Re: [gentoo-dev] [RFC] CFLAGS paragraph for the GWN

[Ciaran McCreesh]

On Tue, 03 Oct 2006 02:56:42 +0200 Lionel Bouton
<lionel-dev@××××××.name> wrote:
| Being able to tune the CFLAGS is part of one of the core principles of
| Gentoo: let the user be in control.

What? No it isn't.

| <li>nss_ldap stopped working with <c>-ffast-math</c> (reported to
| break many packages changing with the actual gcc version)</li>

Uh, -ffast-math has never been and will never be a safe thing to stick
in CFLAGS.

| <li><c>-fvisibility-inlines-hidden</c> still breaks some code</li>

Ditto. In C++, inlining is a *guideline* that the compiler can and will
ignore as it sees fit. Only code specifically designed to use this flag
should specify it, and even then it can still lead to failures because
of the non-guaranteed nature of inlining.

| <li>if you used gcc-4.0, <c>-ftree-loop-linear</c> now breaks in
| gcc-4.1(at least with mesa)</li>

Users shouldn't be sticking that in CFLAGS anyway.

| <li>again for gcc-4.0 users, <c>-ftree-vectorize</c> is known to be
| broken in gcc-4.1 (at least for x86 and ppc, amd64 users seem to be
| safe)</li>

Or that.

| <li><c>-fforce-addr</c> and <c>-fweb</c> break regularly on x86 with
| video libraries or graphic processing apps which use hand-optimised
| ASM</li> </ul>

Or that.

| Users with unsupported CFLAGS (see the <uri
| link='http://gentoo-wiki.com/CFLAGS_matrix'>CFLAGS matrix</uri> for
| example) might want to return to safe CFLAGS (see <uri
| link='http://gentoo-wiki.com/Safe_Cflags'>Safe CFLAGS</uri>) if recent
| updates caused them stability problems. On the other hand, more
| adventurous users might want to experiment with CFLAGS that didn't
| work properly with gcc-3.4.6... As always, the user is in control.

Linking to that is a very bad idea. The wiki is in control of the
minority ricer fringe.

GWN shouldn't be advocating this kind of thing at all. Here's a better
paragraph:

<p>We would like to remind you that using anything beyond -O2
-fomit-frame-pointer -march/-mcpu/-mtune in CFLAGS or CXXLFAGS (and
-mieee, -mabi etc on selected archs that tell you to do this), and using
anything at all in LDFLAGS or ASFLAGS, is pointless and will lead to a
broken system. Your penis length is not proportional to the size of your
CFLAGS.</p>

-- 
Ciaran McCreesh
Mail                : ciaranm at ciaranm.org
Web                 : http://ciaranm.org/
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