[PATCH] D136790: [Clang][Sema] Add -Wincompatible-function-pointer-types-strict

Mon Oct 31 15:53:43 PDT 2022

samitolvanen added a comment.

In D136790#3897184 <https://reviews.llvm.org/D136790#3897184>, @aaron.ballman wrote:

> please be sure to add a release note so users know there's a new warning.

I'll add a release note. Thanks for the reminder!

================
Comment at: clang/include/clang/Basic/DiagnosticSemaKinds.td:8217
+  err_typecheck_convert_incompatible_function_pointer.Text>,
+  InGroup<DiagGroup<"incompatible-function-pointer-types-strict">>, DefaultIgnore;
 def ext_typecheck_convert_discards_qualifiers : ExtWarn<
----------------
aaron.ballman wrote:
> We don't typically add new off-by-default warnings because we have evidence that users don't enable them enough to be worth adding them. Is there a way we can enable this warning by default for CFI compilation units (or when the cfi sanitizer is enabled) so that it's only off by default for non-CFI users? I don't think we have any examples of doing this in the code base, so I believe this would be breaking new ground (and thus is worth thinking about more, perhaps it's a bad idea for some reason).
> Is there a way we can enable this warning by default for CFI compilation units (or when the cfi sanitizer is enabled) so that it's only off by default for non-CFI users?

I can look into it, but I'm not sure if there's a convenient way to do that. An alternative to this could be to enable the warning by default, but only actually perform the check if CFI is enabled. This way non-CFI users would never see the warning because this really isn't a concern for them, but CFI users would still get the warning without explicitly enabling it. Or do you think this behavior would be confusing?

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  https://reviews.llvm.org/D136790/new/

https://reviews.llvm.org/D136790