GNU make’s target-specific variables facility has one weird facet: any variables set for a given target apply to all of its dependencies, too. For example, when running “make exec_cmd.o”, since exec_cmd.o depends on GIT-CFLAGS, the variable assignment in exec_cmd.s exec_cmd.o: ALL_CFLAGS += \ '-DGIT_EXEC_PATH="$(gitexecdir_SQ)"' \ '-DBINDIR="$(bindir_relative_SQ)"' \ '-DPREFIX="$(prefix_SQ)"' applies when refreshing GIT-CFLAGS, and the extra options get included in the tracked compiler flags. If an object file like this is the first target built, GIT-CFLAGS will appear to be out of date, resulting in useless rebuilds and the dreaded “new build flags or prefix” message. This does not happen with every build because GIT-CFLAGS is only refreshed once in a given “make” run, and usually the first target does not set any variables. When this problem does rear its head, it is very annoying. So put target-specific flags in a separate EXTRA_CPPFLAGS variable that is not included in $(TRACK_CFLAGS). Signed-off-by: Jonathan Nieder <jrnieder@xxxxxxxxx> --- Ran into this today. Reproducible by running "make tag.o" and then "make exec_cmd.o". Presumably caused by my commit 373a5ed (Makefile: use target-specific variable to pass flags to cc, 2010-01-06); sorry. Makefile | 21 +++++++++++---------- 1 files changed, 11 insertions(+), 10 deletions(-) diff --git a/Makefile b/Makefile index 7c616f8..fc03436 100644 --- a/Makefile +++ b/Makefile @@ -316,6 +316,7 @@ BUILTIN_OBJS = BUILT_INS = COMPAT_CFLAGS = COMPAT_OBJS = +EXTRA_CPPFLAGS = LIB_H = LIB_OBJS = PROGRAM_OBJS = @@ -1480,7 +1481,7 @@ strip: $(PROGRAMS) git$X $(STRIP) $(STRIP_OPTS) $(PROGRAMS) git$X git.o: common-cmds.h -git.s git.o: ALL_CFLAGS += -DGIT_VERSION='"$(GIT_VERSION)"' \ +git.s git.o: EXTRA_CPPFLAGS = -DGIT_VERSION='"$(GIT_VERSION)"' \ '-DGIT_HTML_PATH="$(htmldir_SQ)"' git$X: git.o $(BUILTIN_OBJS) $(GITLIBS) @@ -1488,7 +1489,7 @@ git$X: git.o $(BUILTIN_OBJS) $(GITLIBS) $(BUILTIN_OBJS) $(ALL_LDFLAGS) $(LIBS) builtin/help.o: common-cmds.h -builtin/help.s builtin/help.o: ALL_CFLAGS += \ +builtin/help.s builtin/help.o: EXTRA_CPPFLAGS = \ '-DGIT_HTML_PATH="$(htmldir_SQ)"' \ '-DGIT_MAN_PATH="$(mandir_SQ)"' \ '-DGIT_INFO_PATH="$(infodir_SQ)"' @@ -1714,13 +1715,13 @@ endif ifndef CHECK_HEADER_DEPENDENCIES $(C_OBJ): %.o: %.c GIT-CFLAGS $(missing_dep_dirs) - $(QUIET_CC)$(CC) -o $*.o -c $(dep_args) $(ALL_CFLAGS) $< + $(QUIET_CC)$(CC) -o $*.o -c $(dep_args) $(ALL_CFLAGS) $(EXTRA_CPPFLAGS) $< $(ASM_OBJ): %.o: %.S GIT-CFLAGS $(missing_dep_dirs) - $(QUIET_CC)$(CC) -o $*.o -c $(dep_args) $(ALL_CFLAGS) $< + $(QUIET_CC)$(CC) -o $*.o -c $(dep_args) $(ALL_CFLAGS) $(EXTRA_CPPFLAGS) $< endif %.s: %.c GIT-CFLAGS FORCE - $(QUIET_CC)$(CC) -S $(ALL_CFLAGS) $< + $(QUIET_CC)$(CC) -S $(ALL_CFLAGS) $(EXTRA_CPPFLAGS) $< ifdef USE_COMPUTED_HEADER_DEPENDENCIES # Take advantage of gcc's on-the-fly dependency generation @@ -1760,20 +1761,20 @@ xdiff-interface.o $(XDIFF_OBJS): \ xdiff/xutils.h xdiff/xprepare.h xdiff/xdiffi.h xdiff/xemit.h endif -exec_cmd.s exec_cmd.o: ALL_CFLAGS += \ +exec_cmd.s exec_cmd.o: EXTRA_CPPFLAGS = \ '-DGIT_EXEC_PATH="$(gitexecdir_SQ)"' \ '-DBINDIR="$(bindir_relative_SQ)"' \ '-DPREFIX="$(prefix_SQ)"' -builtin/init-db.s builtin/init-db.o: ALL_CFLAGS += \ +builtin/init-db.s builtin/init-db.o: EXTRA_CPPFLAGS = \ -DDEFAULT_GIT_TEMPLATE_DIR='"$(template_dir_SQ)"' -config.s config.o: ALL_CFLAGS += -DETC_GITCONFIG='"$(ETC_GITCONFIG_SQ)"' +config.s config.o: EXTRA_CPPFLAGS = -DETC_GITCONFIG='"$(ETC_GITCONFIG_SQ)"' -http.s http.o: ALL_CFLAGS += -DGIT_USER_AGENT='"git/$(GIT_VERSION)"' +http.s http.o: EXTRA_CPPFLAGS = -DGIT_USER_AGENT='"git/$(GIT_VERSION)"' ifdef NO_EXPAT -http-walker.s http-walker.o: ALL_CFLAGS += -DNO_EXPAT +http-walker.s http-walker.o: EXTRA_CPPFLAGS = -DNO_EXPAT endif git-%$X: %.o $(GITLIBS) -- 1.7.0 -- To unsubscribe from this list: send the line "unsubscribe git" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html