Extension type. Issue 54648. Fix 'incompatible with await' predicate.

Stop when see 'X & B', just check `B`, do not continue.

Bug: #54648
Change-Id: Ic447b9facd00efac309695f505df603764d8c096
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/355500
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>
Commit-Queue: Konstantin Shcheglov <scheglov@google.com>
Reviewed-by: Keerti Parthasarathy <keertip@google.com>

pkg/analyzer/lib/src/dart/element/type_system.dart

@@ -1018,16 +1018,12 @@ class TypeSystemImpl implements TypeSystem {
     if (T is TypeParameterTypeImpl) {
       // `T` is `X & B`, and `B` is incompatible with await.
       if (T.promotedBound case var B?) {
-        if (isIncompatibleWithAwait(B)) {
-          return true;
-        }
+        return isIncompatibleWithAwait(B);
       }
       // `T` is a type variable with bound `S`, and `S` is incompatible
       // with await.
       if (T.element.bound case var S?) {
-        if (isIncompatibleWithAwait(S)) {
-          return true;
-        }
+        return isIncompatibleWithAwait(S);
       }
     }
 

pkg/analyzer/test/src/dart/element/incompatible_with_await_test.dart

@@ -115,8 +115,15 @@ class IsIncompatibleWithAwaitTest extends AbstractTypeSystemTest {
   test_typeParameter_promotedBound_extensionType_implementsFuture() {
     var futureOfIntNone = futureNone(intNone);
 
-    var A = extensionType(
-      'A',
+    // Incompatible with `await`, used as a bound.
+    // Does not matter, `T` is promoted to not incompatible.
+    var N = extensionType(
+      'N',
+      representationType: futureOfIntNone,
+    );
+
+    var F = extensionType(
+      'F',
       representationType: futureOfIntNone,
       interfaces: [
         futureOfIntNone,
@@ -125,8 +132,11 @@ class IsIncompatibleWithAwaitTest extends AbstractTypeSystemTest {
 
     isNotIncompatible(
       typeParameterTypeNone(
-        typeParameter('T'),
-        promotedBound: interfaceTypeNone(A),
+        typeParameter(
+          'T',
+          bound: interfaceTypeNone(N),
+        ),
+        promotedBound: interfaceTypeNone(F),
       ),
     );
   }