Re: popdef(undefined), __m4_version__

Hi Eric,

Eric Blake <ebb9 <at> byu.net> writes:
> 
> ~  	autoconf 2.62.45-65ff0	+[a]	+[b]	+[a] and [b]
> m4-1.4.11		20.171	19.858	20.858	19.357
> patched branch-1.6	21.294	20.154	22.202	20.250
> argv_ref branch		19.013	17.750	19.219	17.266
> master branch		29.966	28.948	32.417	27.904
> 
> The differences in base compile times are due somewhat to differing
> compiler options, but it is also a bit depressing that the master branch
> is 50% slower than 1.6.  Someday I'd like to profile that, and figure out
> why the discrepancy.

Position-independent code.  I haven't measured, but would bet on it.
Remaining efficient inside shared libraries requires to either refactor
so that externally visible symbols are not called often, or play tricks
with linkage.

> * src/builtin.c (m4_undefine, m4_popdef): Add warning.
> * src/symtab.c (lookup_symbol): Distinguish when deletion occurred.
> * doc/m4.texinfo (Undefine, Pushdef): Document the warning.
> * NEWS: Document this change, along with a 1.4.x compatibility
> definition.

Aren't those warnings forbidden by POSIX?

Anyway, current git Autoconf fails several tests with current branch-1.6 M4,
most look related to autoupdate.  For example:

+/home/ralf/local/bin/m4:/tmp/auJL1116/unm4.m4:2: Warning: _au__undefine:
undefined macro `'
+/home/ralf/local/bin/m4:/tmp/auJL1116/unm4.m4:2: Warning: _au__undefine:
undefined macro `builtin'

I assume that 2.62 will fail, too, thus M4 needs fixed or it won't be
compatible with Autoconf 2.62.

Cheers,
Ralf