From fa161e9a380c530363c3eb72c9917e4db88287e0 Mon Sep 17 00:00:00 2001 From: Vincent Ambo Date: Mon, 13 Jul 2020 21:20:52 +0100 Subject: [PATCH] refactor(3p/nix/libexpr): Remove the nix::Symbol default constructor Having a default constructor for this causes a variety of annoying situations across the codebase in which this is initialised to an unexpected value, leading to constant guarding against those conditions. It turns out there's actually no intrinsic reason that this default constructor needs to exist. The biggest one was addressed in CL/1138 and this commit cleans up the remaining bits. Change-Id: I4a847f50bc90e72f028598196592a7d8730a4e01 Reviewed-on: https://cl.tvl.fyi/c/depot/+/1139 Reviewed-by: isomer Tested-by: BuildkiteCI --- third_party/nix/src/libexpr/attr-set.cc | 2 +- third_party/nix/src/libexpr/attr-set.hh | 1 - third_party/nix/src/libexpr/eval.cc | 19 ++++++++++------ third_party/nix/src/libexpr/eval.hh | 11 ++++++---- third_party/nix/src/libexpr/nixexpr.cc | 15 +++++-------- third_party/nix/src/libexpr/nixexpr.hh | 24 +++++++++++++++------ third_party/nix/src/libexpr/parser.y | 9 ++++---- third_party/nix/src/libexpr/primops.cc | 2 +- third_party/nix/src/libexpr/symbol-table.hh | 2 -- third_party/nix/src/libexpr/value-to-xml.cc | 2 +- 10 files changed, 50 insertions(+), 37 deletions(-) diff --git a/third_party/nix/src/libexpr/attr-set.cc b/third_party/nix/src/libexpr/attr-set.cc index 8b34be6fd..42ebe629b 100644 --- a/third_party/nix/src/libexpr/attr-set.cc +++ b/third_party/nix/src/libexpr/attr-set.cc @@ -59,7 +59,7 @@ Bindings::iterator Bindings::end() { return attributes_.end(); } void Bindings::merge(const Bindings& other) { for (auto& [key, value] : other.attributes_) { - this->attributes_[key] = value; + this->attributes_.insert_or_assign(key, value); } } diff --git a/third_party/nix/src/libexpr/attr-set.hh b/third_party/nix/src/libexpr/attr-set.hh index 31e5101d8..d4823cb19 100644 --- a/third_party/nix/src/libexpr/attr-set.hh +++ b/third_party/nix/src/libexpr/attr-set.hh @@ -20,7 +20,6 @@ struct Attr { Pos* pos; // TODO(tazjin): Who owns this? Attr(Symbol name, Value* value, Pos* pos = &noPos) : name(name), value(value), pos(pos){}; - Attr() : pos(&noPos){}; }; // Convenience alias for the backing map, with the garbage-collecting diff --git a/third_party/nix/src/libexpr/eval.cc b/third_party/nix/src/libexpr/eval.cc index 6df7e66b6..fb6213069 100644 --- a/third_party/nix/src/libexpr/eval.cc +++ b/third_party/nix/src/libexpr/eval.cc @@ -6,6 +6,7 @@ #include #include #include +#include #include #include @@ -320,6 +321,7 @@ EvalState::EvalState(const Strings& _searchPath, const ref& store) sOutputHash(symbols.Create("outputHash")), sOutputHashAlgo(symbols.Create("outputHashAlgo")), sOutputHashMode(symbols.Create("outputHashMode")), + sDerivationNix(std::nullopt), repair(NoRepair), store(store), baseEnv(allocEnv(128)), @@ -664,9 +666,9 @@ static inline void mkThunk(Value& v, Env& env, Expr* expr) { void EvalState::mkThunk_(Value& v, Expr* expr) { mkThunk(v, baseEnv, expr); } void EvalState::mkPos(Value& v, Pos* pos) { - if ((pos != nullptr) && pos->file.set()) { + if ((pos != nullptr) && pos->file.has_value() && pos->file.value().set()) { mkAttrs(v, 3); - mkString(*allocAttr(v, sFile), pos->file); + mkString(*allocAttr(v, sFile), pos->file.value()); mkInt(*allocAttr(v, sLine), pos->line); mkInt(*allocAttr(v, sColumn), pos->column); } else { @@ -847,7 +849,6 @@ void ExprAttrs::eval(EvalState& state, Env& env, Value& value) { nameSym, i.pos, *j->second.pos); } - i.valueExpr->setName(nameSym); value.attrs->push_back( Attr(nameSym, i.valueExpr->maybeThunk(state, *dynamicEnv), &i.pos)); } @@ -936,7 +937,13 @@ void ExprSelect::eval(EvalState& state, Env& env, Value& v) { state.forceValue(*vAttrs, (pos2 != nullptr ? *pos2 : this->pos)); } catch (Error& e) { - if ((pos2 != nullptr) && pos2->file != state.sDerivationNix) { + // This code relies on 'sDerivationNix' being correcty mutated at + // some prior point (it would previously otherwise have been a + // nullptr). + // + // We haven't seen this fail, so for now the contained value is + // just accessed at the risk of potentially crashing. + if ((pos2 != nullptr) && pos2->file != state.sDerivationNix.value()) { addErrorPrefix(e, "while evaluating the attribute '%1%' at %2%:\n", showAttrPath(state, env, attrPath), *pos2); } @@ -1792,8 +1799,8 @@ void EvalState::printStats() { auto list = topObj.list("functions"); for (auto& i : functionCalls) { auto obj = list.object(); - if (i.first->name.set()) { - obj.attr("name", (const std::string&)i.first->name); + if (i.first->name.has_value()) { + obj.attr("name", (const std::string&)i.first->name.value()); } else { obj.attr("name", nullptr); } diff --git a/third_party/nix/src/libexpr/eval.hh b/third_party/nix/src/libexpr/eval.hh index 9e4e500b4..11cc295b2 100644 --- a/third_party/nix/src/libexpr/eval.hh +++ b/third_party/nix/src/libexpr/eval.hh @@ -62,10 +62,13 @@ class EvalState { SymbolTable symbols; const Symbol sWith, sOutPath, sDrvPath, sType, sMeta, sName, sValue, sSystem, - sOverrides, sOutputs, sOutputName, sIgnoreNulls, sFile, sLine, sColumn, - sFunctor, sToString, sRight, sWrong, sStructuredAttrs, sBuilder, sArgs, - sOutputHash, sOutputHashAlgo, sOutputHashMode; - Symbol sDerivationNix; + sOutputs, sOutputName, sIgnoreNulls, sFile, sLine, sColumn, sFunctor, + sToString, sRight, sWrong, sStructuredAttrs, sBuilder, sArgs, sOutputHash, + sOutputHashAlgo, sOutputHashMode; + + // Symbol representing the path to the built-in 'derivation.nix' + // file, set during primops initialisation. + std::optional sDerivationNix; /* If set, force copying files to the Nix store even if they already exist there. */ diff --git a/third_party/nix/src/libexpr/nixexpr.cc b/third_party/nix/src/libexpr/nixexpr.cc index 2de37f50e..94e7d335c 100644 --- a/third_party/nix/src/libexpr/nixexpr.cc +++ b/third_party/nix/src/libexpr/nixexpr.cc @@ -187,11 +187,11 @@ void ExprConcatStrings::show(std::ostream& str) const { void ExprPos::show(std::ostream& str) const { str << "__curPos"; } std::ostream& operator<<(std::ostream& str, const Pos& pos) { - if (!pos) { + if (!pos || !pos.file.has_value()) { str << "undefined position"; } else { str << (format(ANSI_BOLD "%1%" ANSI_NORMAL ":%2%:%3%") % - (std::string)pos.file % pos.line % pos.column) + (std::string)pos.file.value() % pos.line % pos.column) .str(); } return str; @@ -401,17 +401,12 @@ void ExprConcatStrings::bindVars(const StaticEnv& env) { void ExprPos::bindVars(const StaticEnv& env) {} /* Storing function names. */ - -void Expr::setName(Symbol& name) {} - -void ExprLambda::setName(Symbol& name) { - this->name = name; - body->setName(name); -} +void ExprLambda::setName(Symbol& name) { this->name = name; } std::string ExprLambda::showNamePos() const { return (format("%1% at %2%") % - (name.set() ? "'" + (std::string)name + "'" : "anonymous function") % + (name.has_value() ? "'" + (std::string)name.value() + "'" + : "anonymous function") % pos) .str(); } diff --git a/third_party/nix/src/libexpr/nixexpr.hh b/third_party/nix/src/libexpr/nixexpr.hh index 7ec6f7f17..3bf9e4a1a 100644 --- a/third_party/nix/src/libexpr/nixexpr.hh +++ b/third_party/nix/src/libexpr/nixexpr.hh @@ -1,6 +1,7 @@ #pragma once #include +#include #include #include "libexpr/symbol-table.hh" @@ -21,20 +22,28 @@ MakeError(RestrictedPathError, Error); /* Position objects. */ struct Pos { - Symbol file; + std::optional file; unsigned int line, column; - Pos() : line(0), column(0){}; - Pos(const Symbol& file, unsigned int line, unsigned int column) + Pos(const std::optional& file, unsigned int line, unsigned int column) : file(file), line(line), column(column){}; + + // TODO(tazjin): remove this - empty pos is never useful + Pos() : file(std::nullopt), line(0), column(0){}; + operator bool() const { return line != 0; } + bool operator<(const Pos& p2) const { + if (!file.has_value()) { + return true; + } + if (!line) { return p2.line; } if (!p2.line) { return false; } - int d = ((std::string)file).compare((std::string)p2.file); + int d = ((std::string)file.value()).compare((std::string)p2.file.value()); if (d < 0) { return true; } @@ -75,7 +84,6 @@ struct Expr { virtual void bindVars(const StaticEnv& env); virtual void eval(EvalState& state, Env& env, Value& v); virtual Value* maybeThunk(EvalState& state, Env& env); - virtual void setName(Symbol& name); }; std::ostream& operator<<(std::ostream& str, const Expr& e); @@ -219,8 +227,9 @@ struct Formals { }; struct ExprLambda : Expr { + public: Pos pos; - Symbol name; + std::optional name; Symbol arg; bool matchAttrs; Formals* formals; @@ -233,10 +242,11 @@ struct ExprLambda : Expr { formals(formals), body(body) { if (!arg.empty() && formals && - formals->argNames.find(arg) != formals->argNames.end()) + formals->argNames.find(arg) != formals->argNames.end()) { throw ParseError( format("duplicate formal function argument '%1%' at %2%") % arg % pos); + } }; void setName(Symbol& name); std::string showNamePos() const; diff --git a/third_party/nix/src/libexpr/parser.y b/third_party/nix/src/libexpr/parser.y index eb3f92db7..2ea84fea6 100644 --- a/third_party/nix/src/libexpr/parser.y +++ b/third_party/nix/src/libexpr/parser.y @@ -16,6 +16,7 @@ #ifndef BISON_HEADER #define BISON_HEADER +#include #include #include "libutil/util.hh" #include "libexpr/nixexpr.hh" @@ -28,9 +29,9 @@ namespace nix { { EvalState & state; SymbolTable & symbols; - Expr * result; + Expr* result; Path basePath; - Symbol path; + std::optional path; std::string error; Symbol sLetBody; ParseData(EvalState & state) @@ -139,7 +140,6 @@ static void addAttr(ExprAttrs * attrs, AttrPath & attrPath, } else { // This attr path is not defined. Let's create it. attrs->attrs[*sym] = ExprAttrs::AttrDef(e, pos); - e->setName(*sym); } } else { // Same caveat as the identical line above. @@ -502,8 +502,9 @@ attrpath if (str) { $$->push_back(AttrName(str->s)); delete str; - } else + } else { $$->push_back(AttrName($3)); + } } | attr { $$ = new std::vector; $$->push_back(AttrName(data->symbols.Create($1))); } | string_attr diff --git a/third_party/nix/src/libexpr/primops.cc b/third_party/nix/src/libexpr/primops.cc index b238da762..d96af55f5 100644 --- a/third_party/nix/src/libexpr/primops.cc +++ b/third_party/nix/src/libexpr/primops.cc @@ -234,7 +234,7 @@ void prim_exec(EvalState& state, const Pos& pos, Value** args, Value& v) { auto output = runProgram(program, true, commandArgs); Expr* parsed; try { - parsed = state.parseExprFromString(output, pos.file); + parsed = state.parseExprFromString(output, pos.file.value()); } catch (Error& e) { e.addPrefix(format("While parsing the output from '%1%', at %2%\n") % program % pos); diff --git a/third_party/nix/src/libexpr/symbol-table.hh b/third_party/nix/src/libexpr/symbol-table.hh index efc2314b7..dcb44d32f 100644 --- a/third_party/nix/src/libexpr/symbol-table.hh +++ b/third_party/nix/src/libexpr/symbol-table.hh @@ -13,8 +13,6 @@ class Symbol { friend class SymbolTable; public: - Symbol() : s(0){}; - bool operator==(const Symbol& s2) const { return s == s2.s; } bool operator!=(const Symbol& s2) const { return s != s2.s; } diff --git a/third_party/nix/src/libexpr/value-to-xml.cc b/third_party/nix/src/libexpr/value-to-xml.cc index 2a46ac84b..ea1a85a89 100644 --- a/third_party/nix/src/libexpr/value-to-xml.cc +++ b/third_party/nix/src/libexpr/value-to-xml.cc @@ -20,7 +20,7 @@ static void printValueAsXML(EvalState& state, bool strict, bool location, PathSet& drvsSeen); static void posToXML(XMLAttrs& xmlAttrs, const Pos& pos) { - xmlAttrs["path"] = pos.file; + xmlAttrs["path"] = pos.file.value(); xmlAttrs["line"] = (format("%1%") % pos.line).str(); xmlAttrs["column"] = (format("%1%") % pos.column).str(); }