[cfe-dev] proposal to add new warning -Wdate-time

[Prathamesh Kulkarni]

Hi,
    I was wondering if it's a good idea to add a new warning -Wdate-time,
that warns on use of __DATE__ and __TIME__ macros ?
I have attached patch for the same.

The rationale behind the warning is that these macros might prevent
reproducible builds from the same source.
This warning has been recently added to gcc:
http://gcc.gnu.org/ml/gcc/2013-11/msg00066.html

Here's a sample test-case:
#include <stdio.h>

int main()
{
  printf ("%s\n", __TIME__);
  printf ("%s\n", __DATE__);
  return 0;
}

date-time.c:5:19: warning: macro __TIME__ might prevent reproducible
builds [-Wdate-time]
  printf ("%s\n", __TIME__);
                       ^
date-time.c:6:19: warning: macro __DATE__ might prevent reproducible
builds [-Wdate-time]
  printf ("%s\n", __DATE__);
                       ^
2 warnings generated.


Thanks and Regards,
Prathamesh
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