erichkeane accepted this revision.
erichkeane added a comment.
This revision is now accepted and ready to land.
Agree with backporting to Clang15, that'll break the fewest users.
================
Comment at: clang/test/Sema/prototype-redecls.c:32
// clear that the previous declaration was a builtin.
-float rintf() { // expected-error {{conflicting types for 'rintf'}} \
+float rintf() { // expected-warning {{incompatible redeclaration of library
function 'rintf'}} \
expected-note {{'rintf' is a builtin with type 'float
(float)'}}
----------------
aaron.ballman wrote:
> erichkeane wrote:
> > Hmm... this is a definition of a builtin with a completely incompatible
> > prototype. Do we REALLY want this to not be an error?
> >
> > I guess I could see it being OK with declarations, but it is odd with a
> > definition that is incompatible.
> I think we do want it to not be an error. The user has no choice in whether
> these are predeclared or not, which steals identifiers from users. By giving
> the user a warning, they're alerted to the fact they're doing something that
> may be highly confusing, so I agree we definitely want a diagnostic. If we
> give the user an error, they're stuck. Also, it's even weirder that:
> ```
> float rintf(void) {} // Always a warning, is fine
> float rintf() {} // Error pre C2x, but fine in C2x
> ```
Aren't all those identifiers already stolen by the standard? They are reserved
already, right?
But that behavior you post there is unfortunate... I guess leaving these as
warnings is important so they get suppressed in headers (for cases where a
C-library 'implements' it anyway, despite it being a builtin).
I think I can live with this, and I think backporting it is the least breaking
way to do this.
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D131499/new/
https://reviews.llvm.org/D131499
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