[clangd] Avoid collecting symbols from broken TUs in global-symbol-builder.

[ioeric]

Summary

For example, template parameter might not be resolved in a broken TU,
which can result in wrong USR/SymbolID.

[ilya-biryukov]

LGTM with a minor NIT

clangd/global-symbol-builder/GlobalSymbolBuilderMain.cpp

88

NIT: Maybe use clangd's log here? To get timestamps in the output, etc.

[ioeric]

clangd/global-symbol-builder/GlobalSymbolBuilderMain.cpp

88

The default logger doesn't seem to add timestamp? I'll keep llvm::errs() here for consistency in this file.

[ilya-biryukov]

clangd/global-symbol-builder/GlobalSymbolBuilderMain.cpp

88

The default logger doesn't seem to add timestamp?

Ah, yes, it's the JSONOutput that adds timestamps.... Sorry.

I'll keep llvm::errs() here for consistency in this file.

We write to stderr at the bottom of the file to show errors to the user.
This instance looks much more like a logging routine.

Since our dependencies (e.g. SymbolCollector) use logs, I'd argue it's actually more consistent across the program to use log here as well. E.g. if someone adds a LoggingSession that writes timestamps, not only SymbolCollector logs should start showing those, but this one as well.

clangd/global-symbol-builder/GlobalSymbolBuilderMain.cpp

public:
         // We want all comments, not just the doxygen ones.
         CI.getLangOpts().CommentOpts.ParseAllComments = true;
         return WrapperFrontendAction::BeginInvocation(CI);
       }
 
       void EndSourceFileAction() override {
         WrapperFrontendAction::EndSourceFileAction();
 
+        const auto &CI = getCompilerInstance();
+        if (CI.hasDiagnostics() &&
+            (CI.getDiagnosticClient().getNumErrors() > 0)) {
+          llvm::errs() << "Found errors in the translation unit. Igoring "
+                          "collected symbols...\n";
+          return;
+        }
+
         auto Symbols = Collector->takeSymbols();
         for (const auto &Sym : Symbols) {
           Ctx->reportResult(Sym.ID.str(), SymbolToYAML(Sym));
         }
       }
 
     private:
       tooling::ExecutionContext *Ctx;