From: "Міхаіл Т." <mi+ruby-forum@...>
Date: 2009-10-22T00:31:23+09:00
Subject: gcc-4.4.x -O2 miscompiles Ruby (was: `make check' hangs)

Міхаіл Т. wrote:
> The C-compiler (gcc44) is gcc version 4.4.0 20090514 (Red Hat 4.4.0-6) 
> (GCC).

Simply recompiling from scratch using gcc-4.1.2 solved the hanging 
problem for me. The check is now running (outputting a dot as 
progress-report).

Alternatively, using gcc-4.4.0, but with less aggressive optimization 
(-O1 instead of -O2) avoids the problem as well.

Increasing the compiler warnings level (-Wall), one can see a lot of 
negative comments, including a bunch of strict-aliasing violations...

Indeed, this was is already discussed in:

https://bugzilla.redhat.com/show_bug.cgi?id=489990

The bug is in Ruby...

The work-around is to disable strict-aliasing, when compiling. For gcc 
users, this is done with -fno-strict-aliasing after the -O2 optimization 
flag (see attached patch).

After rebuilding this way, I can get `make check' to start and proceed 
(the errors it reports now are the same as with other compilers and 
platforms).

Other (non-gcc) compilers are on their own...

        -mi

Attachments:
http://www.ruby-forum.com/attachment/4167/patch-Makefile.in

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