[PATCH] D94472: [clang][cli] Command line round-trip for HeaderSearch options

[Jan Svoboda via Phabricator via cfe-commits]

jansvoboda11 added inline comments.


================
Comment at: clang/lib/Frontend/CompilerInvocation.cpp:684-685
+  if (!GeneratedStringsEqual)
+    llvm::report_fatal_error("Mismatch between arguments generated during "
+                             "round-trip");
+
----------------
dexonsmith wrote:
> jansvoboda11 wrote:
> > dexonsmith wrote:
> > > Another option vs. report_fatal_error would be to create (fatal) clang error diagnostics. That applies here, and to my previous comments. WDYT? (@Bigcheese, any thoughts?)
> > > 
> > > Also, I think `-round-trip-args-debug` might not be super discoverable. Maybe we can add a comment in the code where the errors are reported suggesting adding that.
> > If we decide to go with custom diagnostics instead of just using `llvm::errs` and `llvm::report_fatal_error`, we'd need to instantiate a custom `DiagnosticsEngine` here in `RoundTrip`, because we cannot rely on clients passing us reasonable `Diags`.
> > 
> > One such example is `CompilerInvocationTest`, where we don't care what diagnostics get emitted (by using `TextDiagnosticBuffer` consumer). The errors we're emitting here would be still useful to see when testing though.
> I'm not entirely following why this would need a custom Diags. If the client wants to ignore diagnostics that should be up to the client, especially in clang-as-a-library situations. In fact, using `errs` or `dbgs` at all is pretty iffy when clang is used as a library.
> 
> For CompilerInvocationTest, I imagine we could change the consumer / test fixture / etc. somehow to capture this case.
My understanding is that we'd be converting `llvm::report_fatal_error` into error diagnostics and `PrintArgs` into notes and remarks.

The hiccup here is that `Diags` most probably hasn't been configured yet (we're still just parsing the `DiagnosticsOptions`). And by default, `DiagnosticsEngine` ignores all remarks.

So my thinking was that to ensure our remarks are not thrown away, we could modify the existing `Diags` to our liking (too invasive) or set up a custom `DiagnosticsEngine` instance here in `RoundTrip`. In the end, the best solution is probably to do this of setup in `cc1_main`, so that we're emitting diagnostics only when used within compiler.


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https://reviews.llvm.org/D94472