diff --git a/cargo/cargo_build_script.bzl b/cargo/cargo_build_script.bzl
index 80384d7204..69450a283e 100644
--- a/cargo/cargo_build_script.bzl
+++ b/cargo/cargo_build_script.bzl
@@ -7,7 +7,7 @@ load("//rust:defs.bzl", "rust_binary", "rust_common")
load("//rust/private:rustc.bzl", "BuildInfo", "get_compilation_mode_opts", "get_linker_and_args")
# buildifier: disable=bzl-visibility
-load("//rust/private:utils.bzl", "expand_dict_value_locations", "find_cc_toolchain", "find_toolchain", "name_to_crate_name")
+load("//rust/private:utils.bzl", "dedent", "expand_dict_value_locations", "find_cc_toolchain", "find_toolchain", "name_to_crate_name")
def get_cc_compile_env(cc_toolchain, feature_configuration):
"""Gather cc environment variables from the given `cc_toolchain`
@@ -56,11 +56,7 @@ def _build_script_impl(ctx):
pkg_name = _name_to_pkg_name(ctx.label.name)
- toolchain_tools = [
- # Needed for rustc to function.
- toolchain.rustc_lib,
- toolchain.rust_std,
- ]
+ toolchain_tools = [toolchain.all_files]
cc_toolchain = find_cpp_toolchain(ctx)
@@ -121,6 +117,13 @@ def _build_script_impl(ctx):
if cc_toolchain.sysroot:
env["SYSROOT"] = cc_toolchain.sysroot
+ # Inform build scripts of rustc flags
+ # https://github.com/rust-lang/cargo/issues/9600
+ env["CARGO_ENCODED_RUSTFLAGS"] = "\\x1f".join([
+ # Allow build scripts to locate the generated sysroot
+ "--sysroot=${{pwd}}/{}".format(toolchain.sysroot),
+ ] + ctx.attr.rustc_flags)
+
for f in ctx.attr.crate_features:
env["CARGO_FEATURE_" + f.upper().replace("-", "_")] = "1"
@@ -136,7 +139,6 @@ def _build_script_impl(ctx):
direct = [
script,
ctx.executable._cargo_build_script_runner,
- toolchain.rustc,
] + ctx.files.data + ctx.files.tools + ([toolchain.target_json] if toolchain.target_json else []),
transitive = toolchain_tools,
)
@@ -217,6 +219,16 @@ _build_script_run = rule(
"links": attr.string(
doc = "The name of the native library this crate links against.",
),
+ "rustc_flags": attr.string_list(
+ doc = dedent("""\
+ List of compiler flags passed to `rustc`.
+
+ These strings are subject to Make variable expansion for predefined
+ source/output path variables like `$location`, `$execpath`, and
+ `$rootpath`. This expansion is useful if you wish to pass a generated
+ file of arguments to rustc: `@$(location //package:target)`.
+ """),
+ ),
# The source of truth will be the `cargo_build_script` macro until stardoc
# implements documentation inheritence. See https://github.com/bazelbuild/stardoc/issues/27
"script": attr.label(
@@ -262,6 +274,7 @@ def cargo_build_script(
tools = [],
links = None,
rustc_env = {},
+ rustc_flags = [],
visibility = None,
tags = None,
**kwargs):
@@ -333,6 +346,7 @@ def cargo_build_script(
tools (list, optional): Tools (executables) needed by the build script.
links (str, optional): Name of the native library this crate links against.
rustc_env (dict, optional): Environment variables to set in rustc when compiling the build script.
+ rustc_flags (list, optional): List of compiler flags passed to `rustc`.
visibility (list of label, optional): Visibility to apply to the generated build script output.
tags: (list of str, optional): Tags to apply to the generated build script output.
**kwargs: Forwards to the underlying `rust_binary` rule.
@@ -357,6 +371,7 @@ def cargo_build_script(
deps = deps,
data = data,
rustc_env = rustc_env,
+ rustc_flags = rustc_flags,
tags = binary_tags,
**kwargs
)
@@ -370,6 +385,7 @@ def cargo_build_script(
deps = deps,
data = data,
tools = tools,
+ rustc_flags = rustc_flags,
visibility = visibility,
tags = tags,
)
diff --git a/cargo/cargo_build_script_runner/bin.rs b/cargo/cargo_build_script_runner/bin.rs
index 2f305e053f..58f0363831 100644
--- a/cargo/cargo_build_script_runner/bin.rs
+++ b/cargo/cargo_build_script_runner/bin.rs
@@ -123,6 +123,15 @@ fn run_buildrs() -> Result<(), String> {
}
}
+ // Bazel does not support byte strings so in order to correctly represent `CARGO_ENCODED_RUSTFLAGS`
+ // the escaped `\x1f` sequences need to be unescaped
+ if let Ok(encoded_rustflags) = env::var("CARGO_ENCODED_RUSTFLAGS") {
+ command.env(
+ "CARGO_ENCODED_RUSTFLAGS",
+ encoded_rustflags.replace("\\x1f", "\x1f"),
+ );
+ }
+
let (buildrs_outputs, process_output) = BuildScriptOutput::outputs_from_command(&mut command)
.map_err(|process_output| {
format!(
diff --git a/docs/cargo.md b/docs/cargo.md
index bd1dc273b5..146e9e1133 100644
--- a/docs/cargo.md
+++ b/docs/cargo.md
@@ -46,7 +46,7 @@ A rule for bootstrapping a Rust binary using [Cargo](https://doc.rust-lang.org/c
cargo_build_script(name, crate_features, version, deps, build_script_env, data, tools, links,
- rustc_env, visibility, tags, kwargs)
+ rustc_env, rustc_flags, visibility, tags, kwargs)
Compile and execute a rust build script to generate build attributes
@@ -121,6 +121,7 @@ The `hello_lib` target will be build with the flags and the environment variable
| tools | Tools (executables) needed by the build script. | [] |
| links | Name of the native library this crate links against. | None |
| rustc_env | Environment variables to set in rustc when compiling the build script. | {} |
+| rustc_flags | List of compiler flags passed to rustc. | [] |
| visibility | Visibility to apply to the generated build script output. | None |
| tags | (list of str, optional): Tags to apply to the generated build script output. | None |
| kwargs | Forwards to the underlying rust_binary rule. | none |
diff --git a/docs/flatten.md b/docs/flatten.md
index 928b8b6564..88c7388878 100644
--- a/docs/flatten.md
+++ b/docs/flatten.md
@@ -1389,7 +1389,7 @@ A collection of files either found within the `rust-stdlib` artifact or generate
cargo_build_script(name, crate_features, version, deps, build_script_env, data, tools, links,
- rustc_env, visibility, tags, kwargs)
+ rustc_env, rustc_flags, visibility, tags, kwargs)
Compile and execute a rust build script to generate build attributes
@@ -1464,6 +1464,7 @@ The `hello_lib` target will be build with the flags and the environment variable
| tools | Tools (executables) needed by the build script. | [] |
| links | Name of the native library this crate links against. | None |
| rustc_env | Environment variables to set in rustc when compiling the build script. | {} |
+| rustc_flags | List of compiler flags passed to rustc. | [] |
| visibility | Visibility to apply to the generated build script output. | None |
| tags | (list of str, optional): Tags to apply to the generated build script output. | None |
| kwargs | Forwards to the underlying rust_binary rule. | none |
diff --git a/test/cargo_build_script/BUILD.bazel b/test/cargo_build_script/BUILD.bazel
index 84fc960be2..34744cbabd 100644
--- a/test/cargo_build_script/BUILD.bazel
+++ b/test/cargo_build_script/BUILD.bazel
@@ -8,6 +8,8 @@ cargo_build_script(
name = "tools_exec_build_rs",
srcs = ["build.rs"],
build_script_env = {"TOOL": "$(execpath :tool)"},
+ # Add a flag to test that they're exposed to the build script
+ rustc_flags = ["--verbose"],
tools = [":tool"],
)
diff --git a/test/cargo_build_script/build.rs b/test/cargo_build_script/build.rs
index 68cef72321..12d1b53d6e 100644
--- a/test/cargo_build_script/build.rs
+++ b/test/cargo_build_script/build.rs
@@ -1,4 +1,27 @@
+//! A Cargo build script binary used in unit tests for the Bazel `cargo_build_script` rule
+
+/// `cargo_build_script` should always set `CARGO_ENCODED_RUSTFLAGS`
+fn test_encoded_rustflags() {
+ let encoded_rustflags = std::env::var("CARGO_ENCODED_RUSTFLAGS").unwrap();
+
+ let flags: Vec = encoded_rustflags
+ .split('\x1f')
+ .map(str::to_string)
+ .collect();
+ assert_eq!(flags.len(), 2);
+
+ assert!(flags[0].starts_with("--sysroot"));
+
+ // Ensure the `pwd` template has been resolved
+ assert!(!flags[0].contains("${pwd}"));
+
+ assert_eq!(flags[1], "--verbose");
+}
+
fn main() {
+ // Perform some unit testing
+ test_encoded_rustflags();
+
// Pass the TOOL_PATH along to the rust_test so we can assert on it.
println!(
"cargo:rustc-env=TOOL_PATH={}",