On Fri, Aug 18, 2017 at 04:18:16PM -0400, Peter Teeson wrote: > I have been wandering in the GNU APL autotools byzantine(1) labyrinth(2) > and am wondering why the #undefs in config.h are commented out? > See for example lines 244, 247, 250 for WANT_ANDROID, WANT_ERLANG, > WANT_LIBAPL. > > config.h.in shows them not commented out so I’m curious...
Note that config.h.in contains only #undef directives, there is no #define at all. And after deciding which parts to define for given configuration, others are commented out rather than being explicitly undefined. Why? Inside the configure script there's an awk script that is written to config.status which contains the following comment: > # Replace #undef with comments. This is necessary, for example, > # in the case of _POSIX_SOURCE, which is predefined and required > # on some systems where configure will not decide to define it. -k
