[PATCH] D92775: [clang][cli] Add flexible TableGen multiclass for boolean options

[Duncan P. N. Exon Smith via Phabricator via cfe-commits]

dexonsmith accepted this revision.
dexonsmith added a comment.
This revision is now accepted and ready to land.

LGTM if you undo the change to lose support for AlwaysEmit (happy to consider in a separate patch if it’s the right thing to do though).



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Comment at: clang/include/clang/Driver/Options.td:371
+  // TODO: Assert that the flags have different value.
+  // TODO: Assert that only one of the flags can be implied.
+
----------------
jansvoboda11 wrote:
> Does TableGen support some kind of assertion mechanism?
Not that I’m aware of. @Bigcheese?


================
Comment at: clang/unittests/Frontend/CompilerInvocationTest.cpp:226
   ASSERT_THAT(GeneratedArgs,
-              Contains(StrEq("-fno-experimental-new-pass-manager")));
+              Not(Contains(StrEq("-fno-experimental-new-pass-manager"))));
   ASSERT_THAT(GeneratedArgs,
----------------
jansvoboda11 wrote:
> dexonsmith wrote:
> > Can you clarify why this was dropped? Was it previously emitted due to a limitation in the implementation, or are we no longer supporting options that always get emitted for clarity?
> This option was the only one using the old infrastructure (`BooleanMarshalledFFlag`).
> It was set up to always generate the flag, even when it wasn't necessary (this flag sets the keypath to its default value).
> 
> I think we should aim to generate only command line arguments that are necessary to preserve the original invocation semantics.
> I imagine this will be useful when debugging: one won't need to scan hundreds of flags that don't have any effect on CompilerInvocation.
This is a change in direction; the original thinking was that some options should always be emitted for human readability. I don’t feel too strongly about it, but I think this should be changed / dropped independently of other work if it’s done. I suggest splitting this out; I’d also like to hear @Bigcheese’s thoughts on that change since he did more of the original reviews. 


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D92775/new/

https://reviews.llvm.org/D92775