[PATCH] manual/stdio: Clarify putc and putwc

[Florian Weimer]

* Arjun Shankar:

> diff --git a/manual/stdio.texi b/manual/stdio.texi
> index f5e289d58a..c3066114d2 100644
> --- a/manual/stdio.texi
> +++ b/manual/stdio.texi
> @@ -903,21 +903,23 @@ This function is a GNU extension.
>  @deftypefun int putc (int @var{c}, FILE *@var{stream})
>  @standards{ISO, stdio.h}
>  @safety{@prelim{}@mtsafe{}@asunsafe{@asucorrupt{}}@acunsafe{@acucorrupt{} @aculock{}}}
> -This is just like @code{fputc}, except that most systems implement it as
> +This is just like @code{fputc}, except that it may be implemented as
>  a macro, making it faster.  One consequence is that it may evaluate the
>  @var{stream} argument more than once, which is an exception to the
> -general rule for macros.  @code{putc} is usually the best function to
> -use for writing a single character.
> +general rule for macros.  Therefore, @var{stream} should never be an
> +expression with side-effects.  @code{putc} is usually the best function
> +to use for writing a single character.
>  @end deftypefun

I would drop the performance claim.  On glibc, there is no difference
(and we should merge the two implementations we have of the same
function).

Thanks,
Florian