Author: erichkeane Date: Thu Sep 28 13:36:53 2017 New Revision: 314461 URL: http://llvm.org/viewvc/llvm-project?rev=314461&view=rev Log: [Sema] Warn on attribute nothrow conflicting with language specifiers
I discovered it was possible to create a 'nothrow' noexcept(false) function, which is both non-sensical as well as seemingly breaking. This patch warns if attribute nothrow is used with anything besides "noexcept". "noexcept(true)" isn't possible, because the noexcept decl isn't parsed until later. Differential Revision: https://reviews.llvm.org/D38205 Added: cfe/trunk/test/SemaCXX/warn-conflicting-nothrow-attr-exception-spec.cpp (with props) Modified: cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td cfe/trunk/lib/Sema/SemaDeclAttr.cpp Modified: cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td?rev=314461&r1=314460&r2=314461&view=diff ============================================================================== --- cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td (original) +++ cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td Thu Sep 28 13:36:53 2017 @@ -1407,6 +1407,10 @@ def err_noexcept_needs_constant_expressi "argument to noexcept specifier must be a constant expression">; def err_exception_spec_not_parsed : Error< "exception specification is not available until end of class definition">; +def warn_nothrow_attr_disagrees_with_exception_specification + : ExtWarn<"attribute 'nothrow' ignored due to conflicting exception " + "specification">, + InGroup<IgnoredAttributes>; // C++ access checking def err_class_redeclared_with_different_access : Error< Modified: cfe/trunk/lib/Sema/SemaDeclAttr.cpp URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaDeclAttr.cpp?rev=314461&r1=314460&r2=314461&view=diff ============================================================================== --- cfe/trunk/lib/Sema/SemaDeclAttr.cpp (original) +++ cfe/trunk/lib/Sema/SemaDeclAttr.cpp Thu Sep 28 13:36:53 2017 @@ -1985,6 +1985,25 @@ static void handleNoReturnAttr(Sema &S, Attrs.getRange(), S.Context, Attrs.getAttributeSpellingListIndex())); } +static void handleNoThrowAttr(Sema &S, Decl *D, const AttributeList &Attrs) { + assert(isa<FunctionDecl>(D) && "attribute nothrow only valid on functions"); + + auto *FD = cast<FunctionDecl>(D); + const auto *FPT = FD->getType()->getAs<FunctionProtoType>(); + + if (FPT && FPT->hasExceptionSpec() && + FPT->getExceptionSpecType() != EST_BasicNoexcept) { + S.Diag(Attrs.getLoc(), + diag::warn_nothrow_attr_disagrees_with_exception_specification); + S.Diag(FD->getExceptionSpecSourceRange().getBegin(), + diag::note_previous_decl) + << "exception specification"; + } + + D->addAttr(::new (S.Context) NoThrowAttr( + Attrs.getRange(), S.Context, Attrs.getAttributeSpellingListIndex())); +} + static void handleNoCallerSavedRegsAttr(Sema &S, Decl *D, const AttributeList &Attr) { if (S.CheckNoCallerSavedRegsAttr(Attr)) @@ -6211,7 +6230,7 @@ static void ProcessDeclAttribute(Sema &S handleNoReturnAttr(S, D, Attr); break; case AttributeList::AT_NoThrow: - handleSimpleAttribute<NoThrowAttr>(S, D, Attr); + handleNoThrowAttr(S, D, Attr); break; case AttributeList::AT_CUDAShared: handleSharedAttr(S, D, Attr); Added: cfe/trunk/test/SemaCXX/warn-conflicting-nothrow-attr-exception-spec.cpp URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/warn-conflicting-nothrow-attr-exception-spec.cpp?rev=314461&view=auto ============================================================================== --- cfe/trunk/test/SemaCXX/warn-conflicting-nothrow-attr-exception-spec.cpp (added) +++ cfe/trunk/test/SemaCXX/warn-conflicting-nothrow-attr-exception-spec.cpp Thu Sep 28 13:36:53 2017 @@ -0,0 +1,24 @@ +// RUN: %clang_cc1 %s -fcxx-exceptions -fsyntax-only -Wexceptions -verify -std=c++14 + +struct S { + //expected-warning@+2 {{attribute 'nothrow' ignored due to conflicting exception specification}} + //expected-note@+1 {{exception specification declared here}} + __attribute__((nothrow)) S() noexcept(true); + //expected-warning@+2 {{attribute 'nothrow' ignored due to conflicting exception specification}} + //expected-note@+1 {{exception specification declared here}} + __attribute__((nothrow)) void Func1() noexcept(false); + __attribute__((nothrow)) void Func3() noexcept; +}; + +void throwing() noexcept(false); +void non_throwing(bool b = true) noexcept; + +template <typename Fn> +struct T { + __attribute__((nothrow)) void f(Fn) noexcept(Fn()); +}; + +//expected-warning@-3 {{attribute 'nothrow' ignored due to conflicting exception specification}} +//expected-note@-4 {{exception specification declared here}} +template struct T<decltype(throwing)>; +template struct T<decltype(non_throwing)>; Propchange: cfe/trunk/test/SemaCXX/warn-conflicting-nothrow-attr-exception-spec.cpp ------------------------------------------------------------------------------ svn:eol-style = native Propchange: cfe/trunk/test/SemaCXX/warn-conflicting-nothrow-attr-exception-spec.cpp ------------------------------------------------------------------------------ svn:keywords = Author Date Id Rev URL Propchange: cfe/trunk/test/SemaCXX/warn-conflicting-nothrow-attr-exception-spec.cpp ------------------------------------------------------------------------------ svn:mime-type = text/plain _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
