Add support for lowering metatype parameters

Author: DougGregor

Sources/JExtractSwift/Swift2JavaTranslator+FunctionLowering.swift

@@ -127,9 +127,29 @@ extension Swift2JavaTranslator {
     parameterName: String
   ) throws -> LoweredParameters {
     switch type {
-    case .function, .metatype, .optional:
+    case .function, .optional:
       throw LoweringError.unhandledType(type)
 
+    case .metatype(let instanceType):
+      return LoweredParameters(
+        cdeclToOriginal: .unsafeCastPointer(
+          .passDirectly(parameterName),
+          swiftType: instanceType
+        ),
+        cdeclParameters: [
+          SwiftParameter(
+            convention: .byValue,
+            parameterName: parameterName,
+            type: .nominal(
+              SwiftNominalType(
+                nominalTypeDecl: swiftStdlibTypes.unsafeRawPointerDecl
+              )
+            )
+          )
+        ],
+        javaFFMParameters: [.SwiftPointer]
+      )
+
     case .nominal(let nominal):
       // Types from the Swift standard library that we know about.
       if nominal.nominalTypeDecl.moduleName == "Swift",

Tests/JExtractSwiftTests/FunctionLoweringTests.swift

@@ -117,14 +117,15 @@ final class FunctionLoweringTests {
     )
   }
 
-  @Test("Lowering metatypes", .disabled("Metatypes are not yet lowered"))
+  @Test("Lowering metatypes")
   func lowerMetatype() throws {
     try assertLoweredFunction("""
       func f(t: Int.Type) { }
       """,
       expectedCDecl: """
-      func f(t: UnsafeRawPointer) -> () {
-        // implementation
+      @_cdecl("c_f")
+      func c_f(_ t: UnsafeRawPointer) {
+        f(t: unsafeBitCast(t, to: Int.self))
       }
       """
      )