Reland [DebugInfo] Fix the mismatching between C++ language tags and Dwarf versions.""

This reverts commit c965e14a12955355ead9ea093989a8fcbf03a8c1.

GitOrigin-RevId: dff922f39b9bf49b243f6f00c7c9a2e3de77e20e
diff --git a/lib/CodeGen/CGDebugInfo.cpp b/lib/CodeGen/CGDebugInfo.cpp
index d20b309..290cdbf 100644
--- a/lib/CodeGen/CGDebugInfo.cpp
+++ b/lib/CodeGen/CGDebugInfo.cpp
@@ -568,9 +568,9 @@
   if (LO.CPlusPlus) {
     if (LO.ObjC)
       LangTag = llvm::dwarf::DW_LANG_ObjC_plus_plus;
-    else if (LO.CPlusPlus14)
+    else if (LO.CPlusPlus14 && CGM.getCodeGenOpts().DwarfVersion >= 5)
       LangTag = llvm::dwarf::DW_LANG_C_plus_plus_14;
-    else if (LO.CPlusPlus11)
+    else if (LO.CPlusPlus11 && CGM.getCodeGenOpts().DwarfVersion >= 5)
       LangTag = llvm::dwarf::DW_LANG_C_plus_plus_11;
     else
       LangTag = llvm::dwarf::DW_LANG_C_plus_plus;
diff --git a/test/CodeGenCXX/debug-info-programming-language.cpp b/test/CodeGenCXX/debug-info-programming-language.cpp
new file mode 100644
index 0000000..82a6db6
--- /dev/null
+++ b/test/CodeGenCXX/debug-info-programming-language.cpp
@@ -0,0 +1,13 @@
+// RUN: %clang_cc1 -dwarf-version=5  -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-DWARF5 %s
+// 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-DWARF3 %s
+
+int main() {
+  return 0;
+}
+
+// CHECK-DWARF5: distinct !DICompileUnit(language: DW_LANG_C_plus_plus_14,
+// CHECK-DWARF3: distinct !DICompileUnit(language: DW_LANG_C_plus_plus,
diff --git a/test/Modules/ModuleDebugInfo.cpp b/test/Modules/ModuleDebugInfo.cpp
index 3121719..836f0d2 100644
--- a/test/Modules/ModuleDebugInfo.cpp
+++ b/test/Modules/ModuleDebugInfo.cpp
@@ -23,7 +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-CXX: distinct !DICompileUnit(language: DW_LANG_C_plus_plus,
 // CHECK-SAME:                    isOptimized: false,
 // CHECK-NOT:                     splitDebugFilename:
 // CHECK-SAME:                    dwoId: