Cope with concurrency-related function type adjustments in calls to "super".

lib/SILGen/SILGenApply.cpp

@@ -1282,7 +1282,10 @@ class SILGenApply : public Lowering::ExprVisitor<SILGenApply> {
     CanType superFormalType = arg->getType()->getCanonicalType();
 
     // The callee for a super call has to be either a method or constructor.
+    // There might be one level of conversion in between.
     Expr *fn = apply->getFn();
+    if (auto fnConv = dyn_cast<FunctionConversionExpr>(fn))
+      fn = fnConv->getSubExpr();
     SubstitutionMap substitutions;
     SILDeclRef constant;
     if (auto *ctorRef = dyn_cast<OtherConstructorDeclRefExpr>(fn)) {

test/SILGen/global_actor_functions.swift

@@ -0,0 +1,24 @@
+// RUN: %target-swift-frontend -emit-silgen %s -module-name test -swift-version 5  -disable-availability-checking | %FileCheck --enable-var-scope %s
+// REQUIRES: concurrency
+
+actor MyActor { }
+
+@globalActor
+struct GlobalActor {
+  static var shared: MyActor = MyActor()
+}
+
+@GlobalActor
+class Super {
+  func f() { }
+}
+
+@GlobalActor
+class Sub: Super {
+  // CHECK-LABEL: sil hidden [ossa] @$s4test3SubC1fyyF : $@convention(method) (@guaranteed Sub) -> ()
+  // CHECK: function_ref @$s4test5SuperC1fyyF
+  // CHECK-NEXT: apply
+  override func f() {
+    super.f()
+  }
+}