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Merge pull request #14443 from NixOS/inline-unreused-lambda

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Inline only-used-once closures in `ExprConcatStrings::eval`
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Sergei Zimmerman 2025-11-01 21:55:03 +00:00 • committed by GitHub
commit e4e4063f16
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1 changed files with 23 additions and 31 deletions
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54
src/libexpr/eval.cc
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@ -2021,7 +2021,7 @@ void EvalState::concatLists(
void ExprConcatStrings::eval(EvalState & state, Env & env, Value & v)
{
NixStringContext context;
std::vector<BackedStringView> s;
std::vector<BackedStringView> strings;
size_t sSize = 0;
NixInt n{0};
NixFloat nf = 0;
@ -2029,27 +2029,6 @@ void ExprConcatStrings::eval(EvalState & state, Env & env, Value & v)
bool first = !forceString;
ValueType firstType = nString;
const auto str = [&] {
std::string result;
result.reserve(sSize);
for (const auto & part : s)
result += *part;
return result;
};
/* c_str() is not str().c_str() because we want to create a string
Value. allocating a GC'd string directly and moving it into a
Value lets us avoid an allocation and copy. */
const auto c_str = [&] {
char * result = allocString(sSize + 1);
char * tmp = result;
for (const auto & part : s) {
memcpy(tmp, part->data(), part->size());
tmp += part->size();
}
*tmp = 0;
return result;
};
// List of returned strings. References to these Values must NOT be persisted.
SmallTemporaryValueVector<conservativeStackReservation> values(es.size());
Value * vTmpP = values.data();
@ -2097,33 +2076,46 @@ void ExprConcatStrings::eval(EvalState & state, Env & env, Value & v)
.withFrame(env, *this)
.debugThrow();
} else {
if (s.empty())
s.reserve(es.size());
if (strings.empty())
strings.reserve(es.size());
/* skip canonization of first path, which would only be not
canonized in the first place if it's coming from a ./${foo} type
path */
auto part = state.coerceToString(
i_pos, vTmp, context, "while evaluating a path segment", false, firstType == nString, !first);
sSize += part->size();
s.emplace_back(std::move(part));
strings.emplace_back(std::move(part));
}
first = false;
}
if (firstType == nInt)
if (firstType == nInt) {
v.mkInt(n);
else if (firstType == nFloat)
} else if (firstType == nFloat) {
v.mkFloat(nf);
else if (firstType == nPath) {
} else if (firstType == nPath) {
if (!context.empty())
state.error<EvalError>("a string that refers to a store path cannot be appended to a path")
.atPos(pos)
.withFrame(env, *this)
.debugThrow();
v.mkPath(state.rootPath(CanonPath(str())));
} else
v.mkStringMove(c_str(), context);
std::string result_str;
result_str.reserve(sSize);
for (const auto & part : strings) {
result_str += *part;
}
v.mkPath(state.rootPath(CanonPath(result_str)));
} else {
char * result_str = allocString(sSize + 1);
char * tmp = result_str;
for (const auto & part : strings) {
memcpy(tmp, part->data(), part->size());
tmp += part->size();
}
*tmp = 0;
v.mkStringMove(result_str, context);
}
}
void ExprPos::eval(EvalState & state, Env & env, Value & v)