Support for DWARF-5 C++ language tags.

This patch provides support for DW_LANG_C_plus_plus_11,
DW_LANG_C_plus_plus_14 tags in the Clang C++ frontend.

Patch by Sourabh Singh Tomar!
Differential Revision: https://reviews.llvm.org/D67613

Reapplies r372663 after adapting a failing test in the LLDB testsuite.

llvm-svn: 372681

clang/include/clang/AST/DeclCXX.h

@@ -42,6 +42,7 @@
 #include "llvm/ADT/PointerUnion.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/iterator_range.h"
+#include "llvm/BinaryFormat/Dwarf.h"
 #include "llvm/Support/Casting.h"
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/PointerLikeTypeTraits.h"
@@ -2941,8 +2942,10 @@ public:
   /// ensure a stable ABI for this, we choose the DW_LANG_ encodings
   /// from the dwarf standard.
   enum LanguageIDs {
-    lang_c = /* DW_LANG_C */ 0x0002,
-    lang_cxx = /* DW_LANG_C_plus_plus */ 0x0004
+    lang_c = llvm::dwarf::DW_LANG_C,
+    lang_cxx = llvm::dwarf::DW_LANG_C_plus_plus,
+    lang_cxx_11 = llvm::dwarf::DW_LANG_C_plus_plus_11,
+    lang_cxx_14 = llvm::dwarf::DW_LANG_C_plus_plus_14
   };
 
 private:

clang/lib/AST/DeclPrinter.cpp

@@ -1001,12 +1001,19 @@ void DeclPrinter::VisitCXXRecordDecl(CXXRecordDecl *D) {
 
 void DeclPrinter::VisitLinkageSpecDecl(LinkageSpecDecl *D) {
   const char *l;
-  if (D->getLanguage() == LinkageSpecDecl::lang_c)
+  switch (D->getLanguage()) {
+  case LinkageSpecDecl::lang_c:
     l = "C";
-  else {
-    assert(D->getLanguage() == LinkageSpecDecl::lang_cxx &&
-           "unknown language in linkage specification");
+    break;
+  case LinkageSpecDecl::lang_cxx_14:
+    l = "C++14";
+    break;
+  case LinkageSpecDecl::lang_cxx_11:
+    l = "C++11";
+    break;
+  case LinkageSpecDecl::lang_cxx:
     l = "C++";
+    break;
   }
 
   Out << "extern \"" << l << "\" ";

clang/lib/AST/JSONNodeDumper.cpp

@@ -850,6 +850,12 @@ void JSONNodeDumper::VisitLinkageSpecDecl(const LinkageSpecDecl *LSD) {
   switch (LSD->getLanguage()) {
   case LinkageSpecDecl::lang_c: Lang = "C"; break;
   case LinkageSpecDecl::lang_cxx: Lang = "C++"; break;
+  case LinkageSpecDecl::lang_cxx_11:
+    Lang = "C++11";
+    break;
+  case LinkageSpecDecl::lang_cxx_14:
+    Lang = "C++14";
+    break;
   }
   JOS.attribute("language", Lang);
   attributeOnlyIfTrue("hasBraces", LSD->hasBraces());

clang/lib/AST/TextNodeDumper.cpp

@@ -1766,6 +1766,12 @@ void TextNodeDumper::VisitLinkageSpecDecl(const LinkageSpecDecl *D) {
   case LinkageSpecDecl::lang_cxx:
     OS << " C++";
     break;
+  case LinkageSpecDecl::lang_cxx_11:
+    OS << " C++11";
+    break;
+  case LinkageSpecDecl::lang_cxx_14:
+    OS << " C++14";
+    break;
   }
 }
 

clang/lib/CodeGen/CGDebugInfo.cpp

@@ -561,6 +561,10 @@ void CGDebugInfo::CreateCompileUnit() {
   if (LO.CPlusPlus) {
     if (LO.ObjC)
       LangTag = llvm::dwarf::DW_LANG_ObjC_plus_plus;
+    else if (LO.CPlusPlus14)
+      LangTag = llvm::dwarf::DW_LANG_C_plus_plus_14;
+    else if (LO.CPlusPlus11)
+      LangTag = llvm::dwarf::DW_LANG_C_plus_plus_11;
     else
       LangTag = llvm::dwarf::DW_LANG_C_plus_plus;
   } else if (LO.ObjC) {
@@ -878,6 +882,8 @@ llvm::DIType *CGDebugInfo::CreateType(const PointerType *Ty,
 static bool hasCXXMangling(const TagDecl *TD, llvm::DICompileUnit *TheCU) {
   switch (TheCU->getSourceLanguage()) {
   case llvm::dwarf::DW_LANG_C_plus_plus:
+  case llvm::dwarf::DW_LANG_C_plus_plus_11:
+  case llvm::dwarf::DW_LANG_C_plus_plus_14:
     return true;
   case llvm::dwarf::DW_LANG_ObjC_plus_plus:
     return isa<CXXRecordDecl>(TD) || isa<EnumDecl>(TD);

clang/lib/CodeGen/CodeGenModule.cpp

@@ -5132,7 +5132,9 @@ void CodeGenModule::EmitObjCIvarInitializations(ObjCImplementationDecl *D) {
 // EmitLinkageSpec - Emit all declarations in a linkage spec.
 void CodeGenModule::EmitLinkageSpec(const LinkageSpecDecl *LSD) {
   if (LSD->getLanguage() != LinkageSpecDecl::lang_c &&
-      LSD->getLanguage() != LinkageSpecDecl::lang_cxx) {
+      LSD->getLanguage() != LinkageSpecDecl::lang_cxx &&
+      LSD->getLanguage() != LinkageSpecDecl::lang_cxx_11 &&
+      LSD->getLanguage() != LinkageSpecDecl::lang_cxx_14) {
     ErrorUnsupported(LSD, "linkage spec");
     return;
   }

clang/lib/Sema/SemaDeclCXX.cpp

@@ -13982,6 +13982,10 @@ Decl *Sema::ActOnStartLinkageSpecification(Scope *S, SourceLocation ExternLoc,
     Language = LinkageSpecDecl::lang_c;
   else if (Lang == "C++")
     Language = LinkageSpecDecl::lang_cxx;
+  else if (Lang == "C++11")
+    Language = LinkageSpecDecl::lang_cxx_11;
+  else if (Lang == "C++14")
+    Language = LinkageSpecDecl::lang_cxx_14;
   else {
     Diag(LangStr->getExprLoc(), diag::err_language_linkage_spec_unknown)
       << LangStr->getSourceRange();

clang/lib/Sema/SemaModule.cpp

@@ -31,6 +31,8 @@ static void checkModuleImportContext(Sema &S, Module *M,
         ExternCLoc = LSD->getBeginLoc();
       break;
     case LinkageSpecDecl::lang_cxx:
+    case LinkageSpecDecl::lang_cxx_11:
+    case LinkageSpecDecl::lang_cxx_14:
       break;
     }
     DC = LSD->getParent();

clang/test/Modules/ModuleDebugInfo.cpp

@@ -12,7 +12,7 @@
 
 // PCH:
 // RUN: %clang_cc1 -triple %itanium_abi_triple -x c++ -std=c++11  -debugger-tuning=lldb -emit-pch -fmodule-format=obj -I %S/Inputs -o %t.pch %S/Inputs/DebugCXX.h -mllvm -debug-only=pchcontainer &>%t-pch.ll
-// RUN: cat %t-pch.ll | FileCheck %s
+// RUN: cat %t-pch.ll | FileCheck --check-prefix=CHECK-CXX %s
 // RUN: cat %t-pch.ll | FileCheck --check-prefix=CHECK-NEG %s
 
 #ifdef MODULES
@@ -23,6 +23,7 @@
 // CHECK-MOD: distinct !DICompileUnit(language: DW_LANG_{{.*}}C_plus_plus,
 
 // CHECK: distinct !DICompileUnit(language: DW_LANG_{{.*}}C_plus_plus,
+// CHECK-CXX: distinct !DICompileUnit(language: DW_LANG_C_plus_plus_11,
 // CHECK-SAME:                    isOptimized: false,
 // CHECK-NOT:                     splitDebugFilename:
 // CHECK-SAME:                    dwoId: