[Bug c/89525] New: [9 Regression] inform messages from -Wbuiltin-declaration-mismatch even with -w

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89525

            Bug ID: 89525
           Summary: [9 Regression] inform messages from
                    -Wbuiltin-declaration-mismatch even with -w
           Product: gcc
           Version: 9.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: jakub at gcc dot gnu.org
  Target Milestone: ---

/* { dg-do compile } */
/* { dg-options "-w" } */

double sqrt (); /* { dg-bogus "declared here" } */

void
foo (void)
{
  sqrt ();
}

emits a bogus message (warning is not emitted, but inform is).