[Clang] Fix template alias default DWARF version (#89594)

DW_TAG_template_alias DIEs were added in DWARFv4, not DWARFv5

Author: OCHyams

clang/lib/Driver/ToolChains/Clang.cpp

@@ -4634,7 +4634,7 @@ renderDebugOptions(const ToolChain &TC, const Driver &D, const llvm::Triple &T,
 
   // Emit DW_TAG_template_alias for template aliases? True by default for SCE.
   bool UseDebugTemplateAlias =
-      DebuggerTuning == llvm::DebuggerKind::SCE && RequestedDWARFVersion >= 5;
+      DebuggerTuning == llvm::DebuggerKind::SCE && RequestedDWARFVersion >= 4;
   if (const auto *DebugTemplateAlias = Args.getLastArg(
           options::OPT_gtemplate_alias, options::OPT_gno_template_alias)) {
     // DW_TAG_template_alias is only supported from DWARFv5 but if a user

clang/test/Driver/debug-options.c

@@ -456,9 +456,9 @@
 // RUN: %clang -### -target x86_64 -c -g %s 2>&1 | FileCheck --check-prefix=FULL_TEMP_NAMES --implicit-check-not=debug-forward-template-params %s
 // FULL_TEMP_NAMES-NOT: -gsimple-template-names
 
-//// Test -g[no-]template-alias (enabled by default with SCE debugger tuning and DWARFv5).
+//// Test -g[no-]template-alias (enabled by default with SCE debugger tuning and DWARF version >= 4).
 // RUN: %clang -### -target x86_64 -c -gdwarf-5 -gsce %s 2>&1 | FileCheck %s --check-prefixes=TEMPLATE-ALIAS
-// RUN: %clang -### -target x86_64 -c -gdwarf-4 -gsce %s 2>&1 | FileCheck %s --check-prefixes=NO-TEMPLATE-ALIAS
+// RUN: %clang -### -target x86_64 -c -gdwarf-3 -gsce %s 2>&1 | FileCheck %s --check-prefixes=NO-TEMPLATE-ALIAS
 // RUN: %clang -### -target x86_64 -c -gdwarf-5 -gsce -gtemplate-alias %s 2>&1 | FileCheck %s --check-prefixes=TEMPLATE-ALIAS
 // RUN: %clang -### -target x86_64 -c -gdwarf-5 -gsce -gno-template-alias %s 2>&1 | FileCheck %s --check-prefixes=NO-TEMPLATE-ALIAS
 // RUN: %clang -### -target x86_64 -c -gdwarf-5 -gtemplate-alias %s 2>&1 | FileCheck %s --check-prefixes=TEMPLATE-ALIAS