Rerun configure less often

Makefile

@@ -44,13 +44,25 @@ SAGE_ROOT_LOGS = logs
 # except for build/make/Makefile-auto, which is unused by the build system
 CONFIG_FILES = build/make/Makefile src/bin/sage-env-config build/bin/sage-build-env-config pkgs/sage-conf/_sage_conf/_conf.py
 
-# SPKG_COLLECT_FILES contains all files that influence the SAGE_SPKG_COLLECT macro
-SPKG_COLLECT_FILES = build/pkgs/*/type build/pkgs/*/package-version.txt build/pkgs/*/dependencies build/pkgs/*/requirements.txt build/pkgs/*/checksums.ini build/pkgs/*/spkg-install
-
-# If configure was run before, rerun it with the old arguments.
-# Otherwise, run configure with argument $PREREQ_OPTIONS.
+# SPKG_COLLECT_FILES contains the files that influence the *runtime* of the
+# portions of the 'configure' script generated by the SAGE_SPKG_COLLECT macro
+SPKG_COLLECT_FILES = build/pkgs/*/package-version.txt build/pkgs/*/dependencies*
+
+# If configure was not run before, complain.
+# If configure is newer than the files it generated (we test build/make/Makefile),
+#    we regenerate config.status by running the "config.status --recheck".
+# Either way we regenerate the generated files by calling "config.status".
 build/make/Makefile: configure $(SPKG_COLLECT_FILES) $(CONFIG_FILES:%=%.in)
-	$(MAKE) reconfigure
+	@if [ -x config.status ]; then				\
+	    case '$?' in					\
+		*configure*|*package-version*|*dependencies*)	\
+		    $(MAKE) reconfigure;;			\
+		*)						\
+		    ./config.status;;				\
+	    esac;						\
+	else							\
+	    $(MAKE) reconfigure;				\
+	fi
 
 reconfigure:
 	rm -f config.log
@@ -324,7 +336,25 @@ ptestoptionallong-nodoc:
 
 ###############################################################################
 
-configure: bootstrap src/doc/bootstrap configure.ac src/bin/sage-version.sh m4/*.m4 build/pkgs/*/spkg-configure.m4 build/pkgs/*/type build/pkgs/*/install-requires.txt build/pkgs/*/package-version.txt build/pkgs/*/distros/*.txt
+# The 'configure' script is just one of the files generated by 'bootstrap'.
+# CONFIGURE_DEPENDENCIES is the list of files that influence the generation of 'configure'.
+CONFIGURE_DEPENDENCIES =							\
+	configure.ac src/bin/sage-version.sh m4/*.m4				\
+	build/pkgs/*/spkg-configure.m4						\
+	build/pkgs/*/type build/pkgs/*/SPKG.rst					\
+	build/pkgs/*/checksums.ini build/pkgs/*/requirements.txt		\
+	build/pkgs/*/install-requires.txt build/pkgs/*/package-version.txt	\
+	build/pkgs/*/spkg-install build/pkgs/*/spkg-install.in
+
+# SPKG_INFO_DEPENDENCIES is the list of files that influence the run of 'sage-spkg-info' and hence
+# the generation of the files generated in 'src/doc' by 'src/doc/bootstrap'.
+SPKG_INFO_DEPENDENCIES =							\
+	build/pkgs/*/type build/pkgs/*/SPKG.rst					\
+	build/pkgs/*/requirements.txt						\
+	build/pkgs/*/install-requires.txt build/pkgs/*/package-version.txt	\
+	build/pkgs/*/distros/*.txt
+
+configure: bootstrap src/doc/bootstrap $(CONFIGURE_DEPENDENCIES) $(SPKG_INFO_DEPENDENCIES)
 	./bootstrap -d
 
 install: all