[PATCH] D79945: [Sema] Comparison of pointers to complete and incomplete types

Tue Jun 9 11:32:55 PDT 2020

efriedma added inline comments.

================
Comment at: clang/lib/Sema/SemaExpr.cpp:11571
+          Diag(Loc,
+               getLangOpts().C11
+                   ? diag::ext_typecheck_compare_complete_incomplete_pointers
----------------
rsmith wrote:
> pestctrl wrote:
> > efriedma wrote:
> > > I think this condition is backwards?  Should be `!getLangOpts().C11`.  You want the warning with `-std=c99 -pedantic`, you don't want the warning with `std=c11 -pedantic`.
> > I don't think it's backwards. If getLangOpts().C11, then it is an extension. Otherwise, it is the warning. I can switch the conditions if it is confusing though.
> "Extension" means "this is invalid code that we're accepting anyway" -- that's what this is in C99. In C11, I think we shouldn't be diagnosing at all.
> 
> Has anyone checked whether WG14 removed this restriction in C11 as a DR resolution? If so, we shouldn't be diagnosing it at all, in any language mode.
I tracked down the proposal for the change; it's http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1439.pdf .  Beyond the reference to http://www.open-std.org/jtc1/sc22/wg14/www/docs/dr_314.htm , I can't find any relevant defect report.

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https://reviews.llvm.org/D79945