Merge branch 'bc/rust-by-default' into jch

Rust support is enabled by default (but still allows opting out) in
some future version of Git.

* bc/rust-by-default:
  Enable Rust by default
  Linux: link against libdl
  ci: install cargo on Alpine
  docs: update version with default Rust support

Author: gitster

Makefile

@@ -498,9 +498,9 @@ include shared.mak
 #
 # == 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.
+# Define NO_RUST if you want to disable features and subsystems written in Rust
+# from being compiled 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.
 #
@@ -1351,7 +1351,7 @@ LIB_OBJS += urlmatch.o
 LIB_OBJS += usage.o
 LIB_OBJS += userdiff.o
 LIB_OBJS += utf8.o
-ifndef WITH_RUST
+ifdef NO_RUST
 LIB_OBJS += varint.o
 endif
 LIB_OBJS += version.o
@@ -1590,7 +1590,7 @@ endif
 ALL_CFLAGS = $(DEVELOPER_CFLAGS) $(CPPFLAGS) $(CFLAGS) $(CFLAGS_APPEND)
 ALL_LDFLAGS = $(LDFLAGS) $(LDFLAGS_APPEND)
 
-ifdef WITH_RUST
+ifndef NO_RUST
 BASIC_CFLAGS += -DWITH_RUST
 GITLIBS += $(RUST_LIB)
 ifeq ($(uname_S),Windows)

ci/install-dependencies.sh

@@ -29,7 +29,7 @@ alpine-*)
 	apk add --update shadow sudo meson ninja-build gcc libc-dev curl-dev openssl-dev expat-dev gettext \
 		zlib-ng-dev pcre2-dev python3 musl-libintl perl-utils ncurses \
 		apache2 apache2-http2 apache2-proxy apache2-ssl apache2-webdav apr-util-dbd_sqlite3 \
-		bash cvs gnupg perl-cgi perl-dbd-sqlite perl-io-tty >/dev/null
+		bash cvs gnupg perl-cgi perl-dbd-sqlite perl-io-tty cargo >/dev/null
 	;;
 fedora-*|almalinux-*)
 	case "$jobname" in

ci/lib.sh

@@ -372,6 +372,9 @@ linux-asan-ubsan)
 osx-meson)
 	MESONFLAGS="$MESONFLAGS -Dcredential_helpers=osxkeychain"
 	;;
+windows-*)
+	export NO_RUST=UnfortunatelyYes
+	;;
 esac
 
 MAKEFLAGS="$MAKEFLAGS CC=${CC:-cc}"

ci/run-build-and-tests.sh

@@ -8,11 +8,12 @@
 export TEST_CONTRIB_TOO=yes
 
 case "$jobname" in
+linux-musl-meson)
+	MESONFLAGS="$MESONFLAGS -Drust=disabled"
+	;;
 fedora-breaking-changes-musl|linux-breaking-changes)
 	export WITH_BREAKING_CHANGES=YesPlease
-	export WITH_RUST=YesPlease
 	MESONFLAGS="$MESONFLAGS -Dbreaking_changes=true"
-	MESONFLAGS="$MESONFLAGS -Drust=enabled"
 	;;
 linux-TEST-vars)
 	export OPENSSL_SHA1_UNSAFE=YesPlease
@@ -30,6 +31,7 @@ linux-TEST-vars)
 	export GIT_TEST_PACK_USE_BITMAP_BOUNDARY_TRAVERSAL=1
 	;;
 linux-clang)
+	export NO_RUST=UnfortunatelyYes
 	export GIT_TEST_DEFAULT_HASH=sha1
 	;;
 linux-sha256)

config.mak.uname

@@ -63,6 +63,7 @@ ifeq ($(uname_S),Linux)
 	PROCFS_EXECUTABLE_PATH = /proc/self/exe
 	HAVE_PLATFORM_PROCINFO = YesPlease
 	COMPAT_OBJS += compat/linux/procinfo.o
+	EXTLIBS += -ldl
 	# centos7/rhel7 provides gcc 4.8.5 and zlib 1.2.7.
         ifneq ($(findstring .el7.,$(uname_R)),)
 		BASIC_CFLAGS += -std=c99

meson.build

@@ -1751,8 +1751,7 @@ version_def_h = custom_target(
 )
 libgit_sources += version_def_h
 
-cargo = find_program('cargo', dirs: program_path, native: true, required: get_option('rust'))
-rust_option = get_option('rust').disable_auto_if(not cargo.found())
+rust_option = get_option('rust')
 if rust_option.allowed()
   subdir('src')
   libgit_c_args += '-DWITH_RUST'

meson_options.txt

@@ -77,7 +77,7 @@ option('zlib_backend', type: 'combo', choices: ['auto', 'zlib', 'zlib-ng'], valu
 # Build tweaks.
 option('breaking_changes', type: 'boolean', value: false,
   description: 'Enable upcoming breaking changes.')
-option('rust', type: 'feature', value: 'auto',
+option('rust', type: 'feature', value: 'enabled',
   description: 'Enable building with Rust.')
 option('macos_use_homebrew_gettext', type: 'boolean', value: true,
   description: 'Use gettext from Homebrew instead of the slightly-broken system-provided one.')

src/meson.build

@@ -29,6 +29,7 @@ libgit_rs = custom_target('git_rs',
 )
 libgit_dependencies += declare_dependency(link_with: libgit_rs)
 
+cargo = find_program('cargo', dirs: program_path, native: true, required: get_option('rust'))
 if get_option('tests')
   test('rust', cargo,
     args: [