[Bug bootstrap/44426] [4.4/4.5/4.6 Regression] gcc 4.5.0 requires c9x compiler to build

["joseph at codesourcery dot com" <gcc-bugzilla at gcc dot gnu dot org>]

------- Comment #9 from joseph at codesourcery dot com  2010-06-05 21:33 -------
Subject: Re:  [4.4/4.5/4.6 Regression] gcc 4.5.0 requires
 c9x compiler to build

On Sat, 5 Jun 2010, manu at gcc dot gnu dot org wrote:

> 
> 
> ------- Comment #6 from manu at gcc dot gnu dot org  2010-06-05 19:04 -------
> (In reply to comment #4)
> > Subject: Re:  [4.5/4.6 Regression] gcc 4.5.0 requires
> >  c9x compiler to build
> > 
> > On Sat, 5 Jun 2010, manu at gcc dot gnu dot org wrote:
> > 
> > > Do you mean we should not use VA_ARGS in GCC? Then, what? static inline? Is
> > > this warned by -pedantic? Shouldn't it?
> > 
> > Variadic macros are not standard C90 or C++98 and should only be used 
> > *conditionally* if the compiler being used to build GCC supports them.  
> 
> Why add a conditional definition if an alternative without VA_ARGS is needed?
> Using VA_ARGS+alternative does not seem to give any benefits.

At least in some cases for which variadic macros have been used, I suppose 
they result in a faster compiler than the alternative - for example, they 
were used when transitioning from variadic "build" to separate 
(non-variadic, so faster) buildN functions.  There may be less use for 
conditional uses in the present cases.

You can't readily use an inline function to replace the present uses of 
variadic macros; __builtin_va_arg_pack (a GNU extension) would be needed 
for a straightforward conversion.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44426