https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87183
Bug ID: 87183
Summary: -Wformat: format-extra-args fails to catch ex:
printf(PRIu32, 1)
Product: gcc
Version: 9.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: noah.pendleton at gmail dot com
Target Milestone: ---
Created attachment 44644
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=44644&action=edit
preprocessed file
>>Description:
Using <inttypes.h> format specifiers but omitting the `%` prefix causes the
`-Werror=format-extra-args` error to not be omitted:
```c
#include <inttypes.h>
printf(PRIu32, 2); // doesn't warn
printf(PRIu32 "", 2); // doesn't warn
printf("u", 2); // warns
printf("" PRIu32, 2); // warns
```
Interestingly, defining PRIu32 in the test file and not using <inttypes.h>
yields the expected behavior, eg:
```c
#define PRIu32 "u"
printf(PRIu32, 2); // warns
printf(PRIu32 "", 2); // warns
printf("u", 2); // warns
printf("" PRIu32, 2); // warns
```
>>Info:
gcc -v
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/local/libexec/gcc/x86_64-linux-gnu/9.0.0/lto-wrapper
Target: x86_64-linux-gnu
Configured with: ../configure --enable-languages=c,c++,fortran
--disable-multilib --disable-bootstrap --build=x86_64-linux-gnu
Thread model: posix
gcc version 9.0.0 20180831 (experimental) (GCC)
>>Complete Command Line:
gcc -Wall -Werror test.c
>>Complete Compiler Output:
test.c: In function 'main':
test.c:7:12: error: too many arguments for format [-Werror=format-extra-args]
7 | printf("u", 2); // fails
| ^~~
test.c:8:12: error: too many arguments for format [-Werror=format-extra-args]
8 | printf("" PRIu32, 2); // fails
| ^~
cc1: all warnings being treated as errors
>>Preprocessed file attached.
