diff --git a/clang/include/clang/Parse/Parser.h b/clang/include/clang/Parse/Parser.h --- a/clang/include/clang/Parse/Parser.h +++ b/clang/include/clang/Parse/Parser.h @@ -1861,6 +1861,8 @@ Token &Replacement); ExprResult ParseCXXIdExpression(bool isAddressOfOperand = false); + ExprResult ParseCXXMaybeMutableAgnosticExpression(); + bool areTokensAdjacent(const Token &A, const Token &B); void CheckForTemplateAndDigraph(Token &Next, ParsedType ObjectTypePtr, diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h --- a/clang/include/clang/Sema/Sema.h +++ b/clang/include/clang/Sema/Sema.h @@ -787,6 +787,11 @@ /// context. unsigned FunctionScopesStart = 0; + /// Whether we are currently in the context of a mutable agnostic identifier + /// as described by CWG2569. + /// We are handling the unqualified-id of a decltype or noexcept expression. + bool InMutableAgnosticContext = false; + ArrayRef getFunctionScopes() const { return llvm::makeArrayRef(FunctionScopes.begin() + FunctionScopesStart, FunctionScopes.end()); @@ -5270,6 +5275,11 @@ CorrectionCandidateCallback *CCC = nullptr, bool IsInlineAsmIdentifier = false, Token *KeywordReplacement = nullptr); + ExprResult ActOnMutableAgnosticIdExpression(Scope *S, CXXScopeSpec &SS, + UnqualifiedId &Id, + SourceLocation TemplateKwLoc, + bool HasTrailingLParen); + void DecomposeUnqualifiedId(const UnqualifiedId &Id, TemplateArgumentListInfo &Buffer, DeclarationNameInfo &NameInfo, diff --git a/clang/lib/Parse/ParseDeclCXX.cpp b/clang/lib/Parse/ParseDeclCXX.cpp --- a/clang/lib/Parse/ParseDeclCXX.cpp +++ b/clang/lib/Parse/ParseDeclCXX.cpp @@ -1054,7 +1054,7 @@ Actions, Sema::ExpressionEvaluationContext::Unevaluated, nullptr, Sema::ExpressionEvaluationContextRecord::EK_Decltype); Result = Actions.CorrectDelayedTyposInExpr( - ParseExpression(), /*InitDecl=*/nullptr, + ParseCXXMaybeMutableAgnosticExpression(), /*InitDecl=*/nullptr, /*RecoverUncorrectedTypos=*/false, [](Expr *E) { return E->hasPlaceholderType() ? ExprError() : E; }); if (Result.isInvalid()) { diff --git a/clang/lib/Parse/ParseExprCXX.cpp b/clang/lib/Parse/ParseExprCXX.cpp --- a/clang/lib/Parse/ParseExprCXX.cpp +++ b/clang/lib/Parse/ParseExprCXX.cpp @@ -685,6 +685,36 @@ return Result; } +/// ParseCXXMaybeMutableAgnosticExpression - Handle Expressions inside of +/// sizeof, decltype, noexcepr +/// - unqualified-id +/// - expression +/// This serves to silence errors about captured variable refered in lambda +/// parameter list, if they aree used as the unqualified-id of a decltype, +/// sizeof, or noexcept expression +ExprResult Parser::ParseCXXMaybeMutableAgnosticExpression() { + + if (!getLangOpts().CPlusPlus11) + return ParseExpression(); + + if (Tok.is(tok::identifier) && NextToken().is(tok::r_paren)) { + SourceLocation TemplateKWLoc; + UnqualifiedId Name; + CXXScopeSpec SS; + if (!ParseUnqualifiedId(SS, /*ObjectType=*/nullptr, + /*ObjectHadErrors=*/false, + /*EnteringContext=*/false, + /*AllowDestructorName=*/false, + /*AllowConstructorName=*/false, + /*AllowDeductionGuide=*/false, &TemplateKWLoc, + Name)) { + return Actions.ActOnMutableAgnosticIdExpression(getCurScope(), SS, Name, + TemplateKWLoc, false); + } + } + return ParseExpression(); +} + /// ParseLambdaExpression - Parse a C++11 lambda expression. /// /// lambda-expression: diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp --- a/clang/lib/Sema/SemaExpr.cpp +++ b/clang/lib/Sema/SemaExpr.cpp @@ -2698,6 +2698,21 @@ return BuildDeclarationNameExpr(SS, R, ADL); } +ExprResult Sema::ActOnMutableAgnosticIdExpression(Scope *S, CXXScopeSpec &SS, + UnqualifiedId &Id, + SourceLocation TemplateKwLoc, + bool HasTrailingLParen) { + InMutableAgnosticContext = true; + ExprResult Res = + ActOnIdExpression(S, SS, TemplateKwLoc, Id, HasTrailingLParen, + /*IsAddressOfOperand*/ false, + /*CorrectionCandidateCallback*/ nullptr, + /*IsInlineAsmIdentifier*/ false, + /*KeywordReplacement*/ nullptr); + InMutableAgnosticContext = false; + return Res; +} + /// BuildQualifiedDeclarationNameExpr - Build a C++ qualified /// declaration name, generally during template instantiation. /// There's a large number of things which don't need to be done along @@ -18545,6 +18560,11 @@ static bool CheckCaptureUseBeforeLambdaQualifiers(Sema &S, VarDecl *Var, SourceLocation ExprLoc, LambdaScopeInfo *LSI) { + + // Allow `[a = 1](decltype(a)) {}` as per CWG2569. + if (S.InMutableAgnosticContext) + return true; + if (Var->isInvalidDecl()) return false; @@ -18627,7 +18647,7 @@ LSI = dyn_cast_or_null( FunctionScopes[FunctionScopesIndex]); if (LSI && LSI->BeforeLambdaQualifiersScope) { - if (isa(Var)) + if (isa(Var) && !Var->getDeclContext()->isFunctionOrMethod()) return true; IsInLambdaBeforeQualifiers = true; if (!CheckCaptureUseBeforeLambdaQualifiers(*this, Var, ExprLoc, LSI)) { diff --git a/clang/test/SemaCXX/lambda-capture-type-deduction.cpp b/clang/test/SemaCXX/lambda-capture-type-deduction.cpp --- a/clang/test/SemaCXX/lambda-capture-type-deduction.cpp +++ b/clang/test/SemaCXX/lambda-capture-type-deduction.cpp @@ -87,23 +87,23 @@ int y, z; // expected-note 2{{declared here}} auto implicit_tpl = [=]( // expected-note {{variable 'y' is captured here}} decltype( - [&] { return 0; }) y) { //expected-error{{captured variable 'y' cannot appear here}} + [&] { return 0; }) y) { // expected-error{{captured variable 'y' cannot appear here}} return y; }; - auto init_tpl = [x = 1]( // expected-note{{explicitly captured here}} - decltype([&] { return 0; }) y) { // expected-error {{captured variable 'x' cannot appear here}} + auto init_tpl = [x = 1]( // expected-note{{explicitly captured here}} + decltype([&] { return 0; }) y) { // expected-error {{captured variable 'x' cannot appear here}} return x; }; auto implicit = [=]( // expected-note {{variable 'z' is captured here}} decltype( - [&](decltype(z)) { return 0; }) z) { //expected-error{{captured variable 'z' cannot appear here}} + [&](decltype((z))) { return 0; }) z) { // expected-error{{captured variable 'z' cannot appear here}} return z; }; - auto init = [x = 1]( // expected-note{{explicitly captured here}} - decltype([&](decltype(x)) { return 0; }) y) { // expected-error {{captured variable 'x' cannot appear here}} + auto init = [x = 1]( // expected-note{{explicitly captured here}} + decltype([&](decltype((x))) { return 0; }) y) { // expected-error {{captured variable 'x' cannot appear here}} return x; }; @@ -141,20 +141,20 @@ decltype([&]( decltype([=]( // expected-note {{variable 'x' is captured here}} decltype([&]( - decltype([&](decltype(x)) {}) // expected-error{{captured variable 'x' cannot appear here}} + decltype([&](decltype((x))) {}) // expected-error{{captured variable 'x' cannot appear here}} ) {})) {})) {})){}; (void)[&]( decltype([&]( decltype([&]( decltype([&]( - decltype([&](decltype(y)) {})) {})) {})) {})){}; + decltype([&](decltype((y))) {})) {})) {})) {})){}; (void)[=]( decltype([=]( decltype([=]( - decltype([=]( // expected-note {{variable 'z' is captured here}} - decltype([&] {}) // expected-error{{captured variable 'z' cannot appear here}} + decltype([=]( // expected-note {{variable 'z' is captured here}} + decltype([&] {}) // expected-error{{captured variable 'z' cannot appear here}} ) {})) {})) {})){}; } @@ -171,3 +171,13 @@ dependent(r); dependent(cr); } + +void test_CWG2569_tpl(auto a) { + (void)[=](decltype(a) b = decltype(a)()){}; +} + +void test_CWG2569() { + int a = 0; + (void)[=](decltype(a) b = decltype(a)()){}; + test_CWG2569_tpl(0); +}