Merge branch 'fk/make-auto-header-dependencies'

* fk/make-auto-header-dependencies:
Makefile: Use computed header dependencies if the compiler supports it

diff --combined Makefile
index 8d6d4515d2d635ff8b5e59e0ce38ffa566f5bb64,c131439a34a4d80e3c0ba35c13b2ccc53888538f..15fb8c23a34e7cd0242d691bd9427eb443d516d7
--- 1/Makefile
--- 2/Makefile
+++ b/Makefile
@@@ -250,10 -250,6 +250,6 @@@ all:
  #   DEFAULT_EDITOR='$GIT_FALLBACK_EDITOR',
  #   DEFAULT_EDITOR='"C:\Program Files\Vim\gvim.exe" --nofork'
  #
- # Define COMPUTE_HEADER_DEPENDENCIES if your compiler supports the -MMD option
- # and you want to avoid rebuilding objects when an unrelated header file
- # changes.
- #
  # Define CHECK_HEADER_DEPENDENCIES to check for problems in the hard-coded
  # dependency rules.
  #
@@@ -302,7 -298,6 +298,7 @@@ bindir = $(prefix)/$(bindir_relative
  mandir = share/man
  infodir = share/info
  gitexecdir = libexec/git-core
 +mergetoolsdir = $(gitexecdir)/mergetools
  sharedir = $(prefix)/share
  gitwebdir = $(sharedir)/gitweb
  template_dir = share/git-core/templates
@@@ -515,7 -510,6 +511,7 @@@ LIB_H += commit.
  LIB_H += compat/bswap.h
  LIB_H += compat/cygwin.h
  LIB_H += compat/mingw.h
 +LIB_H += compat/obstack.h
  LIB_H += compat/win32/pthread.h
  LIB_H += compat/win32/syslog.h
  LIB_H += compat/win32/sys/poll.h
@@@ -534,7 -528,6 +530,7 @@@ LIB_H += graph.
  LIB_H += grep.h
  LIB_H += hash.h
  LIB_H += help.h
 +LIB_H += kwset.h
  LIB_H += levenshtein.h
  LIB_H += list-objects.h
  LIB_H += ll-merge.h
@@@ -596,7 -589,6 +592,7 @@@ LIB_OBJS += cache-tree.
  LIB_OBJS += color.o
  LIB_OBJS += combine-diff.o
  LIB_OBJS += commit.o
 +LIB_OBJS += compat/obstack.o
  LIB_OBJS += config.o
  LIB_OBJS += connect.o
  LIB_OBJS += convert.o
@@@ -626,7 -618,6 +622,7 @@@ LIB_OBJS += hash.
  LIB_OBJS += help.o
  LIB_OBJS += hex.o
  LIB_OBJS += ident.o
 +LIB_OBJS += kwset.o
  LIB_OBJS += levenshtein.o
  LIB_OBJS += list-objects.o
  LIB_OBJS += ll-merge.o
@@@ -647,7 -638,6 +643,7 @@@ LIB_OBJS += pack-revindex.
  LIB_OBJS += pack-write.o
  LIB_OBJS += pager.o
  LIB_OBJS += parse-options.o
 +LIB_OBJS += parse-options-cb.o
  LIB_OBJS += patch-delta.o
  LIB_OBJS += patch-ids.o
  LIB_OBJS += path.o
@@@ -1242,6 -1232,15 +1238,15 @@@ endi
  ifdef CHECK_HEADER_DEPENDENCIES
  COMPUTE_HEADER_DEPENDENCIES =
  USE_COMPUTED_HEADER_DEPENDENCIES =
+ else
+ ifndef COMPUTE_HEADER_DEPENDENCIES
+ dep_check = $(shell sh -c \
+       '$(CC) -c -MF /dev/null -MMD -MP -x c /dev/null -o /dev/null 2>&1; \
+       echo $$?')
+ ifeq ($(dep_check),0)
+ COMPUTE_HEADER_DEPENDENCIES=YesPlease
+ endif
+ endif
  endif
  
  ifdef COMPUTE_HEADER_DEPENDENCIES
@@@ -2210,7 -2209,7 +2215,7 @@@ test-delta$X: diff-delta.o patch-delta.
  
  test-line-buffer$X: vcs-svn/lib.a
  
 -test-parse-options$X: parse-options.o
 +test-parse-options$X: parse-options.o parse-options-cb.o
  
  test-string-pool$X: vcs-svn/lib.a
  
@@@ -2263,13 -2262,6 +2268,13 @@@ endi
  gitexec_instdir_SQ = $(subst ','\'',$(gitexec_instdir))
  export gitexec_instdir
  
 +ifneq ($(filter /%,$(firstword $(mergetoolsdir))),)
 +mergetools_instdir = $(mergetoolsdir)
 +else
 +mergetools_instdir = $(prefix)/$(mergetoolsdir)
 +endif
 +mergetools_instdir_SQ = $(subst ','\'',$(mergetools_instdir))
 +
  install_bindir_programs := $(patsubst %,%$X,$(BINDIR_PROGRAMS_NEED_X)) $(BINDIR_PROGRAMS_NO_X)
  
  install: all
@@@ -2279,9 -2271,6 +2284,9 @@@
        $(INSTALL) -m 644 $(SCRIPT_LIB) '$(DESTDIR_SQ)$(gitexec_instdir_SQ)'
        $(INSTALL) $(install_bindir_programs) '$(DESTDIR_SQ)$(bindir_SQ)'
        $(MAKE) -C templates DESTDIR='$(DESTDIR_SQ)' install
 +      $(INSTALL) -d -m 755 '$(DESTDIR_SQ)$(mergetools_instdir_SQ)'
 +      (cd mergetools && $(TAR) cf - .) | \
 +      (cd '$(DESTDIR_SQ)$(mergetools_instdir_SQ)' && umask 022 && $(TAR) xof -)
  ifndef NO_PERL
        $(MAKE) -C perl prefix='$(prefix_SQ)' DESTDIR='$(DESTDIR_SQ)' install
        $(MAKE) -C gitweb install