[Bug c++/96412] New: format suggestion issue

[Bug c++/96412] New: format suggestion issue

[jg at jguk dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96412

            Bug ID: 96412
           Summary: format suggestion issue
           Product: gcc
           Version: 10.2.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: jg at jguk dot org
  Target Milestone: ---

Running on godbolt trunk

The suggestion is '%ld' in green type colour in the terminal, but should it
actually be '%zu' ? 

-Wformat-signedness -Wall



#include <cstdio>
int main()
{
size_t i = 0;
printf("%ld\n", i);
}



#1 with x86-64 gcc (trunk)
<source>: In function 'int main()':

<source>:5:11: warning: format '%ld' expects argument of type 'long int', but
argument 2 has type 'size_t' {aka 'long unsigned int'} [-Wformat=]

    5 | printf("%ld\n", i);

      |         ~~^     ~

      |           |     |

      |           |     size_t {aka long unsigned int}

      |           long int

      |         %ld

Compiler returned: 0

[Bug c++/96412] format suggestion issue

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96412

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |diagnostic
   Last reconfirmed|                            |2020-08-02
     Ever confirmed|0                           |1
             Status|UNCONFIRMED                 |NEW

--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Confirmed. If the conversion specification is "%d" it still recommends %ld for
size_t.

[Bug c++/96412] format suggestion issue

[jg at jguk dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96412

--- Comment #2 from Jonny Grant <jg at jguk dot org> ---
Just posted this on bug 90205 but maybe more appropriate here
gcc (Ubuntu 12.2.0-3ubuntu1) 12.2.0

Another example, but suggesting the same %ld from a sizeof


printf("sizeof time_t %zu\n", sizeof(time_t));

broken.c:35:35: warning: format ‘%ld’ expects argument of type ‘long int’, but
argument 2 has type ‘long unsigned int’ [-Wformat=]
   35 |     printf("sizeof unsigned int %ld\n", sizeof(unsigned int));
      |                                 ~~^     ~~~~~~~~~~~~~~~~~~~~
      |                                   |     |
      |                                   |     long unsigned int
      |                                   long int
      |                                 %ld