Merge branch 'ab/install-symlinks'

The build procedure learned to optionally use symbolic links
(instead of hardlinks and copies) to install "git-foo" for built-in
commands, whose binaries are all identical.

* ab/install-symlinks:
Makefile: optionally symlink libexec/git-core binaries to bin/git
Makefile: add a gitexecdir_relative variable
Makefile: fix broken bindir_relative variable

diff --combined Makefile
index 180a768690e9883cd9d6f3cb68ae084cc40b9629,ac7616422d04f8d80385cabb04560cf6227490fb..96f6138f634b6aaf009edd5026320494b27a77f5
--- 1/Makefile
--- 2/Makefile
+++ b/Makefile
@@@ -29,10 -29,10 +29,10 @@@ all:
  # Perl-compatible regular expressions instead of standard or extended
  # POSIX regular expressions.
  #
 -# Currently USE_LIBPCRE is a synonym for USE_LIBPCRE1, define
 -# USE_LIBPCRE2 instead if you'd like to use version 2 of the PCRE
 -# library. The USE_LIBPCRE flag will likely be changed to mean v2 by
 -# default in future releases.
 +# USE_LIBPCRE is a synonym for USE_LIBPCRE2, define USE_LIBPCRE1
 +# instead if you'd like to use the legacy version 1 of the PCRE
 +# library. Support for version 1 will likely be removed in some future
 +# release of Git, as upstream has all but abandoned it.
  #
  # When using USE_LIBPCRE1, define NO_LIBPCRE1_JIT if the PCRE v1
  # library is compiled without --enable-jit. We will auto-detect
@@@ -296,12 -296,6 +296,12 @@@
  #
  # Define NO_PERL if you do not want Perl scripts or libraries at all.
  #
 +# Define NO_PERL_CPAN_FALLBACKS if you do not want to install bundled
 +# copies of CPAN modules that serve as a fallback in case the modules
 +# are not available on the system. This option is intended for
 +# distributions that want to use their packaged versions of Perl
 +# modules, instead of the fallbacks shipped with Git.
 +#
  # Define PYTHON_PATH to the path of your Python binary (often /usr/bin/python
  # but /usr/bin/python2.7 on some platforms).
  #
@@@ -335,6 -329,13 +335,13 @@@
  # when hardlinking a file to another name and unlinking the original file right
  # away (some NTFS drivers seem to zero the contents in that scenario).
  #
+ # Define INSTALL_SYMLINKS if you prefer to have everything that can be
+ # symlinked between bin/ and libexec/ to use relative symlinks between
+ # the two. This option overrides NO_CROSS_DIRECTORY_HARDLINKS and
+ # NO_INSTALL_HARDLINKS which will also use symlinking by indirection
+ # within the same directory in some cases, INSTALL_SYMLINKS will
+ # always symlink to the final target directly.
+ #
  # Define NO_CROSS_DIRECTORY_HARDLINKS if you plan to distribute the installed
  # programs as a tar, where bin/ and libexec/ might be on different file systems.
  #
@@@ -474,8 -475,7 +481,7 @@@ ARFLAGS = rc
  # This can help installing the suite in a relocatable way.
  
  prefix = $(HOME)
- bindir_relative = bin
- bindir = $(prefix)/$(bindir_relative)
+ bindir = $(prefix)/bin
  mandir = $(prefix)/share/man
  infodir = $(prefix)/share/info
  gitexecdir = libexec/git-core
@@@ -492,8 -492,10 +498,10 @@@ lib = li
  # DESTDIR =
  pathsep = :
  
+ bindir_relative = $(patsubst $(prefix)/%,%,$(bindir))
  mandir_relative = $(patsubst $(prefix)/%,%,$(mandir))
  infodir_relative = $(patsubst $(prefix)/%,%,$(infodir))
+ gitexecdir_relative = $(patsubst $(prefix)/%,%,$(gitexecdir))
  htmldir_relative = $(patsubst $(prefix)/%,%,$(htmldir))
  
  export prefix bindir sharedir sysconfdir gitwebdir perllibdir localedir
@@@ -1170,18 -1172,13 +1178,18 @@@ ifdef NO_LIBGEN_
        COMPAT_OBJS += compat/basename.o
  endif
  
 -USE_LIBPCRE1 ?= $(USE_LIBPCRE)
 +USE_LIBPCRE2 ?= $(USE_LIBPCRE)
  
 -ifneq (,$(USE_LIBPCRE1))
 -      ifdef USE_LIBPCRE2
 -$(error Only set USE_LIBPCRE1 (or its alias USE_LIBPCRE) or USE_LIBPCRE2, not both!)
 +ifneq (,$(USE_LIBPCRE2))
 +      ifdef USE_LIBPCRE1
 +$(error Only set USE_LIBPCRE2 (or its alias USE_LIBPCRE) or USE_LIBPCRE1, not both!)
        endif
  
 +      BASIC_CFLAGS += -DUSE_LIBPCRE2
 +      EXTLIBS += -lpcre2-8
 +endif
 +
 +ifdef USE_LIBPCRE1
        BASIC_CFLAGS += -DUSE_LIBPCRE1
        EXTLIBS += -lpcre
  
@@@ -1190,6 -1187,11 +1198,6 @@@ ifdef NO_LIBPCRE1_JI
  endif
  endif
  
 -ifdef USE_LIBPCRE2
 -      BASIC_CFLAGS += -DUSE_LIBPCRE2
 -      EXTLIBS += -lpcre2-8
 -endif
 -
  ifdef LIBPCREDIR
        BASIC_CFLAGS += -I$(LIBPCREDIR)/include
        EXTLIBS += -L$(LIBPCREDIR)/$(lib) $(CC_LD_DYNPATH)$(LIBPCREDIR)/$(lib)
@@@ -1741,6 -1743,7 +1749,7 @@@ infodir_relative_SQ = $(subst ','\'',$(
  perllibdir_SQ = $(subst ','\'',$(perllibdir))
  localedir_SQ = $(subst ','\'',$(localedir))
  gitexecdir_SQ = $(subst ','\'',$(gitexecdir))
+ gitexecdir_relative_SQ = $(subst ','\'',$(gitexecdir_relative))
  template_dir_SQ = $(subst ','\'',$(template_dir))
  htmldir_relative_SQ = $(subst ','\'',$(htmldir_relative))
  prefix_SQ = $(subst ','\'',$(prefix))
@@@ -2310,22 -2313,14 +2319,22 @@@ po/build/locale/%/LC_MESSAGES/git.mo: p
  
  LIB_PERL := $(wildcard perl/Git.pm perl/Git/*.pm perl/Git/*/*.pm perl/Git/*/*/*.pm)
  LIB_PERL_GEN := $(patsubst perl/%.pm,perl/build/lib/%.pm,$(LIB_PERL))
 +LIB_CPAN := $(wildcard perl/FromCPAN/*.pm perl/FromCPAN/*/*.pm)
 +LIB_CPAN_GEN := $(patsubst perl/%.pm,perl/build/lib/%.pm,$(LIB_CPAN))
  
  ifndef NO_PERL
  all:: $(LIB_PERL_GEN)
 +ifndef NO_PERL_CPAN_FALLBACKS
 +all:: $(LIB_CPAN_GEN)
 +endif
 +NO_PERL_CPAN_FALLBACKS_SQ = $(subst ','\'',$(NO_PERL_CPAN_FALLBACKS))
  endif
  
  perl/build/lib/%.pm: perl/%.pm
        $(QUIET_GEN)mkdir -p $(dir $@) && \
 -      sed -e 's|@@LOCALEDIR@@|$(localedir_SQ)|g' < $< > $@
 +      sed -e 's|@@LOCALEDIR@@|$(localedir_SQ)|g' \
 +          -e 's|@@NO_PERL_CPAN_FALLBACKS@@|$(NO_PERL_CPAN_FALLBACKS_SQ)|g' \
 +      < $< > $@
  
  perl/build/man/man3/Git.3pm: perl/Git.pm
        $(QUIET_GEN)mkdir -p $(dir $@) && \
@@@ -2606,35 -2601,44 +2615,44 @@@ endi
  
        bindir=$$(cd '$(DESTDIR_SQ)$(bindir_SQ)' && pwd) && \
        execdir=$$(cd '$(DESTDIR_SQ)$(gitexec_instdir_SQ)' && pwd) && \
+       destdir_from_execdir_SQ=$$(echo '$(gitexecdir_relative_SQ)' | sed -e 's|[^/][^/]*|..|g') && \
        { test "$$bindir/" = "$$execdir/" || \
          for p in git$X $(filter $(install_bindir_programs),$(ALL_PROGRAMS)); do \
                $(RM) "$$execdir/$$p" && \
-               test -z "$(NO_INSTALL_HARDLINKS)$(NO_CROSS_DIRECTORY_HARDLINKS)" && \
-               ln "$$bindir/$$p" "$$execdir/$$p" 2>/dev/null || \
-               cp "$$bindir/$$p" "$$execdir/$$p" || exit; \
+               test -n "$(INSTALL_SYMLINKS)" && \
+               ln -s "$$destdir_from_execdir_SQ/$(bindir_relative_SQ)/$$p" "$$execdir/$$p" || \
+               { test -z "$(NO_INSTALL_HARDLINKS)$(NO_CROSS_DIRECTORY_HARDLINKS)" && \
+                 ln "$$bindir/$$p" "$$execdir/$$p" 2>/dev/null || \
+                 cp "$$bindir/$$p" "$$execdir/$$p" || exit; } \
          done; \
        } && \
        for p in $(filter $(install_bindir_programs),$(BUILT_INS)); do \
                $(RM) "$$bindir/$$p" && \
-               test -z "$(NO_INSTALL_HARDLINKS)" && \
-               ln "$$bindir/git$X" "$$bindir/$$p" 2>/dev/null || \
-               ln -s "git$X" "$$bindir/$$p" 2>/dev/null || \
-               cp "$$bindir/git$X" "$$bindir/$$p" || exit; \
+               test -n "$(INSTALL_SYMLINKS)" && \
+               ln -s "git$X" "$$bindir/$$p" || \
+               { test -z "$(NO_INSTALL_HARDLINKS)" && \
+                 ln "$$bindir/git$X" "$$bindir/$$p" 2>/dev/null || \
+                 ln -s "git$X" "$$bindir/$$p" 2>/dev/null || \
+                 cp "$$bindir/git$X" "$$bindir/$$p" || exit; } \
        done && \
        for p in $(BUILT_INS); do \
                $(RM) "$$execdir/$$p" && \
-               test -z "$(NO_INSTALL_HARDLINKS)" && \
-               ln "$$execdir/git$X" "$$execdir/$$p" 2>/dev/null || \
-               ln -s "git$X" "$$execdir/$$p" 2>/dev/null || \
-               cp "$$execdir/git$X" "$$execdir/$$p" || exit; \
+               test -n "$(INSTALL_SYMLINKS)" && \
+               ln -s "$$destdir_from_execdir_SQ/$(bindir_relative_SQ)/git$X" "$$execdir/$$p" || \
+               { test -z "$(NO_INSTALL_HARDLINKS)" && \
+                 ln "$$execdir/git$X" "$$execdir/$$p" 2>/dev/null || \
+                 ln -s "git$X" "$$execdir/$$p" 2>/dev/null || \
+                 cp "$$execdir/git$X" "$$execdir/$$p" || exit; } \
        done && \
        remote_curl_aliases="$(REMOTE_CURL_ALIASES)" && \
        for p in $$remote_curl_aliases; do \
                $(RM) "$$execdir/$$p" && \
-               test -z "$(NO_INSTALL_HARDLINKS)" && \
-               ln "$$execdir/git-remote-http$X" "$$execdir/$$p" 2>/dev/null || \
-               ln -s "git-remote-http$X" "$$execdir/$$p" 2>/dev/null || \
-               cp "$$execdir/git-remote-http$X" "$$execdir/$$p" || exit; \
+               test -n "$(INSTALL_SYMLINKS)" && \
+               ln -s "git-remote-http$X" "$$execdir/$$p" || \
+               { test -z "$(NO_INSTALL_HARDLINKS)" && \
+                 ln "$$execdir/git-remote-http$X" "$$execdir/$$p" 2>/dev/null || \
+                 ln -s "git-remote-http$X" "$$execdir/$$p" 2>/dev/null || \
+                 cp "$$execdir/git-remote-http$X" "$$execdir/$$p" || exit; } \
        done && \
        ./check_bindir "z$$bindir" "z$$execdir" "$$bindir/git-add$X"