bug#68267: closed ([PATCH] maint: add attributes to two functions without side effects)

[GNU bug Tracking System]

Your message dated Sat, 6 Jan 2024 15:34:07 +0000
with message-id <8f5a4d0c-4cd7-02ae-e48a-e2a8fa71e3e6@draigBrady.com>
and subject line Re: bug#68267: [PATCH] maint: add attributes to two functions 
without side effects
has caused the debbugs.gnu.org bug report #68267,
regarding [PATCH] maint: add attributes to two functions without side effects
to be marked as done.

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-- 
68267: https://debbugs.gnu.org/cgi/bugreport.cgi?bug=68267
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> --- Begin Message ---
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> Subject: 
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> [PATCH] maint: add attributes to two functions without side effects
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> Date: 
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> Fri,  5 Jan 2024 17:44:06 +0100
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> * src/date.c (res_width): This function computes its result solely
> from the value of its parameter and qualifies for the const attribute.
> * src/tee.c (get_next_out): This function has no side effect and
> qualifies for the pure attribute.
>
> Those two functions were flagged by GCC 12.3.0.
> ---
> Resent here, I sent it to the coreutils@ mailing-list while the hacking
> doc says to send it here.
>
>  src/date.c | 1 +
>  src/tee.c  | 1 +
>  2 files changed, 2 insertions(+)
>
> diff --git a/src/date.c b/src/date.c
> index 39fc0715d..03bf012e2 100644
> --- a/src/date.c
> +++ b/src/date.c
> @@ -294,6 +294,7 @@ Show the local time for 9AM next Friday on the west coast 
> of the US\n\
>  /* Yield the number of decimal digits needed to output a time with the
>     nanosecond resolution RES, without losing information.  */
>  
> +ATTRIBUTE_CONST
>  static int
>  res_width (long int res)
>  {
> diff --git a/src/tee.c b/src/tee.c
> index 07d525c95..eb074427c 100644
> --- a/src/tee.c
> +++ b/src/tee.c
> @@ -185,6 +185,7 @@ main (int argc, char **argv)
>  /* Return the index of the first non-null descriptor after idx,
>     or -1 if all are null.  */
>  
> +ATTRIBUTE_PURE
>  static int
>  get_next_out (FILE **descriptors, int nfiles, int idx)
>  {
> -- 
> 2.42.0
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> --- End Message ---
> --- Begin Message ---
>
>
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> Subject: 
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> Re: bug#68267: [PATCH] maint: add attributes to two functions without side effects
>
>
>
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> Date: 
>
> Sat, 6 Jan 2024 15:34:07 +0000
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>
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> User-agent: 
>
> Mozilla Thunderbird
>
>
>
>
> On 05/01/2024 16:44, Samuel Tardieu wrote:
> > * src/date.c (res_width): This function computes its result solely
> > from the value of its parameter and qualifies for the const attribute.
> > * src/tee.c (get_next_out): This function has no side effect and
> > qualifies for the pure attribute.
> >
> > Those two functions were flagged by GCC 12.3.0.
>
> I'm guessing GCC 12 needs help here as it can't determine the loops are finite.
> (as per: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109914 )
>
> Though I'm not seeing this suggestion with GCC 13.2.1,
> so perhaps GCC 12 can determine the loops are finite?
>
> I'll apply this since GCC 13 is less that a year old,
> but in general we try to avoid littering code like this.
>
> thanks,
> Pádraig
>
>
> --- End Message ---