[lldb] Make ParseTemplateParameterInfos return false if there are no template params

[aeubanks]

Summary

This factors out the check from various callers.

[dblaikie]

lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp

1262

This part changes behavior, yeah? (previously the code was only conditional on has_template_params and is now conditional on both that and there actually being template parameter DIEs) Was that intended? If so, is there any testing that could be done to demonstrate the change in behavior?

[aeubanks]

lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp

1262

presumably any visible change would only happen with broken debug info

has_template_params is true if there are any template parameter child DIEs, but now we do more checking that those DIEs are actually reasonable

I can revert this back if you want, but this seems better and I don't think I'm going to find time to add a test for broken debug info which may or may not actually hit this code path

[Michael137]

lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp

1262

Agree with David that if it's behaviour changing we should either test or leave as is

[aeubanks]

revert one change to make this nfc

lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp

 
 ConstString
 DWARFASTParserClang::GetDIEClassTemplateParams(const DWARFDIE &die) {
   if (llvm::StringRef(die.GetName()).contains("<"))
     return ConstString();
 
   clang::DeclContext *decl_ctx = GetClangDeclContextContainingDIE(die, nullptr);
   TypeSystemClang::TemplateParameterInfos template_param_infos;
-  if (ParseTemplateParameterInfos(die, template_param_infos) &&
-      (!template_param_infos.args.empty() ||
-       template_param_infos.packed_args)) {
+  if (ParseTemplateParameterInfos(die, template_param_infos)) {
     // Most of the parameters here don't matter, but we make sure the base name
     // is empty so when we print the name we only get the template parameters.
     clang::ClassTemplateDecl *class_template_decl =
         m_ast.ParseClassTemplateDecl(decl_ctx, GetOwningClangModule(die),
                                      eAccessPublic, "", clang::TTK_Struct,
                                      template_param_infos);
     if (!class_template_decl)
       return ConstString();
if (!type_handled) {
               GetOwningClangModule(die), attrs.name.GetStringRef(), clang_type,
               attrs.storage, attrs.is_inline);
           clang::FunctionTemplateDecl *func_template_decl =
               m_ast.CreateFunctionTemplateDecl(
                   containing_decl_ctx, GetOwningClangModule(die),
                   template_function_decl, template_param_infos);
           m_ast.CreateFunctionTemplateSpecializationInfo(
               template_function_decl, func_template_decl, template_param_infos);
         }
 
         lldbassert(function_decl);
 
         if (function_decl) {
           // Attach an asm(<mangled_name>) label to the FunctionDecl.
           // This ensures that clang::CodeGen emits function calls
           // using symbols that are mangled according to the DW_AT_linkage_name.
           // If we didn't do this, the external symbols wouldn't exactly
if (attrs.accessibility == eAccessNone && decl_ctx) {
         attrs.accessibility = default_accessibility;
     }
 
     ClangASTMetadata metadata;
     metadata.SetUserID(die.GetID());
     metadata.SetIsDynamicCXXType(dwarf->ClassOrStructIsVirtual(die));
 
     TypeSystemClang::TemplateParameterInfos template_param_infos;
-    if (ParseTemplateParameterInfos(die, template_param_infos) &&
-        (!template_param_infos.args.empty() ||
-         template_param_infos.packed_args)) {
+    if (ParseTemplateParameterInfos(die, template_param_infos)) {
       clang::ClassTemplateDecl *class_template_decl =
           m_ast.ParseClassTemplateDecl(
               decl_ctx, GetOwningClangModule(die), attrs.accessibility,
               attrs.name.GetCString(), tag_decl_kind, template_param_infos);
       if (!class_template_decl) {
         if (log) {
           dwarf->GetObjectFile()->GetModule()->LogMessage(
               log,
for (DWARFDIE die : parent_die.children()) {
     case DW_TAG_GNU_template_template_param:
       ParseTemplateDIE(die, template_param_infos);
       break;
 
     default:
       break;
     }
   }
-  return template_param_infos.args.size() == template_param_infos.names.size();
+  return template_param_infos.args.size() ==
+             template_param_infos.names.size() &&
+         (!template_param_infos.args.empty() ||
+          template_param_infos.packed_args);
 }
 
 bool DWARFASTParserClang::CompleteRecordType(const DWARFDIE &die,
                                              lldb_private::Type *type,
                                              CompilerType &clang_type) {
   const dw_tag_t tag = die.Tag();
   SymbolFileDWARF *dwarf = die.GetDWARF();