bootstrap: do not rely on LIBRARY_PATH env variable

Clang will not respect this value in cross configurations.

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

@@ -24,8 +24,8 @@ use crate::core::config::flags::{Subcommand, get_completion};
 use crate::utils::build_stamp::{self, BuildStamp};
 use crate::utils::exec::{BootstrapCommand, command};
 use crate::utils::helpers::{
-    self, LldThreads, add_link_lib_path, add_rustdoc_cargo_linker_args, dylib_path, dylib_path_var,
-    linker_args, linker_flags, t, target_supports_cranelift_backend, up_to_date,
+    self, LldThreads, add_rustdoc_cargo_linker_args, dylib_path, dylib_path_var, linker_args,
+    linker_flags, t, target_supports_cranelift_backend, up_to_date,
 };
 use crate::utils::render_tests::{add_flags_and_try_run_tests, try_run_tests};
 use crate::{CLang, DocTests, GitRepo, Mode, PathSet, envify};
@@ -1975,11 +1975,17 @@ NOTE: if you're sure you want to do this, please open an issue as to why. In the
             // Tests that use compiler libraries may inherit the `-lLLVM` link
             // requirement, but the `-L` library path is not propagated across
             // separate compilations. We can add LLVM's library path to the
-            // platform-specific environment variable as a workaround.
+            // rustc args as a workaround.
             if !builder.config.dry_run() && suite.ends_with("fulldeps") {
                 let llvm_libdir =
                     command(&llvm_config).arg("--libdir").run_capture_stdout(builder).stdout();
-                add_link_lib_path(vec![llvm_libdir.trim().into()], &mut cmd);
+                let mut rustflags = env::var("RUSTFLAGS").unwrap_or_default();
+                if target.is_msvc() {
+                    rustflags.push_str(&format!("-Clink-arg=-LIBPATH:{llvm_libdir}"));
+                } else {
+                    rustflags.push_str(&format!("-Clink-arg=-L{llvm_libdir}"));
+                }
+                cmd.env("RUSTFLAGS", rustflags);
             }
 
             if !builder.config.dry_run() && matches!(mode, "run-make" | "coverage-run") {

src/bootstrap/src/core/builder/cargo.rs

@@ -8,9 +8,7 @@ use crate::core::build_steps::{compile, test};
 use crate::core::config::SplitDebuginfo;
 use crate::core::config::flags::Color;
 use crate::utils::build_stamp;
-use crate::utils::helpers::{
-    self, LldThreads, add_link_lib_path, check_cfg_arg, linker_args, linker_flags,
-};
+use crate::utils::helpers::{self, LldThreads, check_cfg_arg, linker_args, linker_flags};
 use crate::{
     BootstrapCommand, CLang, Compiler, DocTests, DryRun, EXTRA_CHECK_CFGS, GitRepo, Mode,
     TargetSelection, command, prepare_behaviour_dump_dir, t,
@@ -947,12 +945,16 @@ impl Builder<'_> {
         // Tools that use compiler libraries may inherit the `-lLLVM` link
         // requirement, but the `-L` library path is not propagated across
         // separate Cargo projects. We can add LLVM's library path to the
-        // platform-specific environment variable as a workaround.
+        // rustc args as a workaround.
         if mode == Mode::ToolRustc || mode == Mode::Codegen {
             if let Some(llvm_config) = self.llvm_config(target) {
                 let llvm_libdir =
                     command(llvm_config).arg("--libdir").run_capture_stdout(self).stdout();
-                add_link_lib_path(vec![llvm_libdir.trim().into()], &mut cargo);
+                if target.is_msvc() {
+                    rustflags.arg(&format!("-Clink-arg=-LIBPATH:{llvm_libdir}"));
+                } else {
+                    rustflags.arg(&format!("-Clink-arg=-L{llvm_libdir}"));
+                }
             }
         }
 

src/bootstrap/src/utils/helpers.rs

@@ -106,31 +106,6 @@ pub fn add_dylib_path(path: Vec<PathBuf>, cmd: &mut BootstrapCommand) {
     cmd.env(dylib_path_var(), t!(env::join_paths(list)));
 }
 
-/// Adds a list of lookup paths to `cmd`'s link library lookup path.
-pub fn add_link_lib_path(path: Vec<PathBuf>, cmd: &mut BootstrapCommand) {
-    let mut list = link_lib_path();
-    for path in path {
-        list.insert(0, path);
-    }
-    cmd.env(link_lib_path_var(), t!(env::join_paths(list)));
-}
-
-/// Returns the environment variable which the link library lookup path
-/// resides in for this platform.
-fn link_lib_path_var() -> &'static str {
-    if cfg!(target_env = "msvc") { "LIB" } else { "LIBRARY_PATH" }
-}
-
-/// Parses the `link_lib_path_var()` environment variable, returning a list of
-/// paths that are members of this lookup path.
-fn link_lib_path() -> Vec<PathBuf> {
-    let var = match env::var_os(link_lib_path_var()) {
-        Some(v) => v,
-        None => return vec![],
-    };
-    env::split_paths(&var).collect()
-}
-
 pub struct TimeIt(bool, Instant);
 
 /// Returns an RAII structure that prints out how long it took to drop.