Unify passing of flags to rustdoc

src/bootstrap/src/bin/rustdoc.rs

@@ -3,7 +3,6 @@
 //! See comments in `src/bootstrap/rustc.rs` for more information.
 
 use std::env;
-use std::ffi::OsString;
 use std::path::PathBuf;
 use std::process::Command;
 
@@ -52,15 +51,6 @@ fn main() {
     if env::var_os("RUSTC_FORCE_UNSTABLE").is_some() {
         cmd.arg("-Z").arg("force-unstable-if-unmarked");
     }
-    if let Some(linker) = env::var_os("RUSTDOC_LINKER") {
-        let mut arg = OsString::from("-Clinker=");
-        arg.push(&linker);
-        cmd.arg(arg);
-    }
-    if let Ok(no_threads) = env::var("RUSTDOC_LLD_NO_THREADS") {
-        cmd.arg("-Clink-arg=-fuse-ld=lld");
-        cmd.arg(format!("-Clink-arg=-Wl,{no_threads}"));
-    }
     // Cargo doesn't pass RUSTDOCFLAGS to proc_macros:
     // https://github.com/rust-lang/cargo/issues/4423
     // Thus, if we are on stage 0, we explicitly set `--cfg=bootstrap`.

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

@@ -29,7 +29,7 @@ use crate::utils;
 use crate::utils::cache::{Interned, INTERNER};
 use crate::utils::exec::BootstrapCommand;
 use crate::utils::helpers::{
-    self, add_link_lib_path, dylib_path, dylib_path_var, output, t,
+    self, add_link_lib_path, add_rustdoc_lld_flags, dylib_path, dylib_path_var, output, t,
     target_supports_cranelift_backend, up_to_date,
 };
 use crate::utils::render_tests::{add_flags_and_try_run_tests, try_run_tests};
@@ -862,15 +862,8 @@ impl Step for RustdocTheme {
             .env("CFG_RELEASE_CHANNEL", &builder.config.channel)
             .env("RUSTDOC_REAL", builder.rustdoc(self.compiler))
             .env("RUSTC_BOOTSTRAP", "1");
-        if let Some(linker) = builder.linker(self.compiler.host) {
-            cmd.env("RUSTDOC_LINKER", linker);
-        }
-        if builder.is_fuse_ld_lld(self.compiler.host) {
-            cmd.env(
-                "RUSTDOC_LLD_NO_THREADS",
-                helpers::lld_flag_no_threads(self.compiler.host.contains("windows")),
-            );
-        }
+        add_rustdoc_lld_flags(&mut cmd, builder, self.compiler.host, true);
+
         builder.run_delaying_failure(&mut cmd);
     }
 }

src/bootstrap/src/core/builder.rs

@@ -18,7 +18,9 @@ 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, exe, libdir, output, t};
+use crate::utils::helpers::{
+    self, add_dylib_path, add_link_lib_path, add_rustdoc_lld_flags, exe, libdir, output, t,
+};
 use crate::Crate;
 use crate::EXTRA_CHECK_CFGS;
 use crate::{Build, CLang, DocTests, GitRepo, Mode};
@@ -1173,9 +1175,7 @@ impl<'a> Builder<'a> {
         cmd.env_remove("MAKEFLAGS");
         cmd.env_remove("MFLAGS");
 
-        if let Some(linker) = self.linker(compiler.host) {
-            cmd.env("RUSTDOC_LINKER", linker);
-        }
+        add_rustdoc_lld_flags(&mut cmd, self, compiler.host, false);
         cmd
     }
 

src/bootstrap/src/utils/helpers.rs

@@ -470,3 +470,22 @@ pub fn extract_beta_rev(version: &str) -> Option<String> {
 
     count
 }
+
+pub fn add_rustdoc_lld_flags(
+    cmd: &mut Command,
+    builder: &Builder<'_>,
+    target: TargetSelection,
+    single_threaded: bool,
+) {
+    if let Some(linker) = builder.linker(target) {
+        let mut flag = std::ffi::OsString::from("-Clinker=");
+        flag.push(linker);
+        cmd.arg(flag);
+    }
+    if builder.is_fuse_ld_lld(target) {
+        cmd.arg("-Clink-arg=-fuse-ld=lld");
+        if single_threaded {
+            cmd.arg(format!("-Clink-arg=-Wl,{}", lld_flag_no_threads(target.contains("windows"))));
+        }
+    }
+}