Merge pull request swiftlang#76681 from kubamracek/embedded-default-arg-metatypes

[embedded] Support default arguments with metatypes-as-type-hints in Embedded Swift

Author: kubamracek

lib/SIL/IR/SILDeclRef.cpp

@@ -820,6 +820,20 @@ bool SILDeclRef::isTransparent() const {
     }
   }
 
+  // To support using metatypes as type hints in Embedded Swift. A default
+  // argument generator might be returning a metatype, which we normally don't
+  // support in Embedded Swift, but to still allow metatypes as type hints, we
+  // make the generator always inline to the callee by marking it transparent.
+  if (getASTContext().LangOpts.hasFeature(Feature::Embedded)) {
+    if (isDefaultArgGenerator() && hasDecl()) {
+      auto *decl = getDecl();
+      auto *param = getParameterAt(decl, defaultArgIndex);
+      Type paramType = param->getTypeOfDefaultExpr();
+      if (paramType && paramType->is<MetatypeType>())
+        return true;
+    }
+  }
+
   if (hasDecl()) {
     if (auto *AFD = dyn_cast<AbstractFunctionDecl>(getDecl()))
       return AFD->isTransparent();

test/embedded/metatype-type-hint.swift

@@ -0,0 +1,45 @@
+// RUN: %target-run-simple-swift(-enable-experimental-feature Embedded -parse-as-library -wmo) | %FileCheck %s
+// RUN: %target-run-simple-swift(-enable-experimental-feature Embedded -parse-as-library -wmo -O) | %FileCheck %s
+// RUN: %target-run-simple-swift(-enable-experimental-feature Embedded -parse-as-library -wmo -Osize) | %FileCheck %s
+
+// REQUIRES: swift_in_compiler
+// REQUIRES: executable_test
+// REQUIRES: optimized_stdlib
+// REQUIRES: OS=macosx || OS=linux-gnu
+
+public struct AsyncStream2<Element> {
+  var x: Int
+  var y: Int
+}
+
+extension AsyncStream2 {
+  public static func makeStream2(of elementType: Element.Type = Element.self) -> AsyncStream2<Element> {
+    return AsyncStream2<Element>()
+  }
+
+  public init(
+    _ elementType: Element.Type = Element.self
+  ) {
+    fatalError()
+  }
+}
+
+struct MyStruct<T> {
+  static func makeStruct(of t: T.Type = T.self) -> MyStruct<T> {
+    var s = MyStruct.init()
+    return s
+  }
+  public init(_ t: T.Type = T.self) {
+    print("x")
+  }
+}
+
+@main
+struct Main {
+  static func main() {
+    _ = MyStruct<String>.makeStruct()
+    _ = MyStruct.makeStruct(of: String.self)
+    print("OK!")
+    // CHECK: OK!
+  }
+}

test/embedded/metatype-type-hint2.swift

@@ -0,0 +1,37 @@
+// RUN: %empty-directory(%t)
+// RUN: %{python} %utils/split_file.py -o %t %s
+
+// RUN: %target-swift-frontend -emit-module -o %t/MyModule.swiftmodule %t/MyModule.swift -enable-experimental-feature Embedded -parse-as-library
+// RUN: %target-swift-frontend -c -o %t/Main.o -I %t %t/Main.swift -enable-experimental-feature Embedded -parse-as-library
+
+// REQUIRES: swift_in_compiler
+// REQUIRES: executable_test
+// REQUIRES: optimized_stdlib
+// REQUIRES: OS=macosx || OS=linux-gnu
+
+// BEGIN MyModule.swift
+
+public struct MyStruct<T> {
+  var x: Int
+}
+
+extension MyStruct {
+  public static func makeStruct(of: T.Type) -> MyStruct<T> {
+    return MyStruct<T>()
+  }
+
+  public init(_: T.Type = T.self) {
+    self.x = 42
+  }
+}
+
+// BEGIN Main.swift
+
+import MyModule
+
+@main
+struct Main {
+  static func main() {
+    _ = MyStruct.makeStruct(of: String.self)
+  }
+}