Re: [gentoo-dev] Common make.conf screwups?

[Robert Moss <robmoss@gentoo.org>]

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A couple of CFLAGS that were never stable in any version of gcc:

-freduce-all-givs
-mfpmath=sse,387

The first flag will break things such as gcc, glibc, the kernel, 
binutils, bash and other nontrivial packages with every version of gcc 
I've ever tried (which is most of them). The flag has been denoted an 
experiment gone wrong and is no longer in CVS HEAD. The latter flag 
doesn't work properly and generates bad (sometimes segfaulting) code 
wherever SSE-related inline assembly is involved, and is slower than 
either -mfpmath=sse or -mfpmath=387 in 100% of cases according to those 
upstream.

But yeah, -freduce-all-givs is a far, FAR more dangerous global flag 
than -ffast-math, which can in theory give you a working (if not 
supported) system when set globally.

Also, perhaps highlight -fPIC in those cases where it shouldn't be used? 
Is that possible? Ehm. I don't mean that. Is that feasible? :-P

Rob

Ciaran McCreesh wrote:
> I've got some better vim syntax highlighting rules for make.conf lined
> up to go into the next app-vim/gentoo-syntax. One of the things that
> this lets me do is highlighting of (some kinds of) mistakes. What're the
> most common screwups that people see? My current list is:
> 
> * CFLAGS: -0[123s] instead of -O[123s], -ffast-math globally
> 
> * USE: +foo flags
> 
> * ACCEPT_KEYWORDS: random duff entries (syntax is easy enough for me to
> validate the whole thing)
> 
> * CHOST: there're certain settings that will cause glibc to fall over
> and die that people who are used to debian/sparc will sometimes use
> 
> * MAKEOPTS: I'm kinda tempted to highlight "-j N" (where n is integer)
> 

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