Emit an autoconf config header carrying every autoconf define -- at least
all the -D options that appear on the compiler command lines, plus
anything else configure knows -- available to the tree as
#include <magic/autoconf/config.h>
It is built directly from confdefs.h just before AC_OUTPUT (which removes
that file), NOT via AC_CONFIG_HEADERS. This is deliberate:
* AC_CONFIG_HEADERS would rewrite @DEFS@ to -DHAVE_CONFIG_H and move the
defines into the header, changing every compiler command line and
breaking the build until sources #include it. Building from confdefs.h
leaves @DEFS@ (and the whole build) exactly as-is, so the header is a
pure additional artifact with no consumers yet.
* confdefs.h already holds every AC_DEFINE, including the many that have
no autoheader template (CALMA_MODULE, HAVE_READLINE, ...), which
AC_CONFIG_HEADERS/autoheader would have dropped.
Location mirrors the generated database.h (defs.mak GENINC): magic/autoconf/
config.h at the build top when in-tree (build dir == source dir), else
include/magic/autoconf/config.h so the clean -I include/ rule finds it and
the raw build dir stays off the search path. The directory is created on
demand and the header is rewritten on every ./configure. No defs.mak.in
change is needed -- the existing -I${GENINC} already resolves it.
.gitignore: ignore the in-tree magic/autoconf/config.h (out-of-tree it is
under the build dir and already ignored).
Verified: out-of-tree writes include/magic/autoconf/config.h, in-tree
writes magic/autoconf/config.h; both contain the command-line defines
(SIZEOF_VOID_P, CALMA_MODULE, HAVE_*, ...); #include <magic/autoconf/
config.h> resolves via -I${GENINC} from a subdir; @DEFS@ is unchanged
(-DHAVE_CONFIG_H absent) and modules still build.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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