SILGen: Fix edge case where we didn't erase opaque result type in constructor

- Fixes #68298.
- Fixes #68277.

Author: slavapestov

lib/SILGen/SILGenApply.cpp

@@ -1502,7 +1502,7 @@ class SILGenApply : public Lowering::ExprVisitor<SILGenApply> {
     SILType loweredResultTy;
     auto selfMetaTy = selfValue.getType().getAs<AnyMetatypeType>();
     if (selfMetaTy) {
-      loweredResultTy = SILType::getPrimitiveObjectType(
+      loweredResultTy = SGF.getLoweredLoadableType(
         CanMetatypeType::get(resultTy, selfMetaTy->getRepresentation()));
     } else {
       loweredResultTy = SGF.getLoweredLoadableType(resultTy);

validation-test/SILGen/SwiftUI/issue-68298.swift

@@ -0,0 +1,34 @@
+// RUN: %target-swift-emit-silgen %s -target %target-cpu-apple-macosx10.15 -swift-version 5
+
+// REQUIRES: objc_interop
+// REQUIRES: OS=macosx
+
+import SwiftUI
+
+protocol StaticFactory {
+    associatedtype Result
+
+    func callAsFunction() -> Self.Result
+}
+
+struct ViewFactory: StaticFactory {
+    let systemName: String
+    
+    func callAsFunction() -> some View {
+        Image(systemName: systemName)
+            .frame(width: 20, height: 20)
+    }
+}
+
+extension Button where Label == ViewFactory.Result {
+    init(
+        systemName: String,
+        action: @escaping () -> Void
+    ) {
+        self.init(
+            action: action
+        ) {
+            ViewFactory(systemName: systemName)()
+        }
+    }
+}