map system from "darwin" to "macos" when parsing triple #3296

christianscott · 2025-02-25T07:19:51Z

Map darwin to macos when parsing target triples to align with Rust’s internal naming convention

Rust’s target triple format and internal OS naming conventions use different terms for macOS:
• The target triple follows LLVM conventions and uses -darwin, e.g., aarch64-apple-darwin.
• Rust itself uses macos for OS-based conditionals, e.g., #[cfg(target_os = "macos")].

This mismatch originates from upstream toolchains— LLVM and GCC have historically used darwin in triples to denote macOS. Meanwhile, Rust internally adopted macos before 1.0, as discussed in this early thread: Rust Internals Discussion.

Fixes: bazelbuild/rules_rust#3291

UebelAndre

Thanks! Curious though, why not make the change to update the triple function to map darwin to macos?

rules_rust/rust/platform/triple.bzl

Lines 48 to 63 in 14f3829

    
           cpu_arch = component_parts[0] 
        
           vendor = component_parts[1] 
        
           system = component_parts[2] 
        
           abi = None 
        
           if cpu_arch.startswith(("thumbv8m", "thumbv7m", "thumbv7e", "thumbv6m")): 
        
               abi = system 
        
               system = vendor 
        
               vendor = None 
        
           if system == "androideabi": 
        
               system = "android" 
        
               abi = "eabi" 
        
           if len(component_parts) == 4: 
        
               abi = component_parts[3]

It seems like rustc also expects the name to be "macos" which I determine from the json dump from the command below where you can see "os": "macos",

rustc +nightly --print target-spec-json -Z unstable-options

rustc +nightly --print target-spec-json -Z unstable-options
{
  "abi-return-struct-as-int": true,
  "arch": "aarch64",
  "archive-format": "darwin",
  "cpu": "apple-m1",
  "crt-objects-fallback": "false",
  "data-layout": "e-m:o-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-n32:64-S128-Fn32",
  "debuginfo-kind": "dwarf-dsym",
  "dll-suffix": ".dylib",
  "dynamic-linking": true,
  "eh-frame-header": false,
  "emit-debug-gdb-scripts": false,
  "frame-pointer": "non-leaf",
  "function-sections": false,
  "has-rpath": true,
  "has-thread-local": true,
  "is-like-osx": true,
  "link-env": [
    "ZERO_AR_DATE=1"
  ],
  "link-env-remove": [
    "IPHONEOS_DEPLOYMENT_TARGET",
    "TVOS_DEPLOYMENT_TARGET",
    "XROS_DEPLOYMENT_TARGET"
  ],
  "linker-flavor": "darwin-cc",
  "linker-is-gnu": false,
  "lld-flavor": "darwin",
  "llvm-floatabi": "hard",
  "llvm-target": "arm64-apple-macosx",
  "max-atomic-width": 128,
  "metadata": {
    "description": "ARM64 Apple macOS (11.0+, Big Sur+)",
    "host_tools": true,
    "std": true,
    "tier": 1
  },
  "os": "macos",
  "split-debuginfo": "packed",
  "stack-probes": {
    "kind": "inline"
  },
  "supported-sanitizers": [
    "address",
    "thread",
    "cfi"
  ],
  "supported-split-debuginfo": [
    "packed",
    "unpacked",
    "off"
  ],
  "target-family": [
    "unix"
  ],
  "target-mcount": "\u0001mcount",
  "target-pointer-width": "64",
  "vendor": "apple"
}

But there definitely isn't a triple with "macos"

rustc +nightly --print target-list -Z unstable-options | grep macos

prints nothing

rustc +nightly --print target-list -Z unstable-options | grep darwin

aarch64-apple-darwin
arm64e-apple-darwin
i686-apple-darwin
x86_64-apple-darwin
x86_64h-apple-darwin

UebelAndre · 2025-02-25T22:37:07Z

@christianscott be advised, there may be places in code that only account for "darwin" you might wanna look at all uses of target_os and make sure anything that compares it to "darwin" also checks "macos". And both should be supported for backward compatibility.

christianscott · 2025-02-25T22:45:51Z

Will do!

christianscott · 2025-02-25T23:41:36Z

Fixing the CI failure (no bzlmod on macos aarch64). I can repro locally.

Error message

# bazel build --noenable_bzlmod --enable_workspace //...
WARNING: /Users/christian.s/Code/github.com/bazelbuild/rules_rust/rust/platform/BUILD.bazel:6:24: target '//rust/platform:aarch64-fuchsia' is deprecated: Use `@rules_rust//rust/platform:aarch64-unknown-fuchsia` instead.
WARNING: /Users/christian.s/Code/github.com/bazelbuild/rules_rust/rust/platform/BUILD.bazel:6:24: target '//rust/platform:darwin' is deprecated: Use `@rules_rust//rust/platform:macos` instead.
WARNING: /Users/christian.s/Code/github.com/bazelbuild/rules_rust/rust/platform/BUILD.bazel:6:24: target '//rust/platform:wasi' is deprecated: Use `@rules_rust//rust/platform:wasip1` instead
WARNING: /Users/christian.s/Code/github.com/bazelbuild/rules_rust/rust/platform/BUILD.bazel:6:24: target '//rust/platform:wasm' is deprecated: Use `@rules_rust//rust/platform:wasm32` instead
WARNING: /Users/christian.s/Code/github.com/bazelbuild/rules_rust/rust/platform/BUILD.bazel:6:24: target '//rust/platform:wasm32-wasi' is deprecated: Use `@rules_rust//rust/platform:wasm-wasip1` instead.
WARNING: /Users/christian.s/Code/github.com/bazelbuild/rules_rust/rust/platform/BUILD.bazel:6:24: target '//rust/platform:x86_64-fuchsia' is deprecated: Use `@rules_rust//rust/platform:x86_64-unknown-fuchsia` instead.
WARNING: /Users/christian.s/Code/github.com/bazelbuild/rules_rust/rust/toolchain/BUILD.bazel:55:6: target '//rust/toolchain:current_rustfmt_files' is deprecated: Instead use `@rules_rust//rust/toolchain:current_rustfmt_toolchain
WARNING: /Users/christian.s/Code/github.com/bazelbuild/rules_rust/tools/rustfmt/BUILD.bazel:36:6: target '//tools/rustfmt:rustfmt' is deprecated: Prefer //tools/upstream_wrapper:rustfmt
WARNING: /Users/christian.s/Code/github.com/bazelbuild/rules_rust/tools/rustfmt/BUILD.bazel:89:6: target '//tools/rustfmt:upstream_rustfmt' is deprecated: Prefer //tools/upstream_wrapper:rustfmt
INFO: Repository cross_rs_host_bin instantiated at:
  /Users/christian.s/Code/github.com/bazelbuild/rules_rust/WORKSPACE.bazel:19:21: in <toplevel>
  /Users/christian.s/Code/github.com/bazelbuild/rules_rust/crate_universe/tools/cross_installer/cross_installer_deps.bzl:45:10: in cross_installer_deps
  /private/var/tmp/_bazel_christian.s/5d56531c13be109e912a77d9e9ce5c4e/external/bazel_tools/tools/build_defs/repo/utils.bzl:268:18: in maybe
Repository rule cargo_bootstrap_repository defined at:
  /Users/christian.s/Code/github.com/bazelbuild/rules_rust/cargo/private/cargo_bootstrap.bzl:240:45: in <toplevel>
ERROR: /Users/christian.s/Code/github.com/bazelbuild/rules_rust/cargo/private/cargo_bootstrap.bzl:222:40: An error occurred during the fetch of repository 'cross_rs_host_bin':
   Traceback (most recent call last):
        File "/Users/christian.s/Code/github.com/bazelbuild/rules_rust/cargo/private/cargo_bootstrap.bzl", line 222, column 40, in _cargo_bootstrap_repository_impl
                cargo_bin = repository_ctx.path(tools.cargo),
Error in path: Unable to load package for @@rust_macos_aarch64__aarch64-apple-darwin__stable_tools//:bin/cargo: The repository '@@rust_macos_aarch64__aarch64-apple-darwin__stable_tools' could not be resolved: Repository '@@rust_macos_aarch64__aarch64-apple-darwin__stable_tools' is not defined
ERROR: no such package '@@cross_rs_host_bin//': Unable to load package for @@rust_macos_aarch64__aarch64-apple-darwin__stable_tools//:bin/cargo: The repository '@@rust_macos_aarch64__aarch64-apple-darwin__stable_tools' could not be resolved: Repository '@@rust_macos_aarch64__aarch64-apple-darwin__stable_tools' is not defined
ERROR: /Users/christian.s/Code/github.com/bazelbuild/rules_rust/crate_universe/tools/cross_installer/BUILD.bazel:9:6: //crate_universe/tools/cross_installer:cross depends on @@cross_rs_host_bin//:cross in repository @@cross_rs_host_bin which failed to fetch. no such package '@@cross_rs_host_bin//': Unable to load package for @@rust_macos_aarch64__aarch64-apple-darwin__stable_tools//:bin/cargo: The repository '@@rust_macos_aarch64__aarch64-apple-darwin__stable_tools' could not be resolved: Repository '@@rust_macos_aarch64__aarch64-apple-darwin__stable_tools' is not defined
ERROR: Analysis of target '//crate_universe/tools/cross_installer:cross' failed; build aborted: Analysis failed
INFO: Elapsed time: 2.166s, Critical Path: 1.26s
INFO: 57 processes: 57 internal.
ERROR: Build did NOT complete successfully
FAILED: 
    Fetching repository @@rust_analyzer_1.84.1_tools; starting
    Fetching repository @@cargo_bazel.buildifier-darwin-arm64; starting
    Fetching repository @@rrra__anyhow-1.0.71; starting
    Fetching repository @@cui__crates-index-3.6.0; starting
    Fetching repository @@rrra__clap_derive-4.3.2; starting
    Fetching repository @@rrra__clap_builder-4.3.11; starting
    Fetching https://static.rust-lang.org/dist/rust-src-1.84.1.tar.xz; 60.1 KiB (2.0%)
    Fetching https://static.crates.io/crates/crates-index/3.6.0/download ... (10 fetches)

UebelAndre · 2025-02-25T23:58:12Z

Fixing the CI failure (no bzlmod on macos aarch64). I can repro locally.

I think this is complaining about these not being updated

rules_rust/rust/repositories.bzl

Lines 42 to 51 in 14f3829

    
           DEFAULT_TOOLCHAIN_TRIPLES = { 
        
               "aarch64-apple-darwin": "rust_darwin_aarch64", 
        
               "aarch64-pc-windows-msvc": "rust_windows_aarch64", 
        
               "aarch64-unknown-linux-gnu": "rust_linux_aarch64", 
        
               "s390x-unknown-linux-gnu": "rust_linux_s390x", 
        
               "x86_64-apple-darwin": "rust_darwin_x86_64", 
        
               "x86_64-pc-windows-msvc": "rust_windows_x86_64", 
        
               "x86_64-unknown-freebsd": "rust_freebsd_x86_64", 
        
               "x86_64-unknown-linux-gnu": "rust_linux_x86_64", 
        
           }

christianscott · 2025-02-26T00:18:23Z

The build has passed 🎉 I've updated the description as well.

rust/repositories.bzl

rust/private/rustc.bzl

rust/platform/triple.bzl

UebelAndre

@christianscott responded to all the comments!

UebelAndre · 2025-02-26T01:54:58Z

rust/platform/platform.bzl

@@ -46,17 +46,17 @@ def declare_config_settings():
            constraint_values = system_to_constraints(system),
        )

-    # Add alias for OSX to "darwin" to match what users will be expecting.


It'd probably be best to add an additional alias.

rust/private/rustc.bzl

test/unit/native_deps/native_deps_test.bzl

Co-authored-by: UebelAndre <github@uebelandre.com>

UebelAndre

Sick! Thank you!

UebelAndre · 2025-02-26T02:27:13Z

@christianscott looks like you gotta run buildifier!

christianscott · 2025-02-26T03:02:20Z

Oops 🙈 pushed a fix

christianscott mentioned this pull request Feb 25, 2025

CARGO_CFG_TARGET_OS should be macos on MacOS, not darwin #3291

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christianscott marked this pull request as ready for review February 25, 2025 09:14

UebelAndre requested changes Feb 25, 2025

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christianscott changed the title ~~CARGO_CFG_TARGET_OS should be "macos" on MacOS, not "darwin"~~ map system from "darwin" to "macos" when parsing triple Feb 25, 2025

christianscott force-pushed the macos_cargo_cfg_target_os branch from d13a045 to fc2de05 Compare February 25, 2025 22:33

christianscott requested a review from UebelAndre February 26, 2025 00:18

christianscott commented Feb 26, 2025

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christianscott commented Feb 26, 2025

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map system from "darwin" to "macos" when parsing triple

eecccda

christianscott force-pushed the macos_cargo_cfg_target_os branch from 3e591e7 to eecccda Compare February 26, 2025 01:26

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simplify target_os checks

e829315

Co-authored-by: UebelAndre <github@uebelandre.com>

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fix dict sorting

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map system from "darwin" to "macos" when parsing triple #3296

map system from "darwin" to "macos" when parsing triple #3296

christianscott commented Feb 25, 2025 •

edited

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christianscott commented Feb 26, 2025

	cpu_arch = component_parts[0]
	vendor = component_parts[1]
	system = component_parts[2]
	abi = None

	if cpu_arch.startswith(("thumbv8m", "thumbv7m", "thumbv7e", "thumbv6m")):
	abi = system
	system = vendor
	vendor = None

	if system == "androideabi":
	system = "android"
	abi = "eabi"

	if len(component_parts) == 4:
	abi = component_parts[3]

map system from "darwin" to "macos" when parsing triple #3296

Are you sure you want to change the base?

map system from "darwin" to "macos" when parsing triple #3296

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