Re: Bug #593838: AX_CFLAGS_GCC_OPTION misuses AS_VAR_PUSHDEF variable

[Paolo Bonzini]

On 09/27/2010 07:46 PM, Eric Blake wrote:
> > I was able to reduce the problem
> > to the following trivial case:
> >
> > --8<--------------------------cut here-------------------------->8--
> > AC_DEFUN([MY_MACRO],
> > [AS_VAR_PUSHDEF([VAR],[prefix_$1])
> >
> > dnl This is the version used by AX_CFLAGS_GCC_OPTION.
> > dnl I believe that it is incorrect. It does not work on Autoconf>= 2.67.
> > VAR=the_value
>
> You are correct that this will not work if VAR is an indirect variable
> name. It all depends on whether $1 is determined to be an indirection.

The testcase with MY_MACRO([a=b]), which was in Ben's email, does point 
out however a small efficiency regression.  I think this is worth fixing 
in Autoconf:

Up to 2.67, the AS_TR_SH would be evaluated at autoconf-time:

 prefix_a_b=value

Now instead it is evaluated at configure-time:

 as_VAR=`$as_echo "prefix_a=b" | $as_tr_sh`

 eval "$as_VAR=value"

Paolo