Merge pull request #487 from artemcm/53workaroundImplementationOnly

Workaround a compiler error with SPI public type using `implementationOnly` properties.

Author: artemcm

Sources/SwiftDriver/SwiftScan/SwiftScan.swift

@@ -55,7 +55,7 @@ public enum DependencyScanningError: Error, DiagnosticData {
 }
 
 /// Wrapper for libSwiftScan, taking care of initialization, shutdown, and dispatching dependency scanning queries.
-@_spi(Testing) public final class SwiftScan {
+internal final class SwiftScan {
   /// The path to the libSwiftScan dylib.
   let path: AbsolutePath
 
@@ -197,6 +197,23 @@ public enum DependencyScanningError: Error, DiagnosticData {
   }
 }
 
+// Used for testing purposes only
+@_spi(Testing) public extension Driver {
+  func querySupportedArgumentsForTest() throws -> Set<String>? {
+    // If a capable libSwiftScan is found, manually ensure we can get the supported arguments
+    let scanLibPath = try Self.getScanLibPath(of: toolchain,
+                                              hostTriple: hostTriple,
+                                              env: env)
+    if fileSystem.exists(scanLibPath) {
+      let libSwiftScanInstance = try SwiftScan(dylib: scanLibPath)
+      if libSwiftScanInstance.canQuerySupportedArguments() {
+        return try libSwiftScanInstance.querySupportedArguments()
+      }
+    }
+    return nil
+  }
+}
+
 private extension swiftscan_functions_t {
   init(_ swiftscan: DLHandle) throws {
     self.init()

Tests/SwiftDriverTests/SwiftDriverTests.swift

@@ -3124,16 +3124,8 @@ final class SwiftDriverTests: XCTestCase {
     do {
       let driver = try Driver(args: ["swift", "-target", "arm64-apple-ios12.0",
                                      "-resource-dir", "baz"])
-      // If a capable libSwiftScan is found, manually ensure we can get the supported arguments
-      let scanLibPath = try Driver.getScanLibPath(of: driver.toolchain,
-                                                  hostTriple: driver.hostTriple,
-                                                  env: ProcessEnv.vars)
-      if localFileSystem.exists(scanLibPath) {
-        let libSwiftScanInstance = try SwiftScan(dylib: scanLibPath)
-        if libSwiftScanInstance.canQuerySupportedArguments() {
-          let supportedArguments = try libSwiftScanInstance.querySupportedArguments()
-          XCTAssertTrue(supportedArguments.contains("emit-module"))
-        }
+      if let libraryBasedResult = try driver.querySupportedArgumentsForTest() {
+        XCTAssertTrue(libraryBasedResult.contains("emit-module"))
       }
     }
     do {