[Sema] Look through ActorIsolationErasureExpr when finding function DeclRefs for rethrows checking.

This conversion has no effect on `rethrows` checking and should
be ignored.

Resolves: rdar://142562250
(cherry picked from commit e0bfa13f8fa7d22da01952b50ad25361f010660d)

Author: xedin

lib/Sema/TypeCheckEffects.cpp

@@ -468,6 +468,10 @@ class AbstractFunction {
         // Look through optional evaluations.
       } else if (auto optionalEval = dyn_cast<OptionalEvaluationExpr>(fn)) {
         fn = optionalEval->getSubExpr()->getValueProvidingExpr();
+        // Look through actor isolation erasures.
+      } else if (auto actorIsolationErasure =
+                     dyn_cast<ActorIsolationErasureExpr>(fn)) {
+        fn = actorIsolationErasure->getSubExpr()->getValueProvidingExpr();
       } else {
         break;
       }

test/Concurrency/dynamic_actor_isolation.swift

@@ -0,0 +1,20 @@
+// RUN: %target-typecheck-verify-swift -swift-version 5 -strict-concurrency=complete -enable-upcoming-feature DynamicActorIsolation -verify-additional-prefix swift6-
+// RUN: %target-typecheck-verify-swift -swift-version 6 -verify-additional-prefix swift6-
+
+// REQUIRES: swift_feature_DynamicActorIsolation
+
+// Tests related to DynamicActorIsolation feature
+
+// rdar://142562250 - error: call can throw, but it is not marked with ‘try’ and the error is not handled
+@MainActor
+struct TestNoErrorsAboutThrows {
+  struct Column {
+    @MainActor
+    init?(_ column: Int) {}
+  }
+
+  func test(columns: [Int]) {
+    // MainActor isolation erasure shouldn't interfere with effects checking
+    _ = columns.compactMap(Column.init) // Ok
+  }
+}