[lldb][DWARFASTParser] Don't pass CompilerType by non-const reference in the DWARFASTParserClang APIs (#103245)

The `CompilerType` is just a wrapper around two pointers, and there is
no usage of the `CompilerType` where those are expected to change
underneath the caller.

To make the interface more straightforward to reason about, this patch
changes all instances of `CompilerType&` to `const CompilerType&` around
the `DWARFASTParserClang` APIs.

We could probably pass these by-value, but all other APIs don't, and
this patch just makes the parameter passing convention consistent with
the rest of the file.

Author: Michael137

lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParser.h

@@ -45,7 +45,7 @@ class DWARFASTParser {
                                            const AddressRange &range) = 0;
 
   virtual bool CompleteTypeFromDWARF(const DWARFDIE &die, Type *type,
-                                     CompilerType &compiler_type) = 0;
+                                     const CompilerType &compiler_type) = 0;
 
   virtual CompilerDecl GetDeclForUIDFromDWARF(const DWARFDIE &die) = 0;
 

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

@@ -2057,7 +2057,7 @@ bool DWARFASTParserClang::ParseTemplateParameterInfos(
 
 bool DWARFASTParserClang::CompleteRecordType(const DWARFDIE &die,
                                              lldb_private::Type *type,
-                                             CompilerType &clang_type) {
+                                             const CompilerType &clang_type) {
   const dw_tag_t tag = die.Tag();
   SymbolFileDWARF *dwarf = die.GetDWARF();
 
@@ -2152,7 +2152,7 @@ bool DWARFASTParserClang::CompleteRecordType(const DWARFDIE &die,
 
 bool DWARFASTParserClang::CompleteEnumType(const DWARFDIE &die,
                                            lldb_private::Type *type,
-                                           CompilerType &clang_type) {
+                                           const CompilerType &clang_type) {
   if (TypeSystemClang::StartTagDeclarationDefinition(clang_type)) {
     if (die.HasChildren()) {
       bool is_signed = false;
@@ -2165,9 +2165,9 @@ bool DWARFASTParserClang::CompleteEnumType(const DWARFDIE &die,
   return (bool)clang_type;
 }
 
-bool DWARFASTParserClang::CompleteTypeFromDWARF(const DWARFDIE &die,
-                                                lldb_private::Type *type,
-                                                CompilerType &clang_type) {
+bool DWARFASTParserClang::CompleteTypeFromDWARF(
+    const DWARFDIE &die, lldb_private::Type *type,
+    const CompilerType &clang_type) {
   SymbolFileDWARF *dwarf = die.GetDWARF();
 
   std::lock_guard<std::recursive_mutex> guard(
@@ -2244,7 +2244,7 @@ DWARFASTParserClang::GetDeclContextContainingUIDFromDWARF(const DWARFDIE &die) {
 }
 
 size_t DWARFASTParserClang::ParseChildEnumerators(
-    lldb_private::CompilerType &clang_type, bool is_signed,
+    const lldb_private::CompilerType &clang_type, bool is_signed,
     uint32_t enumerator_byte_size, const DWARFDIE &parent_die) {
   if (!parent_die)
     return 0;
@@ -3032,7 +3032,7 @@ void DWARFASTParserClang::ParseSingleMember(
 }
 
 bool DWARFASTParserClang::ParseChildMembers(
-    const DWARFDIE &parent_die, CompilerType &class_clang_type,
+    const DWARFDIE &parent_die, const CompilerType &class_clang_type,
     std::vector<std::unique_ptr<clang::CXXBaseSpecifier>> &base_classes,
     std::vector<DWARFDIE> &member_function_dies,
     std::vector<DWARFDIE> &contained_type_dies,
@@ -3763,7 +3763,8 @@ bool DWARFASTParserClang::ShouldCreateUnnamedBitfield(
 }
 
 void DWARFASTParserClang::ParseRustVariantPart(
-    DWARFDIE &die, const DWARFDIE &parent_die, CompilerType &class_clang_type,
+    DWARFDIE &die, const DWARFDIE &parent_die,
+    const CompilerType &class_clang_type,
     const lldb::AccessType default_accesibility,
     ClangASTImporter::LayoutInfo &layout_info) {
   assert(die.Tag() == llvm::dwarf::DW_TAG_variant_part);

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

@@ -61,10 +61,10 @@ class DWARFASTParserClang : public lldb_private::plugin::dwarf::DWARFASTParser {
                          const lldb_private::plugin::dwarf::DWARFDIE &die,
                          const lldb_private::AddressRange &func_range) override;
 
-  bool
-  CompleteTypeFromDWARF(const lldb_private::plugin::dwarf::DWARFDIE &die,
-                        lldb_private::Type *type,
-                        lldb_private::CompilerType &compiler_type) override;
+  bool CompleteTypeFromDWARF(
+      const lldb_private::plugin::dwarf::DWARFDIE &die,
+      lldb_private::Type *type,
+      const lldb_private::CompilerType &compiler_type) override;
 
   lldb_private::CompilerDecl GetDeclForUIDFromDWARF(
       const lldb_private::plugin::dwarf::DWARFDIE &die) override;
@@ -178,7 +178,7 @@ class DWARFASTParserClang : public lldb_private::plugin::dwarf::DWARFASTParser {
 
   bool ParseChildMembers(
       const lldb_private::plugin::dwarf::DWARFDIE &die,
-      lldb_private::CompilerType &class_compiler_type,
+      const lldb_private::CompilerType &class_compiler_type,
       std::vector<std::unique_ptr<clang::CXXBaseSpecifier>> &base_classes,
       std::vector<lldb_private::plugin::dwarf::DWARFDIE> &member_function_dies,
       std::vector<lldb_private::plugin::dwarf::DWARFDIE> &contained_type_dies,
@@ -196,7 +196,7 @@ class DWARFASTParserClang : public lldb_private::plugin::dwarf::DWARFASTParser {
                        unsigned &type_quals);
 
   size_t ParseChildEnumerators(
-      lldb_private::CompilerType &compiler_type, bool is_signed,
+      const lldb_private::CompilerType &compiler_type, bool is_signed,
       uint32_t enumerator_byte_size,
       const lldb_private::plugin::dwarf::DWARFDIE &parent_die);
 
@@ -362,10 +362,10 @@ class DWARFASTParserClang : public lldb_private::plugin::dwarf::DWARFASTParser {
 
   bool CompleteRecordType(const lldb_private::plugin::dwarf::DWARFDIE &die,
                           lldb_private::Type *type,
-                          lldb_private::CompilerType &clang_type);
+                          const lldb_private::CompilerType &clang_type);
   bool CompleteEnumType(const lldb_private::plugin::dwarf::DWARFDIE &die,
                         lldb_private::Type *type,
-                        lldb_private::CompilerType &clang_type);
+                        const lldb_private::CompilerType &clang_type);
 
   lldb::TypeSP
   ParseTypeModifier(const lldb_private::SymbolContext &sc,
@@ -467,7 +467,7 @@ class DWARFASTParserClang : public lldb_private::plugin::dwarf::DWARFASTParser {
   void
   ParseRustVariantPart(lldb_private::plugin::dwarf::DWARFDIE &die,
                        const lldb_private::plugin::dwarf::DWARFDIE &parent_die,
-                       lldb_private::CompilerType &class_clang_type,
+                       const lldb_private::CompilerType &class_clang_type,
                        const lldb::AccessType default_accesibility,
                        lldb_private::ClangASTImporter::LayoutInfo &layout_info);
 };