From fabda7312b91a768617f4ff1fabe0e1cc7d9131c Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?=E5=88=98=E9=9B=A8=E5=9F=B9?= Date: Wed, 1 Nov 2023 21:45:48 +0800 Subject: [PATCH] [Clang] Defer the instantiation of explicit-specifier until constraint checking completes (#70548) MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Modifications: - Skip the instantiation of the explicit-specifier during Decl substitution if we are deducing template arguments and the explicit-specifier is value dependent. - Instantiate the explicit-specifier after the constraint checking completes. - Make `instantiateExplicitSpecifier` a member function in order to instantiate the explicit-specifier in different stages. This PR doesn’t defer the instantiation of the explicit specifier for deduction guides, because I’m not familiar with deduction guides yet. I’ll dig into it after this PR. According to my local test, GCC 13 tuple works with this PR. Fixes #59827. --------- Co-authored-by: Erich Keane (cherry picked from commit 128b3b61fe6768c724975fd1df2be0abec848cf6) --- clang/docs/ReleaseNotes.rst | 4 ++ clang/include/clang/Sema/Sema.h | 3 ++ clang/lib/Sema/SemaTemplateDeduction.cpp | 53 +++++++++++++++++++ .../lib/Sema/SemaTemplateInstantiateDecl.cpp | 40 +++++++++----- .../SemaCXX/cxx2a-explicit-bool-deferred.cpp | 31 +++++++++++ 5 files changed, 117 insertions(+), 14 deletions(-) create mode 100644 clang/test/SemaCXX/cxx2a-explicit-bool-deferred.cpp diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst index a1143e14562e..8e3b94ca2017 100644 --- a/clang/docs/ReleaseNotes.rst +++ b/clang/docs/ReleaseNotes.rst @@ -857,6 +857,10 @@ Bug Fixes to C++ Support (`#64172 `_) and (`#64723 `_). +- Clang now defers the instantiation of explicit specifier until constraint checking + completes (except deduction guides). Fixes: + (`#59827 `_) + Bug Fixes to AST Handling ^^^^^^^^^^^^^^^^^^^^^^^^^ diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h index 3752a23faa85..b2ab6d0f8445 100644 --- a/clang/include/clang/Sema/Sema.h +++ b/clang/include/clang/Sema/Sema.h @@ -10293,6 +10293,9 @@ public: const CXXConstructorDecl *Tmpl, const MultiLevelTemplateArgumentList &TemplateArgs); + ExplicitSpecifier instantiateExplicitSpecifier( + const MultiLevelTemplateArgumentList &TemplateArgs, ExplicitSpecifier ES); + NamedDecl *FindInstantiatedDecl(SourceLocation Loc, NamedDecl *D, const MultiLevelTemplateArgumentList &TemplateArgs, bool FindingInstantiatedContext = false); diff --git a/clang/lib/Sema/SemaTemplateDeduction.cpp b/clang/lib/Sema/SemaTemplateDeduction.cpp index 31ea7be2975e..58dd1b783bac 100644 --- a/clang/lib/Sema/SemaTemplateDeduction.cpp +++ b/clang/lib/Sema/SemaTemplateDeduction.cpp @@ -3546,6 +3546,48 @@ static unsigned getPackIndexForParam(Sema &S, llvm_unreachable("parameter index would not be produced from template"); } +// if `Specialization` is a `CXXConstructorDecl` or `CXXConversionDecl`, +// we'll try to instantiate and update its explicit specifier after constraint +// checking. +static Sema::TemplateDeductionResult instantiateExplicitSpecifierDeferred( + Sema &S, FunctionDecl *Specialization, + const MultiLevelTemplateArgumentList &SubstArgs, + TemplateDeductionInfo &Info, FunctionTemplateDecl *FunctionTemplate, + ArrayRef DeducedArgs) { + auto GetExplicitSpecifier = [](FunctionDecl *D) { + return isa(D) + ? cast(D)->getExplicitSpecifier() + : cast(D)->getExplicitSpecifier(); + }; + auto SetExplicitSpecifier = [](FunctionDecl *D, ExplicitSpecifier ES) { + isa(D) + ? cast(D)->setExplicitSpecifier(ES) + : cast(D)->setExplicitSpecifier(ES); + }; + + ExplicitSpecifier ES = GetExplicitSpecifier(Specialization); + Expr *ExplicitExpr = ES.getExpr(); + if (!ExplicitExpr) + return Sema::TDK_Success; + if (!ExplicitExpr->isValueDependent()) + return Sema::TDK_Success; + + Sema::InstantiatingTemplate Inst( + S, Info.getLocation(), FunctionTemplate, DeducedArgs, + Sema::CodeSynthesisContext::DeducedTemplateArgumentSubstitution, Info); + if (Inst.isInvalid()) + return Sema::TDK_InstantiationDepth; + Sema::SFINAETrap Trap(S); + const ExplicitSpecifier InstantiatedES = + S.instantiateExplicitSpecifier(SubstArgs, ES); + if (InstantiatedES.isInvalid() || Trap.hasErrorOccurred()) { + Specialization->setInvalidDecl(true); + return Sema::TDK_SubstitutionFailure; + } + SetExplicitSpecifier(Specialization, InstantiatedES); + return Sema::TDK_Success; +} + /// Finish template argument deduction for a function template, /// checking the deduced template arguments for completeness and forming /// the function template specialization. @@ -3675,6 +3717,17 @@ Sema::TemplateDeductionResult Sema::FinishTemplateArgumentDeduction( } } + // We skipped the instantiation of the explicit-specifier during the + // substitution of `FD` before. So, we try to instantiate it back if + // `Specialization` is either a constructor or a conversion function. + if (isa(Specialization)) { + if (TDK_Success != instantiateExplicitSpecifierDeferred( + *this, Specialization, SubstArgs, Info, + FunctionTemplate, DeducedArgs)) { + return TDK_SubstitutionFailure; + } + } + if (OriginalCallArgs) { // C++ [temp.deduct.call]p4: // In general, the deduction process attempts to find template argument diff --git a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp index f78d46f59503..a40510ce5f2c 100644 --- a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp +++ b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp @@ -555,18 +555,16 @@ static void instantiateDependentAMDGPUFlatWorkGroupSizeAttr( S.addAMDGPUFlatWorkGroupSizeAttr(New, Attr, MinExpr, MaxExpr); } -static ExplicitSpecifier -instantiateExplicitSpecifier(Sema &S, - const MultiLevelTemplateArgumentList &TemplateArgs, - ExplicitSpecifier ES, FunctionDecl *New) { +ExplicitSpecifier Sema::instantiateExplicitSpecifier( + const MultiLevelTemplateArgumentList &TemplateArgs, ExplicitSpecifier ES) { if (!ES.getExpr()) return ES; Expr *OldCond = ES.getExpr(); Expr *Cond = nullptr; { EnterExpressionEvaluationContext Unevaluated( - S, Sema::ExpressionEvaluationContext::ConstantEvaluated); - ExprResult SubstResult = S.SubstExpr(OldCond, TemplateArgs); + *this, Sema::ExpressionEvaluationContext::ConstantEvaluated); + ExprResult SubstResult = SubstExpr(OldCond, TemplateArgs); if (SubstResult.isInvalid()) { return ExplicitSpecifier::Invalid(); } @@ -574,7 +572,7 @@ instantiateExplicitSpecifier(Sema &S, } ExplicitSpecifier Result(Cond, ES.getKind()); if (!Cond->isTypeDependent()) - S.tryResolveExplicitSpecifier(Result); + tryResolveExplicitSpecifier(Result); return Result; } @@ -2065,8 +2063,8 @@ Decl *TemplateDeclInstantiator::VisitFunctionDecl( ExplicitSpecifier InstantiatedExplicitSpecifier; if (auto *DGuide = dyn_cast(D)) { - InstantiatedExplicitSpecifier = instantiateExplicitSpecifier( - SemaRef, TemplateArgs, DGuide->getExplicitSpecifier(), DGuide); + InstantiatedExplicitSpecifier = SemaRef.instantiateExplicitSpecifier( + TemplateArgs, DGuide->getExplicitSpecifier()); if (InstantiatedExplicitSpecifier.isInvalid()) return nullptr; } @@ -2440,11 +2438,25 @@ Decl *TemplateDeclInstantiator::VisitCXXMethodDecl( } } - ExplicitSpecifier InstantiatedExplicitSpecifier = - instantiateExplicitSpecifier(SemaRef, TemplateArgs, - ExplicitSpecifier::getFromDecl(D), D); - if (InstantiatedExplicitSpecifier.isInvalid()) - return nullptr; + auto InstantiatedExplicitSpecifier = ExplicitSpecifier::getFromDecl(D); + // deduction guides need this + const bool CouldInstantiate = + InstantiatedExplicitSpecifier.getExpr() == nullptr || + !InstantiatedExplicitSpecifier.getExpr()->isValueDependent(); + + // Delay the instantiation of the explicit-specifier until after the + // constraints are checked during template argument deduction. + if (CouldInstantiate || + SemaRef.CodeSynthesisContexts.back().Kind != + Sema::CodeSynthesisContext::DeducedTemplateArgumentSubstitution) { + InstantiatedExplicitSpecifier = SemaRef.instantiateExplicitSpecifier( + TemplateArgs, InstantiatedExplicitSpecifier); + + if (InstantiatedExplicitSpecifier.isInvalid()) + return nullptr; + } else { + InstantiatedExplicitSpecifier.setKind(ExplicitSpecKind::Unresolved); + } // Implicit destructors/constructors created for local classes in // DeclareImplicit* (see SemaDeclCXX.cpp) might not have an associated TSI. diff --git a/clang/test/SemaCXX/cxx2a-explicit-bool-deferred.cpp b/clang/test/SemaCXX/cxx2a-explicit-bool-deferred.cpp new file mode 100644 index 000000000000..4d667008f2e2 --- /dev/null +++ b/clang/test/SemaCXX/cxx2a-explicit-bool-deferred.cpp @@ -0,0 +1,31 @@ +// RUN: %clang_cc1 -fsyntax-only -verify -std=c++2a %s + +template struct is_same { + static constexpr bool value = false; +}; + +template struct is_same { + static constexpr bool value = true; +}; + +template +concept SameHelper = is_same::value; +template +concept same_as = SameHelper && SameHelper; + +namespace deferred_instantiation { +template constexpr X do_not_instantiate() { return nullptr; } + +struct T { + template X> explicit(do_not_instantiate()) T(X) {} + + T(int) {} +}; + +T t(5); +// expected-error@17{{cannot initialize}} +// expected-note@20{{in instantiation of function template specialization}} +// expected-note@30{{while substituting deduced template arguments}} +// expected-note@30{{in instantiation of function template specialization}} +T t2(5.0f); +} // namespace deferred_instantiation -- 2.43.0