Add support for link-flavor rust-lld for iOS, tvOS and watchOS

This adds support for rust-lld for Apple *OS targets.

This was tested against targets "aarch64-apple-ios" and "aarch64-apple-ios-sim".

For targets "armv7-apple-ios" and "armv7s-apple-ios", it doesn't link because of
"symbols.o" not being generated with the correct CPU subtype (changes in
the "object" crate needs to be done to support it).

1 files changed, 10 insertions, 7 deletions

diff --git a/compiler/rustc_codegen_ssa/src/back/link.rs b/compiler/rustc_codegen_ssa/src/back/link.rs
index 13a7b6be947..8197872bf30 100644
--- a/compiler/rustc_codegen_ssa/src/back/link.rs
+++ b/compiler/rustc_codegen_ssa/src/back/link.rs
@@ -2675,7 +2675,7 @@ fn add_apple_sdk(cmd: &mut dyn Linker, sess: &Session, flavor: LinkerFlavor) {
     let llvm_target = &sess.target.llvm_target;
     if sess.target.vendor != "apple"
         || !matches!(os.as_ref(), "ios" | "tvos" | "watchos")
-        || flavor != LinkerFlavor::Gcc
+        || (flavor != LinkerFlavor::Gcc && flavor != LinkerFlavor::Lld(LldFlavor::Ld64))
     {
         return;
     }
@@ -2706,13 +2706,16 @@ fn add_apple_sdk(cmd: &mut dyn Linker, sess: &Session, flavor: LinkerFlavor) {
             return;
         }
     };
-    if llvm_target.contains("macabi") {
-        cmd.args(&["-target", llvm_target])
-    } else {
-        let arch_name = llvm_target.split('-').next().expect("LLVM target must have a hyphen");
-        cmd.args(&["-arch", arch_name])
+
+    match flavor {
+        LinkerFlavor::Gcc => {
+            cmd.args(&["-isysroot", &sdk_root, "-Wl,-syslibroot", &sdk_root]);
+        }
+        LinkerFlavor::Lld(LldFlavor::Ld64) => {
+            cmd.args(&["-syslibroot", &sdk_root]);
+        }
+        _ => unreachable!(),
     }
-    cmd.args(&["-isysroot", &sdk_root, "-Wl,-syslibroot", &sdk_root]);
 }
 
 fn get_apple_sdk_root(sdk_name: &str) -> Result<String, String> {