Revert "DebugInfo: Add/support new DW_LANG codes for recent C and C++ versions"

Some buildbots are failing in Clang and LLDB tests. (I guess the LLDB
failure is due to the explicit C language tests in DwarfUnit.cpp that
need to be updated - not sure what the Clang failures are about, they
seem to be still emitting C99 when we're expecting C11 and I checked
those tests pass... maybe systems with a different C language version
default?)

This reverts commit 3c312e4.

Author: dwblaikie

clang/lib/CodeGen/CGDebugInfo.cpp

@@ -526,8 +526,7 @@ void CGDebugInfo::CreateCompileUnit() {
 
   // Get absolute path name.
   SourceManager &SM = CGM.getContext().getSourceManager();
-  auto &CGO = CGM.getCodeGenOpts();
-  std::string MainFileName = CGO.MainFileName;
+  std::string MainFileName = CGM.getCodeGenOpts().MainFileName;
   if (MainFileName.empty())
     MainFileName = "<stdin>";
 
@@ -563,11 +562,11 @@ void CGDebugInfo::CreateCompileUnit() {
   if (LO.CPlusPlus) {
     if (LO.ObjC)
       LangTag = llvm::dwarf::DW_LANG_ObjC_plus_plus;
-    else if (CGO.DebugStrictDwarf && CGO.DwarfVersion < 5)
-      LangTag = llvm::dwarf::DW_LANG_C_plus_plus;
-    else if (LO.CPlusPlus14)
+    else if (LO.CPlusPlus14 && (!CGM.getCodeGenOpts().DebugStrictDwarf ||
+                                CGM.getCodeGenOpts().DwarfVersion >= 5))
       LangTag = llvm::dwarf::DW_LANG_C_plus_plus_14;
-    else if (LO.CPlusPlus11)
+    else if (LO.CPlusPlus11 && (!CGM.getCodeGenOpts().DebugStrictDwarf ||
+                                CGM.getCodeGenOpts().DwarfVersion >= 5))
       LangTag = llvm::dwarf::DW_LANG_C_plus_plus_11;
     else
       LangTag = llvm::dwarf::DW_LANG_C_plus_plus;
@@ -578,8 +577,6 @@ void CGDebugInfo::CreateCompileUnit() {
     LangTag = llvm::dwarf::DW_LANG_OpenCL;
   } else if (LO.RenderScript) {
     LangTag = llvm::dwarf::DW_LANG_GOOGLE_RenderScript;
-  } else if (LO.C11) {
-    LangTag = llvm::dwarf::DW_LANG_C11;
   } else if (LO.C99) {
     LangTag = llvm::dwarf::DW_LANG_C99;
   } else {

clang/test/CodeGen/debug-info-preprocessed-file.i

@@ -7,5 +7,5 @@
 # 1 "preprocessed-input.c" 2
 
 // RUN: %clang -g -c -S -emit-llvm -o - %s | FileCheck %s
-// CHECK: !DICompileUnit(language: DW_LANG_C11, file: ![[FILE:[0-9]+]]
+// CHECK: !DICompileUnit(language: DW_LANG_C99, file: ![[FILE:[0-9]+]] 
 // CHECK: ![[FILE]] = !DIFile(filename: "/foo/bar/preprocessed-input.c"

clang/test/CodeGen/debug-info-programming-language.c

@@ -4,12 +4,6 @@
 // RUN: %clang_cc1 -dwarf-version=3 -emit-llvm -triple %itanium_abi_triple %s -o - \
 // RUN:   -x c++ -std=c++14 -O0 -disable-llvm-passes -debug-info-kind=limited \
 // RUN:   | FileCheck --check-prefix=CHECK-CPP14 %s
-// RUN: %clang_cc1 -dwarf-version=3 -emit-llvm -triple %itanium_abi_triple %s -o - \
-// RUN:   -x c++ -std=c++17 -O0 -disable-llvm-passes -debug-info-kind=limited \
-// RUN:   | FileCheck --check-prefix=CHECK-CPP17 %s
-// RUN: %clang_cc1 -dwarf-version=3 -emit-llvm -triple %itanium_abi_triple %s -o - \
-// RUN:   -x c++ -std=c++20 -O0 -disable-llvm-passes -debug-info-kind=limited \
-// RUN:   | FileCheck --check-prefix=CHECK-CPP20 %s
 // RUN: %clang_cc1 -dwarf-version=3 -gstrict-dwarf -emit-llvm -triple %itanium_abi_triple %s -o - \
 // RUN:   -x c++ -std=c++14 -O0 -disable-llvm-passes -debug-info-kind=limited | FileCheck %s
 // RUN: %clang_cc1 -dwarf-version=5 -gstrict-dwarf -emit-llvm -triple %itanium_abi_triple %s -o - \
@@ -20,15 +14,5 @@ int main() {
   return 0;
 }
 
-// Update these tests once support for DW_LANG_C_plus_plus_17/20 is added - it's
-// a complicated tradeoff. The language codes are already published/blessed by
-// the DWARF committee, but haven't been released in a published standard yet,
-// so consumers might not be ready for these codes & could regress functionality
-// (because they wouldn't be able to identify that the language was C++). The
-// DWARFv6 language encoding, separating language from language version, would
-// remove this problem/not require new codes for new language versions and make
-// it possible to identify the base language irrespective of the version.
 // CHECK-CPP14: distinct !DICompileUnit(language: DW_LANG_C_plus_plus_14,
-// CHECK-CPP17: distinct !DICompileUnit(language: DW_LANG_C_plus_plus_14,
-// CHECK-CPP20: distinct !DICompileUnit(language: DW_LANG_C_plus_plus_14,
 // CHECK: distinct !DICompileUnit(language: DW_LANG_C_plus_plus,

clang/test/CodeGenCXX/debug-info-programming-language.cpp

@@ -14,7 +14,7 @@
 // RUN: cat %t-container.ll | FileCheck %s
 
 // CHECK: distinct !DICompileUnit(
-// CHECK-SAME:                    language: DW_LANG_C11,
+// CHECK-SAME:                    language: DW_LANG_C99,
 // CHECK-SAME:                    file: ![[FILE:[0-9]+]],
 // CHECK: ![[FILE]] = !DIFile(
 // CHECK-SAME:                filename: "SOURCE/debug-info-limited-struct.h",