Re: Bug #593838: AX_CFLAGS_GCC_OPTION misuses AS_VAR_PUSHDEF variable

[Eric Blake]

On 10/01/2010 09:07 AM, Paolo Bonzini wrote:
> On 10/01/2010 03:57 PM, Eric Blake wrote:
> > Either way, the name of the indirect variable being assigned is
> > $prefix_a_b, whether you use pre- or post-2.67. Why is 'a=b' being
> > passed instead of 'a_b' in the first place? I'd need to see more
> > context of the real macro usage (rather than this trivial test case) to
> > see whether the efficiency hit is a corner case of a=b is likely in real
> > life and thus a performance regression, or just an extreme that is not
> > worth worrying about.
>
> Given it's about GCC options, I'd guess the real parameter was akin to
> -Wformat=2 and it's building something like ax_cv_gcc_option__Wformat_2.

Aha; that makes sense to me; and yes, this seems like something enough 
packages would want to do.  Not only autoconf-archives (with the AX_ 
prefix), but also gnulib has a macro for detecting compiler warning options.

Next question - should AX_CFLAGS_GCC_OPTION be doing 
m4_translit([$1],[=],[_]) itself prior to using AS_VAR_PUSH, or should 
this be folded directly into AS_VAR_PUSH's use of AS_TR_CPP?  It boils 
down to whether the fix should be in autoconf for all users (and at the 
expense of admittedly unlikely indirections like ${foo=bar}), or in the 
few macros like AX_CFLAGS_GCC_OPTION that specifically handle =?

--
Eric Blake   address@hidden    +1-801-349-2682
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