Handle external LLVM config

Author: Kobzol

src/bootstrap/src/core/config/config.rs

@@ -954,45 +954,15 @@ impl Config {
             }
         }
 
-        for (target, linker_override) in default_linux_linker_overrides() {
-            // If the user overrode the default Linux linker, do not apply bootstrap defaults
-            if targets_with_user_linker_override.contains(&target) {
-                continue;
-            }
-            let default_linux_linker_override = match linker_override {
-                DefaultLinuxLinkerOverride::Off => continue,
-                DefaultLinuxLinkerOverride::SelfContainedLldCc => {
-                    // If we automatically default to the self-contained LLD linker,
-                    // we also need to handle the rust.lld option.
-                    match rust_lld_enabled {
-                        // If LLD was not enabled explicitly, we enable it
-                        None => {
-                            lld_enabled = true;
-                            Some(DefaultLinuxLinkerOverride::SelfContainedLldCc)
-                        }
-                        // If it was enabled already, we don't need to do anything
-                        Some(true) => Some(DefaultLinuxLinkerOverride::SelfContainedLldCc),
-                        // If it was explicitly disabled, we do not apply the
-                        // linker override
-                        Some(false) => None,
-                    }
-                }
-            };
-            if let Some(linker_override) = default_linux_linker_override {
-                target_config
-                    .entry(TargetSelection::from_user(&target))
-                    .or_default()
-                    .default_linker_linux_override = linker_override;
-            }
-        }
-
         let llvm_from_ci = parse_download_ci_llvm(
             &dwn_ctx,
             &rust_info,
             &download_rustc_commit,
             llvm_download_ci_llvm,
             llvm_assertions,
         );
+        let is_host_system_llvm =
+            is_system_llvm(&target_config, llvm_from_ci, host_target, host_target);
 
         if llvm_from_ci {
             let warn = |option: &str| {
@@ -1040,6 +1010,41 @@ impl Config {
             build_target.llvm_filecheck = Some(ci_llvm_bin.join(exe("FileCheck", host_target)));
         }
 
+        for (target, linker_override) in default_linux_linker_overrides() {
+            // If the user overrode the default Linux linker, do not apply bootstrap defaults
+            if targets_with_user_linker_override.contains(&target) {
+                continue;
+            }
+
+            let default_linux_linker_override = match linker_override {
+                DefaultLinuxLinkerOverride::Off => continue,
+                DefaultLinuxLinkerOverride::SelfContainedLldCc => {
+                    // If we automatically default to the self-contained LLD linker,
+                    // we also need to handle the rust.lld option.
+                    match rust_lld_enabled {
+                        // If LLD was not enabled explicitly, we enable it, unless LLVM config has
+                        // been set
+                        None if !is_host_system_llvm => {
+                            lld_enabled = true;
+                            Some(DefaultLinuxLinkerOverride::SelfContainedLldCc)
+                        }
+                        None => None,
+                        // If it was enabled already, we don't need to do anything
+                        Some(true) => Some(DefaultLinuxLinkerOverride::SelfContainedLldCc),
+                        // If it was explicitly disabled, we do not apply the
+                        // linker override
+                        Some(false) => None,
+                    }
+                }
+            };
+            if let Some(linker_override) = default_linux_linker_override {
+                target_config
+                    .entry(TargetSelection::from_user(&target))
+                    .or_default()
+                    .default_linker_linux_override = linker_override;
+            }
+        }
+
         let initial_rustfmt = build_rustfmt.or_else(|| maybe_download_rustfmt(&dwn_ctx, &out));
 
         if matches!(bootstrap_override_lld, BootstrapOverrideLld::SelfContained)
@@ -1051,7 +1056,7 @@ impl Config {
             );
         }
 
-        if lld_enabled && is_system_llvm(&dwn_ctx, &target_config, llvm_from_ci, host_target) {
+        if lld_enabled && is_host_system_llvm {
             panic!("Cannot enable LLD with `rust.lld = true` when using external llvm-config.");
         }
 
@@ -1845,8 +1850,7 @@ impl Config {
     ///
     /// NOTE: this is not the same as `!is_rust_llvm` when `llvm_has_patches` is set.
     pub fn is_system_llvm(&self, target: TargetSelection) -> bool {
-        let dwn_ctx = DownloadContext::from(self);
-        is_system_llvm(dwn_ctx, &self.target_config, self.llvm_from_ci, target)
+        is_system_llvm(&self.target_config, self.llvm_from_ci, self.host_target, target)
     }
 
     /// Returns `true` if this is our custom, patched, version of LLVM.
@@ -2449,16 +2453,15 @@ pub fn submodules_(submodules: &Option<bool>, rust_info: &channel::GitInfo) -> b
 /// In particular, we expect llvm sources to be available when this is false.
 ///
 /// NOTE: this is not the same as `!is_rust_llvm` when `llvm_has_patches` is set.
-pub fn is_system_llvm<'a>(
-    dwn_ctx: impl AsRef<DownloadContext<'a>>,
+pub fn is_system_llvm(
     target_config: &HashMap<TargetSelection, Target>,
     llvm_from_ci: bool,
+    host_target: TargetSelection,
     target: TargetSelection,
 ) -> bool {
-    let dwn_ctx = dwn_ctx.as_ref();
     match target_config.get(&target) {
         Some(Target { llvm_config: Some(_), .. }) => {
-            let ci_llvm = llvm_from_ci && is_host_target(&dwn_ctx.host_target, &target);
+            let ci_llvm = llvm_from_ci && is_host_target(&host_target, &target);
             !ci_llvm
         }
         // We're building from the in-tree src/llvm-project sources.