Generalize setting rust-lld as the default linker on Linux

Author: Kobzol

compiler/rustc_target/src/spec/base/linux_musl.rs

@@ -1,11 +1,22 @@
-use crate::spec::{LinkSelfContainedDefault, TargetOptions, base, crt_objects};
+use crate::spec::{
+    Cc, LinkSelfContainedDefault, LinkerFlavor, Lld, TargetOptions, base, crt_objects,
+};
 
 pub(crate) fn opts() -> TargetOptions {
-    TargetOptions {
+    let mut base = TargetOptions {
         env: "musl".into(),
         pre_link_objects_self_contained: crt_objects::pre_musl_self_contained(),
         post_link_objects_self_contained: crt_objects::post_musl_self_contained(),
         link_self_contained: LinkSelfContainedDefault::InferredForMusl,
         ..base::linux::opts()
+    };
+
+    // When we're asked to use the `rust-lld` linker by default, set the appropriate lld-using
+    // linker flavor, and self-contained linker component.
+    if option_env!("CFG_DEFAULT_LINKER_SELF_CONTAINED_LLD_CC").is_some() {
+        base.linker_flavor = LinkerFlavor::Gnu(Cc::Yes, Lld::Yes);
+        base.link_self_contained = crate::spec::LinkSelfContainedDefault::with_linker();
     }
+
+    base
 }

compiler/rustc_target/src/spec/targets/x86_64_unknown_linux_gnu.rs

@@ -20,13 +20,6 @@ pub(crate) fn target() -> Target {
         | SanitizerSet::THREAD;
     base.supports_xray = true;
 
-    // When we're asked to use the `rust-lld` linker by default, set the appropriate lld-using
-    // linker flavor, and self-contained linker component.
-    if option_env!("CFG_USE_SELF_CONTAINED_LINKER").is_some() {
-        base.linker_flavor = LinkerFlavor::Gnu(Cc::Yes, Lld::Yes);
-        base.link_self_contained = crate::spec::LinkSelfContainedDefault::with_linker();
-    }
-
     Target {
         llvm_target: "x86_64-unknown-linux-gnu".into(),
         metadata: TargetMetadata {

src/bootstrap/src/core/build_steps/compile.rs

@@ -1352,7 +1352,7 @@ pub fn rustc_cargo_env(builder: &Builder<'_>, cargo: &mut Cargo, target: TargetS
 
     // Enable rustc's env var for `rust-lld` when requested.
     if builder.config.lld_enabled {
-        cargo.env("CFG_USE_SELF_CONTAINED_LINKER", "1");
+        cargo.env("CFG_DEFAULT_LINKER_SELF_CONTAINED_LLD_CC", "1");
     }
 
     if builder.config.rust_verify_llvm_ir {