check whether system type is the same as stored in the cache (full

stand-alone macro, candidate for inclusion in the next release of autoconf)

create configure flag --enable-maintainer-mode, that enables automatic
rebuilding of configure from configure.in and aclocal.m4, and of
config.h.in based on acconfig.h.  This assumes autoconf and autoheader
are available.  Maintainer mode also introduces automatic dependency
tracking of include files, but it depends on features provided by gcc
and GNU make, so you must not enable maintainer mode if you are not
using any of these

source/Makefile.in

@@ -201,9 +201,12 @@ CHECK:
 	@echo "Using FLAGS = $(FLAGS)"
 	@echo "Using LIBS = $(LIBS)"
 
-.c.o: $(INCLUDES)
+.c.o: @MAINT@ .deps/.dummy
 	@echo Compiling $*.c
-	@$(CC) -I. -I$(srcdir) $(FLAGS) -c $< -o $@
+	@$(CC) -I. -I$(srcdir) $(FLAGS) -c $< -o $@ \
+	@MAINT@ -Wp,-MD,.deps/`echo $* | sed s,/,_,g`.P && : >.deps/.stamp
+# the line above is for atomatic dependency tracking
+# it will only work with GNU make, gcc and --enable-maintainer-mode
 
 bin/smbd: $(SMBD_OBJ) 
 	@echo Linking $@
@@ -301,7 +304,7 @@ uninstallcp:
 	@$(SHELL) $(srcdir)/script/uninstallcp.sh $(CODEPAGEDIR) $(CODEPAGELIST)
 
 clean: 
-	-rm -f core */*~ *~ */*.o 
+	-rm -f core */*~ *~ */*.o
 
 proto:
 	@echo rebuilding include/proto.h
@@ -319,6 +322,7 @@ realclean: clean
 distclean: realclean
 	-rm -f include/config.h include/stamp-h */dummy Makefile
 	-rm -f config.status config.cache
+	-rm -rf .deps
 
 # this target is really just for my use. It only works on a limited
 # range of machines and is used to produce a list of potentially
@@ -328,6 +332,14 @@ finddead:
 	nm */*.o |grep 'T ' | awk '{print $$3}' | sort -u > nmfns.txt
 	comm -13 nmused.txt nmfns.txt 
 
+# Rules for maintainers (--enable-maintainer-mode)
+AUTOCONF=@AUTOCONF@
+AUTOHEADER=@AUTOHEADER@
+
+# when configure.in is updated, reconfigure
+$(srcdir)/configure: @MAINT@ $(srcdir)/configure.in $(srcdir)/aclocal.m4
+	cd $(srcdir) && $(AUTOCONF)
+
 config.status: $(srcdir)/configure
 	$(SHELL) ./config.status --recheck
 
@@ -341,10 +353,24 @@ include/config.h: include/stamp-h
 
 include/stamp-h: $(srcdir)/include/config.h.in config.status
 	CONFIG_FILES= CONFIG_HEADERS=include/config.h $(SHELL) ./config.status
-	@ls -l config.status $(srcdir)/include/config.h.in > include/stamp-h
+	@echo > include/stamp-h
 
 $(srcdir)/include/config.h.in: $(srcdir)/include/stamp-h.in
 	@:
 
-$(srcdir)/include/stamp-h.in: $(srcdir)/acconfig.h $(srcdir)/configure.in
-	@cd $(srcdir) && ls -l acconfig.h configure.in > include/stamp-h.in
+$(srcdir)/include/stamp-h.in: @MAINT@ $(srcdir)/acconfig.h $(srcdir)/configure.in
+	cd $(srcdir) && $(AUTOHEADER)
+	@cd $(srcdir) && echo > include/stamp-h.in
+
+# automatic dependency tracking rules
+.deps/.dummy:
+	@-if test ! -d .deps; then rm -rf .deps; mkdir .deps; fi
+	@: >$@
+
+.deps/.stamp: .deps/.dummy
+	@:
+
+.deps/.P: .deps/.stamp
+	@-cat .deps/*.P >$@ 2>/dev/null
+
+@MAINT@-include .deps/.P

source/aclocal.m4

@@ -0,0 +1,36 @@
+dnl AC_VALIDATE_CACHE_SYSTEM_TYPE[(cmd)]
+dnl if the cache file is inconsistent with the current host,
+dnl target and build system types, execute CMD or print a default
+dnl error message.
+AC_DEFUN(AC_VALIDATE_CACHE_SYSTEM_TYPE, [
+    AC_REQUIRE([AC_CANONICAL_SYSTEM])
+    AC_MSG_CHECKING([config.cache system type])
+    if { test x"${ac_cv_host_system_type+set}" = x"set" &&
+         test x"$ac_cv_host_system_type" != x"$host"; } ||
+       { test x"${ac_cv_build_system_type+set}" = x"set" &&
+         test x"$ac_cv_build_system_type" != x"$build"; } ||
+       { test x"${ac_cv_target_system_type+set}" = x"set" &&
+         test x"$ac_cv_target_system_type" != x"$target"; }; then
+	AC_MSG_RESULT([different])
+	ifelse($#, 1, [$1],
+		[AC_MSG_ERROR(["you must remove config.cache and restart configure"])])
+    else
+	AC_MSG_RESULT([same])
+    fi
+    ac_cv_host_system_type="$host"
+    ac_cv_build_system_type="$build"
+    ac_cv_target_system_type="$target"
+])
+
+dnl based on Automake's maintainer mode
+AC_DEFUN(SAMBA_MAINTAINER_MODE,[
+  AC_ARG_ENABLE(maintainer-mode,
+	[  --enable-maintainer-mode enable some make rules for maintainers],
+      maint_mode=$enableval, maint_mode=no)
+  if test x"$maint_mode" = x"yes"; then MAINT=; else MAINT='#'; fi
+  AC_SUBST(MAINT)
+  AC_PATH_PROG(AUTOCONF, autoconf, autoconf)
+  AC_SUBST(AUTOCONF)
+  AC_PATH_PROG(AUTOHEADER, autoheader, autoheader)
+  AC_SUBST(AUTOHEADER)
+])

source/configure.in

@@ -22,13 +22,8 @@ case "$host_os" in
         *next2*) AC_DEFINE(NEXT2);;
 esac
 
-if test x"$ac_cv_canonical_host" != x &&
-   test x"$ac_cv_canonical_host" != x"$host"; then
-   echo "system config has changed - remove config.cache"; exit 1;
-fi
-
-AC_CACHE_VAL(ac_cv_canonical_host, ac_cv_canonical_host=$host;)
-
+AC_VALIDATE_CACHE_SYSTEM_TYPE
+SAMBA_MAINTAINER_MODE
 
 AC_INLINE
 AC_HEADER_STDC
@@ -810,7 +805,6 @@ AC_TRY_RUN([#include "${srcdir-.}/tests/summary.c"],
            echo "configure OK";,
 	   AC_MSG_ERROR([summary failure. Aborting config]),:)
 
-
 AC_OUTPUT(Makefile tests/dummy client/dummy lib/dummy ubiqx/dummy
 web/dummy param/dummy nmbd/dummy smbd/dummy rpc_server/dummy
 rpc_client/dummy rpc_parse/dummy locking/dummy passdb/dummy