[clang][tooling] Create SourceManager for DiagnosticsEngine before command-line parsing

[jansvoboda11]

Summary

In D84673, we started using DiagnosticsEngine during command-line parsing in more contexts.

When using ToolInvocation, a custom DiagnosticsConsumer can be specified and it might expect SourceManager to be present on the emitted diagnostics.

This patch ensures the SourceManager is set up in such scenarios.

Test authored by Jordan Rupprecht.

[rupprecht]

Thanks, the error message is much better now!

When applying this patch locally and also undoing the fix in our internal tool (i.e. change it to -ferror-limit=-1), the error I get is:

message: "invalid integral value \'-1\' in \'-ferror-limit -1\'"

which, you know, actually tells me what to fix instead of giving some weird internal assertion :)

clang/lib/Tooling/Tooling.cpp

bool ToolInvocation::run() {
   llvm::opt::InputArgList ParsedArgs = driver::getDriverOptTable().ParseArgs(
       ArrayRef<const char *>(Argv).slice(1), MissingArgIndex, MissingArgCount);
   ParseDiagnosticArgs(*DiagOpts, ParsedArgs);
   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);
 
   const std::unique_ptr<driver::Driver> Driver(
       newDriver(&Diagnostics, BinaryName, &Files->getVirtualFileSystem()));
   // The "input file not found" diagnostics from the driver are useful.
   // The driver is only aware of the VFS working directory, but some clients
   // change this at the FileManager level instead.
   // In this case the checks have false positives, so skip them.
   if (!Files->getFileSystemOpts().WorkingDir.empty())

clang/unittests/Tooling/ToolingTest.cpp

InMemoryFileSystem->addFile("def/abc", 0,
                               llvm::MemoryBuffer::getMemBuffer("\n"));
   // Add a module.map file in the include directory of our header, so we trigger
   // the module.map header search logic.
   InMemoryFileSystem->addFile("def/module.map", 0,
                               llvm::MemoryBuffer::getMemBuffer("\n"));
   EXPECT_TRUE(Invocation.run());
 }
 
+struct DiagnosticConsumerExpectingSourceManager : public DiagnosticConsumer {
+  bool SawSourceManager;
+
+  DiagnosticConsumerExpectingSourceManager() : SawSourceManager(false) {}
+
+  void HandleDiagnostic(clang::DiagnosticsEngine::Level,
+                        const clang::Diagnostic &info) override {
+    SawSourceManager = info.hasSourceManager();
+  }
+};
+
+TEST(ToolInvocation, DiagConsumerExpectingSourceManager) {
+  llvm::IntrusiveRefCntPtr<llvm::vfs::OverlayFileSystem> OverlayFileSystem(
+      new llvm::vfs::OverlayFileSystem(llvm::vfs::getRealFileSystem()));
+  llvm::IntrusiveRefCntPtr<llvm::vfs::InMemoryFileSystem> InMemoryFileSystem(
+      new llvm::vfs::InMemoryFileSystem);
+  OverlayFileSystem->pushOverlay(InMemoryFileSystem);
+  llvm::IntrusiveRefCntPtr<FileManager> Files(
+      new FileManager(FileSystemOptions(), OverlayFileSystem));
+  std::vector<std::string> Args;
+  Args.push_back("tool-executable");
+  // Note: intentional error; user probably meant -ferror-limit=0.
+  Args.push_back("-ferror-limit=-1");
+  Args.push_back("-fsyntax-only");
+  Args.push_back("test.cpp");
+  clang::tooling::ToolInvocation Invocation(
+      Args, std::make_unique<SyntaxOnlyAction>(), Files.get());
+  InMemoryFileSystem->addFile(
+      "test.cpp", 0, llvm::MemoryBuffer::getMemBuffer("int main() {}\n"));
+
+  DiagnosticConsumerExpectingSourceManager Consumer;
+  Invocation.setDiagnosticConsumer(&Consumer);
+
+  EXPECT_TRUE(Invocation.run());
+  EXPECT_TRUE(Consumer.SawSourceManager);
+}
+
 struct VerifyEndCallback : public SourceFileCallbacks {
   VerifyEndCallback() : BeginCalled(0), EndCalled(0), Matched(false) {}
   bool handleBeginSource(CompilerInstance &CI) override {
     ++BeginCalled;
     return true;
   }
   void handleEndSource() override { ++EndCalled; }
   std::unique_ptr<ASTConsumer> newASTConsumer() {