From f3165f48aa960a0167c403ec99320affd8425004 Mon Sep 17 00:00:00 2001 From: Vincent Ambo Date: Mon, 13 Jul 2020 20:52:35 +0100 Subject: [PATCH] refactor(3p/nix/libexpr): Make nix::AttrName a std::variant nix:AttrName was one of the few classes that relied on the default constructor of nix::Symbol (which I am trying to remove in a separate change). The class essentially represents the name of an attribute in a set, which is either just a string expression or a dynamically evaluated expression (e.g. string interpolation). Previously it would be constructed by only setting one of the fields and defaulting the other, now it is an explicit std::variant. Note that there are several code paths where not all eventualities are handled and this code is bug-for-bug compatible with those, except that unknown conditions (which should never work) are now throwing instead of silently doing ... something. The language tests pass with this change, and the depot derivations that I tested with evaluated successfully. Change-Id: Icf1ee60a5f8308f4ab18a82749e00cf37a938a8f Reviewed-on: https://cl.tvl.fyi/c/depot/+/1138 Reviewed-by: edef Reviewed-by: glittershark Tested-by: BuildkiteCI --- third_party/nix/src/libexpr/eval.cc | 25 +++++---- third_party/nix/src/libexpr/nixexpr.cc | 22 ++++---- third_party/nix/src/libexpr/nixexpr.hh | 8 +-- third_party/nix/src/libexpr/parser.y | 57 +++++++++++++------- third_party/nix/src/libexpr/symbol-table.hh | 2 +- third_party/nix/src/libutil/config.cc | 4 +- third_party/nix/src/nix-daemon/nix-daemon.cc | 2 +- 7 files changed, 67 insertions(+), 53 deletions(-) diff --git a/third_party/nix/src/libexpr/eval.cc b/third_party/nix/src/libexpr/eval.cc index 6d77928d7..6df7e66b6 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 @@ -24,6 +25,7 @@ #include "libutil/hash.hh" #include "libutil/json.hh" #include "libutil/util.hh" +#include "libutil/visitor.hh" namespace nix { @@ -185,13 +187,15 @@ static void* oomHandler(size_t requested) { #endif static Symbol getName(const AttrName& name, EvalState& state, Env& env) { - if (name.symbol.set()) { - return name.symbol; - } - Value nameValue; - name.expr->eval(state, env, nameValue); - state.forceStringNoCtx(nameValue); - return state.symbols.Create(nameValue.string.s); + return std::visit( + util::overloaded{[&](const Symbol& name) -> Symbol { return name; }, + [&](Expr* expr) -> Symbol { + Value nameValue; + expr->eval(state, env, nameValue); + state.forceStringNoCtx(nameValue); + return state.symbols.Create(nameValue.string.s); + }}, + name); } static bool gcInitialised = false; @@ -890,12 +894,7 @@ static std::string showAttrPath(EvalState& state, Env& env, } else { first = false; } - try { - out << getName(i, state, env); - } catch (Error& e) { - assert(!i.symbol.set()); - out << "\"${" << *i.expr << "}\""; - } + out << getName(i, state, env); } return out.str(); } diff --git a/third_party/nix/src/libexpr/nixexpr.cc b/third_party/nix/src/libexpr/nixexpr.cc index 28d8eee7a..2de37f50e 100644 --- a/third_party/nix/src/libexpr/nixexpr.cc +++ b/third_party/nix/src/libexpr/nixexpr.cc @@ -1,9 +1,11 @@ #include "libexpr/nixexpr.hh" #include +#include #include "libstore/derivations.hh" #include "libutil/util.hh" +#include "libutil/visitor.hh" namespace nix { @@ -198,17 +200,17 @@ std::ostream& operator<<(std::ostream& str, const Pos& pos) { std::string showAttrPath(const AttrPath& attrPath) { std::ostringstream out; bool first = true; - for (auto& i : attrPath) { + for (auto& attr : attrPath) { if (!first) { out << '.'; } else { first = false; } - if (i.symbol.set()) { - out << i.symbol; - } else { - out << "\"${" << *i.expr << "}\""; - } + + std::visit(util::overloaded{ + [&](const Symbol& sym) { out << sym; }, + [&](const Expr* expr) { out << "\"${" << *expr << "}\""; }}, + attr); } return out.str(); } @@ -268,8 +270,8 @@ void ExprSelect::bindVars(const StaticEnv& env) { def->bindVars(env); } for (auto& i : attrPath) { - if (!i.symbol.set()) { - i.expr->bindVars(env); + if (auto* expr = std::get_if(&i)) { + (*expr)->bindVars(env); } } } @@ -277,8 +279,8 @@ void ExprSelect::bindVars(const StaticEnv& env) { void ExprOpHasAttr::bindVars(const StaticEnv& env) { e->bindVars(env); for (auto& i : attrPath) { - if (!i.symbol.set()) { - i.expr->bindVars(env); + if (auto* expr = std::get_if(&i)) { + (*expr)->bindVars(env); } } } diff --git a/third_party/nix/src/libexpr/nixexpr.hh b/third_party/nix/src/libexpr/nixexpr.hh index 0bf524518..7ec6f7f17 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 "libexpr/symbol-table.hh" #include "libexpr/value.hh" @@ -60,12 +61,7 @@ class EvalState; struct StaticEnv; /* An attribute path is a sequence of attribute names. */ -struct AttrName { - Symbol symbol; - Expr* expr; - AttrName(const Symbol& s) : symbol(s){}; - AttrName(Expr* e) : expr(e){}; -}; +using AttrName = std::variant; typedef std::vector AttrPath; diff --git a/third_party/nix/src/libexpr/parser.y b/third_party/nix/src/libexpr/parser.y index fe8759f3c..eb3f92db7 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 "libutil/util.hh" #include "libexpr/nixexpr.hh" #include "libexpr/eval.hh" @@ -84,30 +85,39 @@ static void addAttr(ExprAttrs * attrs, AttrPath & attrPath, // Checking attrPath validity. // =========================== for (i = attrPath.begin(); i + 1 < attrPath.end(); i++) { - if (i->symbol.set()) { - ExprAttrs::AttrDefs::iterator j = attrs->attrs.find(i->symbol); + if (const auto* sym = std::get_if(&(*i)); sym && sym->set()) { + ExprAttrs::AttrDefs::iterator j = attrs->attrs.find(*sym); if (j != attrs->attrs.end()) { if (!j->second.inherited) { ExprAttrs * attrs2 = dynamic_cast(j->second.e); if (!attrs2) { dupAttr(attrPath, pos, j->second.pos); } attrs = attrs2; - } else + } else { dupAttr(attrPath, pos, j->second.pos); + } } else { - ExprAttrs * nested = new ExprAttrs; - attrs->attrs[i->symbol] = ExprAttrs::AttrDef(nested, pos); + ExprAttrs* nested = new ExprAttrs; + attrs->attrs[*sym] = ExprAttrs::AttrDef(nested, pos); attrs = nested; } } else { - ExprAttrs *nested = new ExprAttrs; - attrs->dynamicAttrs.push_back(ExprAttrs::DynamicAttrDef(i->expr, nested, pos)); - attrs = nested; + // Yes, this code does not handle all conditions + // exhaustively. We use std::get to throw if the condition + // that isn't covered happens, which is potentially a + // behaviour change from the previous default constructed + // Symbol. It should alert us about anything untoward going + // on here. + auto* expr = std::get(*i); + + ExprAttrs *nested = new ExprAttrs; + attrs->dynamicAttrs.push_back(ExprAttrs::DynamicAttrDef(expr, nested, pos)); + attrs = nested; } } // Expr insertion. // ========================== - if (i->symbol.set()) { - ExprAttrs::AttrDefs::iterator j = attrs->attrs.find(i->symbol); + if (auto* sym = std::get_if(&(*i)); sym && sym->set()) { + ExprAttrs::AttrDefs::iterator j = attrs->attrs.find(*sym); if (j != attrs->attrs.end()) { // This attr path is already defined. However, if both // e and the expr pointed by the attr path are two attribute sets, @@ -118,8 +128,9 @@ static void addAttr(ExprAttrs * attrs, AttrPath & attrPath, if (jAttrs && ae) { for (auto & ad : ae->attrs) { auto j2 = jAttrs->attrs.find(ad.first); - if (j2 != jAttrs->attrs.end()) // Attr already defined in iAttrs, error. + if (j2 != jAttrs->attrs.end()) {// Attr already defined in iAttrs, error. dupAttr(ad.first, j2->second.pos, ad.second.pos); + } jAttrs->attrs[ad.first] = ad.second; } } else { @@ -127,11 +138,13 @@ static void addAttr(ExprAttrs * attrs, AttrPath & attrPath, } } else { // This attr path is not defined. Let's create it. - attrs->attrs[i->symbol] = ExprAttrs::AttrDef(e, pos); - e->setName(i->symbol); + attrs->attrs[*sym] = ExprAttrs::AttrDef(e, pos); + e->setName(*sym); } } else { - attrs->dynamicAttrs.push_back(ExprAttrs::DynamicAttrDef(i->expr, e, pos)); + // Same caveat as the identical line above. + auto* expr = std::get(*i); + attrs->dynamicAttrs.push_back(ExprAttrs::DynamicAttrDef(expr, e, pos)); } } @@ -444,19 +457,23 @@ binds | binds INHERIT attrs ';' { $$ = $1; for (auto & i : *$3) { - if ($$->attrs.find(i.symbol) != $$->attrs.end()) - dupAttr(i.symbol, makeCurPos(@3, data), $$->attrs[i.symbol].pos); + auto sym = std::get(i); + if ($$->attrs.find(sym) != $$->attrs.end()) { + dupAttr(sym, makeCurPos(@3, data), $$->attrs[sym].pos); + } Pos pos = makeCurPos(@3, data); - $$->attrs[i.symbol] = ExprAttrs::AttrDef(new ExprVar(CUR_POS, i.symbol), pos, true); + $$->attrs[sym] = ExprAttrs::AttrDef(new ExprVar(CUR_POS, sym), pos, true); } } | binds INHERIT '(' expr ')' attrs ';' { $$ = $1; /* !!! Should ensure sharing of the expression in $4. */ for (auto & i : *$6) { - if ($$->attrs.find(i.symbol) != $$->attrs.end()) - dupAttr(i.symbol, makeCurPos(@6, data), $$->attrs[i.symbol].pos); - $$->attrs[i.symbol] = ExprAttrs::AttrDef(new ExprSelect(CUR_POS, $4, i.symbol), makeCurPos(@6, data)); + auto sym = std::get(i); + if ($$->attrs.find(sym) != $$->attrs.end()) { + dupAttr(sym, makeCurPos(@6, data), $$->attrs[sym].pos); + } + $$->attrs[sym] = ExprAttrs::AttrDef(new ExprSelect(CUR_POS, $4, sym), makeCurPos(@6, data)); } } | { $$ = new ExprAttrs; } diff --git a/third_party/nix/src/libexpr/symbol-table.hh b/third_party/nix/src/libexpr/symbol-table.hh index c4c1163be..efc2314b7 100644 --- a/third_party/nix/src/libexpr/symbol-table.hh +++ b/third_party/nix/src/libexpr/symbol-table.hh @@ -21,7 +21,7 @@ class Symbol { bool operator<(const Symbol& s2) const { return *s < *s2.s; } - operator const std::string&() const { return *s; } + operator const std::string &() const { return *s; } bool set() const { return s; } diff --git a/third_party/nix/src/libutil/config.cc b/third_party/nix/src/libutil/config.cc index 20c70c823..5d28b7a20 100644 --- a/third_party/nix/src/libutil/config.cc +++ b/third_party/nix/src/libutil/config.cc @@ -102,8 +102,8 @@ void AbstractConfig::applyConfigFile(const Path& path) { } // TODO(tazjin): absl::string_view after path functions are fixed. - std::vector tokens = - absl::StrSplit(line, absl::ByAnyChar(" \t\n\r"), absl::SkipWhitespace()); + std::vector tokens = absl::StrSplit( + line, absl::ByAnyChar(" \t\n\r"), absl::SkipWhitespace()); if (tokens.empty()) { continue; } diff --git a/third_party/nix/src/nix-daemon/nix-daemon.cc b/third_party/nix/src/nix-daemon/nix-daemon.cc index c7967307c..da3d909f1 100644 --- a/third_party/nix/src/nix-daemon/nix-daemon.cc +++ b/third_party/nix/src/nix-daemon/nix-daemon.cc @@ -16,6 +16,7 @@ #include #include "libmain/shared.hh" +#include "libproto/worker.pb.h" #include "libstore/derivations.hh" #include "libstore/globals.hh" #include "libstore/local-store.hh" @@ -27,7 +28,6 @@ #include "libutil/serialise.hh" #include "libutil/util.hh" #include "nix/legacy.hh" -#include "libproto/worker.pb.h" using namespace nix;