move rust gitcore crate to a different subdirectory

Having `Cargo.toml` at the top-level of the repository implies that one
can run `cargo build` directly, but this doesn't produce anything useful
on its own.

Additionally, when including the git source as a submodule of a Rust
project, it prevents the git source from being included at all in the
crate package because cargo skips directories that contain a Cargo.toml,
assuming that everything in the directory is relevant to the crate.

Move all Rust-specific files into a dedicated `rust/` subdirectory.

Signed-off-by: Mike Hommey <mh@glandium.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

.gitignore

@@ -1,6 +1,4 @@
 /fuzz_corpora
-/target/
-/Cargo.lock
 /GIT-BUILD-DIR
 /GIT-BUILD-OPTIONS
 /GIT-CFLAGS
@@ -261,3 +259,5 @@ Release/
 /contrib/buildsystems/out
 /contrib/libgit-rs/target
 /contrib/libgit-sys/target
+/rust/target
+/rust/Cargo.lock

Makefile

@@ -959,7 +959,7 @@ RUST_LIB_NAME = gitcore.lib
 else
 RUST_LIB_NAME = libgitcore.a
 endif
-RUST_LIB = target$(if $(CARGO_BUILD_TARGET),/$(CARGO_BUILD_TARGET))/$(RUST_BUILD_CONFIG)/$(RUST_LIB_NAME)
+RUST_LIB = rust/target$(if $(CARGO_BUILD_TARGET),/$(CARGO_BUILD_TARGET))/$(RUST_BUILD_CONFIG)/$(RUST_LIB_NAME)
 endif
 
 GITLIBS = common-main.o $(LIB_FILE)
@@ -1571,11 +1571,11 @@ CLAR_TEST_OBJS += $(UNIT_TEST_DIR)/unit-test.o
 
 UNIT_TEST_OBJS += $(UNIT_TEST_DIR)/test-lib.o
 
-RUST_SOURCES += src/csum_file.rs
-RUST_SOURCES += src/hash.rs
-RUST_SOURCES += src/lib.rs
-RUST_SOURCES += src/loose.rs
-RUST_SOURCES += src/varint.rs
+RUST_SOURCES += rust/src/csum_file.rs
+RUST_SOURCES += rust/src/hash.rs
+RUST_SOURCES += rust/src/lib.rs
+RUST_SOURCES += rust/src/loose.rs
+RUST_SOURCES += rust/src/varint.rs
 
 GIT-VERSION-FILE: FORCE
 	@OLD=$$(cat $@ 2>/dev/null || :) && \
@@ -3038,8 +3038,8 @@ $(LIB_FILE): $(LIB_OBJS)
 
 ifndef NO_RUST
 ifeq ($(RUST_TARGETS),)
-$(RUST_LIB): Cargo.toml $(RUST_SOURCES) $(LIB_FILE)
-	$(QUIET_CARGO)cargo build $(CARGO_ARGS)
+$(RUST_LIB): rust/Cargo.toml $(RUST_SOURCES) $(LIB_FILE)
+	$(QUIET_CARGO)cargo build --manifest-path rust/Cargo.toml $(CARGO_ARGS)
 else
 ifneq ($(words $(RUST_TARGETS)),1)
 ifneq ($(uname_S),Darwin)
@@ -3047,9 +3047,9 @@ $(error Building universal Rust libraries requires macOS (lipo is not available
 endif
 endif
 
-RUST_MEMBER_LIBS = $(foreach target,$(RUST_TARGETS),target/$(target)/$(RUST_BUILD_CONFIG)/$(RUST_LIB_NAME))
-$(RUST_MEMBER_LIBS): target/%/$(RUST_BUILD_CONFIG)/$(RUST_LIB_NAME): Cargo.toml $(RUST_SOURCES) $(LIB_FILE)
-	$(QUIET_CARGO)cargo build $(CARGO_ARGS) --target $*
+RUST_MEMBER_LIBS = $(foreach target,$(RUST_TARGETS),rust/target/$(target)/$(RUST_BUILD_CONFIG)/$(RUST_LIB_NAME))
+$(RUST_MEMBER_LIBS): rust/target/%/$(RUST_BUILD_CONFIG)/$(RUST_LIB_NAME): rust/Cargo.toml $(RUST_SOURCES) $(LIB_FILE)
+	$(QUIET_CARGO)cargo build --manifest-path rust/Cargo.toml $(CARGO_ARGS) --target $*
 
 $(RUST_LIB): $(RUST_MEMBER_LIBS)
 	$(call mkdir_p_parent_template)
@@ -3913,7 +3913,7 @@ clean: profile-clean coverage-clean cocciclean
 	$(RM) $(FUZZ_PROGRAMS)
 	$(RM) $(SP_OBJ)
 	$(RM) $(HCC)
-	$(RM) -r Cargo.lock target/
+	$(RM) -r rust/Cargo.lock rust/target/
 	$(RM) version-def.h
 	$(RM) -r $(dep_dirs) $(compdb_dir) compile_commands.json
 	$(RM) $(test_bindir_programs)

ci/run-rust-checks.sh

@@ -4,17 +4,17 @@
 
 set +x
 
-if ! group "Check Rust formatting" cargo fmt --all --check
+if ! group "Check Rust formatting" cargo fmt --manifest-path rust/Cargo.toml --all --check
 then
 	RET=1
 fi
 
-if ! group "Check for common Rust mistakes" cargo clippy --all-targets --all-features -- -Dwarnings
+if ! group "Check for common Rust mistakes" cargo clippy --manifest-path rust/Cargo.toml --all-targets --all-features -- -Dwarnings
 then
 	RET=1
 fi
 
-if ! group "Check for minimum required Rust version" cargo msrv verify
+if ! group "Check for minimum required Rust version" cargo msrv --path rust verify
 then
 	RET=1
 fi

meson.build

@@ -1795,7 +1795,7 @@ libgit_sources += version_def_h
 
 rust_option = get_option('rust')
 if rust_option.allowed()
-  subdir('src')
+  subdir('rust')
   libgit_c_args += '-DWITH_RUST'
 
   if host_machine.system() == 'windows'

rust/meson.build

@@ -1,9 +1,9 @@
 libgit_rs_sources = [
-  'csum_file.rs',
-  'hash.rs',
-  'lib.rs',
-  'loose.rs',
-  'varint.rs',
+  'src/csum_file.rs',
+  'src/hash.rs',
+  'src/lib.rs',
+  'src/loose.rs',
+  'src/varint.rs',
 ]
 
 # Unfortunately we must use a wrapper command to move the output file into the
@@ -13,7 +13,7 @@ libgit_rs_sources = [
 cargo_command = [
   shell,
   meson.current_source_dir() / 'cargo-meson.sh',
-  meson.project_source_root(),
+  meson.current_source_dir(),
   meson.current_build_dir(),
 ]
 if get_option('buildtype') == 'release'
@@ -22,7 +22,7 @@ endif
 
 libgit_rs = custom_target('git_rs',
   input: libgit_rs_sources + [
-    meson.project_source_root() / 'Cargo.toml',
+    meson.current_source_dir() / 'Cargo.toml',
   ],
   output: 'libgitcore.a',
   command: cargo_command,
@@ -35,7 +35,7 @@ if get_option('tests')
     args: [
       'test',
       '--manifest-path',
-      meson.project_source_root() / 'Cargo.toml',
+      meson.current_source_dir() / 'Cargo.toml',
       '--target-dir',
       meson.current_build_dir() / 'target',
     ],