Re: clang-10 warning in hash.c

[Bruno Haible]

Paul Eggert wrote:
> In the past I've worked around problems like these by writing things 
> like "SIZE_MAX + 1.0f <= new_candidate" instead of "SIZE_MAX <= 
> new_candidate"

This may deserve a warning that adding 1.0f does not change the value.

> Presumably the Clang folks want us to insert a cast to 'float', e.g., 
> "(float) SIZE_MAX <= new_candidate". However, I dislike casts because 
> they're too powerful.

And I dislike it because the transformation is correct only if
(float) SIZE_MAX >= SIZE_MAX. In the other case,
(float) SIZE_MAX < SIZE_MAX, the transformation is incorrect
[think of the particular value new_candidate = (float) SIZE_MAX].

The compiler should make correct transformations of comparisons;
that's not the job of the programmer.

> If there's no way to pacify Clang without casting, then I suggest 
> disabling the warning instead.

I agree. When a compiler makes a normal and correct optimization,
we don't want to hear about it. Only when the compiler makes a
dangerous optimization, we want to see a warning.

Bruno