[SILGen]Check if baseType is DynamicSelfType

Author: stzn

lib/SILGen/SILGenExpr.cpp

@@ -3399,7 +3399,11 @@ static ManagedValue emitKeyPathRValueBase(SILGenFunction &subSGF,
 
   // Upcast a class instance to the property's declared type if necessary.
   if (auto propertyClass = storage->getDeclContext()->getSelfClassDecl()) {
-    if (baseType->getClassOrBoundGenericClass() != propertyClass) {
+    auto baseClass = baseType->getClassOrBoundGenericClass();
+    if (auto dynamicSelfType = baseType->getAs<DynamicSelfType>()) {
+      baseClass = dynamicSelfType->getSelfType()->getClassOrBoundGenericClass();
+    }
+    if (baseClass != propertyClass) {
       baseType = baseType->getSuperclassForDecl(propertyClass)
         ->getCanonicalType();
       paramSubstValue = subSGF.B.createUpcast(loc, paramSubstValue,

test/SILGen/keypaths.swift

@@ -805,3 +805,24 @@ protocol HasAlias {
 func testHasAlias() {
   _ = \HasAlias.id
 }
+
+// https://github.com/swiftlang/swift/issues/80669
+func type<Root, Value>(at keyPath: KeyPath<Root, Value>) -> Value.Type {
+  return Value.self
+}
+
+class DynamicSelfTypeTestClass {
+  var other = DynamicSelfTypeTestClass()
+
+  static func staticFunc() {
+    type(at: \Self.other).bar()
+  }
+
+  static func bar() {
+    print("Hello")
+  }
+}
+
+func testDynamicSelfType() {
+  DynamicSelfTypeTestClass.staticFunc()
+}