Author: Younan Zhang Date: 2024-08-21T17:01:05+08:00 New Revision: 8ac140f390847e4e85e0a4fd910baaf46e5d115b
URL: https://github.com/llvm/llvm-project/commit/8ac140f390847e4e85e0a4fd910baaf46e5d115b DIFF: https://github.com/llvm/llvm-project/commit/8ac140f390847e4e85e0a4fd910baaf46e5d115b.diff LOG: [Clang][NFCI] Cleanup the fix for default function argument substitution (#104911) (This is one step towards tweaking `getTemplateInstantiationArgs()` as discussed in https://github.com/llvm/llvm-project/pull/102922) We don't always substitute into default arguments while transforming a function parameter. In that case, we would preserve the uninstantiated expression until after, e.g. building up a CXXDefaultArgExpr and instantiate the expression there. For member function instantiation, this algorithm used to cause a problem in that the default argument of an out-of-line member function specialization couldn't get properly instantiated. This is because, in `getTemplateInstantiationArgs()`, we would give up visiting a function's declaration context if the function is a specialization of a member template. For example, ```cpp template <class T> struct S { template <class U> void f(T = sizeof(T)); }; template <> template <class U> void S<int>::f(int) {} ``` The default argument `sizeof(U)` that lexically appears inside the declaration would be copied to the function declaration in the class template specialization `S<int>`, as well as to the function's out-of-line definition. We use template arguments collected from the out-of-line function definition when substituting into the default arguments. We would therefore give up the traversal after the function, resulting in a single-level template argument of the `f` itself. However the default argument here could still reference the template parameters of the primary template, hence the error. In fact, this is similar to constraint checking in some respects: we actually want the "whole" template arguments relative to the primary template, not those relative to the function definition. So this patch adds another flag to indicate `getTemplateInstantiationArgs()` for that. This patch also consolidates the tests for default arguments and removes some unnecessary tests. Added: Modified: clang/include/clang/Sema/Sema.h clang/lib/Sema/SemaTemplateInstantiate.cpp clang/lib/Sema/SemaTemplateInstantiateDecl.cpp Removed: ################################################################################ diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h index 299a916b9abf8d..1f7e555d1b8717 100644 --- a/clang/include/clang/Sema/Sema.h +++ b/clang/include/clang/Sema/Sema.h @@ -13071,12 +13071,19 @@ class Sema final : public SemaBase { /// ForConstraintInstantiation indicates we should continue looking when /// encountering a lambda generic call operator, and continue looking for /// arguments on an enclosing class template. + /// + /// \param SkipForSpecialization when specified, any template specializations + /// in a traversal would be ignored. + /// \param ForDefaultArgumentSubstitution indicates we should continue looking + /// when encountering a specialized member function template, rather than + /// returning immediately. MultiLevelTemplateArgumentList getTemplateInstantiationArgs( const NamedDecl *D, const DeclContext *DC = nullptr, bool Final = false, std::optional<ArrayRef<TemplateArgument>> Innermost = std::nullopt, bool RelativeToPrimary = false, const FunctionDecl *Pattern = nullptr, bool ForConstraintInstantiation = false, - bool SkipForSpecialization = false); + bool SkipForSpecialization = false, + bool ForDefaultArgumentSubstitution = false); /// RAII object to handle the state changes required to synthesize /// a function body. diff --git a/clang/lib/Sema/SemaTemplateInstantiate.cpp b/clang/lib/Sema/SemaTemplateInstantiate.cpp index 9a6cd2cd0ab751..fd90f83f3976ca 100644 --- a/clang/lib/Sema/SemaTemplateInstantiate.cpp +++ b/clang/lib/Sema/SemaTemplateInstantiate.cpp @@ -256,7 +256,8 @@ HandleClassTemplateSpec(const ClassTemplateSpecializationDecl *ClassTemplSpec, Response HandleFunction(Sema &SemaRef, const FunctionDecl *Function, MultiLevelTemplateArgumentList &Result, const FunctionDecl *Pattern, bool RelativeToPrimary, - bool ForConstraintInstantiation) { + bool ForConstraintInstantiation, + bool ForDefaultArgumentSubstitution) { // Add template arguments from a function template specialization. if (!RelativeToPrimary && Function->getTemplateSpecializationKindForInstantiation() == @@ -286,7 +287,8 @@ Response HandleFunction(Sema &SemaRef, const FunctionDecl *Function, // If this function was instantiated from a specialized member that is // a function template, we're done. assert(Function->getPrimaryTemplate() && "No function template?"); - if (Function->getPrimaryTemplate()->isMemberSpecialization()) + if (!ForDefaultArgumentSubstitution && + Function->getPrimaryTemplate()->isMemberSpecialization()) return Response::Done(); // If this function is a generic lambda specialization, we are done. @@ -468,7 +470,7 @@ MultiLevelTemplateArgumentList Sema::getTemplateInstantiationArgs( const NamedDecl *ND, const DeclContext *DC, bool Final, std::optional<ArrayRef<TemplateArgument>> Innermost, bool RelativeToPrimary, const FunctionDecl *Pattern, bool ForConstraintInstantiation, - bool SkipForSpecialization) { + bool SkipForSpecialization, bool ForDefaultArgumentSubstitution) { assert((ND || DC) && "Can't find arguments for a decl if one isn't provided"); // Accumulate the set of template argument lists in this structure. MultiLevelTemplateArgumentList Result; @@ -510,7 +512,8 @@ MultiLevelTemplateArgumentList Sema::getTemplateInstantiationArgs( SkipForSpecialization); } else if (const auto *Function = dyn_cast<FunctionDecl>(CurDecl)) { R = HandleFunction(*this, Function, Result, Pattern, RelativeToPrimary, - ForConstraintInstantiation); + ForConstraintInstantiation, + ForDefaultArgumentSubstitution); } else if (const auto *Rec = dyn_cast<CXXRecordDecl>(CurDecl)) { R = HandleRecordDecl(*this, Rec, Result, Context, ForConstraintInstantiation); @@ -3227,7 +3230,6 @@ bool Sema::SubstDefaultArgument( // default argument expression appears. ContextRAII SavedContext(*this, FD); std::unique_ptr<LocalInstantiationScope> LIS; - MultiLevelTemplateArgumentList NewTemplateArgs = TemplateArgs; if (ForCallExpr) { // When instantiating a default argument due to use in a call expression, @@ -3240,19 +3242,10 @@ bool Sema::SubstDefaultArgument( /*ForDefinition*/ false); if (addInstantiatedParametersToScope(FD, PatternFD, *LIS, TemplateArgs)) return true; - const FunctionTemplateDecl *PrimaryTemplate = FD->getPrimaryTemplate(); - if (PrimaryTemplate && PrimaryTemplate->isOutOfLine()) { - TemplateArgumentList *CurrentTemplateArgumentList = - TemplateArgumentList::CreateCopy(getASTContext(), - TemplateArgs.getInnermost()); - NewTemplateArgs = getTemplateInstantiationArgs( - FD, FD->getDeclContext(), /*Final=*/false, - CurrentTemplateArgumentList->asArray(), /*RelativeToPrimary=*/true); - } } runWithSufficientStackSpace(Loc, [&] { - Result = SubstInitializer(PatternExpr, NewTemplateArgs, + Result = SubstInitializer(PatternExpr, TemplateArgs, /*DirectInit*/ false); }); } diff --git a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp index a58854acb21fa5..0e064be2391838 100644 --- a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp +++ b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp @@ -4699,10 +4699,12 @@ bool Sema::InstantiateDefaultArgument(SourceLocation CallLoc, FunctionDecl *FD, // // template<typename T> // A<T> Foo(int a = A<T>::FooImpl()); - MultiLevelTemplateArgumentList TemplateArgs = - getTemplateInstantiationArgs(FD, FD->getLexicalDeclContext(), - /*Final=*/false, /*Innermost=*/std::nullopt, - /*RelativeToPrimary=*/true); + MultiLevelTemplateArgumentList TemplateArgs = getTemplateInstantiationArgs( + FD, FD->getLexicalDeclContext(), + /*Final=*/false, /*Innermost=*/std::nullopt, + /*RelativeToPrimary=*/true, /*Pattern=*/nullptr, + /*ForConstraintInstantiation=*/false, /*SkipForSpecialization=*/false, + /*ForDefaultArgumentSubstitution=*/true); if (SubstDefaultArgument(CallLoc, Param, TemplateArgs, /*ForCallExpr*/ true)) return true; _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
