On 11/29/2011 02:38 PM, Jim Meyering wrote: >> I'm not convinced about removing it from manywarnings.m4 - it's not that >> hard to disable the warning if you don't want it, but leaving it in >> leads to smaller executable size for the cases where 1.0F is sufficient >> (compared to the extra size required to represent 1.0 which is 1.0D). >> By explicitly marking F or D to all float constants, it shows you've >> thought about which precision is worth using; omitting the suffix could >> be the sign of sloppy code that has other problems with misuse of >> floating point. > > Inspired by that, I went to see what would be required for coreutils to pass. > Are these "D" and "F" really worth it? > > Unless there are objections (portability?)
Aargh. I just reread C99.
F (and f) for float, and L (or l) for long double are required, but D
(or d) for double is a GNU extension.
Since we can't silence the warning without adding an explicit 'D', but
'D' is not standardized, I have changed my mind. Let's nuke the warning.
Meanwhile, your patch for adding 'F' is okay, but not for adding 'D'.
That is,
> +++ b/lib/hash.c
> @@ -113,8 +113,8 @@ struct hash_table
> 1.0). The growth threshold defaults to 0.8, and the growth factor
> defaults to 1.414, meaning that the table will have doubled its size
> every second time 80% of the buckets get used. */
> -#define DEFAULT_GROWTH_THRESHOLD 0.8
> -#define DEFAULT_GROWTH_FACTOR 1.414
> +#define DEFAULT_GROWTH_THRESHOLD 0.8F
> +#define DEFAULT_GROWTH_FACTOR 1.414F
this change makes sense,
> @@ -238,7 +238,7 @@ hash_print_statistics (const Hash_table *table, FILE
> *stream)
> fprintf (stream, "# buckets: %lu\n", (unsigned long int)
> n_buckets);
> fprintf (stream, "# buckets used: %lu (%.2f%%)\n",
> (unsigned long int) n_buckets_used,
> - (100.0 * n_buckets_used) / n_buckets);
> + (100.0F * n_buckets_used) / n_buckets);
but this does not (in var-args, float gets promoted to double, so you
probably aren't gaining anything by using 'float' as an intermediary,
and starting with '100.0' as double is better to begin with).
> @@ -73,7 +73,7 @@ struct timespec dtotimespec (double);
> static inline double
> timespectod (struct timespec a)
> {
> - return a.tv_sec + a.tv_nsec / 1e9;
> + return a.tv_sec + a.tv_nsec / 1e9D;
Likewise, this one is not portable.
--
Eric Blake ebl...@redhat.com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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