[lld][macho][NFC] Add specific namespace scope for objc symbol names (#83618)

Move symbol names from directly under `objc` scope to
`objc::symbol_names`.
Ex: `objc::klass` -> `objc::symbol_names::klass`

Co-authored-by: Alex B <[email protected]>

Author: alx32

lld/MachO/Driver.cpp

@@ -340,7 +340,7 @@ static InputFile *addFile(StringRef path, LoadType loadType,
       }
     } else if (isCommandLineLoad && config->forceLoadObjC) {
       for (const object::Archive::Symbol &sym : file->getArchive().symbols())
-        if (sym.getName().starts_with(objc::klass))
+        if (sym.getName().starts_with(objc::symbol_names::klass))
           file->fetch(sym);
 
       // TODO: no need to look for ObjC sections for a given archive member if
@@ -395,7 +395,7 @@ static InputFile *addFile(StringRef path, LoadType loadType,
     if ((isa<ObjFile>(newFile) || isa<BitcodeFile>(newFile)) && newFile->lazy &&
         config->forceLoadObjC) {
       for (Symbol *sym : newFile->symbols)
-        if (sym && sym->getName().starts_with(objc::klass)) {
+        if (sym && sym->getName().starts_with(objc::symbol_names::klass)) {
           extract(*newFile, "-ObjC");
           break;
         }

lld/MachO/InputFiles.cpp

@@ -1921,14 +1921,14 @@ DylibFile::DylibFile(const InterfaceFile &interface, DylibFile *umbrella,
     case EncodeKind::ObjectiveCClass:
       // XXX ld64 only creates these symbols when -ObjC is passed in. We may
       // want to emulate that.
-      addSymbol(*symbol, objc::klass + symbol->getName());
-      addSymbol(*symbol, objc::metaclass + symbol->getName());
+      addSymbol(*symbol, objc::symbol_names::klass + symbol->getName());
+      addSymbol(*symbol, objc::symbol_names::metaclass + symbol->getName());
       break;
     case EncodeKind::ObjectiveCClassEHType:
-      addSymbol(*symbol, objc::ehtype + symbol->getName());
+      addSymbol(*symbol, objc::symbol_names::ehtype + symbol->getName());
       break;
     case EncodeKind::ObjectiveCInstanceVariable:
-      addSymbol(*symbol, objc::ivar + symbol->getName());
+      addSymbol(*symbol, objc::symbol_names::ivar + symbol->getName());
       break;
     }
   }

lld/MachO/ObjC.h

@@ -15,10 +15,12 @@ namespace lld::macho {
 
 namespace objc {
 
+namespace symbol_names {
 constexpr const char klass[] = "_OBJC_CLASS_$_";
 constexpr const char metaclass[] = "_OBJC_METACLASS_$_";
 constexpr const char ehtype[] = "_OBJC_EHTYPE_$_";
 constexpr const char ivar[] = "_OBJC_IVAR_$_";
+} // namespace symbol_names
 
 // Check for duplicate method names within related categories / classes.
 void checkCategories();