https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88687
Bug ID: 88687
Summary: redundant -Wbuiltin-declaration-mismatch after
-Wimplicit-function-declaration
Product: gcc
Version: 9.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: msebor at gcc dot gnu.org
Target Milestone: ---
The -Wbuiltin-declaration-mismatch warning below should probably only be issued
if -Wimplicit-function-declaration is disabled, otherwise it's mostly redundant
(although only one instance of the latter warning is issued for each implicit
declaration regardless of the number of calls).
In addition, the <built-in>: note after the -Wbuiltin-declaration-mismatch
warning is meaningless.
$ cat t.c && gcc -O2 -S -Wall -Wextra t.c
int f (const char *s)
{
return memcmp (s, "1234", 4);
}
t.c: In function ‘f’:
t.c:3:10: warning: implicit declaration of function ‘memcmp’
[-Wimplicit-function-declaration]
3 | return memcmp (s, "1234", 4);
| ^~~~~~
t.c:3:29: warning: ‘memcmp’ argument 3 type is ‘int’ where ‘long unsigned int’
is expected in a call to built-in function declared without prototype
[-Wbuiltin-declaration-mismatch]
3 | return memcmp (s, "1234", 4);
| ^
<built-in>: note: built-in ‘memcmp’ declared here
