Move knowledge of SDK names to rustc_target

Also make the SDK name be the same casing as used in the file system.

compiler/rustc_codegen_ssa/messages.ftl

@@ -337,8 +337,6 @@ codegen_ssa_unknown_atomic_ordering = unknown ordering in atomic intrinsic
 
 codegen_ssa_unknown_reuse_kind = unknown cgu-reuse-kind `{$kind}` specified
 
-codegen_ssa_unsupported_arch = unsupported arch `{$arch}` for os `{$os}`
-
 codegen_ssa_unsupported_link_self_contained = option `-C link-self-contained` is not supported on this target
 
 codegen_ssa_use_cargo_directive = use the `cargo:rustc-link-lib` directive to specify the native libraries to link with Cargo (see https://doc.rust-lang.org/cargo/reference/build-scripts.html#rustc-link-lib)

compiler/rustc_codegen_ssa/src/back/link.rs

@@ -3123,9 +3123,7 @@ fn add_apple_link_args(cmd: &mut dyn Linker, sess: &Session, flavor: LinkerFlavo
 }
 
 fn add_apple_sdk(cmd: &mut dyn Linker, sess: &Session, flavor: LinkerFlavor) -> Option<PathBuf> {
-    let arch = &sess.target.arch;
     let os = &sess.target.os;
-    let llvm_target = &sess.target.llvm_target;
     if sess.target.vendor != "apple"
         || !matches!(os.as_ref(), "ios" | "tvos" | "watchos" | "visionos" | "macos")
         || !matches!(flavor, LinkerFlavor::Darwin(..))
@@ -3137,30 +3135,8 @@ fn add_apple_sdk(cmd: &mut dyn Linker, sess: &Session, flavor: LinkerFlavor) ->
         return None;
     }
 
-    let sdk_name = match (arch.as_ref(), os.as_ref()) {
-        ("aarch64", "tvos") if llvm_target.ends_with("-simulator") => "appletvsimulator",
-        ("aarch64", "tvos") => "appletvos",
-        ("x86_64", "tvos") => "appletvsimulator",
-        ("arm", "ios") => "iphoneos",
-        ("aarch64", "ios") if llvm_target.contains("macabi") => "macosx",
-        ("aarch64", "ios") if llvm_target.ends_with("-simulator") => "iphonesimulator",
-        ("aarch64", "ios") => "iphoneos",
-        ("x86", "ios") => "iphonesimulator",
-        ("x86_64", "ios") if llvm_target.contains("macabi") => "macosx",
-        ("x86_64", "ios") => "iphonesimulator",
-        ("x86_64", "watchos") => "watchsimulator",
-        ("arm64_32", "watchos") => "watchos",
-        ("aarch64", "watchos") if llvm_target.ends_with("-simulator") => "watchsimulator",
-        ("aarch64", "watchos") => "watchos",
-        ("aarch64", "visionos") if llvm_target.ends_with("-simulator") => "xrsimulator",
-        ("aarch64", "visionos") => "xros",
-        ("arm", "watchos") => "watchos",
-        (_, "macos") => "macosx",
-        _ => {
-            sess.dcx().emit_err(errors::UnsupportedArch { arch, os });
-            return None;
-        }
-    };
+    let sdk_name = rustc_target::spec::apple_sdk_name(&sess.target);
+
     let sdk_root = match get_apple_sdk_root(sdk_name) {
         Ok(s) => s,
         Err(e) => {
@@ -3197,7 +3173,7 @@ fn get_apple_sdk_root(sdk_name: &str) -> Result<String, errors::AppleSdkRootErro
     // can fall back to checking for xcrun on PATH.)
     if let Ok(sdkroot) = env::var("SDKROOT") {
         let p = Path::new(&sdkroot);
-        match sdk_name {
+        match &*sdk_name.to_lowercase() {
             // Ignore `SDKROOT` if it's clearly set for the wrong platform.
             "appletvos"
                 if sdkroot.contains("TVSimulator.platform")
@@ -3228,18 +3204,21 @@ fn get_apple_sdk_root(sdk_name: &str) -> Result<String, errors::AppleSdkRootErro
             _ => return Ok(sdkroot),
         }
     }
-    let res =
-        Command::new("xcrun").arg("--show-sdk-path").arg("-sdk").arg(sdk_name).output().and_then(
-            |output| {
-                if output.status.success() {
-                    Ok(String::from_utf8(output.stdout).unwrap())
-                } else {
-                    let error = String::from_utf8(output.stderr);
-                    let error = format!("process exit with error: {}", error.unwrap());
-                    Err(io::Error::new(io::ErrorKind::Other, &error[..]))
-                }
-            },
-        );
+
+    let res = Command::new("xcrun")
+        .arg("--show-sdk-path")
+        .arg("-sdk")
+        .arg(sdk_name.to_lowercase())
+        .output()
+        .and_then(|output| {
+            if output.status.success() {
+                Ok(String::from_utf8(output.stdout).unwrap())
+            } else {
+                let error = String::from_utf8(output.stderr);
+                let error = format!("process exit with error: {}", error.unwrap());
+                Err(io::Error::new(io::ErrorKind::Other, &error[..]))
+            }
+        });
 
     match res {
         Ok(output) => Ok(output.trim().to_string()),

compiler/rustc_codegen_ssa/src/errors.rs

@@ -532,13 +532,6 @@ pub enum ExtractBundledLibsError<'a> {
     ExtractSection { rlib: &'a Path, error: Box<dyn std::error::Error> },
 }
 
-#[derive(Diagnostic)]
-#[diag(codegen_ssa_unsupported_arch)]
-pub(crate) struct UnsupportedArch<'a> {
-    pub arch: &'a str,
-    pub os: &'a str,
-}
-
 #[derive(Diagnostic)]
 pub(crate) enum AppleSdkRootError<'a> {
     #[diag(codegen_ssa_apple_sdk_error_sdk_path)]

compiler/rustc_target/src/spec/base/apple/mod.rs

@@ -158,6 +158,23 @@ pub(crate) fn base(
     (opts, llvm_target(os, arch, abi), arch.target_arch())
 }
 
+pub fn sdk_name(target: &Target) -> &'static str {
+    match (&*target.os, &*target.abi) {
+        ("ios", "") => "iPhoneOS",
+        ("ios", "sim") => "iPhoneSimulator",
+        // Mac Catalyst uses the macOS SDK
+        ("ios", "macabi") => "MacOSX",
+        ("macos", "") => "MacOSX",
+        ("tvos", "") => "AppleTVOS",
+        ("tvos", "sim") => "AppleTVSimulator",
+        ("visionos", "") => "XROS",
+        ("visionos", "sim") => "XRSimulator",
+        ("watchos", "") => "WatchOS",
+        ("watchos", "sim") => "WatchSimulator",
+        (os, abi) => unreachable!("invalid os '{os}' / abi '{abi}' combination for Apple target"),
+    }
+}
+
 pub fn platform(target: &Target) -> Option<u32> {
     Some(match (&*target.os, &*target.abi) {
         ("macos", _) => object::macho::PLATFORM_MACOS,

compiler/rustc_target/src/spec/mod.rs

@@ -61,7 +61,7 @@ pub mod crt_objects;
 mod base;
 pub use base::apple::{
     deployment_target_for_target as current_apple_deployment_target,
-    platform as current_apple_platform,
+    platform as current_apple_platform, sdk_name as apple_sdk_name,
 };
 pub use base::avr_gnu::ef_avr_arch;