From: Alex Lorenz Date: Wed, 2 Nov 2016 15:46:34 +0000 (+0000) Subject: Add a note that points to the linkage specifier for the C++ linkage errors X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=d257640fedfff91b1eddcf4fe66f9b679d27ff92;p=clang Add a note that points to the linkage specifier for the C++ linkage errors This commit improves the "must have C++ linkage" error diagnostics that are emitted for C++ declarations like templates and literal operators by adding an additional note that points to the appropriate extern "C" linkage specifier. rdar://19021120 Differential Revision: https://reviews.llvm.org/D26189 git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@285823 91177308-0d34-0410-b5e6-96231b3b80d8 --- diff --git a/include/clang/AST/DeclBase.h b/include/clang/AST/DeclBase.h index 3a80ff5b23..5de1d0588e 100644 --- a/include/clang/AST/DeclBase.h +++ b/include/clang/AST/DeclBase.h @@ -1334,6 +1334,9 @@ public: /// linkage specification context that specifies C linkage. bool isExternCContext() const; + /// \brief Retrieve the nearest enclosing C linkage specification context. + const LinkageSpecDecl *getExternCContext() const; + /// \brief Determines whether this context or some of its ancestors is a /// linkage specification context that specifies C++ linkage. bool isExternCXXContext() const; diff --git a/include/clang/Basic/DiagnosticSemaKinds.td b/include/clang/Basic/DiagnosticSemaKinds.td index e4290d8945..74fed48806 100644 --- a/include/clang/Basic/DiagnosticSemaKinds.td +++ b/include/clang/Basic/DiagnosticSemaKinds.td @@ -4502,6 +4502,8 @@ def err_extern_c_global_conflict : Error< "conflicts with declaration %select{in global scope|with C language linkage}0">; def note_extern_c_global_conflict : Note< "declared %select{in global scope|with C language linkage}0 here">; +def note_extern_c_begins_here : Note< + "extern \"C\" language linkage specification begins here">; def warn_weak_import : Warning < "an already-declared variable is made a weak_import declaration %0">; def ext_static_non_static : Extension< @@ -8605,8 +8607,6 @@ def ext_module_import_in_extern_c : ExtWarn< "import of C++ module '%0' appears within extern \"C\" language linkage " "specification">, DefaultError, InGroup>; -def note_module_import_in_extern_c : Note< - "extern \"C\" language linkage specification begins here">; def err_module_import_not_at_top_level_fatal : Error< "import of module '%0' appears within %1">, DefaultFatal; def ext_module_import_not_at_top_level_noop : ExtWarn< diff --git a/lib/AST/DeclBase.cpp b/lib/AST/DeclBase.cpp index 7e790cec68..5d130acfbe 100644 --- a/lib/AST/DeclBase.cpp +++ b/lib/AST/DeclBase.cpp @@ -992,6 +992,18 @@ bool DeclContext::isExternCContext() const { return isLinkageSpecContext(this, clang::LinkageSpecDecl::lang_c); } +const LinkageSpecDecl *DeclContext::getExternCContext() const { + const DeclContext *DC = this; + while (DC->getDeclKind() != Decl::TranslationUnit) { + if (DC->getDeclKind() == Decl::LinkageSpec && + cast(DC)->getLanguage() == + clang::LinkageSpecDecl::lang_c) + return cast(DC); + DC = DC->getLexicalParent(); + } + return nullptr; +} + bool DeclContext::isExternCXXContext() const { return isLinkageSpecContext(this, clang::LinkageSpecDecl::lang_cxx); } diff --git a/lib/Sema/SemaDecl.cpp b/lib/Sema/SemaDecl.cpp index 1813aa0b64..e20ae1a015 100644 --- a/lib/Sema/SemaDecl.cpp +++ b/lib/Sema/SemaDecl.cpp @@ -15341,7 +15341,7 @@ static void checkModuleImportContext(Sema &S, Module *M, } else if (!M->IsExternC && ExternCLoc.isValid()) { S.Diag(ImportLoc, diag::ext_module_import_in_extern_c) << M->getFullModuleName(); - S.Diag(ExternCLoc, diag::note_module_import_in_extern_c); + S.Diag(ExternCLoc, diag::note_extern_c_begins_here); } } diff --git a/lib/Sema/SemaDeclCXX.cpp b/lib/Sema/SemaDeclCXX.cpp index 17d1978de0..fb3b737397 100644 --- a/lib/Sema/SemaDeclCXX.cpp +++ b/lib/Sema/SemaDeclCXX.cpp @@ -12757,6 +12757,9 @@ bool Sema::CheckLiteralOperatorDeclaration(FunctionDecl *FnDecl) { if (FnDecl->isExternC()) { Diag(FnDecl->getLocation(), diag::err_literal_operator_extern_c); + if (const LinkageSpecDecl *LSD = + FnDecl->getDeclContext()->getExternCContext()) + Diag(LSD->getExternLoc(), diag::note_extern_c_begins_here); return true; } diff --git a/lib/Sema/SemaTemplate.cpp b/lib/Sema/SemaTemplate.cpp index 71b2153d05..ce41a5eb74 100644 --- a/lib/Sema/SemaTemplate.cpp +++ b/lib/Sema/SemaTemplate.cpp @@ -5939,9 +5939,13 @@ Sema::CheckTemplateDeclScope(Scope *S, TemplateParameterList *TemplateParams) { // C++ [temp]p4: // A template [...] shall not have C linkage. DeclContext *Ctx = S->getEntity(); - if (Ctx && Ctx->isExternCContext()) - return Diag(TemplateParams->getTemplateLoc(), diag::err_template_linkage) - << TemplateParams->getSourceRange(); + if (Ctx && Ctx->isExternCContext()) { + Diag(TemplateParams->getTemplateLoc(), diag::err_template_linkage) + << TemplateParams->getSourceRange(); + if (const LinkageSpecDecl *LSD = Ctx->getExternCContext()) + Diag(LSD->getExternLoc(), diag::note_extern_c_begins_here); + return true; + } Ctx = Ctx->getRedeclContext(); // C++ [temp]p2: diff --git a/test/CXX/over/over.oper/over.literal/p6.cpp b/test/CXX/over/over.oper/over.literal/p6.cpp index 6bfb8560d6..9ecf9ccccb 100644 --- a/test/CXX/over/over.oper/over.literal/p6.cpp +++ b/test/CXX/over/over.oper/over.literal/p6.cpp @@ -1,9 +1,11 @@ // RUN: %clang_cc1 -std=c++11 %s -verify +// expected-note@+1 {{extern "C" language linkage specification begins here}} extern "C" void operator "" _a(const char *); // expected-error {{must have C++ linkage}} extern "C" template void operator "" _b(); // expected-error {{must have C++ linkage}} +// expected-note@-1 {{extern "C" language linkage specification begins here}} -extern "C" { +extern "C" { // expected-note 4 {{extern "C" language linkage specification begins here}} void operator "" _c(const char *); // expected-error {{must have C++ linkage}} template void operator "" _d(); // expected-error {{must have C++ linkage}} namespace N { diff --git a/test/SemaCXX/cxx0x-defaulted-functions.cpp b/test/SemaCXX/cxx0x-defaulted-functions.cpp index f4bbce818d..f623dc765f 100644 --- a/test/SemaCXX/cxx0x-defaulted-functions.cpp +++ b/test/SemaCXX/cxx0x-defaulted-functions.cpp @@ -180,7 +180,7 @@ namespace PR14577 { Outer::Inner2::~Inner2() = default; // expected-error {{nested name specifier 'Outer::Inner2::' for declaration does not refer into a class, class template or class template partial specialization}} expected-error {{only special member functions may be defaulted}} } -extern "C" { +extern "C" { // expected-note {{extern "C" language linkage specification begins here}} template // expected-error {{templates must have C++ linkage}} void PR13573(const _Tp&) = delete; } diff --git a/test/SemaTemplate/class-template-decl.cpp b/test/SemaTemplate/class-template-decl.cpp index 63482d84df..2e36cae14f 100644 --- a/test/SemaTemplate/class-template-decl.cpp +++ b/test/SemaTemplate/class-template-decl.cpp @@ -10,11 +10,11 @@ namespace N { template class C; } -extern "C" { +extern "C" { // expected-note {{extern "C" language linkage specification begins here}} template class D; // expected-error{{templates must have C++ linkage}} } -extern "C" { +extern "C" { // expected-note 2 {{extern "C" language linkage specification begins here}} class PR17968 { template class D; // expected-error{{templates must have C++ linkage}} template void f(); // expected-error{{templates must have C++ linkage}} @@ -148,7 +148,7 @@ namespace redecl { } extern "C" template // expected-error{{templates must have C++ linkage}} -void DontCrashOnThis() { +void DontCrashOnThis() { // expected-note@-1 {{extern "C" language linkage specification begins here}} T &pT = T(); pT; }