Teach spm about arvm7em and os none

- Adds preliminary knowledge of armv7em and no os environments to spm.
  Future diffs will be required to fully support these triples. This
  change allows a armv7em-apple-none-macho build via a destination v3
  bundle to make it further through spm.

Author: rauhul

Sources/Basics/Triple.swift

@@ -48,6 +48,7 @@ public struct Triple: Encodable, Equatable, Sendable {
         case aarch64
         case amd64
         case armv7
+        case armv7em
         case armv6
         case armv5
         case arm
@@ -73,6 +74,8 @@ public struct Triple: Encodable, Equatable, Sendable {
         case windows
         case wasi
         case openbsd
+        // 'OS' suffix purely to avoid name clash with Optional.none
+        case noneOS = "none"
     }
 
     public enum ABI: Encodable, Equatable, RawRepresentable, Sendable {
@@ -259,6 +262,11 @@ extension Triple {
             return ".dll"
         case .wasi:
             return ".wasm"
+        case .noneOS:
+            // Better as dynamic error or "fatalError", but it is a larger
+            // undertaking to teach spm that dylibs are not available on some
+            // platforms.
+            return ".os-none-dynamic-library"
         }
     }
 
@@ -272,6 +280,8 @@ extension Triple {
             return ".wasm"
         case .windows:
             return ".exe"
+        case .noneOS:
+            return ""
         }
     }
 

Sources/SPMBuildCore/BinaryTarget+Extensions.swift

@@ -97,7 +97,7 @@ extension Triple.OS {
     /// Returns a representation of the receiver that can be compared with platform strings declared in an XCFramework.
     fileprivate var asXCFrameworkPlatformString: String? {
         switch self {
-        case .darwin, .linux, .wasi, .windows, .openbsd:
+        case .darwin, .linux, .wasi, .windows, .openbsd, .noneOS:
             return nil // XCFrameworks do not support any of these platforms today.
         case .macOS:
             return "macos"