auto-detect changed prefix and/or changed build flags

Detect changed prefix and/or changed build flags in the middle
of the build (or between 'make' and 'make install'), and if change
is detected, make sure all objects are compiled with same build
flags and same prefix, thus avoiding inconsistent/broken build.

[jc: removed otherwise unnecessary Makefile target to test the
 change this patch introduces. ]

Signed-off-by: Yakov Lerner <iler.ml@gmail.com>
Signed-off-by: Junio C Hamano <junkio@cox.net>

diff --git a/Makefile b/Makefile
index 2a1e6392dddeac520b90e5bccfb841f58018f858..ec91181c090eaaa8f2cbbccdb6f0c280b8bc2ee9 100644 (file)
--- a/Makefile
+++ b/Makefile
@@ -464,6 +464,7 @@ DESTDIR_SQ = $(subst ','\'',$(DESTDIR))
 bindir_SQ = $(subst ','\'',$(bindir))
 gitexecdir_SQ = $(subst ','\'',$(gitexecdir))
 template_dir_SQ = $(subst ','\'',$(template_dir))
+prefix_SQ = $(subst ','\'',$(prefix))
 
 SHELL_PATH_SQ = $(subst ','\'',$(SHELL_PATH))
 PERL_PATH_SQ = $(subst ','\'',$(PERL_PATH))
@@ -484,7 +485,7 @@ all:
 strip: $(PROGRAMS) git$X
        $(STRIP) $(STRIP_OPTS) $(PROGRAMS) git$X
 
-git$X: git.c common-cmds.h $(BUILTIN_OBJS) $(GITLIBS)
+git$X: git.c common-cmds.h $(BUILTIN_OBJS) $(GITLIBS) GIT-CFLAGS
        $(CC) -DGIT_VERSION='"$(GIT_VERSION)"' \
                $(ALL_CFLAGS) -o $@ $(filter %.c,$^) \
                $(BUILTIN_OBJS) $(ALL_LDFLAGS) $(LIBS)
@@ -516,7 +517,7 @@ $(patsubst %.perl,%,$(SCRIPT_PERL)) : % : %.perl
        chmod +x $@+
        mv $@+ $@
 
-$(patsubst %.py,%,$(SCRIPT_PYTHON)) : % : %.py
+$(patsubst %.py,%,$(SCRIPT_PYTHON)) : % : %.py GIT-CFLAGS
        rm -f $@ $@+
        sed -e '1s|#!.*python|#!$(PYTHON_PATH_SQ)|' \
            -e 's|@@GIT_PYTHON_PATH@@|$(GIT_PYTHON_DIR_SQ)|g' \
@@ -540,19 +541,19 @@ git$X git.spec \
        $(patsubst %.py,%,$(SCRIPT_PYTHON)) \
        : GIT-VERSION-FILE
 
-%.o: %.c
+%.o: %.c GIT-CFLAGS
        $(CC) -o $*.o -c $(ALL_CFLAGS) $<
 %.o: %.S
        $(CC) -o $*.o -c $(ALL_CFLAGS) $<
 
-exec_cmd.o: exec_cmd.c
+exec_cmd.o: exec_cmd.c GIT-CFLAGS
        $(CC) -o $*.o -c $(ALL_CFLAGS) '-DGIT_EXEC_PATH="$(gitexecdir_SQ)"' $<
 
-http.o: http.c
+http.o: http.c GIT-CFLAGS
        $(CC) -o $*.o -c $(ALL_CFLAGS) -DGIT_USER_AGENT='"git/$(GIT_VERSION)"' $<
 
 ifdef NO_EXPAT
-http-fetch.o: http-fetch.c http.h
+http-fetch.o: http-fetch.c http.h GIT-CFLAGS
        $(CC) -o $*.o -c $(ALL_CFLAGS) -DNO_EXPAT $<
 endif
 
@@ -609,6 +610,17 @@ tags:
        rm -f tags
        find . -name '*.[hcS]' -print | xargs ctags -a
 
+### Detect prefix changes
+TRACK_CFLAGS = $(subst ','\'',$(ALL_CFLAGS)):$(GIT_VERSION):\
+             $(bindir_SQ):$(gitexecdir_SQ):$(template_dir_SQ):$(prefix_SQ)
+
+GIT-CFLAGS: .FORCE-GIT-CFLAGS
+       @FLAGS='$(TRACK_CFLAGS)'; \
+           if test x"$$FLAGS" != x"`cat GIT-CFLAGS 2>/dev/null`" ; then \
+               echo 1>&2 "    * new build flags or prefix"; \
+               echo "$$FLAGS" >GIT-CFLAGS; \
+            fi
+
 ### Testing rules
 
 # GNU make supports exporting all variables by "export" without parameters.
@@ -711,10 +723,10 @@ clean:
        $(MAKE) -C Documentation/ clean
        $(MAKE) -C templates clean
        $(MAKE) -C t/ clean
-       rm -f GIT-VERSION-FILE
+       rm -f GIT-VERSION-FILE GIT-CFLAGS
 
 .PHONY: all install clean strip
-.PHONY: .FORCE-GIT-VERSION-FILE TAGS tags
+.PHONY: .FORCE-GIT-VERSION-FILE TAGS tags .FORCE-GIT-CFLAGS
 
 ### Check documentation
 #