The rust_toolchain rule definition and implementation.

Rules

• rust_toolchain

rust_toolchain

Declares a Rust toolchain for use.

This is for declaring a custom toolchain, eg. for configuring a particular version of rust or supporting a new platform.

Example:

Suppose the core rust team has ported the compiler to a new target CPU, called cpuX. This support can be used in Bazel by defining a new toolchain definition and declaration:

load('@rules_rust//rust:toolchain.bzl', 'rust_toolchain')

rust_toolchain(
    name = "rust_cpuX_impl",
    binary_ext = "",
    dylib_ext = ".so",
    exec_triple = "cpuX-unknown-linux-gnu",
    rust_doc = "@rust_cpuX//:rustdoc",
    rust_std = "@rust_cpuX//:rust_std",
    rustc = "@rust_cpuX//:rustc",
    rustc_lib = "@rust_cpuX//:rustc_lib",
    staticlib_ext = ".a",
    stdlib_linkflags = ["-lpthread", "-ldl"],
    target_triple = "cpuX-unknown-linux-gnu",
)

toolchain(
    name = "rust_cpuX",
    exec_compatible_with = [
        "@platforms//cpu:cpuX",
        "@platforms//os:linux",
    ],
    target_compatible_with = [
        "@platforms//cpu:cpuX",
        "@platforms//os:linux",
    ],
    toolchain = ":rust_cpuX_impl",
)

Then, either add the label of the toolchain rule to register_toolchains in the WORKSPACE, or pass it to the "--extra_toolchains" flag for Bazel, and it will be used.

See @rules_rust//rust:repositories.bzl for examples of defining the @rust_cpuX repository with the actual binaries and libraries.

ATTRIBUTES

Name	Description	Type	Mandatory	Default
name	A unique name for this target.	Name	required
allocator_library	Target that provides allocator functions when rust_library targets are embedded in a cc_binary.	Label	optional	"@rules_rust//ffi/cc/allocator_library"
binary_ext	The extension for binaries created from rustc.	String	required
cargo	The location of the cargo binary. Can be a direct source or a filegroup containing one item.	Label	optional	None
cargo_clippy	The location of the cargo_clippy binary. Can be a direct source or a filegroup containing one item.	Label	optional	None
clippy_driver	The location of the clippy-driver binary. Can be a direct source or a filegroup containing one item.	Label	optional	None
debug_info	Rustc debug info levels per opt level	Dictionary: String -> String	optional	{"dbg": "2", "fastbuild": "0", "opt": "0"}
default_edition	The edition to use for rust_* rules that don't specify an edition. If absent, every rule is required to specify its edition attribute.	String	optional	""
dylib_ext	The extension for dynamic libraries created from rustc.	String	required
env	Environment variables to set in actions.	Dictionary: String -> String	optional	{}
exec_triple	The platform triple for the toolchains execution environment. For more details see: https://docs.bazel.build/versions/master/skylark/rules.html#configurations	String	required
experimental_link_std_dylib	Label to a boolean build setting that controls whether whether to link libstd dynamically.	Label	optional	"@rules_rust//rust/settings:experimental_link_std_dylib"
experimental_use_cc_common_link	Label to a boolean build setting that controls whether cc_common.link is used to link rust binaries.	Label	optional	"@rules_rust//rust/settings:experimental_use_cc_common_link"
extra_exec_rustc_flags	Extra flags to pass to rustc in exec configuration	List of strings	optional	[]
extra_rustc_flags	Extra flags to pass to rustc in non-exec configuration. Subject to location expansion with respect to the srcs of the rust_std attribute.	List of strings	optional	[]
extra_rustc_flags_for_crate_types	Extra flags to pass to rustc based on crate type	Dictionary: String -> List of strings	optional	{}
global_allocator_library	Target that provides allocator functions for when a global allocator is present.	Label	optional	"@rules_rust//ffi/cc/global_allocator_library"
llvm_cov	The location of the llvm-cov binary. Can be a direct source or a filegroup containing one item. If None, rust code is not instrumented for coverage.	Label	optional	None
llvm_profdata	The location of the llvm-profdata binary. Can be a direct source or a filegroup containing one item. If llvm_cov is None, this can be None as well and rust code is not instrumented for coverage.	Label	optional	None
llvm_tools	LLVM tools that are shipped with the Rust toolchain.	Label	optional	None
opt_level	Rustc optimization levels.	Dictionary: String -> String	optional	{"dbg": "0", "fastbuild": "0", "opt": "3"}
per_crate_rustc_flags	Extra flags to pass to rustc in non-exec configuration	List of strings	optional	[]
rust_doc	The location of the rustdoc binary. Can be a direct source or a filegroup containing one item.	Label	required
rust_std	The Rust standard library.	Label	required
rustc	The location of the rustc binary. Can be a direct source or a filegroup containing one item.	Label	required
rustc_lib	The libraries used by rustc during compilation.	Label	optional	None
rustfmt	Deprecated: Instead see rustfmt_toolchain	Label	optional	None
staticlib_ext	The extension for static libraries created from rustc.	String	required
stdlib_linkflags	Additional linker flags to use when Rust standard library is linked by a C++ linker (rustc will deal with these automatically). Subject to location expansion with respect to the srcs of the rust_std attribute.	List of strings	required
strip_level	Rustc strip levels. For all potential options, see https://doc.rust-lang.org/rustc/codegen-options/index.html#strip	Dictionary: String -> String	optional	{"dbg": "none", "fastbuild": "none", "opt": "debuginfo"}
target_json	Override the target_triple with a custom target specification. For more details see: https://doc.rust-lang.org/rustc/targets/custom.html	String	optional	""
target_triple	The platform triple for the toolchains target environment. For more details see: https://docs.bazel.build/versions/master/skylark/rules.html#configurations	String	optional	""