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[concepts] Set up an instantiation scope for constraint expression comparison #79698

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Merged
merged 2 commits into from
Jan 30, 2024
Merged

[concepts] Set up an instantiation scope for constraint expression comparison #79698

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[concepts] Set up an instantiation scope for constraint expression co…
zyn0217 Jan 27, 2024
e07fd6a
Merge branch 'main' into gh74447
zyn0217 Jan 30, 2024
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3 changes: 3 additions & 0 deletions clang/docs/ReleaseNotes.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -138,6 +138,9 @@ Bug Fixes to C++ Support
- Fixed a bug where variables referenced by requires-clauses inside
nested generic lambdas were not properly injected into the constraint scope.
(`#73418 <https://github.com/llvm/llvm-project/issues/73418>`_)
- Fixed a crash where substituting into a requires-expression that refers to function
parameters during the equivalence determination of two constraint expressions.
(`#74447 <https://github.com/llvm/llvm-project/issues/74447>`_)
- Fixed deducing auto& from const int in template parameters of partial
specializations.
(`#77189 <https://github.com/llvm/llvm-project/issues/77189>`_)
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9 changes: 9 additions & 0 deletions clang/lib/Sema/SemaConcept.cpp
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Expand Up @@ -797,6 +797,15 @@ static const Expr *SubstituteConstraintExpressionWithoutSatisfaction(
if (Inst.isInvalid())
return nullptr;

// Set up a dummy 'instantiation' scope in the case of reference to function
// parameters that the surrounding function hasn't been instantiated yet. Note
// this may happen while we're comparing two templates' constraint
// equivalence.
LocalInstantiationScope ScopeForParameters(S);
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I could swear I did this at one point and it caused significant problems... I don't have a problem with it as-is, but we need to make sure this passes all the CI (including the libcxx tests)

if (auto *FD = llvm::dyn_cast<FunctionDecl>(DeclInfo.getDecl()))
for (auto *PVD : FD->parameters())
ScopeForParameters.InstantiatedLocal(PVD, PVD);

std::optional<Sema::CXXThisScopeRAII> ThisScope;
if (auto *RD = dyn_cast<CXXRecordDecl>(DeclInfo.getDeclContext()))
ThisScope.emplace(S, const_cast<CXXRecordDecl *>(RD), Qualifiers());
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22 changes: 22 additions & 0 deletions clang/test/SemaTemplate/concepts-out-of-line-def.cpp
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Expand Up @@ -536,3 +536,25 @@ void X<T>::bar(decltype(requires { requires something_interesting<T>; })) {}
template <class T>
void X<T>::bar(decltype(requires { requires is_not_same_v<T, int>; })) {}
} // namespace GH74314

namespace GH74447 {
template <typename T> struct S {
template <typename... U, int V>
void test(T target, U... value)
requires requires {
target;
sizeof...(value) == 1;
V == 2;
};
};

template <typename T>
template <typename... U, int V>
void S<T>::test(T target, U... value)
requires requires {
target;
sizeof...(value) == 1;
V == 2;
}
{}
} // namespace GH74447