lib/systems: use Darwin architecture names for config and uname

`aarch64-apple-darwin` no longer works with LLVM 20.

lib/systems/default.nix

@@ -209,6 +209,8 @@ let
                 "ppc${optionalString final.isLittleEndian "le"}"
               else if final.isMips64 then
                 "mips64" # endianness is *not* included on mips64
+              else if final.isDarwin then
+                final.darwinArch
               else
                 final.parsed.cpu.name;
 
@@ -329,12 +331,7 @@ let
             else
               final.parsed.cpu.name;
 
-          darwinArch =
-            {
-              armv7a = "armv7";
-              aarch64 = "arm64";
-            }
-            .${final.parsed.cpu.name} or final.parsed.cpu.name;
+          darwinArch = parse.darwinArch final.parsed.cpu;
 
           darwinPlatform =
             if final.isMacOS then
@@ -488,8 +485,8 @@ let
                   }
                   .${cpu.name} or cpu.name;
                 vendor_ = final.rust.platform.vendor;
-                # TODO: deprecate args.rustc in favour of args.rust after 23.05 is EOL.
               in
+              # TODO: deprecate args.rustc in favour of args.rust after 23.05 is EOL.
               args.rust.rustcTarget or args.rustc.config or (
                 # Rust uses `wasm32-wasip?` rather than `wasm32-unknown-wasi`.
                 # We cannot know which subversion does the user want, and

lib/systems/examples.nix

@@ -276,7 +276,7 @@ rec {
   #
 
   iphone64 = {
-    config = "aarch64-apple-ios";
+    config = "arm64-apple-ios";
     # config = "aarch64-apple-darwin14";
     darwinSdkVersion = "14.3";
     xcodeVer = "12.3";
@@ -295,7 +295,7 @@ rec {
   };
 
   aarch64-darwin = {
-    config = "aarch64-apple-darwin";
+    config = "arm64-apple-darwin";
     xcodePlatform = "MacOSX";
     platform = { };
   };

lib/systems/parse.nix

@@ -396,6 +396,12 @@ rec {
         significantByte = littleEndian;
         family = "javascript";
       };
+    }
+    // {
+      # aliases
+      # Apple architecture name, as used by `darwinArch`; required by
+      # LLVM ≥ 20.
+      arm64 = cpuTypes.aarch64;
     };
 
   # GNU build systems assume that older NetBSD architectures are using a.out.
@@ -921,6 +927,8 @@ rec {
 
   kernelName = kernel: kernel.name + toString (kernel.version or "");
 
+  darwinArch = cpu: if cpu.name == "aarch64" then "arm64" else cpu.name;
+
   doubleFromSystem =
     {
       cpu,
@@ -949,8 +957,9 @@ rec {
         kernel.name == "netbsd" && gnuNetBSDDefaultExecFormat cpu != kernel.execFormat
       ) kernel.execFormat.name;
       optAbi = optionalString (abi != abis.unknown) "-${abi.name}";
+      cpuName = if kernel.families ? darwin then darwinArch cpu else cpu.name;
     in
-    "${cpu.name}-${vendor.name}-${kernelName kernel}${optExecFormat}${optAbi}";
+    "${cpuName}-${vendor.name}-${kernelName kernel}${optExecFormat}${optAbi}";
 
   ################################################################################