fix(3p/nix): Fix all remaining compiler warnings

This compiles under `-Wall -Werror`.

The largest chunk of this change is `final` qualifiers for the various
Nix CLI command structs, which inherit from a Command class that has
more virtual functions than are implemented by each command.

Change-Id: I0925e6e1a39013f026773db5816e4a77d50f3b4a
Reviewed-on: https://cl.tvl.fyi/c/depot/+/1294
Tested-by: BuildkiteCI
Reviewed-by: isomer <isomer@tvl.fyi>
Reviewed-by: kanepyork <rikingcoding@gmail.com>

third_party/nix/src/libexpr/eval.cc

@@ -1252,7 +1252,6 @@ void EvalState::concatLists(Value& v, const NixList& lists, const Pos& pos) {
 
   auto outlist = new (GC) NixList();
 
-  size_t len = 0;
   for (Value* list : lists) {
     forceList(*list, pos);
     outlist->insert(outlist->end(), list->list->begin(), list->list->end());

third_party/nix/src/libexpr/parser.hh

@@ -34,6 +34,15 @@ struct ParseData : public gc {
         sLetBody(symbols.Create("<let-body>")){};
 };
 
+// Clang fails to identify these functions as used, probably because
+// of some interaction between the lexer/parser codegen and something
+// else.
+//
+// To avoid warnings for that we disable -Wunused-function in this block.
+
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wunused-function"
+
 // TODO(tazjin): move dupAttr to anonymous namespace
 static void dupAttr(const AttrPath& attrPath, const Pos& pos,
                     const Pos& prevPos) {
@@ -85,4 +94,6 @@ static Expr* unescapeStr(SymbolTable& symbols, const char* s, size_t length) {
   return new ExprString(symbols.Create(t));
 }
 
+#pragma clang diagnostic pop  // re-enable -Wunused-function
+
 }  // namespace nix

third_party/nix/src/libexpr/parser.y

@@ -11,7 +11,10 @@
 %expect 1
 %expect-rr 1
 
-%code requires { #include "libexpr/parser.hh" }
+%code requires {
+#define YY_NO_INPUT 1 // disable unused yyinput features
+#include "libexpr/parser.hh"
+}
 
 %{
 

third_party/nix/src/libexpr/primops.cc

@@ -1680,8 +1680,6 @@ static void prim_partition(EvalState& state, const Pos& pos, Value** args,
   state.forceFunction(*args[0], pos);
   state.forceList(*args[1], pos);
 
-  auto len = args[1]->listSize();
-
   NixList* right = new (GC) NixList();
   NixList* wrong = new (GC) NixList();
 

third_party/nix/src/libstore/local-store.cc

@@ -490,10 +490,18 @@ static void canonicalisePathMetaData_(const Path& path, uid_t fromUid,
     if (inodesSeen.find(Inode(st.st_dev, st.st_ino)) == inodesSeen.end()) {
       throw BuildError(format("invalid ownership on file '%1%'") % path);
     }
+
+// `mode` variable is only used in debug builds
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wunused-variable"
+
     mode_t mode = st.st_mode & ~S_IFMT;
     assert(S_ISLNK(st.st_mode) ||
            (st.st_uid == geteuid() && (mode == 0444 || mode == 0555) &&
             st.st_mtime == mtimeStore));
+
+#pragma clang diagnostic pop
+
     return;
   }
 

third_party/nix/src/libstore/nar-info-disk-cache.cc

@@ -49,7 +49,7 @@ create table if not exists LastPurge (
 
 )sql";
 
-class NarInfoDiskCacheImpl : public NarInfoDiskCache {
+class NarInfoDiskCacheImpl final : public NarInfoDiskCache {
  public:
   /* How often to purge expired entries from the cache. */
   const int purgeInterval = 24 * 3600;
@@ -280,8 +280,9 @@ class NarInfoDiskCacheImpl : public NarInfoDiskCache {
   }
 };
 
-ref<NarInfoDiskCache> getNarInfoDiskCache() {
-  static ref<NarInfoDiskCache> cache = make_ref<NarInfoDiskCacheImpl>();
+std::shared_ptr<NarInfoDiskCache> getNarInfoDiskCache() {
+  static std::shared_ptr<NarInfoDiskCache> cache =
+      std::make_shared<NarInfoDiskCacheImpl>();
   return cache;
 }
 

third_party/nix/src/libstore/nar-info-disk-cache.hh

@@ -25,6 +25,6 @@ class NarInfoDiskCache {
 
 /* Return a singleton cache object that can be used concurrently by
    multiple threads. */
-ref<NarInfoDiskCache> getNarInfoDiskCache();
+std::shared_ptr<NarInfoDiskCache> getNarInfoDiskCache();
 
 }  // namespace nix

third_party/nix/src/libutil/util.hh

@@ -390,6 +390,11 @@ class Callback {
     }
   }
 
+// The unused-variable assert is disabled in this block because the
+// `prev` variables are only used in debug mode (in the asserts).
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wunused-variable"
+
   void operator()(T&& t) noexcept {
     auto prev = done.test_and_set();
     assert(!prev);
@@ -406,6 +411,8 @@ class Callback {
     promise.set_exception(exc);
     fun(promise.get_future());
   }
+
+#pragma clang diagnostic pop
 };
 
 /* Start a thread that handles various signals. Also block those signals

third_party/nix/src/nix/add-to-store.cc

@@ -5,7 +5,7 @@
 
 using namespace nix;
 
-struct CmdAddToStore : MixDryRun, StoreCommand {
+struct CmdAddToStore final : MixDryRun, StoreCommand {
   Path path;
   std::optional<std::string> namePart;
 

third_party/nix/src/nix/build.cc

@@ -5,7 +5,7 @@
 
 using namespace nix;
 
-struct CmdBuild : MixDryRun, InstallablesCommand {
+struct CmdBuild final : MixDryRun, InstallablesCommand {
   Path outLink = "result";
 
   CmdBuild() {

third_party/nix/src/nix/cat.cc

@@ -21,7 +21,7 @@ struct MixCat : virtual Args {
   }
 };
 
-struct CmdCatStore : StoreCommand, MixCat {
+struct CmdCatStore final : StoreCommand, MixCat {
   CmdCatStore() { expectArg("path", &path); }
 
   std::string name() override { return "cat-store"; }
@@ -33,7 +33,7 @@ struct CmdCatStore : StoreCommand, MixCat {
   void run(ref<Store> store) override { cat(store->getFSAccessor()); }
 };
 
-struct CmdCatNar : StoreCommand, MixCat {
+struct CmdCatNar final : StoreCommand, MixCat {
   Path narPath;
 
   CmdCatNar() {

third_party/nix/src/nix/copy.cc

@@ -8,7 +8,7 @@
 
 using namespace nix;
 
-struct CmdCopy : StorePathsCommand {
+struct CmdCopy final : StorePathsCommand {
   std::string srcUri, dstUri;
 
   CheckSigsFlag checkSigs = CheckSigs;

third_party/nix/src/nix/doctor.cc

@@ -19,7 +19,7 @@ std::string formatProtocol(unsigned int proto) {
   return "unknown";
 }
 
-struct CmdDoctor : StoreCommand {
+struct CmdDoctor final : StoreCommand {
   bool success = true;
 
   std::string name() override { return "doctor"; }

third_party/nix/src/nix/dump-path.cc

@@ -3,7 +3,7 @@
 
 using namespace nix;
 
-struct CmdDumpPath : StorePathCommand {
+struct CmdDumpPath final : StorePathCommand {
   std::string name() override { return "dump-path"; }
 
   std::string description() override {

third_party/nix/src/nix/edit.cc

@@ -9,7 +9,7 @@
 
 using namespace nix;
 
-struct CmdEdit : InstallableCommand {
+struct CmdEdit final : InstallableCommand {
   std::string name() override { return "edit"; }
 
   std::string description() override {

third_party/nix/src/nix/eval.cc

@@ -9,7 +9,7 @@
 
 using namespace nix;
 
-struct CmdEval : MixJSON, InstallableCommand {
+struct CmdEval final : MixJSON, InstallableCommand {
   bool raw = false;
 
   CmdEval() { mkFlag(0, "raw", "print strings unquoted", &raw); }

third_party/nix/src/nix/hash.cc

@@ -6,7 +6,7 @@
 
 using namespace nix;
 
-struct CmdHash : Command {
+struct CmdHash final : Command {
   enum Mode { mFile, mPath };
   Mode mode;
   Base base = SRI;
@@ -47,7 +47,7 @@ struct CmdHash : Command {
 static RegisterCommand r1(make_ref<CmdHash>(CmdHash::mFile));
 static RegisterCommand r2(make_ref<CmdHash>(CmdHash::mPath));
 
-struct CmdToBase : Command {
+struct CmdToBase final : Command {
   Base base;
   HashType ht = htUnknown;
   std::vector<std::string> args;

third_party/nix/src/nix/installables.cc

@@ -98,7 +98,7 @@ Buildable Installable::toBuildable() {
   return std::move(buildables[0]);
 }
 
-struct InstallableStorePath : Installable {
+struct InstallableStorePath final : Installable {
   Path storePath;
 
   explicit InstallableStorePath(Path storePath)
@@ -158,7 +158,7 @@ struct InstallableValue : Installable {
   }
 };
 
-struct InstallableExpr : InstallableValue {
+struct InstallableExpr final : InstallableValue {
   std::string text;
 
   InstallableExpr(SourceExprCommand& cmd, std::string text)
@@ -173,7 +173,7 @@ struct InstallableExpr : InstallableValue {
   }
 };
 
-struct InstallableAttrPath : InstallableValue {
+struct InstallableAttrPath final : InstallableValue {
   std::string attrPath;
 
   InstallableAttrPath(SourceExprCommand& cmd, std::string attrPath)

third_party/nix/src/nix/log.cc

@@ -7,7 +7,7 @@
 
 using namespace nix;
 
-struct CmdLog : InstallableCommand {
+struct CmdLog final : InstallableCommand {
   CmdLog() = default;
 
   std::string name() override { return "log"; }

third_party/nix/src/nix/ls.cc

@@ -88,7 +88,7 @@ struct MixLs : virtual Args, MixJSON {
   }
 };
 
-struct CmdLsStore : StoreCommand, MixLs {
+struct CmdLsStore final : StoreCommand, MixLs {
   CmdLsStore() { expectArg("path", &path); }
 
   Examples examples() override {
@@ -108,7 +108,7 @@ struct CmdLsStore : StoreCommand, MixLs {
   void run(ref<Store> store) override { list(store->getFSAccessor()); }
 };
 
-struct CmdLsNar : Command, MixLs {
+struct CmdLsNar final : Command, MixLs {
   Path narPath;
 
   CmdLsNar() {

third_party/nix/src/nix/optimise-store.cc

@@ -6,7 +6,7 @@
 
 using namespace nix;
 
-struct CmdOptimiseStore : StoreCommand {
+struct CmdOptimiseStore final : StoreCommand {
   CmdOptimiseStore() = default;
 
   std::string name() override { return "optimise-store"; }

third_party/nix/src/nix/path-info.cc

@@ -9,7 +9,7 @@
 
 using namespace nix;
 
-struct CmdPathInfo : StorePathsCommand, MixJSON {
+struct CmdPathInfo final : StorePathsCommand, MixJSON {
   bool showSize = false;
   bool showClosureSize = false;
   bool humanReadable = false;

third_party/nix/src/nix/ping-store.cc

@@ -4,7 +4,7 @@
 
 using namespace nix;
 
-struct CmdPingStore : StoreCommand {
+struct CmdPingStore final : StoreCommand {
   std::string name() override { return "ping-store"; }
 
   std::string description() override {

third_party/nix/src/nix/repl.cc

@@ -799,7 +799,7 @@ std::ostream& NixRepl::printValue(std::ostream& str, Value& v,
   return str;
 }
 
-struct CmdRepl : StoreCommand, MixEvalArgs {
+struct CmdRepl final : StoreCommand, MixEvalArgs {
   std::vector<std::string> files;
 
   CmdRepl() { expectArgs("files", &files); }

third_party/nix/src/nix/run.cc

@@ -17,7 +17,7 @@ using namespace nix;
 
 std::string chrootHelperName = "__run_in_chroot";
 
-struct CmdRun : InstallablesCommand {
+struct CmdRun final : InstallablesCommand {
   std::vector<std::string> command = {"bash"};
   StringSet keep, unset;
   bool ignoreEnvironment = false;

third_party/nix/src/nix/search.cc

@@ -27,7 +27,7 @@ std::string hilite(const std::string& s, const std::smatch& m,
                          postfix + std::string(m.suffix());
 }
 
-struct CmdSearch : SourceExprCommand, MixJSON {
+struct CmdSearch final : SourceExprCommand, MixJSON {
   std::vector<std::string> res;
 
   bool writeCache = true;

third_party/nix/src/nix/show-config.cc

@@ -6,7 +6,7 @@
 
 using namespace nix;
 
-struct CmdShowConfig : Command, MixJSON {
+struct CmdShowConfig final : Command, MixJSON {
   CmdShowConfig() = default;
 
   std::string name() override { return "show-config"; }

third_party/nix/src/nix/show-derivation.cc

@@ -9,7 +9,7 @@
 
 using namespace nix;
 
-struct CmdShowDerivation : InstallablesCommand {
+struct CmdShowDerivation final : InstallablesCommand {
   bool recursive = false;
 
   CmdShowDerivation() {

third_party/nix/src/nix/sigs.cc

@@ -9,7 +9,7 @@
 
 using namespace nix;
 
-struct CmdCopySigs : StorePathsCommand {
+struct CmdCopySigs final : StorePathsCommand {
   Strings substituterUris;
 
   CmdCopySigs() {
@@ -99,7 +99,7 @@ struct CmdCopySigs : StorePathsCommand {
 
 static RegisterCommand r1(make_ref<CmdCopySigs>());
 
-struct CmdSignPaths : StorePathsCommand {
+struct CmdSignPaths final : StorePathsCommand {
   Path secretKeyFile;
 
   CmdSignPaths() {

third_party/nix/src/nix/upgrade-nix.cc

@@ -13,7 +13,7 @@
 
 using namespace nix;
 
-struct CmdUpgradeNix : MixDryRun, StoreCommand {
+struct CmdUpgradeNix final : MixDryRun, StoreCommand {
   Path profileDir;
   std::string storePathsUrl =
       "https://github.com/NixOS/nixpkgs/raw/master/nixos/modules/installer/"

third_party/nix/src/nix/verify.cc

@@ -10,7 +10,7 @@
 
 using namespace nix;
 
-struct CmdVerify : StorePathsCommand {
+struct CmdVerify final : StorePathsCommand {
   bool noContents = false;
   bool noTrust = false;
   Strings substituterUris;

third_party/nix/src/nix/why-depends.cc

@@ -23,7 +23,7 @@ static std::string filterPrintable(const std::string& s) {
   return res;
 }
 
-struct CmdWhyDepends : SourceExprCommand {
+struct CmdWhyDepends final : SourceExprCommand {
   std::string _package, _dependency;
   bool all = false;
 

third_party/nix/src/tests/language-tests.cc

@@ -174,7 +174,7 @@ TEST_P(EvalFailureTest, Fails) {
   EvalState state({}, ref<Store>(store));
   auto path = GetParam();
 
-  Expr* expr;
+  Expr* expr = nullptr;
   EXPECT_NO_THROW(expr = state.parseExprFromFile(GetParam().string()))
       << path.stem().string() << ": should parse successfully";