Re: Removing -Wunsuffixed-float-constants, -Wdouble-promotion, -Wformat-zero-length

[Paul Eggert]

On 11/29/11 13:18, Jim Meyering wrote:
> Have you found code that triggers a -Wformat-zero-length warning
> yet that doesn't seem worth adjusting?

I haven't run into it one way or another, but all my instincts are
against that diagnostic.  I suspect that the most-common way that it
would happen would be something like this admittedly-contrived example:

   #if FEATURE_ENABLED
    #define FEATURE_FORMAT "feature"
   #else
    #define FEATURE_FORMAT ""
   #endif
   ...
   printf (buf, FEATURE_FORMAT);

where the printf can be optimized away if FEATURE_ENABLED
is zero, and the compiler is warning us about that.
This reminds me too much about bogus warnings that some compilers
give for this:

   enum { N = FEATURE_ENABLED ? 1000 : 0 };
   ...
   for (i = 0; i < N; i++)
     foo (i);

where the compiler proudly warns that it has optimized the loop
away entirely, and did I really mean that?  (Yes I did! and I don't
want to be warned about it! :-)