Author: Krystian Stasiowski Date: 2024-04-09T08:31:52-04:00 New Revision: 4657ab1c968e486e9f45329daa07340ebcf3bffd
URL: https://github.com/llvm/llvm-project/commit/4657ab1c968e486e9f45329daa07340ebcf3bffd DIFF: https://github.com/llvm/llvm-project/commit/4657ab1c968e486e9f45329daa07340ebcf3bffd.diff LOG: [Clang][Sema] Fix crash when 'this' is used in a dependent class scope function template specialization that instantiates to a static member function (#87541) This patch fixes a crash that happens when '`this`' is referenced (implicitly or explicitly) in a dependent class scope function template specialization that instantiates to a static member function. For example: ``` template<typename T> struct A { template<typename U> static void f(); template<> void f<int>() { this; // causes crash during instantiation } }; template struct A<int>; ``` This happens because during instantiation of the function body, `Sema::getCurrentThisType` will return a null `QualType` which we rebuild the `CXXThisExpr` with. A similar problem exists for implicit class member access expressions in such contexts (which shouldn't really happen within templates anyways per [class.mfct.non.static] p2, but changing that is non-trivial). This patch fixes the crash by building `UnresolvedLookupExpr`s instead of `MemberExpr`s for these implicit member accesses, which will then be correctly rebuilt as `MemberExpr`s during instantiation. Added: Modified: clang/docs/ReleaseNotes.rst clang/include/clang/Sema/Sema.h clang/lib/Sema/SemaExpr.cpp clang/lib/Sema/SemaExprCXX.cpp clang/lib/Sema/SemaExprMember.cpp clang/lib/Sema/SemaTemplateInstantiateDecl.cpp clang/lib/Sema/TreeTransform.h clang/test/SemaTemplate/ms-function-specialization-class-scope.cpp Removed: ################################################################################ diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst index 8d9ccf789d9cb8..30cedbe774be96 100644 --- a/clang/docs/ReleaseNotes.rst +++ b/clang/docs/ReleaseNotes.rst @@ -507,6 +507,8 @@ Bug Fixes to C++ Support - Fix an issue caused by not handling invalid cases when substituting into the parameter mapping of a constraint. Fixes (#GH86757). - Fixed a bug that prevented member function templates of class templates declared with a deduced return type from being explicitly specialized for a given implicit instantiation of the class template. +- Fixed a crash when ``this`` is used in a dependent class scope function template specialization + that instantiates to a static member function. - Fix crash when inheriting from a cv-qualified type. Fixes: (`#35603 <https://github.com/llvm/llvm-project/issues/35603>`_) diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h index 9769d36900664c..f311f9f3743454 100644 --- a/clang/include/clang/Sema/Sema.h +++ b/clang/include/clang/Sema/Sema.h @@ -5439,7 +5439,8 @@ class Sema final : public SemaBase { ExprResult BuildDeclarationNameExpr(const CXXScopeSpec &SS, LookupResult &R, bool NeedsADL, - bool AcceptInvalidDecl = false); + bool AcceptInvalidDecl = false, + bool NeedUnresolved = false); ExprResult BuildDeclarationNameExpr( const CXXScopeSpec &SS, const DeclarationNameInfo &NameInfo, NamedDecl *D, NamedDecl *FoundD = nullptr, @@ -6591,7 +6592,10 @@ class Sema final : public SemaBase { SourceLocation RParenLoc); //// ActOnCXXThis - Parse 'this' pointer. - ExprResult ActOnCXXThis(SourceLocation loc); + ExprResult ActOnCXXThis(SourceLocation Loc); + + /// Check whether the type of 'this' is valid in the current context. + bool CheckCXXThisType(SourceLocation Loc, QualType Type); /// Build a CXXThisExpr and mark it referenced in the current context. Expr *BuildCXXThisExpr(SourceLocation Loc, QualType Type, bool IsImplicit); diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp index 8db4fffeecfe35..7b91bbe0b2054d 100644 --- a/clang/lib/Sema/SemaExpr.cpp +++ b/clang/lib/Sema/SemaExpr.cpp @@ -3442,10 +3442,11 @@ static bool ShouldLookupResultBeMultiVersionOverload(const LookupResult &R) { ExprResult Sema::BuildDeclarationNameExpr(const CXXScopeSpec &SS, LookupResult &R, bool NeedsADL, - bool AcceptInvalidDecl) { + bool AcceptInvalidDecl, + bool NeedUnresolved) { // If this is a single, fully-resolved result and we don't need ADL, // just build an ordinary singleton decl ref. - if (!NeedsADL && R.isSingleResult() && + if (!NeedUnresolved && !NeedsADL && R.isSingleResult() && !R.getAsSingle<FunctionTemplateDecl>() && !ShouldLookupResultBeMultiVersionOverload(R)) return BuildDeclarationNameExpr(SS, R.getLookupNameInfo(), R.getFoundDecl(), diff --git a/clang/lib/Sema/SemaExprCXX.cpp b/clang/lib/Sema/SemaExprCXX.cpp index dee6b658cd0054..9ba41432401962 100644 --- a/clang/lib/Sema/SemaExprCXX.cpp +++ b/clang/lib/Sema/SemaExprCXX.cpp @@ -1415,26 +1415,42 @@ bool Sema::CheckCXXThisCapture(SourceLocation Loc, const bool Explicit, } ExprResult Sema::ActOnCXXThis(SourceLocation Loc) { - /// C++ 9.3.2: In the body of a non-static member function, the keyword this - /// is a non-lvalue expression whose value is the address of the object for - /// which the function is called. + // C++20 [expr.prim.this]p1: + // The keyword this names a pointer to the object for which an + // implicit object member function is invoked or a non-static + // data member's initializer is evaluated. QualType ThisTy = getCurrentThisType(); - if (ThisTy.isNull()) { - DeclContext *DC = getFunctionLevelDeclContext(); + if (CheckCXXThisType(Loc, ThisTy)) + return ExprError(); - if (const auto *Method = dyn_cast<CXXMethodDecl>(DC); - Method && Method->isExplicitObjectMemberFunction()) { - return Diag(Loc, diag::err_invalid_this_use) << 1; - } + return BuildCXXThisExpr(Loc, ThisTy, /*IsImplicit=*/false); +} - if (isLambdaCallWithExplicitObjectParameter(CurContext)) - return Diag(Loc, diag::err_invalid_this_use) << 1; +bool Sema::CheckCXXThisType(SourceLocation Loc, QualType Type) { + if (!Type.isNull()) + return false; - return Diag(Loc, diag::err_invalid_this_use) << 0; + // C++20 [expr.prim.this]p3: + // If a declaration declares a member function or member function template + // of a class X, the expression this is a prvalue of type + // "pointer to cv-qualifier-seq X" wherever X is the current class between + // the optional cv-qualifier-seq and the end of the function-definition, + // member-declarator, or declarator. It shall not appear within the + // declaration of either a static member function or an explicit object + // member function of the current class (although its type and value + // category are defined within such member functions as they are within + // an implicit object member function). + DeclContext *DC = getFunctionLevelDeclContext(); + if (const auto *Method = dyn_cast<CXXMethodDecl>(DC); + Method && Method->isExplicitObjectMemberFunction()) { + Diag(Loc, diag::err_invalid_this_use) << 1; + } else if (isLambdaCallWithExplicitObjectParameter(CurContext)) { + Diag(Loc, diag::err_invalid_this_use) << 1; + } else { + Diag(Loc, diag::err_invalid_this_use) << 0; } - - return BuildCXXThisExpr(Loc, ThisTy, /*IsImplicit=*/false); + return true; } Expr *Sema::BuildCXXThisExpr(SourceLocation Loc, QualType Type, diff --git a/clang/lib/Sema/SemaExprMember.cpp b/clang/lib/Sema/SemaExprMember.cpp index 32998ae60eafe2..8cd2288d279cc7 100644 --- a/clang/lib/Sema/SemaExprMember.cpp +++ b/clang/lib/Sema/SemaExprMember.cpp @@ -61,6 +61,10 @@ enum IMAKind { /// The reference is a contextually-permitted abstract member reference. IMA_Abstract, + /// Whether the context is static is dependent on the enclosing template (i.e. + /// in a dependent class scope explicit specialization). + IMA_Dependent, + /// The reference may be to an unresolved using declaration and the /// context is not an instance method. IMA_Unresolved_StaticOrExplicitContext, @@ -91,10 +95,18 @@ static IMAKind ClassifyImplicitMemberAccess(Sema &SemaRef, DeclContext *DC = SemaRef.getFunctionLevelDeclContext(); - bool isStaticOrExplicitContext = - SemaRef.CXXThisTypeOverride.isNull() && - (!isa<CXXMethodDecl>(DC) || cast<CXXMethodDecl>(DC)->isStatic() || - cast<CXXMethodDecl>(DC)->isExplicitObjectMemberFunction()); + bool couldInstantiateToStatic = false; + bool isStaticOrExplicitContext = SemaRef.CXXThisTypeOverride.isNull(); + + if (auto *MD = dyn_cast<CXXMethodDecl>(DC)) { + if (MD->isImplicitObjectMemberFunction()) { + isStaticOrExplicitContext = false; + // A dependent class scope function template explicit specialization + // that is neither declared 'static' nor with an explicit object + // parameter could instantiate to a static or non-static member function. + couldInstantiateToStatic = MD->getDependentSpecializationInfo(); + } + } if (R.isUnresolvableResult()) return isStaticOrExplicitContext ? IMA_Unresolved_StaticOrExplicitContext @@ -123,6 +135,9 @@ static IMAKind ClassifyImplicitMemberAccess(Sema &SemaRef, if (Classes.empty()) return IMA_Static; + if (couldInstantiateToStatic) + return IMA_Dependent; + // C++11 [expr.prim.general]p12: // An id-expression that denotes a non-static data member or non-static // member function of a class can only be used: @@ -268,27 +283,30 @@ ExprResult Sema::BuildPossibleImplicitMemberExpr( const CXXScopeSpec &SS, SourceLocation TemplateKWLoc, LookupResult &R, const TemplateArgumentListInfo *TemplateArgs, const Scope *S, UnresolvedLookupExpr *AsULE) { - switch (ClassifyImplicitMemberAccess(*this, R)) { + switch (IMAKind Classification = ClassifyImplicitMemberAccess(*this, R)) { case IMA_Instance: - return BuildImplicitMemberExpr(SS, TemplateKWLoc, R, TemplateArgs, true, S); - case IMA_Mixed: case IMA_Mixed_Unrelated: case IMA_Unresolved: - return BuildImplicitMemberExpr(SS, TemplateKWLoc, R, TemplateArgs, false, - S); - + return BuildImplicitMemberExpr( + SS, TemplateKWLoc, R, TemplateArgs, + /*IsKnownInstance=*/Classification == IMA_Instance, S); case IMA_Field_Uneval_Context: Diag(R.getNameLoc(), diag::warn_cxx98_compat_non_static_member_use) << R.getLookupNameInfo().getName(); [[fallthrough]]; case IMA_Static: case IMA_Abstract: + case IMA_Dependent: case IMA_Mixed_StaticOrExplicitContext: case IMA_Unresolved_StaticOrExplicitContext: if (TemplateArgs || TemplateKWLoc.isValid()) - return BuildTemplateIdExpr(SS, TemplateKWLoc, R, false, TemplateArgs); - return AsULE ? AsULE : BuildDeclarationNameExpr(SS, R, false); + return BuildTemplateIdExpr(SS, TemplateKWLoc, R, /*RequiresADL=*/false, + TemplateArgs); + return AsULE ? AsULE + : BuildDeclarationNameExpr( + SS, R, /*NeedsADL=*/false, /*AcceptInvalidDecl=*/false, + /*NeedUnresolved=*/Classification == IMA_Dependent); case IMA_Error_StaticOrExplicitContext: case IMA_Error_Unrelated: diff --git a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp index 127a432367b95d..8248b10814fea5 100644 --- a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp +++ b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp @@ -5093,6 +5093,14 @@ void Sema::InstantiateFunctionDefinition(SourceLocation PointOfInstantiation, EnterExpressionEvaluationContext EvalContext( *this, Sema::ExpressionEvaluationContext::PotentiallyEvaluated); + Qualifiers ThisTypeQuals; + CXXRecordDecl *ThisContext = nullptr; + if (CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(Function)) { + ThisContext = Method->getParent(); + ThisTypeQuals = Method->getMethodQualifiers(); + } + CXXThisScopeRAII ThisScope(*this, ThisContext, ThisTypeQuals); + // Introduce a new scope where local variable instantiations will be // recorded, unless we're actually a member function within a local // class, in which case we need to merge our results with the parent diff --git a/clang/lib/Sema/TreeTransform.h b/clang/lib/Sema/TreeTransform.h index ab97b375f5161a..6ebca07eaa4f95 100644 --- a/clang/lib/Sema/TreeTransform.h +++ b/clang/lib/Sema/TreeTransform.h @@ -3307,12 +3307,13 @@ class TreeTransform { /// Build a new C++ "this" expression. /// - /// By default, builds a new "this" expression without performing any - /// semantic analysis. Subclasses may override this routine to provide - /// diff erent behavior. + /// By default, performs semantic analysis to build a new "this" expression. + /// Subclasses may override this routine to provide diff erent behavior. ExprResult RebuildCXXThisExpr(SourceLocation ThisLoc, QualType ThisType, bool isImplicit) { + if (getSema().CheckCXXThisType(ThisLoc, ThisType)) + return ExprError(); return getSema().BuildCXXThisExpr(ThisLoc, ThisType, isImplicit); } diff --git a/clang/test/SemaTemplate/ms-function-specialization-class-scope.cpp b/clang/test/SemaTemplate/ms-function-specialization-class-scope.cpp index dcab9bfaeabcb0..6977623a0816ed 100644 --- a/clang/test/SemaTemplate/ms-function-specialization-class-scope.cpp +++ b/clang/test/SemaTemplate/ms-function-specialization-class-scope.cpp @@ -1,7 +1,6 @@ -// RUN: %clang_cc1 -fms-extensions -fsyntax-only -verify %s -// RUN: %clang_cc1 -fms-extensions -fdelayed-template-parsing -fsyntax-only -verify %s +// RUN: %clang_cc1 -fms-extensions -fsyntax-only -Wno-unused-value -verify %s +// RUN: %clang_cc1 -fms-extensions -fdelayed-template-parsing -fsyntax-only -Wno-unused-value -verify %s -// expected-no-diagnostics class A { public: template<class U> A(U p) {} @@ -76,3 +75,42 @@ struct S { int f<0>(int); }; } + +namespace UsesThis { + template<typename T> + struct A { + int x; + + template<typename U> + static void f(); + + template<> + void f<int>() { + this->x; // expected-error {{invalid use of 'this' outside of a non-static member function}} + x; // expected-error {{invalid use of member 'x' in static member function}} + A::x; // expected-error {{invalid use of member 'x' in static member function}} + +x; // expected-error {{invalid use of member 'x' in static member function}} + +A::x; // expected-error {{invalid use of member 'x' in static member function}} + } + + template<typename U> + void g(); + + template<> + void g<int>() { + this->x; + x; + A::x; + +x; + +A::x; + } + + template<typename U> + static auto h() -> A*; + + template<> + auto h<int>() -> decltype(this); // expected-error {{'this' cannot be used in a static member function declaration}} + }; + + template struct A<int>; // expected-note 2{{in instantiation of}} +} _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
