Bug#778163: vim: ftbfs with GCC-5

[James McCoy]

On Thu, Feb 12, 2015 at 10:37:46AM +0000, Matthias Klose wrote:
> The package fails to build in a test rebuild on at least amd64 with
> gcc-5/g++-5, but succeeds to build with gcc-4.9/g++-4.9.

Looking into this some, the build fails with -O1 and -O2 but succeeds
with -O0.  I used the diff between “gcc -O0 -Q --help=optimize” and
“gcc -O1 -Q --help=optimize” to get the list of optimizations enabled in
-O1 but not -O0.

Building with -O0 and all the -O1 optimizations enabled still succeeded,
but building with -O1 and some of those optimizations disabled did not.
I eventually narrowed it down to “-O1 -fno-tree-dominator-opts
-fno-tree-fre” as the minimal set that will cause the build to succeed.
Dropping either of those -fno-tree-… will cause the build to fail.

This seems like a GCC bug to me.  Let me know if you need more
information and, more importantly, how to get the right information.
Note that Vim's source compiles fine in all situations but the tests
fail when those optimizations aren't disabled.

Cheers,
-- 
James
GPG Key: 4096R/331BA3DB 2011-12-05 James McCoy <jamessan at debian.org>