aclocal.m4 incorrectly remove parts of python-cflags output

[Cyprien Nicolas]

Hi,

At Gentoo, we've got a bug [1] about lilypond-2.14.2 configure's process.

To summary the bug report:

Line 978 of aclocal.m4, a sed rule is applied to remove "junk" in
python-cflags output, according to python issue 3290 [2].

It turns out that this sed expression is not correct, and strips parts
of some cflags. The remaining part is no longer a valid CFLAGS, making
the configure fails, saying it can't find Python.h.

The sed rule's purpose is to remove unnecessary CFLAGS like -march,
warning flags, optimization flags or definition flags. The sed rule
matches strings that start with -[WDOm].

We observed that if some flags contains the above described pattern, the
matching part will be removed, event if it is part of another flag. For
instance: -floop-strip-mime or -fvector-cost-model. -mime and -model
will match the sed rule, and will get removed. Thus -floop-strip and
-fvector-cost are passed to the C compiler which does not know about
those flags. It then exit on failure, making the configure check failing.

We propose a corrected sed rule [3] to match only -[WDOm] at the
beginning of a string element, in order to not match substrings.


1. https://bugs.gentoo.org/show_bug.cgi?id=415793
2. http://bugs.python.org/issue3290
3, https://415793.bugs.gentoo.org/attachment.cgi?id=316865


Τhanks,

-- 
Cyprien