Re: string manipulation : removing a part of a string

[Vincent Torri]

On Fri, 15 Jun 2012, Eric Blake wrote:

> On 06/15/2012 07:09 AM, Vincent Torri wrote:
> > On Thu, 14 Jun 2012, Eric Blake wrote:
> >
> > > On 06/14/2012 05:36 PM, Vincent Torri wrote:
> > > > Hey
> > > >
> > > > I pass -Wno-foo as a parameter of an m4 macro. What I would like is to
> > > > store into a variable -Wfoo, so removing 'no-'
> > > >
> > > > Is it possible with the m4 macro string manipulation ? If not, what's
> > > > the best solution ?
> > >
> > > m4_bpatsubst([[$1]], [no-])
> > >
> > > will delete the first instance of the regular expression 'no-' (if any)
> > > from parameter $1.  Yes, the first argument is double-quoted, so that
> > > the output of m4_bpatsubst will still be single-quoted.
> > >
> > > > Another related question: if I pass -Wbar, I would like to know if it
> > > > begins by '-Wno-'. How can I do that with m4 ?
> > >
> > > m4_if(m4_index([$1], [-Wno-]), 0, [yes...], [no...])
> >
> > I try that to set flagm4 to -Wfoo if tmp is -Wno-foo, but it seems that
> > i don't use correctly the m4 macros
> >
> > m4_if(m4_index([$tmp], [-Wno-]), 0, [m4_define([flagm4],
>
> $tmp is NOT an m4 parameter.
>
> Are you trying to do this at m4 time (ie. while running autoconf) or at
> shell time (ie. while running configure)?  Make up your mind,

it's in an m4 macro

> Show more context of what you are trying to do.

dnl Macro that checks for a compiler flag availability
dnl
dnl EFL_CHECK_COMPILER_FLAG(EFL, FLAG[, ACTION-IF-FOUND[ ,ACTION-IF-NOT-FOUND]])
dnl AC_SUBST : EFL_CFLAGS (EFL being replaced by its value)
dnl AM_CONDITIONAL : EFL_HAVE_FLAG (FLAG being replaced by its value)

AC_DEFUN([EFL_CHECK_COMPILER_FLAG],
[
m4_pushdef([UPEFL], m4_translit([$1], [-a-z], [_A-Z]))dnl
m4_pushdef([UP], m4_translit([$2], [-a-z], [_A-Z]))dnl

tmp=$2
m4_if(m4_index([$tmp], [-Wno-]), 0, [m4_define([flagm4], 
[m4_bpatsubst([[$tmp]], [no-])])], [m4_define([flagm4], [$tmp])])

flag=flagm4
AC_MSG_NOTICE([flagval :: $flag])

etc...
])