[Bug lto/63603] [4.9/5 Regression] Linking with -fno-lto still invokes LTO

["rguenther at suse dot de" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63603

--- Comment #4 from rguenther at suse dot de <rguenther at suse dot de> ---
On Tue, 21 Oct 2014, burnus at gcc dot gnu.org wrote:

> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63603
> 
> --- Comment #3 from Tobias Burnus <burnus at gcc dot gnu.org> ---
> (In reply to Tobias Burnus from comment #2)
> > COLLECT_GCC_OPTIONS='-v' '-fno-use-linker-plugin' '-fno-lto'
> > '-mtune=generic' '-march=x86-64'
> > [...]/collect2 [...]
> 
> I haven't shown it, but the collect2 arguments doesn't contain the -fno-lto,
> only COLLECT_GCC_OPTIONS has it.
> 
> And in collect2.c's main(), there is a check for
>         else if (!strncmp (argv[i], "-fno-lto", 8))
>           lto_mode = LTO_MODE_NONE;
> but that only operates on argv and not on COLLECT_GCC_OPTIONS.

That means that

/* We pass any -flto flags on to the linker, which is expected
   to understand them.  In practice, this means it had better be collect2.  
*/
/* %{e*} includes -export-dynamic; see comment in common.opt.  */
#ifndef LINK_COMMAND_SPEC
#define LINK_COMMAND_SPEC "\
%{!fsyntax-only:%{!c:%{!M:%{!MM:%{!E:%{!S:\
    %(linker) " \
    LINK_PLUGIN_SPEC \
   "%{flto|flto=*:%<fcompare-debug*} \
    %{flto} %{flto=*} %l " LINK_PIE_SPEC \

doesn't pass on -fno-lto as expected.  Does adding %{fno-lto} after
%{flto} work?