Optionally include scalar when building/testing Git

The Scalar project started out as a separate project. As designated
successor of VFS for Git, its goal has been from the start to apply the
learnings from the VFS for Git project to allow Git to scale. In
contrast to VFS for Git, Scalar very much wants Git to be aware that the
checkout is sparse and the clone is partial (as opposed to VFS for Git
which tried to pretend that everything is there via a virtual file
system driver).

The intention has always been to integrate as much as possible of Scalar
into Git proper. And this has been the case: the partial clone feature,
the sparse checkout (cone mode), the commit graph, multi-pack index
files, scheduled maintenance tasks, all of these wonderful things can
now be enjoyed by Git users _without_ having to install Scalar.

So what remains of Scalar was ported to C, and put into
`contrib/scalar/`. And to make it easier for folks to build and install
it along with Git, this here patch makes it possible to simply drop
`INCLUDE_SCALAR = YesPlease` into the `config.mak` file to make it so.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

Author: dscho

Makefile

@@ -1942,6 +1942,10 @@ ifndef PAGER_ENV
 PAGER_ENV = LESS=FRX LV=-c
 endif
 
+ifneq (,$(INCLUDE_SCALAR))
+EXTRA_PROGRAMS += contrib/scalar/scalar$X
+endif
+
 QUIET_SUBDIR0  = +$(MAKE) -C # space to separate -C and subdir
 QUIET_SUBDIR1  =
 
@@ -2595,6 +2599,9 @@ contrib/scalar/scalar$X: $(SCALAR_OBJECTS) GIT-LDFLAGS $(GITLIBS)
 	$(QUIET_LINK)$(CC) $(ALL_CFLAGS) -o $@ $(ALL_LDFLAGS) \
 		$(filter %.o,$^) $(LIBS)
 
+bin-wrappers/scalar: contrib/scalar/Makefile
+	$(QUIET_SUBDIR0)contrib/scalar $(QUIET_SUBDIR1) ../../bin-wrappers/scalar
+
 $(LIB_FILE): $(LIB_OBJS)
 	$(QUIET_AR)$(RM) $@ && $(AR) $(ARFLAGS) $@ $^
 
@@ -2614,14 +2621,23 @@ Documentation/GIT-EXCLUDED-PROGRAMS: FORCE
 .PHONY: doc man man-perl html info pdf
 doc: man-perl
 	$(MAKE) -C Documentation all
+ifneq (,$(INCLUDE_SCALAR))
+	$(QUIET_SUBDIR0)contrib/scalar $(QUIET_SUBDIR1) scalar.html scalar.1
+endif
 
 man: man-perl
 	$(MAKE) -C Documentation man
+ifneq (,$(INCLUDE_SCALAR))
+	$(QUIET_SUBDIR0)contrib/scalar $(QUIET_SUBDIR1) scalar.1
+endif
 
 man-perl: perl/build/man/man3/Git.3pm
 
 html:
 	$(MAKE) -C Documentation html
+ifneq (,$(INCLUDE_SCALAR))
+	$(QUIET_SUBDIR0)contrib/scalar $(QUIET_SUBDIR1) scalar.html
+endif
 
 info:
 	$(MAKE) -C Documentation info
@@ -2852,6 +2868,10 @@ endif
 
 test_bindir_programs := $(patsubst %,bin-wrappers/%,$(BINDIR_PROGRAMS_NEED_X) $(BINDIR_PROGRAMS_NO_X) $(TEST_PROGRAMS_NEED_X))
 
+ifneq (,$(INCLUDE_SCALAR))
+test_bindir_programs += bin-wrappers/scalar
+endif
+
 all:: $(TEST_PROGRAMS) $(test_bindir_programs)
 
 bin-wrappers/%: wrap-for-bin.sh
@@ -2872,6 +2892,9 @@ export TEST_NO_MALLOC_CHECK
 
 test: all
 	$(MAKE) -C t/ all
+ifneq (,$(INCLUDE_SCALAR))
+	$(MAKE) -C contrib/scalar/t
+endif
 
 perf: all
 	$(MAKE) -C t/perf/ all
@@ -2997,6 +3020,9 @@ install: all
 	$(INSTALL) $(ALL_PROGRAMS) '$(DESTDIR_SQ)$(gitexec_instdir_SQ)'
 	$(INSTALL) -m 644 $(SCRIPT_LIB) '$(DESTDIR_SQ)$(gitexec_instdir_SQ)'
 	$(INSTALL) $(install_bindir_programs) '$(DESTDIR_SQ)$(bindir_SQ)'
+ifneq (,$(INCLUDE_SCALAR))
+	$(INSTALL) contrib/scalar/scalar$X '$(DESTDIR_SQ)$(bindir_SQ)'
+endif
 ifdef MSVC
 	# We DO NOT install the individual foo.o.pdb files because they
 	# have already been rolled up into the exe's pdb file.
@@ -3090,6 +3116,10 @@ install-doc: install-man-perl
 
 install-man: install-man-perl
 	$(MAKE) -C Documentation install-man
+ifneq (,$(INCLUDE_SCALAR))
+	$(MAKE) -C contrib/scalar scalar.1
+	$(INSTALL) contrib/scalar/scalar.1 '$(DESTDIR_SQ)$(mandir_SQ)/man1'
+endif
 
 install-man-perl: man-perl
 	$(INSTALL) -d -m 755 '$(DESTDIR_SQ)$(mandir_SQ)/man3'
@@ -3098,6 +3128,10 @@ install-man-perl: man-perl
 
 install-html:
 	$(MAKE) -C Documentation install-html
+ifneq (,$(INCLUDE_SCALAR))
+	$(MAKE) -C contrib/scalar scalar.html
+	$(INSTALL) contrib/scalar/scalar.html '$(DESTDIR_SQ)$(htmldir)'
+endif
 
 install-info:
 	$(MAKE) -C Documentation install-info
@@ -3234,6 +3268,9 @@ endif
 ifndef NO_TCLTK
 	$(MAKE) -C gitk-git clean
 	$(MAKE) -C git-gui clean
+endif
+ifneq (,$(INCLUDE_SCALAR))
+	$(MAKE) -C contrib/scalar clean
 endif
 	$(RM) GIT-VERSION-FILE GIT-CFLAGS GIT-LDFLAGS GIT-BUILD-OPTIONS
 	$(RM) GIT-USER-AGENT GIT-PREFIX

contrib/buildsystems/CMakeLists.txt

@@ -700,6 +700,13 @@ if(CURL_FOUND)
 	endif()
 endif()
 
+if(DEFINED ENV{INCLUDE_SCALAR} AND NOT ENV{INCLUDE_SCALAR} STREQUAL "")
+	add_executable(scalar ${CMAKE_SOURCE_DIR}/contrib/scalar/scalar.c)
+	target_link_libraries(scalar common-main)
+	set_target_properties(scalar PROPERTIES RUNTIME_OUTPUT_DIRECTORY_DEBUG ${CMAKE_BINARY_DIR}/contrib/scalar)
+	set_target_properties(scalar PROPERTIES RUNTIME_OUTPUT_DIRECTORY_RELEASE ${CMAKE_BINARY_DIR}/contrib/scalar)
+endif()
+
 parse_makefile_for_executables(git_builtin_extra "BUILT_INS")
 
 option(SKIP_DASHED_BUILT_INS "Skip hardlinking the dashed versions of the built-ins")
@@ -924,6 +931,13 @@ string(REPLACE "@@BUILD_DIR@@" "${CMAKE_BINARY_DIR}" content "${content}")
 string(REPLACE "@@PROG@@" "git-cvsserver" content "${content}")
 file(WRITE ${CMAKE_BINARY_DIR}/bin-wrappers/git-cvsserver ${content})
 
+if(DEFINED ENV{INCLUDE_SCALAR} AND NOT ENV{INCLUDE_SCALAR} STREQUAL "")
+	file(STRINGS ${CMAKE_SOURCE_DIR}/wrap-for-bin.sh content NEWLINE_CONSUME)
+	string(REPLACE "@@BUILD_DIR@@" "${CMAKE_BINARY_DIR}" content "${content}")
+	string(REPLACE "@@PROG@@" "contrib/scalar/scalar${EXE_EXTENSION}" content "${content}")
+	file(WRITE ${CMAKE_BINARY_DIR}/bin-wrappers/scalar ${content})
+endif()
+
 #options for configuring test options
 option(PERL_TESTS "Perform tests that use perl" ON)
 option(PYTHON_TESTS "Perform tests that use python" ON)