[clang] [clang] Introduce copy-on-write `CompilerInvocation` (PR #65412)

[Shafik Yaghmour via cfe-commits]

================
@@ -4588,28 +4641,29 @@ std::string CompilerInvocation::getModuleHash() const {
   return toString(llvm::APInt(64, Hash), 36, /*Signed=*/false);
 }
 
-void CompilerInvocation::generateCC1CommandLine(
+void CompilerInvocationBase::generateCC1CommandLine(
     ArgumentConsumer Consumer) const {
-  llvm::Triple T(TargetOpts->Triple);
-
-  GenerateFileSystemArgs(FileSystemOpts, Consumer);
-  GenerateMigratorArgs(MigratorOpts, Consumer);
-  GenerateAnalyzerArgs(*AnalyzerOpts, Consumer);
-  GenerateDiagnosticArgs(*DiagnosticOpts, Consumer, false);
-  GenerateFrontendArgs(FrontendOpts, Consumer, LangOpts->IsHeaderFile);
-  GenerateTargetArgs(*TargetOpts, Consumer);
-  GenerateHeaderSearchArgs(*HeaderSearchOpts, Consumer);
-  GenerateLangArgs(*LangOpts, Consumer, T, FrontendOpts.DashX);
-  GenerateCodeGenArgs(CodeGenOpts, Consumer, T, FrontendOpts.OutputFile,
-                      &*LangOpts);
-  GeneratePreprocessorArgs(*PreprocessorOpts, Consumer, *LangOpts, FrontendOpts,
-                           CodeGenOpts);
-  GeneratePreprocessorOutputArgs(PreprocessorOutputOpts, Consumer,
-                                 FrontendOpts.ProgramAction);
-  GenerateDependencyOutputArgs(DependencyOutputOpts, Consumer);
+  llvm::Triple T(getTargetOpts().Triple);
+
+  GenerateFileSystemArgs(getFileSystemOpts(), Consumer);
+  GenerateMigratorArgs(getMigratorOpts(), Consumer);
+  GenerateAnalyzerArgs(getAnalyzerOpts(), Consumer);
+  GenerateDiagnosticArgs(getDiagnosticOpts(), Consumer, false);
----------------
shafik wrote:

```suggestion
  GenerateDiagnosticArgs(getDiagnosticOpts(), Consumer, /*DefaultDiagColor=*/false);
```

https://github.com/llvm/llvm-project/pull/65412