Add cargo:rustc-link-arg-bin flag.

src/cargo/core/compiler/custom_build.rs

@@ -25,7 +25,7 @@ pub struct BuildOutput {
  /// Names and link kinds of libraries, suitable for the `-l` flag.
  pub library_links: Vec<String>,
  /// Linker arguments suitable to be passed to `-C link-arg=<args>`
- pub linker_args: Vec<(Option<LinkType>, String)>,
+ pub linker_args: Vec<(LinkType, String)>,
  /// Various `--cfg` flags to pass to the compiler.
  pub cfgs: Vec<String>,
  /// Additional environment variables to run the compiler with.
@@ -562,18 +562,36 @@ impl BuildOutput {
  "rustc-link-lib" => library_links.push(value.to_string()),
  "rustc-link-search" => library_paths.push(PathBuf::from(value)),
  "rustc-link-arg-cdylib" | "rustc-cdylib-link-arg" => {
- linker_args.push((Some(LinkType::Cdylib), value))
+ linker_args.push((LinkType::Cdylib, value))
  }
  "rustc-link-arg-bins" => {
  if extra_link_arg {
- linker_args.push((Some(LinkType::Bin), value));
+ linker_args.push((LinkType::Bin, value));
+ } else {
+ warnings.push(format!("cargo:{} requires -Zextra-link-arg flag", key));
+ }
+ }
+ "rustc-link-arg-bin" => {
+ if extra_link_arg {
+ let parts = value.splitn(2, "=").collect::<Vec<_>>();
+ if parts.len() == 2 {
+ linker_args.push((
+ LinkType::SingleBin(parts[0].to_string()),
+ parts[1].to_string(),
+ ));
+ } else {
+ warnings.push(format!(
+ "cargo:{} has invalid syntax: expected `cargo:{}=BIN=ARG`",
+ key, key
+ ));
+ }
  } else {
  warnings.push(format!("cargo:{} requires -Zextra-link-arg flag", key));
  }
  }
  "rustc-link-arg" => {
  if extra_link_arg {
- linker_args.push((None, value));
+ linker_args.push((LinkType::All, value));
  } else {
  warnings.push(format!("cargo:{} requires -Zextra-link-arg flag", key));
  }

src/cargo/core/compiler/mod.rs

@@ -62,29 +62,27 @@ use cargo_util::{paths, ProcessBuilder, ProcessError};
 
 const RUSTDOC_CRATE_VERSION_FLAG: &str = "--crate-version";
 
-#[derive(Copy, Clone, Hash, Debug, PartialEq, Eq)]
+#[derive(Clone, Hash, Debug, PartialEq, Eq)]
 pub enum LinkType {
+ All,
  Cdylib,
  Bin,
+ SingleBin(String),
  Test,
  Bench,
  Example,
 }
 
-impl From<&super::Target> for Option<LinkType> {
- fn from(value: &super::Target) -> Self {
- if value.is_cdylib() {
- Some(LinkType::Cdylib)
- } else if value.is_bin() {
- Some(LinkType::Bin)
- } else if value.is_test() {
- Some(LinkType::Test)
- } else if value.is_bench() {
- Some(LinkType::Bench)
- } else if value.is_exe_example() {
- Some(LinkType::Example)
- } else {
- None
+impl LinkType {
+ pub fn applies_to(&self, target: &Target) -> bool {
+ match self {
+ LinkType::All => true,
+ LinkType::Cdylib => target.is_cdylib(),
+ LinkType::Bin => target.is_bin(),
+ LinkType::SingleBin(name) => target.is_bin() && target.name() == name,
+ LinkType::Test => target.is_test(),
+ LinkType::Bench => target.is_bench(),
+ LinkType::Example => target.is_exe_example(),
  }
  }
 }
@@ -227,7 +225,6 @@ fn rustc(cx: &mut Context<'_, '_>, unit: &Unit, exec: &Arc<dyn Executor>) -> Car
  // If we are a binary and the package also contains a library, then we
  // don't pass the `-l` flags.
  let pass_l_flag = unit.target.is_lib() || !unit.pkg.targets().iter().any(|t| t.is_lib());
- let link_type = (&unit.target).into();
 
  let dep_info_name = if cx.files().use_extra_filename(unit) {
  format!(
@@ -280,7 +277,7 @@ fn rustc(cx: &mut Context<'_, '_>, unit: &Unit, exec: &Arc<dyn Executor>) -> Car
  &script_outputs,
  &build_scripts,
  pass_l_flag,
- link_type,
+ &target,
  current_id,
  )?;
  add_plugin_deps(&mut rustc, &script_outputs, &build_scripts, &root_output)?;
@@ -371,7 +368,7 @@ fn rustc(cx: &mut Context<'_, '_>, unit: &Unit, exec: &Arc<dyn Executor>) -> Car
  build_script_outputs: &BuildScriptOutputs,
  build_scripts: &BuildScripts,
  pass_l_flag: bool,
- link_type: Option<LinkType>,
+ target: &Target,
  current_id: PackageId,
  ) -> CargoResult<()> {
  for key in build_scripts.to_link.iter() {
@@ -396,11 +393,9 @@ fn rustc(cx: &mut Context<'_, '_>, unit: &Unit, exec: &Arc<dyn Executor>) -> Car
  }
  }
 
- if link_type.is_some() {
- for (lt, arg) in &output.linker_args {
- if lt.is_none() || *lt == link_type {
- rustc.arg("-C").arg(format!("link-arg={}", arg));
- }
+ for (lt, arg) in &output.linker_args {
+ if lt.applies_to(&target) {
+ rustc.arg("-C").arg(format!("link-arg={}", arg));
  }
  }
  }

src/cargo/util/config/target.rs

@@ -134,13 +134,13 @@ fn parse_links_overrides(
  }
  "rustc-link-arg-cdylib" | "rustc-cdylib-link-arg" => {
  let args = value.list(key)?;
- let args = args.iter().map(|v| (Some(LinkType::Cdylib), v.0.clone()));
+ let args = args.iter().map(|v| (LinkType::Cdylib, v.0.clone()));
  output.linker_args.extend(args);
  }
  "rustc-link-arg-bins" => {
  if extra_link_arg {
  let args = value.list(key)?;
- let args = args.iter().map(|v| (Some(LinkType::Bin), v.0.clone()));
+ let args = args.iter().map(|v| (LinkType::Bin, v.0.clone()));
  output.linker_args.extend(args);
  } else {
  config.shell().warn(format!(
@@ -152,7 +152,7 @@ fn parse_links_overrides(
  "rustc-link-arg" => {
  if extra_link_arg {
  let args = value.list(key)?;
- let args = args.iter().map(|v| (None, v.0.clone()));
+ let args = args.iter().map(|v| (LinkType::All, v.0.clone()));
  output.linker_args.extend(args);
  } else {
  config.shell().warn(format!(

src/doc/src/reference/unstable.md

@@ -137,11 +137,13 @@ Cargo _or_ Rust features can be used.
 * Tracking Issue: [#9426](https://github.com/rust-lang/cargo/issues/9426)
 * Original Pull Request: [#7811](https://github.com/rust-lang/cargo/pull/7811)
 
-The `-Z extra-link-arg` flag makes the following two instructions available
+The `-Z extra-link-arg` flag makes the following instructions available
 in build scripts:
 
 * [`cargo:rustc-link-arg-bins=FLAG`](#rustc-link-arg-bins) – Passes custom
  flags to a linker for binaries.
+* [`cargo:rustc-link-arg-bin=BIN=FLAG`](#rustc-link-arg-bin) – Passes custom
+ flags to a linker for the binary `BIN`.
 * [`cargo:rustc-link-arg=FLAG`](#rustc-link-arg) – Passes custom flags to a
  linker for benchmarks, binaries, `cdylib` crates, examples, and tests.
 
@@ -155,6 +157,16 @@ to set a linker script or other linker options.
 
 [link-arg]: ../../rustc/codegen-options/index.md#link-arg
 
+<a id="rustc-link-arg-bin"></a>
+#### `cargo:rustc-link-arg-bin=BIN=FLAG`
+
+The `rustc-link-arg-bin` instruction tells Cargo to pass the [`-C
+link-arg=FLAG` option][link-arg] to the compiler, but only when building
+the binary target with name `BIN`. Its usage is highly platform specific. It is useful
+to set a linker script or other linker options.
+
+[link-arg]: ../../rustc/codegen-options/index.md#link-arg
+
 <a id="rustc-link-arg"></a>
 #### `cargo:rustc-link-arg=FLAG`
 

tests/testsuite/build_script_extra_link_arg.rs

@@ -26,6 +26,49 @@ fn build_script_extra_link_arg_bin() {
  .run();
 }
 
+#[cargo_test]
+fn build_script_extra_link_arg_bin_single() {
+ let p = project()
+ .file(
+ "Cargo.toml",
+ r#"
+ [package]
+
+ name = "foobar"
+ version = "0.5.0"
+ authors = ["wycats@example.com"]
+
+ [[bin]]
+ name = "foo"
+ [[bin]]
+ name = "bar"
+ "#,
+ )
+ .file("src/main.rs", "fn main() {}")
+ .file(
+ "build.rs",
+ r#"
+ fn main() {
+ println!("cargo:rustc-link-arg-bins=--bogus-flag-all");
+ println!("cargo:rustc-link-arg-bin=foo=--bogus-flag-foo");
+ println!("cargo:rustc-link-arg-bin=bar=--bogus-flag-bar");
+ }
+ "#,
+ )
+ .build();
+
+ p.cargo("build -Zextra-link-arg -v")
+ .masquerade_as_nightly_cargo()
+ .without_status()
+ .with_stderr_contains(
+ "[RUNNING] `rustc --crate-name foo [..]-C link-arg=--bogus-flag-all -C link-arg=--bogus-flag-foo[..]",
+ )
+ .with_stderr_contains(
+ "[RUNNING] `rustc --crate-name bar [..]-C link-arg=--bogus-flag-all -C link-arg=--bogus-flag-bar[..]",
+ )
+ .run();
+}
+
 #[cargo_test]
 fn build_script_extra_link_arg() {
  let p = project()