From 69789347134b4b04411ae22f6eb516552b6ac365 Mon Sep 17 00:00:00 2001 From: Jonathan Nieder Date: Fri, 18 Nov 2011 17:23:24 -0600 Subject: [PATCH] Makefile: explicitly set target name for autogenerated dependencies MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit "gcc -MF depfile -MMD -MP -c -o path/to/file.o" produces a makefile snippet named "depfile" describing what files are needed to build the target given by "-o". When ccache versions before v3.0pre0~187 (Fix handling of the -MD and -MDD options, 2009-11-01) run, they execute gcc -MF depfile -MMD -MP -E instead to get the final content for hashing. Notice that the "-c -o" combination is replaced by "-E". The result is a target name without a leading path. Thus when building git with such versions of ccache with COMPUTE_HEADER_DEPENDENCIES enabled, the generated makefile snippets define dependencies for the wrong target: $ make builtin/add.o GIT_VERSION = 1.7.8.rc3 * new build flags or prefix CC builtin/add.o $ head -1 builtin/.depend/add.o.d add.o: builtin/add.c cache.h git-compat-util.h compat/bswap.h strbuf.h \ After a change in a header file, object files in a subdirectory are not automatically rebuilt by "make": $ touch cache.h $ make builtin/add.o $ Luckily we can prevent trouble by explicitly supplying the name of the target to ccache and gcc, using the -MQ option. Do so. Reported-and-tested-by: Nguyễn Thái Ngọc Duy Reported-by: : 허종만 Signed-off-by: Jonathan Nieder Reviewed-by: Jeff King Signed-off-by: Junio C Hamano --- Makefile | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/Makefile b/Makefile index 26b697d175..05626b3926 100644 --- a/Makefile +++ b/Makefile @@ -1388,7 +1388,8 @@ endif ifeq ($(COMPUTE_HEADER_DEPENDENCIES),auto) dep_check = $(shell $(CC) $(ALL_CFLAGS) \ - -c -MF /dev/null -MMD -MP -x c /dev/null -o /dev/null 2>&1; \ + -c -MF /dev/null -MQ /dev/null -MMD -MP \ + -x c /dev/null -o /dev/null 2>&1; \ echo $$?) ifeq ($(dep_check),0) override COMPUTE_HEADER_DEPENDENCIES = yes @@ -2211,7 +2212,7 @@ $(dep_dirs): missing_dep_dirs := $(filter-out $(wildcard $(dep_dirs)),$(dep_dirs)) dep_file = $(dir $@).depend/$(notdir $@).d -dep_args = -MF $(dep_file) -MMD -MP +dep_args = -MF $(dep_file) -MQ $@ -MMD -MP ifdef CHECK_HEADER_DEPENDENCIES $(error cannot compute header dependencies outside a normal build. \ Please unset CHECK_HEADER_DEPENDENCIES and try again)