Refactor rust(do)c linker flags

src/bootstrap/src/core/build_steps/test.rs

@@ -29,8 +29,8 @@ use crate::utils;
 use crate::utils::cache::{Interned, INTERNER};
 use crate::utils::exec::BootstrapCommand;
 use crate::utils::helpers::{
-    self, add_link_lib_path, add_rustdoc_cargo_lld_flags, add_rustdoc_lld_flags, dylib_path,
-    dylib_path_var, output, t, target_supports_cranelift_backend, up_to_date, LldThreads,
+    self, add_link_lib_path, add_rustdoc_cargo_linker_args, dylib_path, dylib_path_var,
+    linker_args, output, t, target_supports_cranelift_backend, up_to_date, LldThreads,
 };
 use crate::utils::render_tests::{add_flags_and_try_run_tests, try_run_tests};
 use crate::{envify, CLang, DocTests, GitRepo, Mode};
@@ -277,7 +277,7 @@ impl Step for Cargotest {
             .args(builder.config.test_args())
             .env("RUSTC", builder.rustc(compiler))
             .env("RUSTDOC", builder.rustdoc(compiler));
-        add_rustdoc_cargo_lld_flags(&mut cmd, builder, compiler.host, LldThreads::No);
+        add_rustdoc_cargo_linker_args(&mut cmd, builder, compiler.host, LldThreads::No);
         builder.run_delaying_failure(cmd);
     }
 }
@@ -863,7 +863,7 @@ impl Step for RustdocTheme {
             .env("CFG_RELEASE_CHANNEL", &builder.config.channel)
             .env("RUSTDOC_REAL", builder.rustdoc(self.compiler))
             .env("RUSTC_BOOTSTRAP", "1");
-        add_rustdoc_lld_flags(&mut cmd, builder, self.compiler.host, LldThreads::No);
+        cmd.args(linker_args(builder, self.compiler.host, LldThreads::No));
 
         builder.run_delaying_failure(&mut cmd);
     }
@@ -1039,7 +1039,7 @@ impl Step for RustdocGUI {
         cmd.env("RUSTDOC", builder.rustdoc(self.compiler))
             .env("RUSTC", builder.rustc(self.compiler));
 
-        add_rustdoc_cargo_lld_flags(&mut cmd, builder, self.compiler.host, LldThreads::No);
+        add_rustdoc_cargo_linker_args(&mut cmd, builder, self.compiler.host, LldThreads::No);
 
         for path in &builder.paths {
             if let Some(p) = helpers::is_valid_test_suite_arg(path, "tests/rustdoc-gui", builder) {
@@ -1746,14 +1746,14 @@ NOTE: if you're sure you want to do this, please open an issue as to why. In the
 
         let mut hostflags = flags.clone();
         hostflags.push(format!("-Lnative={}", builder.test_helpers_out(compiler.host).display()));
-        hostflags.extend(builder.lld_flags(compiler.host));
+        hostflags.extend(linker_args(builder, compiler.host, LldThreads::No));
         for flag in hostflags {
             cmd.arg("--host-rustcflags").arg(flag);
         }
 
         let mut targetflags = flags;
         targetflags.push(format!("-Lnative={}", builder.test_helpers_out(target).display()));
-        targetflags.extend(builder.lld_flags(target));
+        targetflags.extend(linker_args(builder, compiler.host, LldThreads::No));
         for flag in targetflags {
             cmd.arg("--target-rustcflags").arg(flag);
         }

src/bootstrap/src/core/builder.rs

@@ -19,7 +19,9 @@ use crate::core::build_steps::{check, clean, compile, dist, doc, install, run, s
 use crate::core::config::flags::{Color, Subcommand};
 use crate::core::config::{DryRun, SplitDebuginfo, TargetSelection};
 use crate::utils::cache::{Cache, Interned, INTERNER};
-use crate::utils::helpers::{self, add_dylib_path, add_link_lib_path, add_rustdoc_lld_flags, exe};
+use crate::utils::helpers::{
+    self, add_dylib_path, add_link_lib_path, exe, linker_args, linker_flags,
+};
 use crate::utils::helpers::{libdir, output, t, LldThreads};
 use crate::Crate;
 use crate::EXTRA_CHECK_CFGS;
@@ -1174,7 +1176,7 @@ impl<'a> Builder<'a> {
         cmd.env_remove("MAKEFLAGS");
         cmd.env_remove("MFLAGS");
 
-        add_rustdoc_lld_flags(&mut cmd, self, compiler.host, LldThreads::Yes);
+        cmd.args(linker_args(self, compiler.host, LldThreads::Yes));
         cmd
     }
 
@@ -1673,21 +1675,20 @@ impl<'a> Builder<'a> {
             rustflags.arg(&format!("-Zstack-protector={stack_protector}"));
         }
 
-        if let Some(host_linker) = self.linker(compiler.host) {
-            hostflags.arg(format!("-Clinker={}", host_linker.display()));
-        }
-        if self.is_fuse_ld_lld(compiler.host) {
-            hostflags.arg("-Clink-args=-fuse-ld=lld");
-        }
+        linker_args(self, compiler.host, LldThreads::Yes).into_iter().for_each(|flag| {
+            hostflags.arg(flag);
+        });
 
         if let Some(target_linker) = self.linker(target) {
             let target = crate::envify(&target.triple);
             cargo.env(&format!("CARGO_TARGET_{target}_LINKER"), target_linker);
         }
-        if self.is_fuse_ld_lld(target) {
-            rustflags.arg("-Clink-args=-fuse-ld=lld");
-        }
-        self.lld_flags(target).for_each(|flag| {
+        // We want to set -Clinker using Cargo, therefore we only call `linker_flags` and not
+        // `linker_args` here.
+        linker_flags(self, target, LldThreads::Yes).into_iter().for_each(|flag| {
+            rustflags.arg(&flag);
+        });
+        linker_args(self, target, LldThreads::Yes).into_iter().for_each(|flag| {
             rustdocflags.arg(&flag);
         });
 

src/bootstrap/src/lib.rs

@@ -1271,21 +1271,6 @@ impl Build {
         self.config.use_lld && !target.is_msvc()
     }
 
-    fn lld_flags(&self, target: TargetSelection) -> impl Iterator<Item = String> {
-        let mut options = [None, None];
-
-        if self.config.use_lld {
-            if self.is_fuse_ld_lld(target) {
-                options[0] = Some("-Clink-arg=-fuse-ld=lld".to_string());
-            }
-
-            let no_threads = helpers::lld_flag_no_threads(target.contains("windows"));
-            options[1] = Some(format!("-Clink-arg=-Wl,{no_threads}"));
-        }
-
-        IntoIterator::into_iter(options).flatten()
-    }
-
     /// Returns if this target should statically link the C runtime, if specified
     fn crt_static(&self, target: TargetSelection) -> Option<bool> {
         if target.contains("pc-windows-msvc") {

src/bootstrap/src/utils/helpers.rs

@@ -5,7 +5,7 @@
 
 use build_helper::util::fail;
 use std::env;
-use std::ffi::{OsStr, OsString};
+use std::ffi::OsStr;
 use std::fs;
 use std::io;
 use std::path::{Path, PathBuf};
@@ -476,22 +476,46 @@ pub enum LldThreads {
     No,
 }
 
-pub fn add_rustdoc_lld_flags(
-    cmd: &mut Command,
+/// Returns the linker arguments for rustc/rustdoc for the given builder and target.
+pub fn linker_args(
     builder: &Builder<'_>,
     target: TargetSelection,
     lld_threads: LldThreads,
-) {
-    cmd.args(build_rustdoc_lld_flags(builder, target, lld_threads));
+) -> Vec<String> {
+    let mut args = linker_flags(builder, target, lld_threads);
+
+    if let Some(linker) = builder.linker(target) {
+        args.push(format!("-Clinker={}", linker.display()));
+    }
+
+    args
 }
 
-pub fn add_rustdoc_cargo_lld_flags(
+/// Returns the linker arguments for rustc/rustdoc for the given builder and target, without the
+/// -Clinker flag.
+pub fn linker_flags(
+    builder: &Builder<'_>,
+    target: TargetSelection,
+    lld_threads: LldThreads,
+) -> Vec<String> {
+    let mut args = vec![];
+    if builder.is_fuse_ld_lld(target) {
+        args.push(String::from("-Clink-arg=-fuse-ld=lld"));
+
+        if matches!(lld_threads, LldThreads::No) {
+            args.push(format!("-Clink-arg=-Wl,{}", lld_flag_no_threads(target.is_msvc())));
+        }
+    }
+    args
+}
+
+pub fn add_rustdoc_cargo_linker_args(
     cmd: &mut Command,
     builder: &Builder<'_>,
     target: TargetSelection,
     lld_threads: LldThreads,
 ) {
-    let args = build_rustdoc_lld_flags(builder, target, lld_threads);
+    let args = linker_args(builder, target, lld_threads);
     let mut flags = cmd
         .get_envs()
         .find_map(|(k, v)| if k == OsStr::new("RUSTDOCFLAGS") { v } else { None })
@@ -507,27 +531,3 @@ pub fn add_rustdoc_cargo_lld_flags(
         cmd.env("RUSTDOCFLAGS", flags);
     }
 }
-
-fn build_rustdoc_lld_flags(
-    builder: &Builder<'_>,
-    target: TargetSelection,
-    lld_threads: LldThreads,
-) -> Vec<OsString> {
-    let mut args = vec![];
-
-    if let Some(linker) = builder.linker(target) {
-        let mut flag = std::ffi::OsString::from("-Clinker=");
-        flag.push(linker);
-        args.push(flag);
-    }
-    if builder.is_fuse_ld_lld(target) {
-        args.push(OsString::from("-Clink-arg=-fuse-ld=lld"));
-        if matches!(lld_threads, LldThreads::No) {
-            args.push(OsString::from(format!(
-                "-Clink-arg=-Wl,{}",
-                lld_flag_no_threads(target.contains("windows"))
-            )));
-        }
-    }
-    args
-}