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Fix out of line Concept-comparisons of NestedNameSpecifiers #65993

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Merged
merged 4 commits into from
Sep 12, 2023
Merged

Fix out of line Concept-comparisons of NestedNameSpecifiers #65993

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52bcb55
Fix out of line Concept-comparisons of NestedNameSpecifiers
erichkeane Sep 11, 2023
7258e88
Make sure we add injected template args from the FTD
erichkeane Sep 11, 2023
a5bf5e5
Only add arguments when they participate in depth
erichkeane Sep 11, 2023
2b86194
Move release note to C++ section, move period.
erichkeane Sep 12, 2023
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4 changes: 4 additions & 0 deletions clang/docs/ReleaseNotes.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -275,6 +275,10 @@ Bug Fixes to C++ Support
(`#65067 <https://github.com/llvm/llvm-project/issues/65067>`_` and
`#63675 <https://github.com/llvm/llvm-project/issues/63675>`_`)

- Clang now properly handles out of line template specializations when there is
a non-template inner-class between the function and the class template.
(`#65810 <https://github.com/llvm/llvm-project/issues/65810>`_)

Bug Fixes to AST Handling
^^^^^^^^^^^^^^^^^^^^^^^^^
- Fixed an import failure of recursive friend class template.
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24 changes: 17 additions & 7 deletions clang/lib/Sema/SemaTemplateInstantiate.cpp
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Expand Up @@ -230,15 +230,25 @@ Response HandleFunction(const FunctionDecl *Function,
Response HandleFunctionTemplateDecl(const FunctionTemplateDecl *FTD,
MultiLevelTemplateArgumentList &Result) {
if (!isa<ClassTemplateSpecializationDecl>(FTD->getDeclContext())) {
Result.addOuterTemplateArguments(
const_cast<FunctionTemplateDecl *>(FTD),
const_cast<FunctionTemplateDecl *>(FTD)->getInjectedTemplateArgs(),
/*Final=*/false);

NestedNameSpecifier *NNS = FTD->getTemplatedDecl()->getQualifier();
const Type *Ty;
const TemplateSpecializationType *TSTy;
if (NNS && (Ty = NNS->getAsType()) &&
(TSTy = Ty->getAs<TemplateSpecializationType>()))
Result.addOuterTemplateArguments(const_cast<FunctionTemplateDecl *>(FTD),
TSTy->template_arguments(),
/*Final=*/false);

while (const Type *Ty = NNS ? NNS->getAsType() : nullptr) {
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This make sense, I was just looking at the AST: https://godbolt.org/z/P3brjcsMG

and I see that InnerClass has:

| |-NestedNameSpecifier TypeSpec 'Base<T>'

and I wondering what the prefix is there? Maybe the AST is not telling the whole story?

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So that one you're seeing there is for the InnerClass on line 13, the NestedNameSpecifier is for 'everything else' outside of that declaration. So in THAT case, the Prefix of that one is nothing, since the Base<T> is the entirety of the thing.

However, that AST doesn't show the NNS of func on line 22, for some reason we're not dumping that. In THAT case, the NNS is Base<T>::InnerClass. At that point, the InnerClass doesn't have template arguments (since it isn't a template!), but its Prefix is just the Base<T>, which has them (which is why/how this loop works).

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It does not look like there is a simple way of getting like w/ CXXRecordDecl so some work would be involved.

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I don't understand what you mean? TagDecl (IIRC?) has a getQualifier() to get the appropriate NestedNameSpecifier. I believe our NNS tree is correct the way I've implemented it above, with the exception of the issue I posted about a moment ago.

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Yeah, I just realized I was looking at the code a moment ago FTD->getTemplatedDecl()->getQualifier()

if (NNS->isInstantiationDependent()) {
if (const auto *TSTy = Ty->getAs<TemplateSpecializationType>())
Result.addOuterTemplateArguments(
const_cast<FunctionTemplateDecl *>(FTD), TSTy->template_arguments(),
/*Final=*/false);
}

NNS = NNS->getPrefix();
}
}

return Response::ChangeDecl(FTD->getLexicalDeclContext());
}

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48 changes: 48 additions & 0 deletions clang/test/SemaTemplate/concepts-out-of-line-def.cpp
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Expand Up @@ -418,3 +418,51 @@ template<typename T> concept A = true;
template<typename T> struct X { A<T> auto f(); };
template<typename T> A<T> auto X<T>::f() {}
}

namespace GH65810 {
template<typename Param>
concept TrivialConcept =
requires(Param param) {
(void)param;
};

template <typename T>
struct Base {
class InnerClass;
};

template <typename T>
class Base<T>::InnerClass {
template <typename Param>
requires TrivialConcept<Param>
int func(Param param) const;
};

template <typename T>
template <typename Param>
requires TrivialConcept<Param>
int Base<T>::InnerClass::func(Param param) const {
return 0;
}

template<typename T>
struct Outermost {
struct Middle {
template<typename U>
struct Innermost {
template <typename Param>
requires TrivialConcept<Param>
int func(Param param) const;
};
};
};

template <typename T>
template <typename U>
template <typename Param>
requires TrivialConcept<Param>
int Outermost<T>::Middle::Innermost<U>::func(Param param) const {
return 0;
}

} // namespace GH65810