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[Clang] Remove the wrong assumption when rebuilding SizeOfPackExprs for constraint normalization #115120

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Merged
merged 3 commits into from
Nov 8, 2024
Merged

[Clang] Remove the wrong assumption when rebuilding SizeOfPackExprs for constraint normalization #115120

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0017e08
[Clang] Remove the wrong assumption when rebuilding SizeOfPackExprs f…
zyn0217 Nov 6, 2024
f9d44b9
Merge branch 'main' into regression-115098
zyn0217 Nov 6, 2024
c34b918
Avoid layering violation
zyn0217 Nov 7, 2024
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2 changes: 2 additions & 0 deletions clang/include/clang/AST/ExprCXX.h
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Original file line number Diff line number Diff line change
Expand Up @@ -4326,6 +4326,8 @@ class SizeOfPackExpr final
/// Retrieve the parameter pack.
NamedDecl *getPack() const { return Pack; }

void setPack(NamedDecl *NewPack) { Pack = NewPack; }

/// Retrieve the length of the parameter pack.
///
/// This routine may only be invoked when the expression is not
Expand Down
49 changes: 24 additions & 25 deletions clang/lib/Sema/SemaTemplateInstantiate.cpp
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Expand Up @@ -1731,31 +1731,21 @@ namespace {
return inherited::TransformLambdaBody(E, Body);
}

ExprResult RebuildSizeOfPackExpr(SourceLocation OperatorLoc,
NamedDecl *Pack, SourceLocation PackLoc,
SourceLocation RParenLoc,
std::optional<unsigned> Length,
ArrayRef<TemplateArgument> PartialArgs) {
if (SemaRef.CodeSynthesisContexts.back().Kind !=
Sema::CodeSynthesisContext::ConstraintNormalization)
return inherited::RebuildSizeOfPackExpr(OperatorLoc, Pack, PackLoc,
RParenLoc, Length, PartialArgs);

#ifndef NDEBUG
for (auto *Iter = TemplateArgs.begin(); Iter != TemplateArgs.end();
++Iter)
for (const TemplateArgument &TA : Iter->Args)
assert(TA.getKind() != TemplateArgument::Pack || TA.pack_size() == 1);
#endif
Sema::ArgumentPackSubstitutionIndexRAII SubstIndex(
SemaRef, /*NewSubstitutionIndex=*/0);
Decl *NewPack = TransformDecl(PackLoc, Pack);
if (!NewPack)
return ExprError();

return inherited::RebuildSizeOfPackExpr(OperatorLoc,
cast<NamedDecl>(NewPack), PackLoc,
RParenLoc, Length, PartialArgs);
ExprResult TransformSizeOfPackExpr(SizeOfPackExpr *E) {
ExprResult Transformed = inherited::TransformSizeOfPackExpr(E);
if (!Transformed.isUsable())
return Transformed;
auto *TransformedExpr = cast<SizeOfPackExpr>(Transformed.get());
if (SemaRef.CodeSynthesisContexts.back().Kind ==
Sema::CodeSynthesisContext::ConstraintNormalization &&
TransformedExpr->getPack() == E->getPack()) {
Decl *NewPack =
TransformDecl(E->getPackLoc(), TransformedExpr->getPack());
if (!NewPack)
return ExprError();
TransformedExpr->setPack(cast<NamedDecl>(NewPack));
Comment on lines +1739 to +1746
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It looks like there is some dance here that could be avoided if we moved this into the inherited transform function in TreeTransform.h instead.

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(I was hesitant about whether we should do much special casing in TreeTransform. Putting it in Instantiator at least minimizes the blast radius. :)

}
return TransformedExpr;
}

ExprResult TransformRequiresExpr(RequiresExpr *E) {
Expand Down Expand Up @@ -1881,6 +1871,15 @@ Decl *TemplateInstantiator::TransformDecl(SourceLocation Loc, Decl *D) {
TemplateArgument Arg = TemplateArgs(TTP->getDepth(), TTP->getPosition());

if (TTP->isParameterPack()) {
// We might not have an index for pack expansion when normalizing
// constraint expressions. In that case, resort to instantiation scopes
// for the transformed declarations.
if (SemaRef.ArgumentPackSubstitutionIndex == -1 &&
SemaRef.CodeSynthesisContexts.back().Kind ==
Sema::CodeSynthesisContext::ConstraintNormalization) {
return SemaRef.FindInstantiatedDecl(Loc, cast<NamedDecl>(D),
TemplateArgs);
}
assert(Arg.getKind() == TemplateArgument::Pack &&
"Missing argument pack");
Arg = getPackSubstitutedTemplateArgument(getSema(), Arg);
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19 changes: 19 additions & 0 deletions clang/test/SemaTemplate/concepts-out-of-line-def.cpp
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Expand Up @@ -703,6 +703,25 @@ C v;

} // namespace GH93099

namespace GH115098 {

template <typename... Ts> struct c {
template <typename T>
requires(sizeof...(Ts) > 0)
friend bool operator==(c, c);
};

template <typename... Ts> struct d {
template <typename T>
requires(sizeof...(Ts) > 0)
friend bool operator==(d, d);
};

template struct c<int>;
template struct d<int, int>;

} // namespace GH115098

namespace GH114685 {

template <typename T> struct ptr {
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