Merge branch 'ps/rust-balloon' into ps/ci-rust

* ps/rust-balloon:
  ci: enable Rust for breaking-changes jobs
  ci: convert "pedantic" job into full build with breaking changes
  BreakingChanges: announce Rust becoming mandatory
  varint: reimplement as test balloon for Rust
  varint: use explicit width for integers
  help: report on whether or not Rust is enabled
  Makefile: introduce infrastructure to build internal Rust library
  Makefile: reorder sources after includes
  meson: add infrastructure to build internal Rust library

1 files changed, 127 insertions, 87 deletions

diff --git a/Makefile b/Makefile
index 92fd8d86d8..7ea149598d 100644
--- a/Makefile
+++ b/Makefile
@@ -483,6 +483,14 @@ include shared.mak
 # Define LIBPCREDIR=/foo/bar if your PCRE header and library files are
 # in /foo/bar/include and /foo/bar/lib directories.
 #
+# == Optional Rust support ==
+#
+# Define WITH_RUST if you want to include features and subsystems written in
+# Rust into Git. For now, Rust is still an optional feature of the build
+# process. With Git 3.0 though, Rust will always be enabled.
+#
+# Building Rust code requires Cargo.
+#
 # == SHA-1 and SHA-256 defines ==
 #
 # === SHA-1 backend ===
@@ -683,6 +691,7 @@ OBJECTS =
 OTHER_PROGRAMS =
 PROGRAM_OBJS =
 PROGRAMS =
+RUST_SOURCES =
 EXCLUDED_PROGRAMS =
 SCRIPT_PERL =
 SCRIPT_PYTHON =
@@ -920,6 +929,108 @@ TEST_SHELL_PATH = $(SHELL_PATH)
 LIB_FILE = libgit.a
 XDIFF_LIB = xdiff/lib.a
 REFTABLE_LIB = reftable/libreftable.a
+ifdef DEBUG
+RUST_LIB = target/debug/libgitcore.a
+else
+RUST_LIB = target/release/libgitcore.a
+endif
+
+# xdiff and reftable libs may in turn depend on what is in libgit.a
+GITLIBS = common-main.o $(LIB_FILE) $(XDIFF_LIB) $(REFTABLE_LIB) $(LIB_FILE)
+EXTLIBS =
+
+GIT_USER_AGENT = git/$(GIT_VERSION)
+
+ifeq ($(wildcard sha1collisiondetection/lib/sha1.h),sha1collisiondetection/lib/sha1.h)
+DC_SHA1_SUBMODULE = auto
+endif
+
+# Set CFLAGS, LDFLAGS and other *FLAGS variables. These might be
+# tweaked by config.* below as well as the command-line, both of
+# which'll override these defaults.
+# Older versions of GCC may require adding "-std=gnu99" at the end.
+CFLAGS = -g -O2 -Wall
+LDFLAGS =
+CC_LD_DYNPATH = -Wl,-rpath,
+BASIC_CFLAGS = -I.
+BASIC_LDFLAGS =
+
+# library flags
+ARFLAGS = rcs
+PTHREAD_CFLAGS =
+
+# Rust flags
+CARGO_ARGS =
+ifndef V
+CARGO_ARGS += --quiet
+endif
+ifndef DEBUG
+CARGO_ARGS += --release
+endif
+
+# For the 'sparse' target
+SPARSE_FLAGS ?= -std=gnu99 -D__STDC_NO_VLA__
+SP_EXTRA_FLAGS =
+
+# For informing GIT-BUILD-OPTIONS of the SANITIZE=leak,address targets
+SANITIZE_LEAK =
+SANITIZE_ADDRESS =
+
+# For the 'coccicheck' target
+SPATCH_INCLUDE_FLAGS = --all-includes
+SPATCH_FLAGS =
+SPATCH_TEST_FLAGS =
+
+# If *.o files are present, have "coccicheck" depend on them, with
+# COMPUTE_HEADER_DEPENDENCIES this will speed up the common-case of
+# only needing to re-generate coccicheck results for the users of a
+# given API if it's changed, and not all files in the project. If
+# COMPUTE_HEADER_DEPENDENCIES=no this will be unset too.
+SPATCH_USE_O_DEPENDENCIES = YesPlease
+
+# Set SPATCH_CONCAT_COCCI to concatenate the contrib/cocci/*.cocci
+# files into a single contrib/cocci/ALL.cocci before running
+# "coccicheck".
+#
+# Pros:
+#
+# - Speeds up a one-shot run of "make coccicheck", as we won't have to
+#   parse *.[ch] files N times for the N *.cocci rules
+#
+# Cons:
+#
+# - Will make incremental development of *.cocci slower, as
+#   e.g. changing strbuf.cocci will re-run all *.cocci.
+#
+# - Makes error and performance analysis harder, as rules will be
+#   applied from a monolithic ALL.cocci, rather than
+#   e.g. strbuf.cocci. To work around this either undefine this, or
+#   generate a specific patch, e.g. this will always use strbuf.cocci,
+#   not ALL.cocci:
+#
+#	make contrib/coccinelle/strbuf.cocci.patch
+SPATCH_CONCAT_COCCI = YesPlease
+
+# Rebuild 'coccicheck' if $(SPATCH), its flags etc. change
+TRACK_SPATCH_DEFINES =
+TRACK_SPATCH_DEFINES += $(SPATCH)
+TRACK_SPATCH_DEFINES += $(SPATCH_INCLUDE_FLAGS)
+TRACK_SPATCH_DEFINES += $(SPATCH_FLAGS)
+TRACK_SPATCH_DEFINES += $(SPATCH_TEST_FLAGS)
+GIT-SPATCH-DEFINES: FORCE
+	@FLAGS='$(TRACK_SPATCH_DEFINES)'; \
+	    if test x"$$FLAGS" != x"`cat GIT-SPATCH-DEFINES 2>/dev/null`" ; then \
+		echo >&2 "    * new spatch flags"; \
+		echo "$$FLAGS" >GIT-SPATCH-DEFINES; \
+            fi
+
+include config.mak.uname
+-include config.mak.autogen
+-include config.mak
+
+ifdef DEVELOPER
+include config.mak.dev
+endif
 
 GENERATED_H += command-list.h
 GENERATED_H += config-list.h
@@ -1198,7 +1309,9 @@ LIB_OBJS += urlmatch.o
 LIB_OBJS += usage.o
 LIB_OBJS += userdiff.o
 LIB_OBJS += utf8.o
+ifndef WITH_RUST
 LIB_OBJS += varint.o
+endif
 LIB_OBJS += version.o
 LIB_OBJS += versioncmp.o
 LIB_OBJS += walker.o
@@ -1390,93 +1503,8 @@ CLAR_TEST_OBJS += $(UNIT_TEST_DIR)/unit-test.o
 
 UNIT_TEST_OBJS += $(UNIT_TEST_DIR)/test-lib.o
 
-# xdiff and reftable libs may in turn depend on what is in libgit.a
-GITLIBS = common-main.o $(LIB_FILE) $(XDIFF_LIB) $(REFTABLE_LIB) $(LIB_FILE)
-EXTLIBS =
-
-GIT_USER_AGENT = git/$(GIT_VERSION)
-
-ifeq ($(wildcard sha1collisiondetection/lib/sha1.h),sha1collisiondetection/lib/sha1.h)
-DC_SHA1_SUBMODULE = auto
-endif
-
-# Set CFLAGS, LDFLAGS and other *FLAGS variables. These might be
-# tweaked by config.* below as well as the command-line, both of
-# which'll override these defaults.
-# Older versions of GCC may require adding "-std=gnu99" at the end.
-CFLAGS = -g -O2 -Wall
-LDFLAGS =
-CC_LD_DYNPATH = -Wl,-rpath,
-BASIC_CFLAGS = -I.
-BASIC_LDFLAGS =
-
-# library flags
-ARFLAGS = rcs
-PTHREAD_CFLAGS =
-
-# For the 'sparse' target
-SPARSE_FLAGS ?= -std=gnu99 -D__STDC_NO_VLA__
-SP_EXTRA_FLAGS =
-
-# For informing GIT-BUILD-OPTIONS of the SANITIZE=leak,address targets
-SANITIZE_LEAK =
-SANITIZE_ADDRESS =
-
-# For the 'coccicheck' target
-SPATCH_INCLUDE_FLAGS = --all-includes
-SPATCH_FLAGS =
-SPATCH_TEST_FLAGS =
-
-# If *.o files are present, have "coccicheck" depend on them, with
-# COMPUTE_HEADER_DEPENDENCIES this will speed up the common-case of
-# only needing to re-generate coccicheck results for the users of a
-# given API if it's changed, and not all files in the project. If
-# COMPUTE_HEADER_DEPENDENCIES=no this will be unset too.
-SPATCH_USE_O_DEPENDENCIES = YesPlease
-
-# Set SPATCH_CONCAT_COCCI to concatenate the contrib/cocci/*.cocci
-# files into a single contrib/cocci/ALL.cocci before running
-# "coccicheck".
-#
-# Pros:
-#
-# - Speeds up a one-shot run of "make coccicheck", as we won't have to
-#   parse *.[ch] files N times for the N *.cocci rules
-#
-# Cons:
-#
-# - Will make incremental development of *.cocci slower, as
-#   e.g. changing strbuf.cocci will re-run all *.cocci.
-#
-# - Makes error and performance analysis harder, as rules will be
-#   applied from a monolithic ALL.cocci, rather than
-#   e.g. strbuf.cocci. To work around this either undefine this, or
-#   generate a specific patch, e.g. this will always use strbuf.cocci,
-#   not ALL.cocci:
-#
-#	make contrib/coccinelle/strbuf.cocci.patch
-SPATCH_CONCAT_COCCI = YesPlease
-
-# Rebuild 'coccicheck' if $(SPATCH), its flags etc. change
-TRACK_SPATCH_DEFINES =
-TRACK_SPATCH_DEFINES += $(SPATCH)
-TRACK_SPATCH_DEFINES += $(SPATCH_INCLUDE_FLAGS)
-TRACK_SPATCH_DEFINES += $(SPATCH_FLAGS)
-TRACK_SPATCH_DEFINES += $(SPATCH_TEST_FLAGS)
-GIT-SPATCH-DEFINES: FORCE
-	@FLAGS='$(TRACK_SPATCH_DEFINES)'; \
-	    if test x"$$FLAGS" != x"`cat GIT-SPATCH-DEFINES 2>/dev/null`" ; then \
-		echo >&2 "    * new spatch flags"; \
-		echo "$$FLAGS" >GIT-SPATCH-DEFINES; \
-            fi
-
-include config.mak.uname
--include config.mak.autogen
--include config.mak
-
-ifdef DEVELOPER
-include config.mak.dev
-endif
+RUST_SOURCES += src/lib.rs
+RUST_SOURCES += src/varint.rs
 
 GIT-VERSION-FILE: FORCE
 	@OLD=$$(cat $@ 2>/dev/null || :) && \
@@ -1507,6 +1535,11 @@ endif
 ALL_CFLAGS = $(DEVELOPER_CFLAGS) $(CPPFLAGS) $(CFLAGS) $(CFLAGS_APPEND)
 ALL_LDFLAGS = $(LDFLAGS) $(LDFLAGS_APPEND)
 
+ifdef WITH_RUST
+BASIC_CFLAGS += -DWITH_RUST
+GITLIBS += $(RUST_LIB)
+endif
+
 ifdef SANITIZE
 SANITIZERS := $(foreach flag,$(subst $(comma),$(space),$(SANITIZE)),$(flag))
 BASIC_CFLAGS += -fsanitize=$(SANITIZE) -fno-sanitize-recover=$(SANITIZE)
@@ -2921,6 +2954,12 @@ scalar$X: scalar.o GIT-LDFLAGS $(GITLIBS)
 $(LIB_FILE): $(LIB_OBJS)
 	$(QUIET_AR)$(RM) $@ && $(AR) $(ARFLAGS) $@ $^
 
+$(RUST_LIB): Cargo.toml $(RUST_SOURCES)
+	$(QUIET_CARGO)cargo build $(CARGO_ARGS)
+
+.PHONY: rust
+rust: $(RUST_LIB)
+
 $(XDIFF_LIB): $(XDIFF_OBJS)
 	$(QUIET_AR)$(RM) $@ && $(AR) $(ARFLAGS) $@ $^
 
@@ -3771,6 +3810,7 @@ clean: profile-clean coverage-clean cocciclean
 	$(RM) $(FUZZ_PROGRAMS)
 	$(RM) $(SP_OBJ)
 	$(RM) $(HCC)
+	$(RM) -r Cargo.lock target/
 	$(RM) version-def.h
 	$(RM) -r $(dep_dirs) $(compdb_dir) compile_commands.json
 	$(RM) $(test_bindir_programs)