Patch PyMix AUR package: fix 'undefined symbol cblas_*' error: record libgslcblase as dependency

0001-remove-as-needed-to-record-libgslcblase-dep.patch

From 798db16996767608bfa3c082a300e3756cb46eac Mon Sep 17 00:00:00 2001
From: Alexei Colin <ac@alexeicolin.com>
Date: Thu, 18 Feb 2016 00:24:15 -0500
Subject: [PATCH] remove --as-needed to record libgslcblas dep

---
 PKGBUILD | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/PKGBUILD b/PKGBUILD
index 1676ef3..b267f74 100644
--- a/PKGBUILD
+++ b/PKGBUILD
@@ -20,6 +20,27 @@ prepare() {
 }
 
 build() {
+    # Issue: libgsl depends on libgslcblas, but the NEEDED flag is not set for
+    # this dependency (libgslcblas.so doesn't show up in ldd libgsl.so). This
+    # might or might not be intentional, but in any case '--as-needed' is not
+    # being passed during libgsl build, so that's not the problem.
+    #
+    # PyMix does list libgslcblas as a dependency explicitly. But, it the
+    # NEEDED flag for this dependency does not get set in the extension shared
+    # library, because --as-needed is passed to the linker. The following
+    # manipulation of env variables removes --as-needed from the linker line.
+    # To make matters worse, this flag gets included twice.
+    #
+    # Python's distutils ends up using two sets of LDFLAGS: (1) LDFLAGS from
+    # 'build time' (see _init_posix in distutils/sysconfig.py), (2) LDFLAGS
+    # from makepkg.conf.  There's no way to override the build time flags. But,
+    # luckily distutils first checks LDSHARED var, and uses it instead of the
+    # build time LDFLAGS, so we set LDSHARED (note that it must contain the
+    # linker's name, not just flags). We edit out --as-needed from LDFLAGS,
+    # which seems nicer than clearing LDFLAGS completely.
+    export LDFLAGS=$(echo $LDFLAGS | sed 's/,--as-needed//g')
+    export LDSHARED="gcc -shared"
+
     cd "$srcdir/$_pkgname-$pkgver"
     python2 setup.py build
 }
-- 
2.7.0