Merge branch 'bc/rust-by-default-in-2.54' into seen

Rust support is enabled by default (but still allows opting out) in
Git 2.54.

* bc/rust-by-default-in-2.54:
  Enable Rust by default
  Linux: link against libdl
  ci: install cargo on Alpine
  docs: update version with default Rust support

Author: gitster

Documentation/BreakingChanges.adoc

@@ -190,7 +190,7 @@ milestones for the introduction of Rust:
 1. Initially, with Git 2.52, support for Rust will be auto-detected by Meson and
    disabled in our Makefile so that the project can sort out the initial
    infrastructure.
-2. In Git 2.53, both build systems will default-enable support for Rust.
+2. In Git 2.54, both build systems will default-enable support for Rust.
    Consequently, builds will break by default if Rust is not available on the
    build host. The use of Rust can still be explicitly disabled via build
    flags.

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.
 #
@@ -1353,7 +1353,7 @@ 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
@@ -1592,7 +1592,7 @@ 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

@@ -10,7 +10,6 @@ export TEST_CONTRIB_TOO=yes
 case "$jobname" in
 fedora-breaking-changes-musl|linux-breaking-changes)
 	export WITH_BREAKING_CHANGES=YesPlease
-	export WITH_RUST=YesPlease
 	MESONFLAGS="$MESONFLAGS -Dbreaking_changes=true"
 	MESONFLAGS="$MESONFLAGS -Drust=enabled"
 	;;
@@ -30,6 +29,7 @@ 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

@@ -1755,7 +1755,7 @@ 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.')