build(release): build tools for more python-build-standalone platforms

.github/workflows/release_build_tools.yaml

@@ -1,7 +1,8 @@
-# Builds `//dev/release_artifacts:artifacts_for_release` for each platform; see
-# dev/release_artifacts/build.sh. Linux x86_64 runners cross-compile the files
-# for other Linux CPUs. macOS and Windows files need those OSes' SDKs, so
-# they're built natively.
+# Builds `//dev/release_artifacts:artifacts_for_release` for the platforms in
+# dev/platforms, which cover python-build-standalone's platforms except s390x;
+# see dev/release_artifacts/build.sh. Linux x86_64 runners cross-compile the
+# files for other Linux CPUs. macOS and Windows files need those OSes' SDKs, so
+# they're built on those OSes.
 #
 # For now, this only verifies that the artifacts build; they aren't attached to
 # releases yet.
@@ -42,15 +43,25 @@ jobs:
             runner: macos-15
           - triple: aarch64-pc-windows-msvc
             runner: windows-11-arm
-          # Cross-compiled; see dev/platforms/BUILD.bazel.
-          - triple: aarch64-unknown-linux-musl
-            runner: ubuntu-24.04
           - triple: x86_64-apple-darwin
             runner: macos-15-intel
           - triple: x86_64-pc-windows-msvc
             runner: windows-2022
           - triple: x86_64-unknown-linux-gnu
             runner: ubuntu-24.04
+          # Cross-compiled; see dev/platforms/BUILD.bazel.
+          - triple: aarch64-unknown-linux-musl
+            runner: ubuntu-24.04
+          - triple: armv7-unknown-linux-musleabihf
+            runner: ubuntu-24.04
+          - triple: i686-pc-windows-msvc
+            runner: windows-2022
+          - triple: i686-unknown-linux-musl
+            runner: ubuntu-24.04
+          - triple: powerpc64le-unknown-linux-musl
+            runner: ubuntu-24.04
+          - triple: riscv64gc-unknown-linux-musl
+            runner: ubuntu-24.04
     env:
       REF: ${{ inputs.ref || github.ref_name }}
       TRIPLE: ${{ matrix.triple }}
@@ -69,8 +80,9 @@ jobs:
           bazelisk-version: 1.29.0
 
       # Release commands run main's workflows, even for patch releases of older
-      # release branches. Skip refs without the platforms that build.sh takes,
-      # since their scripts don't build for the job's platform, or don't exist.
+      # release branches. Skip refs without dev/platforms, since their scripts
+      # don't build for the job's platform, or don't exist. Refs whose
+      # dev/platforms lacks the job's platform fail the build, which only warns.
       - name: Build artifacts
         id: build
         if: hashFiles('dev/platforms/BUILD.bazel') != ''

MODULE.bazel

@@ -109,11 +109,37 @@ rust_crates.spec(
     package = "sha2",
     version = "0.10.8",
 )
-rust_crates.from_specs()
+
+# The crates must build for every platform in dev/platforms. Conditional
+# dependencies are resolved for these triples; rules_rust matches them by CPU
+# and OS, e.g. i686-unknown-linux-gnu also matches the i686-unknown-linux-musl
+# platform.
+rust_crates.from_specs(
+    supported_platform_triples = [
+        "aarch64-apple-darwin",
+        "aarch64-pc-windows-msvc",
+        "aarch64-unknown-linux-gnu",
+        "armv7-unknown-linux-gnueabi",
+        "i686-pc-windows-msvc",
+        "i686-unknown-linux-gnu",
+        "riscv64gc-unknown-linux-gnu",
+        "x86_64-apple-darwin",
+        "x86_64-pc-windows-msvc",
+        "x86_64-unknown-linux-gnu",
+    ],
+)
+
+# rules_rust has no @rules_rust//rust/platform config_setting for Linux ppc64le,
+# so don't mark the crates as incompatible with platforms that don't match one
+# of the triples above. Such platforms get only the unconditional dependencies,
+# which suffice for sha2.
+rust_crates.render_config(
+    generate_target_compatible_with = False,
+)
 use_repo(rust_crates, "crates")
 
-# A Rust toolchain to cross-compile the release artifacts for Linux aarch64
-# from Linux x86_64; see dev/release_artifacts. It targets musl, which Rust can
+# Rust toolchains to cross-compile the release artifacts for other Linux CPUs
+# from Linux x86_64; see dev/release_artifacts. They target musl, which Rust can
 # link statically with its bundled rust-lld, so no C cross toolchain is needed.
 rust = use_extension(
     "@rules_rust//rust:extensions.bzl",
@@ -124,7 +150,7 @@ rust.repository_set(
     # rules_rust also registers an x86_64 to x86_64 toolchain from this set, in
     # name order with its default ones, so the name must sort after
     # rust_linux_x86_64 for the default x86_64 toolchain to take precedence.
-    name = "rust_release_linux_x86_64",
+    name = "rust_release_linux",
     # The default allocator library needs a C toolchain for the target platform,
     # but there isn't one. This one is what rules_rust uses for e.g. Windows.
     allocator_library = "@rules_rust//rust/private/cc:empty",
@@ -141,15 +167,85 @@ rust.repository_set(
     # built by the same version.
     versions = ["1.97.1"],
 )
-use_repo(rust, "rust_release_linux_x86_64__aarch64-unknown-linux-musl__stable")
 
-# Registered here so that it takes precedence over rules_rust's default
-# toolchains, whose Linux x86_64 to aarch64 one also matches the musl platform.
+# Other targets for the same set; the first tag sets the shared attributes.
+rust.repository_set(
+    name = "rust_release_linux",
+    target_compatible_with = [
+        "@platforms//cpu:armv7",
+        "@platforms//os:linux",
+        "//dev/platforms:musl",
+    ],
+    target_triple = "armv7-unknown-linux-musleabihf",
+)
+rust.repository_set(
+    name = "rust_release_linux",
+    target_compatible_with = [
+        "@platforms//cpu:x86_32",
+        "@platforms//os:linux",
+        "//dev/platforms:musl",
+    ],
+    target_triple = "i686-unknown-linux-musl",
+)
+rust.repository_set(
+    name = "rust_release_linux",
+    target_compatible_with = [
+        "@platforms//cpu:ppc64le",
+        "@platforms//os:linux",
+        "//dev/platforms:musl",
+    ],
+    target_triple = "powerpc64le-unknown-linux-musl",
+)
+rust.repository_set(
+    name = "rust_release_linux",
+    target_compatible_with = [
+        "@platforms//cpu:riscv64",
+        "@platforms//os:linux",
+        "//dev/platforms:musl",
+    ],
+    target_triple = "riscv64gc-unknown-linux-musl",
+)
+use_repo(
+    rust,
+    "rust_release_linux__aarch64-unknown-linux-musl__stable",
+    "rust_release_linux__armv7-unknown-linux-musleabihf__stable",
+    "rust_release_linux__i686-unknown-linux-musl__stable",
+    "rust_release_linux__powerpc64le-unknown-linux-musl__stable",
+    "rust_release_linux__riscv64gc-unknown-linux-musl__stable",
+)
+
+# Registered here so that they take precedence over rules_rust's default
+# toolchains, e.g. its Linux x86_64 to aarch64 one also matches the aarch64
+# musl platform.
 register_toolchains(
-    "@rust_release_linux_x86_64__aarch64-unknown-linux-musl__stable//:toolchain",
+    "@rust_release_linux__aarch64-unknown-linux-musl__stable//:toolchain",
+    "@rust_release_linux__armv7-unknown-linux-musleabihf__stable//:toolchain",
+    "@rust_release_linux__i686-unknown-linux-musl__stable//:toolchain",
+    "@rust_release_linux__powerpc64le-unknown-linux-musl__stable//:toolchain",
+    "@rust_release_linux__riscv64gc-unknown-linux-musl__stable//:toolchain",
     dev_dependency = True,
 )
 
+# A Rust toolchain to cross-compile the release artifacts for 32-bit Windows
+# from Windows x86_64, with MSVC's x86 tools. Unlike the Linux ones, it isn't
+# registered here: no default toolchain targets 32-bit Windows, and rules_rust
+# registers it.
+rust.repository_set(
+    # As above, its x86_64 toolchain's name must sort after the default one's.
+    # On Windows, rules_rust names toolchains after a hash of the full name:
+    # rw-1886791612 for this one, after rust_windows_x86_64's rw-1704990954.
+    name = "rust_release_windows",
+    edition = "2021",
+    exec_triple = "x86_64-pc-windows-msvc",
+    target_compatible_with = [
+        "@platforms//cpu:x86_32",
+        "@platforms//os:windows",
+    ],
+    target_triple = "i686-pc-windows-msvc",
+    # See above.
+    versions = ["1.97.1"],
+)
+
 # Use the Rust-based build tools when developing rules_python itself.
 register_toolchains(
     "//dev/dev_only_toolchains:exe_zip_maker_toolchain",

dev/platforms/BUILD.bazel

@@ -1,7 +1,13 @@
 # Platforms that rules_python's release artifacts are built for, named after
-# their Rust target triples; see dev/release_artifacts/build.sh. Linux x86_64
-# hosts cross-compile for the musl one with the musl Rust toolchain in
-# MODULE.bazel. The others are built on hosts that match them.
+# their Rust target triples; see dev/release_artifacts/build.sh. They cover the
+# platforms that python-build-standalone supports: the Linux files are static,
+# so they also run on Linux platforms with other libcs, and arm64e Macs run the
+# aarch64 macOS file. s390x isn't covered yet: Rust ships no musl std for it,
+# and a static glibc build needs a C cross toolchain.
+#
+# Linux x86_64 hosts cross-compile for the musl ones, and Windows x86_64 hosts
+# for i686-pc-windows-msvc, with the Rust toolchains in MODULE.bazel. The
+# others are built on hosts that match them.
 
 package(default_visibility = ["//:__subpackages__"])
 
@@ -30,6 +36,50 @@ platform(
     ],
 )
 
+platform(
+    name = "armv7-unknown-linux-musleabihf",
+    constraint_values = [
+        "@platforms//cpu:armv7",
+        "@platforms//os:linux",
+        ":musl",
+    ],
+)
+
+platform(
+    name = "i686-pc-windows-msvc",
+    constraint_values = [
+        "@platforms//cpu:x86_32",
+        "@platforms//os:windows",
+    ],
+)
+
+platform(
+    name = "i686-unknown-linux-musl",
+    constraint_values = [
+        "@platforms//cpu:x86_32",
+        "@platforms//os:linux",
+        ":musl",
+    ],
+)
+
+platform(
+    name = "powerpc64le-unknown-linux-musl",
+    constraint_values = [
+        "@platforms//cpu:ppc64le",
+        "@platforms//os:linux",
+        ":musl",
+    ],
+)
+
+platform(
+    name = "riscv64gc-unknown-linux-musl",
+    constraint_values = [
+        "@platforms//cpu:riscv64",
+        "@platforms//os:linux",
+        ":musl",
+    ],
+)
+
 platform(
     name = "x86_64-apple-darwin",
     constraint_values = [
@@ -55,13 +105,13 @@ platform(
 )
 
 # The libc of Linux platforms. Only musl is a constraint value: platforms
-# without it, like the host, use glibc. It also keeps the musl Rust toolchain
+# without it, like the host, use glibc. It also keeps the musl Rust toolchains
 # in MODULE.bazel from being used for glibc platforms.
 constraint_setting(name = "libc")
 
 constraint_value(
     name = "musl",
     constraint_setting = ":libc",
-    # The musl Rust toolchain's repo, generated by rules_rust, refers to it.
+    # The musl Rust toolchains' repos, generated by rules_rust, refer to it.
     visibility = ["//visibility:public"],
 )

dev/release_artifacts/release_files.bzl

@@ -8,15 +8,15 @@ _RUSTC_FLAGS = "@rules_rust//rust/settings:extra_rustc_flags"
 def _release_transition_impl(settings, attr):
     features = []
     rustc_flags = []
-    if attr.target_os == "linux" and attr.target_libc != "musl":
+    if attr.target_os == "linux":
         # Rust links glibc dynamically, so the files would require at least
         # the build machine's glibc version. Link it statically so they run on
-        # older distros too. The gold linker can't link static glibc, so use
-        # bfd. Rust already links musl statically.
-        rustc_flags = [
-            "-Ctarget-feature=+crt-static",
-            "-Clink-arg=-fuse-ld=bfd",
-        ]
+        # older distros too. Rust links musl statically for most CPUs, but not
+        # all, e.g. riscv64.
+        rustc_flags = ["-Ctarget-feature=+crt-static"]
+        if attr.target_libc != "musl":
+            # The gold linker can't link static glibc, so use bfd.
+            rustc_flags.append("-Clink-arg=-fuse-ld=bfd")
     elif attr.target_os == "windows":
         # Statically link the C runtime so that the VC++ redistributable isn't
         # required.

dev/release_artifacts/verify.sh

@@ -21,17 +21,24 @@ while IFS= read -r bin; do
         echo "::error::$bin isn't statically linked: $info"
         exit 1
       fi
-      # Some Linux files are cross-compiled, so check that they're for the
-      # right CPU.
+      # Most Linux files are cross-compiled, so check that they're for the
+      # right CPU, as `file` describes it. `cpu` is a glob because file 5.46
+      # renamed "Intel 80386" to "Intel i386".
       case "$triple" in
         aarch64-*) cpu="ARM aarch64" ;;
+        armv7-*) cpu="ARM" ;;
+        i686-*) cpu="Intel *386" ;;
+        powerpc64le-*) cpu="64-bit PowerPC or cisco 7500" ;;
+        riscv64gc-*) cpu="UCB RISC-V" ;;
         x86_64-*) cpu="x86-64" ;;
         *)
           echo "::error::$bin: no CPU check for $triple"
           exit 1
           ;;
       esac
-      if [[ "$info" != *", $cpu,"* ]]; then
+      pattern="*, $cpu,*"
+      # shellcheck disable=SC2053 # The pattern is a glob.
+      if [[ "$info" != $pattern ]]; then
         echo "::error::$bin isn't for $cpu: $info"
         exit 1
       fi