Re: [PATCH] use m4_require to implement AS_REQUIRE

[Paolo Bonzini]

Eric Blake wrote:
> According to Paolo Bonzini on 10/17/2008 6:19 AM:
>> That's related to tmp being underquoted, see the following even more
>> reduced testcase
> 
>> AS_INIT
>> m4_defun([AS_DOIT], [: $1])
>> m4_define([tmp], [AS_TR_SH(foo)])
>> AS_DOIT(tmp)
> 
>> => : # Sed expression to map a string onto a valid variable name.
>>    as_tr_sh="eval sed 'y%*+%pp%;s%^_$as_cr_alnum%_%g'"
> 
>>    foo
> 
> Thanks; that was what I was missing.  I'm trying to document and test
> AS_VAR, and didn't realize that the temporary variable still needed
> quoting until the last minute.  It turns out that the m4 temporary
> variable created by AS_VAR_PUSHDEF must be expanded only at the outermost
> level (diversions only work for outermost expansions; otherwise the text
> is picked up by argument collection).  AS_VAR patch coming up soon, and
> nothing more to see in this thread.

I still cannot understand why the diversion ends up like this though.

Here is an even smaller testcase:

AS_INIT
m4_defun([AS_FROBIT_PREPARE], [frob=1])
m4_defun([AS_FROBIT], [AS_REQUIRE([AS_FROBIT_PREPARE])$1])
m4_defun([AS_DOIT], [: $1])
m4_define([XXFOO], [AS_FROBIT(exit 1)])
AS_DOIT(XXFOO)

which gives

  : frob=1
  exit 1

as is, and

  frob=1
  : exit 1

when XXFOO is quoted.

So, if this is a bug (and it looks like one, though very minor because
proper quoting works around it) we also have a testcase. :-)

Paolo