[clang][tooling] Accept custom diagnostic options in ToolInvocation

[jansvoboda11]

Summary

This patch allows the clients of ToolInvocation to provide custom diagnostic options to be used during driver -> cc1 command-line transformation and parsing.

[jansvoboda11]

Rebase

[jansvoboda11]

Reorder patches.

[jansvoboda11]

Tests that cover this functionality were moved into a follow-up patch D108974. The reason is to avoid temporary regression pointed out here.

[arphaman]

Could you add a test case for this change? Maybe a unit test?

[arphaman]

In D108976#2979867, @arphaman wrote:

Could you add a test case for this change? Maybe a unit test?

Ah I see, you mentioned that the tests are in a follow-up patch. Sorry about that.

[dexonsmith]

In D108976#2979598, @jansvoboda11 wrote:

Tests that cover this functionality were moved into a follow-up patch D108974. The reason is to avoid temporary regression pointed out here.

Please document in the commit message that tests are coming later and why. With that, LGTM too.

clang/include/clang/Tooling/Tooling.h

public:
   /// \param PCHContainerOps The PCHContainerOperations for loading and creating
   /// clang modules.
   ToolInvocation(std::vector<std::string> CommandLine, ToolAction *Action,
                  FileManager *Files,
                  std::shared_ptr<PCHContainerOperations> PCHContainerOps);
 
   ~ToolInvocation();
 
-  /// Set a \c DiagnosticConsumer to use during parsing.
+  /// Set a \c DiagnosticConsumer to use during driver command-line parsing and
+  /// the action invocation itself.
   void setDiagnosticConsumer(DiagnosticConsumer *DiagConsumer) {
     this->DiagConsumer = DiagConsumer;
   }
 
+  /// Set a \c DiagnosticOptions to use during driver command-line parsing.
+  void setDiagnosticOptions(DiagnosticOptions *DiagOpts) {
+    this->DiagOpts = DiagOpts;
+  }
+
   /// Run the clang invocation.
   ///
   /// \returns True if there were no errors during execution.
   bool run();
 
  private:
   bool runInvocation(const char *BinaryName,
                      driver::Compilation *Compilation,
                      std::shared_ptr<CompilerInvocation> Invocation,
                      std::shared_ptr<PCHContainerOperations> PCHContainerOps);
 
   std::vector<std::string> CommandLine;
   ToolAction *Action;
   bool OwnsAction;
   FileManager *Files;
   std::shared_ptr<PCHContainerOperations> PCHContainerOps;
   DiagnosticConsumer *DiagConsumer = nullptr;
+  DiagnosticOptions *DiagOpts = nullptr;
 };
 
 /// Utility to run a FrontendAction over a set of files.
 ///
 /// This class is written to be usable for command line utilities.
 /// By default the class uses ClangSyntaxOnlyAdjuster to modify
 /// command line arguments before the arguments are used to run
 /// a frontend action. One could install an additional command line

clang/lib/Tooling/Tooling.cpp

if (OwnsAction)
     delete Action;
 }
 
 bool ToolInvocation::run() {
   std::vector<const char*> Argv;
   for (const std::string &Str : CommandLine)
     Argv.push_back(Str.c_str());
   const char *const BinaryName = Argv[0];
-  IntrusiveRefCntPtr<DiagnosticOptions> DiagOpts =
-      CreateAndPopulateDiagOpts(Argv);
-  TextDiagnosticPrinter DiagnosticPrinter(
-      llvm::errs(), &*DiagOpts);
+
+  // Parse diagnostic options from the driver command-line only if none were
+  // explicitly set.
+  IntrusiveRefCntPtr<DiagnosticOptions> ParsedDiagOpts;
+  DiagnosticOptions *DiagOpts = this->DiagOpts;
+  if (!DiagOpts) {
+    ParsedDiagOpts = CreateAndPopulateDiagOpts(Argv);
+    DiagOpts = &*ParsedDiagOpts;
+  }
+
+  TextDiagnosticPrinter DiagnosticPrinter(llvm::errs(), DiagOpts);
   DiagnosticsEngine Diagnostics(
       IntrusiveRefCntPtr<DiagnosticIDs>(new DiagnosticIDs()), &*DiagOpts,
       DiagConsumer ? DiagConsumer : &DiagnosticPrinter, false);
   // Although `Diagnostics` are used only for command-line parsing, the custom
   // `DiagConsumer` might expect a `SourceManager` to be present.
   SourceManager SrcMgr(Diagnostics, *Files);
   Diagnostics.setSourceManager(&SrcMgr);