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Mike Frysinger wrote the following on 30.09.2006 23:48 :
> `man gcc` always seemed fine to me
> in fact, lets read the -ffast-math section:
> This option should never be turned on by any -O option since it can
> result in incorrect output for programs which depend on an exact
> implementation of IEEE or ISO rules/specifications for math func-
> this flag is never safe to use in CFLAGS
Indeed, I'll add a reminder to adventurous users to check `man gcc` (I
believe I added fast-math following an example somewhere on the web
instead of checking the man page).
> no way will our documentation link to gentoo-wiki.com
The GWN paragraph is mainly a 'heads-up' kind of thing, no more. Don't
confuse the GuideXML extract with an official documentation extract, GWN
uses GuideXML too :-)
>> If possible, I'd like to expand the list of 3.4.6 -> 4.1.1 upgrade
>> problems which are linked to experimental CFLAGS
> i find maintaining a list of "safe" CFLAGS on a per-gcc basis to be a waste of
> time ... but that's just me
That's not the idea. The main idea is to remind people that playing with
CFLAGS is allowed, as long as you remember to revert to safe CFLAGS
before reporting bugs.
As I wasted one dev time by forgetting to check my CFLAGS, I merely
thought that maybe this wasn't a common reflex for other users too
(fast-math was the only unsafe flag I used, I'm pretty conservative and
simply was mistaken because roughly 2 years ago I didn't check the
proper source of information: the man page). Maybe very few bug reports
are caused by inadequate CFLAGS. If my problem is an uncommon exception
I won't press the matter further, there would be no point to do so.
I'll wait and see if other devs are aware of common CFLAGS gotchas
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