgs, v, v2);
   addAttrsToScope(v2);
@@ -626,7 +626,7 @@ void NixRepl::addVarToScope(const Symbol& name, Value& v) {
   }
   staticEnv.vars[name] = displ;
   env->values[displ++] = &v;
-  varNames.insert(std::string(name));
+  varNames.insert((std::string)name);
 }
 
 Expr* NixRepl::parseString(const std::string& s) {
diff --git a/third_party/nix/src/nix/search.cc b/third_party/nix/src/nix/search.cc
index b53f0b508..2bfdeac6f 100644
--- a/third_party/nix/src/nix/search.cc
+++ b/third_party/nix/src/nix/search.cc
@@ -196,8 +196,8 @@ struct CmdSearch final : SourceExprCommand, MixJSON {
                     : nullptr;
             doExpr(i.second.value,
                    attrPath.empty()
-                       ? std::string(i.second.name)
-                       : attrPath + "." + std::string(i.second.name),
+                       ? (std::string)i.second.name
+                       : attrPath + "." + (std::string)i.second.name,
                    toplevel2 || fromCache, cache2 ? cache2.get() : nullptr);
           }
         }
@@ -216,7 +216,7 @@ struct CmdSearch final : SourceExprCommand, MixJSON {
     if (useCache && pathExists(jsonCacheFileName)) {
       LOG(WARNING) << "using cached results; pass '-u' to update the cache";
 
-      Value vRoot{};
+      Value vRoot;
       parseJSON(*state, readFile(jsonCacheFileName), vRoot);
 
       fromCache = true;
diff --git a/third_party/nix/src/nix/verify.cc b/third_party/nix/src/nix/verify.cc
index 6552e3d1a..a9959d50d 100644
--- a/third_party/nix/src/nix/verify.cc
+++ b/third_party/nix/src/nix/verify.cc
@@ -99,8 +99,7 @@ struct CmdVerify final : StorePathsCommand {
 
           } else {
             StringSet sigsSeen;
-            size_t actualSigsNeeded =
-                std::max(sigsNeeded, static_cast<size_t>(1));
+            size_t actualSigsNeeded = std::max(sigsNeeded, (size_t)1);
             size_t validSigs = 0;
 
             auto doSigs = [&](const StringSet& sigs) {
diff --git a/third_party/nix/src/tests/attr-set.cc b/third_party/nix/src/tests/attr-set.cc
index 8ebbbb525..e8ad86664 100644
--- a/third_party/nix/src/tests/attr-set.cc
+++ b/third_party/nix/src/tests/attr-set.cc
@@ -113,7 +113,7 @@ using nix::tests::DummyStore;
 
 class AttrSetTest : public ::testing::Test {
  protected:
-  EvalState* eval_state_{};
+  EvalState* eval_state_;
   void SetUp() override {
     nix::initGC();
     auto store = std::make_shared<DummyStore>();
@@ -122,8 +122,8 @@ class AttrSetTest : public ::testing::Test {
   }
 
   void assert_bindings_equal(nix::Bindings& lhs, nix::Bindings& rhs) {
-    Value lhs_val{};
-    Value rhs_val{};
+    Value lhs_val;
+    Value rhs_val;
     lhs_val.type = rhs_val.type = ValueType::tAttrs;
     lhs_val.attrs = &lhs;
     rhs_val.attrs = &lhs;
diff --git a/third_party/nix/src/tests/language-tests.cc b/third_party/nix/src/tests/language-tests.cc
index 9616f5e15..9fb453e5e 100644
--- a/third_party/nix/src/tests/language-tests.cc
+++ b/third_party/nix/src/tests/language-tests.cc
@@ -181,7 +181,7 @@ TEST_P(EvalFailureTest, Fails) {
   // Again, there are multiple expected exception types and the tests
   // don't specify which ones they are looking for.
   try {
-    Value result{};
+    Value result;
     state.eval(expr, result);
     state.forceValue(result);
     std::cout << result;
@@ -216,7 +216,7 @@ TEST_P(EvalSuccessTest, Fails) {
   ASSERT_NO_THROW(expr = state.parseExprFromFile(GetParam().string()))
       << path.stem().string() << ": should parse successfully";
 
-  Value result{};
+  Value result;
 
   ASSERT_NO_THROW({
     state.eval(expr, result);
diff --git a/third_party/nix/src/tests/value-to-json.cc b/third_party/nix/src/tests/value-to-json.cc
index fbc1fa54d..573eb6582 100644
--- a/third_party/nix/src/tests/value-to-json.cc
+++ b/third_party/nix/src/tests/value-to-json.cc
@@ -12,9 +12,9 @@
 
 class ValueTest : public ::testing::Test {
  protected:
-  static void SetUpTestSuite() { nix::initGC(); }
+  static void SetUpTestCase() { nix::initGC(); }
 
-  static void TearDownTestSuite() {}
+  static void TearDownTestCase() {}
 };
 
 class JSONValueTest : public ValueTest {};
@@ -26,7 +26,7 @@ using nix::tests::DummyStore;
 
 TEST_F(JSONValueTest, null) {
   std::stringstream ss;
-  Value v{};
+  Value v;
   PathSet ps;
   std::shared_ptr<Store> store = std::make_shared<DummyStore>();
   EvalState s({}, ref<Store>(store));
@@ -40,7 +40,7 @@ TEST_F(JSONValueTest, BoolFalse) {
   std::stringstream ss;
   auto store = std::make_shared<DummyStore>();
   EvalState s({"."}, ref<Store>(store));
-  Value v{};
+  Value v;
   PathSet ps;
 
   mkBool(v, false);
@@ -52,7 +52,7 @@ TEST_F(JSONValueTest, BoolTrue) {
   std::stringstream ss;
   auto store = std::make_shared<DummyStore>();
   EvalState s({"."}, ref<Store>(store));
-  Value v{};
+  Value v;
   PathSet ps;
 
   mkBool(v, true);
@@ -64,7 +64,7 @@ TEST_F(JSONValueTest, IntPositive) {
   std::stringstream ss;
   auto store = std::make_shared<DummyStore>();
   EvalState s({"."}, ref<Store>(store));
-  Value v{};
+  Value v;
   PathSet ps;
 
   mkInt(v, 100);
@@ -76,7 +76,7 @@ TEST_F(JSONValueTest, IntNegative) {
   std::stringstream ss;
   auto store = std::make_shared<DummyStore>();
   EvalState s({"."}, ref<Store>(store));
-  Value v{};
+  Value v;
   PathSet ps;
 
   mkInt(v, -100);
@@ -88,7 +88,7 @@ TEST_F(JSONValueTest, String) {
   std::stringstream ss;
   auto store = std::make_shared<DummyStore>();
   EvalState s({"."}, ref<Store>(store));
-  Value v{};
+  Value v;
   PathSet ps;
 
   mkString(v, "test");
@@ -100,7 +100,7 @@ TEST_F(JSONValueTest, StringQuotes) {
   std::stringstream ss;
   auto store = std::make_shared<DummyStore>();
   EvalState s({"."}, ref<Store>(store));
-  Value v{};
+  Value v;
   PathSet ps;
 
   mkString(v, "test\"");
@@ -112,7 +112,7 @@ TEST_F(JSONValueTest, Path) {
   std::stringstream ss;
   auto store = std::make_shared<DummyStore>();
   EvalState s({"."}, ref<Store>(store));
-  Value v{};
+  Value v;
   PathSet ps;
 
   mkPathNoCopy(v, "/exists-for-tests");
@@ -124,7 +124,7 @@ TEST_F(JSONValueTest, PathNoCopy) {
   std::stringstream ss;
   auto store = std::make_shared<DummyStore>();
   EvalState s({"."}, ref<Store>(store));
-  Value v{};
+  Value v;
   PathSet ps;
 
   mkPathNoCopy(v, "/exists-for-tests");
@@ -141,7 +141,7 @@ TEST_F(JSONValueTest, PathNoCopy) {
 
 TEST_F(XMLValueTest, null) {
   std::stringstream ss;
-  Value v{};
+  Value v;
   PathSet ps;
   auto store = std::make_shared<DummyStore>();
   EvalState s({}, ref<Store>(store));
@@ -155,7 +155,7 @@ TEST_F(XMLValueTest, BoolFalse) {
   std::stringstream ss;
   auto store = std::make_shared<DummyStore>();
   EvalState s({"."}, ref<Store>(store));
-  Value v{};
+  Value v;
   PathSet ps;
 
   mkBool(v, false);
@@ -167,7 +167,7 @@ TEST_F(XMLValueTest, BoolTrue) {
   std::stringstream ss;
   auto store = std::make_shared<DummyStore>();
   EvalState s({"."}, ref<Store>(store));
-  Value v{};
+  Value v;
   PathSet ps;
 
   mkBool(v, true);
@@ -179,7 +179,7 @@ TEST_F(XMLValueTest, IntPositive) {
   std::stringstream ss;
   auto store = std::make_shared<DummyStore>();
   EvalState s({"."}, ref<Store>(store));
-  Value v{};
+  Value v;
   PathSet ps;
 
   mkInt(v, 100);
@@ -191,7 +191,7 @@ TEST_F(XMLValueTest, IntNegative) {
   std::stringstream ss;
   auto store = std::make_shared<DummyStore>();
   EvalState s({"."}, ref<Store>(store));
-  Value v{};
+  Value v;
   PathSet ps;
 
   mkInt(v, -100);
@@ -203,7 +203,7 @@ TEST_F(XMLValueTest, String) {
   std::stringstream ss;
   auto store = std::make_shared<DummyStore>();
   EvalState s({"."}, ref<Store>(store));
-  Value v{};
+  Value v;
   PathSet ps;
 
   mkString(v, "test-value");
@@ -215,7 +215,7 @@ TEST_F(XMLValueTest, StringQuotes) {
   std::stringstream ss;
   auto store = std::make_shared<DummyStore>();
   EvalState s({"."}, ref<Store>(store));
-  Value v{};
+  Value v;
   PathSet ps;
 
   mkString(v, "test-value\"");
@@ -231,7 +231,7 @@ TEST_F(XMLValueTest, Path) {
   std::stringstream ss;
   auto store = std::make_shared<DummyStore>();
   EvalState s({"."}, ref<Store>(store));
-  Value v{};
+  Value v;
   PathSet ps;
 
   mkPath(v, "some-path");
@@ -247,7 +247,7 @@ TEST_F(XMLValueTest, PathNoCopy) {
   std::stringstream ss;
   auto store = std::make_shared<DummyStore>();
   EvalState s({"."}, ref<Store>(store));
-  Value v{};
+  Value v;
   PathSet ps;
 
   mkPathNoCopy(v, "some-other-path");