Hi,
On Wed, Feb 13 2019, Martin Jambor wrote:
> Hi Gerald and Martin,
>
> On Mon, Jan 28 2019, Gerald Pfeifer wrote:
>> Hi Martin,
>>
>> On Sat, 26 Jan 2019, Martin Jambor wrote:
>>>> What is a "wrong absolute value function"? That might be good to
>>>> show by means of an example? (Also in invoke.texi, which I checked
>>>> before writing this.)
>>> I'm not sure how to change the wording, perhaps "...when a used absolute
>>> value function seems wrong for the type of its argument" ...?
>>
>> yes, that definitely would have helped me as a user. (I guessed
>> it might be that, but seeing it in writing helps.)
>>
>> On Mon, 28 Jan 2019, Martin Sebor wrote:
>>> -Wabsolute-value warns for calls to standard functions that compute
>>> the absolute value of an argument when a more appropriate standard
>>> function is available. For example, calling abs(3.14) triggers
>>> the warning because the appropriate function to call to compute
>>> the absolute value of a double argument is fabs. The option also
>>> triggers warnings when the argument in a call to such a function
>>> has an unsigned type.
>>
>> Lovely.
>>
>> (I'd say "This option...", but that's probably a matter of taste.)
>>
>> Are you going to enhance both invoke.texi and apply a patch to the
>> release notes (changes.html)? That would be ideal.
>>
>
> I have incorporated Martin's extended description to both invoke.texi
> and changes.html, the result is in the two patches below. OK to commit
> to trunk and to wwwdocs CVS repo respectively?
Since it is documentation only and because the change was basically
pre-approved by Gerald, I plan to commit both later today (unless
someone stops me). I hope I'm not stretching the rules too much.
Martin
>
>
> diff -u -r1.38 changes.html
> --- htdocs/gcc-9/changes.html 7 Feb 2019 11:49:26 -0000 1.38
> +++ htdocs/gcc-9/changes.html 13 Feb 2019 17:38:57 -0000
> @@ -89,6 +89,23 @@
> </ul></li>
> </ul>
>
> +<h3 id="c">C</h3>
> +<ul>
> + <li>New warnings:
> + <ul>
> + <li><code>-Wabsolute-value</code> warns for calls to standard
> + functions that compute the absolute value of an argument when a
> + more appropriate standard function is available. For example,
> + calling <code>abs(3.14)</code> triggers the warning because the
> + appropriate function to call to compute the absolute value of a
> + double argument is <code>fabs</code>. The option also triggers
> + warnings when the argument in a call to such a function has an
> + unsigned type. This warning can be suppressed with an explicit
> + type cast and it is also enabled by <code>-Wextra</code>.
> + </li>
> + </ul></li>
> +</ul>
> +
> <h3 id="cxx">C++</h3>
> <ul>
> <li>New warnings:
>
>
>
> 2019-02-13 Martin Jambor <mjam...@suse.cz>
> Martin Sebor <mse...@redhat.com>
>
> * doc/invoke.texi (Warning Options): Reword description of
> -Wno-absolute-value.
> ---
> gcc/doc/invoke.texi | 10 +++++++---
> 1 file changed, 7 insertions(+), 3 deletions(-)
>
> diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
> index c625350d04d..a8bafbebce8 100644
> --- a/gcc/doc/invoke.texi
> +++ b/gcc/doc/invoke.texi
> @@ -6633,9 +6633,13 @@ example, warn if an unsigned variable is compared
> against zero with
> @item -Wabsolute-value @r{(C and Objective-C only)}
> @opindex Wabsolute-value
> @opindex Wno-absolute-value
> -Warn when a wrong absolute value function seems to be used or when it
> -does not have any effect because its argument is an unsigned type.
> -This warning be suppressed with an explicit type cast and it is also
> +Warn for calls to standard functions that compute the absolute value
> +of an argument when a more appropriate standard function is available.
> +For example, calling @code{abs(3.14)} triggers the warning because the
> +appropriate function to call to compute the absolute value of a double
> +argument is @code{fabs}. The option also triggers warnings when the
> +argument in a call to such a function has an unsigned type. This
> +warning can be suppressed with an explicit type cast and it is also
> enabled by @option{-Wextra}.
>
> @include cppwarnopts.texi
> --
> 2.20.1
