Fuchsia Platform Rust Bazel Rules and Macros

This directory contains Fuchsia-specific Rust wrapper macros, rules, and helpers for platform builds.

See Use Fuchsia-specific wrappers for general usage guidance. Load symbols directly from their individual .bzl files rather than the deprecated defs.bzl.

Contents

Wrapper Macros and Rules

These wrappers apply Fuchsia-specific compiler flags, lint configurations, RBE properties, and standard library link dependencies, and are enforced by the bazel_fuchsia_wrappers SHAC check:

• rustc_binary.bzl: Defines rustc_binary(), Fuchsia's wrapper macro for @rules_rust's rust_binary().
• rustc_dylib.bzl: Defines rustc_dylib(), Fuchsia's wrapper macro for @rules_rust's rust_dylib_library().
• rustc_library.bzl: Defines rustc_library(), Fuchsia's wrapper macro for @rules_rust's rust_library().
• rustc_library_group.bzl: Defines rustc_library_group(), Fuchsia's rule equivalent to @rules_rust's rust_library_group() with support for native link_deps.
• rustc_proc_macro.bzl: Defines rustc_proc_macro(), Fuchsia's wrapper macro for @rules_rust's rust_proc_macro().
• rustc_test.bzl: Defines rustc_test(), Fuchsia's wrapper macro for @rules_rust's rust_test().

Additional Macros and Helpers

• common.bzl: Shared helper functions used by the rustc_*() wrapper macros (e.g., with_fuchsia_rustc_flags(), with_fuchsia_rust_stdlib_link_deps()).
• defs.bzl: Deprecated re-export file. Do not load from or add to this file; load from the individual .bzl files instead.
• generate_unit_tests.bzl: Generates implicit unit test targets for legacy with_unit_tests and with_host_unit_tests attributes.
• rustc_bindgen.bzl: Defines rustc_bindgen_golden() and related rules/macros for running bindgen on C headers and verifying golden Rust bindings.
• rustc_check_cfg_build_flags.bzl: Defines rustc_check_cfg_build_flags(), a macro generating a build_flags() target with --check-cfg flags.
• rustc_embed_files.bzl: Defines rustc_embed_files(), a macro for embedding files as byte array constants in a Rust library.

Adding a New Wrapper Macro or Rule

When adding a new Fuchsia wrapper macro or rule equivalent for an upstream @rules_rust symbol (for example, rustc_library_group() for rust_library_group()):

1. Follow Fuchsia naming and style guidelines:
   • See Wrapping built-in and common rules, macros, and functions.
   • Prefix the wrapper name with rustc_ (never fuchsia_) and define it in //build/bazel/rules/rust/<wrapper_name>.bzl. Do not add it to defs.bzl.
2. Register the wrapper in the bazel_fuchsia_wrappers SHAC check:
   • Add an entry to _WRAPPED_RULES in //scripts/shac/bazel_lint/checks/fuchsia_wrappers.py mapping the upstream @rules_rust// symbol to the new wrapper symbol and module label.
3. Add unit tests for the SHAC check:
   • Update //scripts/shac/bazel_lint/checks/tests/fuchsia_wrappers_test.star to verify that loading or calling the upstream symbol (including aliased loads) is flagged as an error, and that loading and calling the new wrapper is allowed.
4. Migrate or allowlist pre-existing uses:
   • Run fx host-tool shac check --only bazel_fuchsia_wrappers --all across the repository.
   • Migrate existing in-tree uses to the new wrapper where feasible, or add remaining pre-existing violations to //scripts/shac/bazel_lint/allowlists/bazel_fuchsia_wrappers.json under https://fxbug.dev/570203009, following the sorting and formatting rules in //scripts/shac/bazel_lint/allowlists/README.md.
5. Update documentation:
   • Update //docs/development/languages/bazel/style/common.md if the new wrapper introduces a new naming pattern or module path.
   • Update //docs/development/languages/bazel/style/rules_macros.md if the new wrapper introduces a new naming convention or exception.
   • Document the new .bzl file and symbol in the Wrapper Macros and Rules section above.
6. Verify tests and checks:
   • Run fx test --host @//scripts/shac/tests:bazel_test.
   • Run fx host-tool shac check --only bazel_fuchsia_wrappers --all.
   • Run fx doc-checker --local-links-only.