Re: Passing -fno-lto by default?

[Zack Weinberg]

On Thu, Feb 6, 2014 at 10:48 AM, Markus Trippelsdorf
<address@hidden> wrote:
> When using gcc with Link Time Optimization (-flto) enabled there are
> certain configuration tests that always fail. For example the following
> test taken from Firefox's configure.in:
>   ac_cv_visibility_default=no
>   if ${CC-cc} -fvisibility=hidden -Werror -S conftest.c -o conftest.s 
> >/dev/null 2>&1; then
>     if ! egrep '\.(hidden|private_extern).*foo' conftest.s >/dev/null; then
>       ac_cv_visibility_default=yes
> ...
> which greps the assembler output, will not succeed with -flto (because
> it produces GIMPLE output in special sections).
>
> Now my question is if it wouldn't be desirable to have autoconf pass the
> -fno-lto flag automatically by default (instead of requiring each
> project to add it by hand when needed)?

I'm not sure about the general case, but Firefox in particular is
still stuck on autoconf 2.13 and therefore anything we do on this end
won't do them the least bit of good.

zw