Re: m4_defun_init

[Eric Blake]

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According to Ralf Wildenhues on 10/25/2008 3:11 AM:
> 
>> -AC_DEFUN([_AC_PREPROC_IFELSE],
>> +m4_defun_init([_AC_PREPROC_IFELSE()],

>> +# Try to preprocess PROGRAM.  Defer to the language-specific copy.
>> +m4_define([_AC_PREPROC_IFELSE],
>> +[m4_indir([$0(]_AC_LANG[)], $@)])
> 
> Doesn't changing _AC_PREPROC_IFELSE from AC_DEFUN to m4_define have
> impact upon the location for expansions of AC_REQUIRE calls within the
> arguments of _AC_PREPROC_IFELSE?

Before Paolo's patch, only AC_PREPROC_IFELSE was defun'd,
_AC_PREPROC_IFELSE was define'd.  Only defun'd macros show up in the
expansion trace.  Paolo changed _AC_PREPROC_IFELSE to be defun'd since it
does a require (since the documentation says that you can't call require
unless you are defun'd).  However, the technical truth is that you can't
call require unless you _or your caller_ is defun'd (in other words, you
can be define'd, as long as you are always evaluated in a defun'd
context), in which case, the define'd functions are omitted from the call
trace.  And since AC_PREPROC_IFELSE is already in the call trace, and
_AC_PREPROC_IFELSE is internal, it really doesn't hurt things to omit
_AC_PREPROC_IFELSE from the call trace.

> 
> Likewise for all the other macros that underwent this transformation,
> in this and the other patch(es?).

Yes, whatever we decide for one function can probably be applied across
the board to all 12 of Paolo's patches.

> 
> Anyway, this bit, and the bit about fatal errors printing the location,
> would be good to have covered in the testsuite (haven't checked if they
> are already, sorry).

Probably not, so I agree that the testsuite needs work before this patch
can graduate to anything worth revisiting.

- --
Don't work too hard, make some time for fun as well!

Eric Blake             address@hidden
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