Merge pull request #30111 from DougGregor/pattern-implicit-some-harder

[Constraint system] Handle implicit "some" patterns implicitly, better.

Author: DougGregor

lib/Sema/CSSimplify.cpp

@@ -6034,10 +6034,29 @@ performMemberLookup(ConstraintKind constraintKind, DeclNameRef memberName,
     }
   }
 
+  // If we have candidates, and we're doing a member lookup for a pattern
+  // match, unwrap optionals and try again to allow implicit creation of
+  // optional "some" patterns (spelled "?").
+  if (result.ViableCandidates.empty() && result.UnviableCandidates.empty() &&
+      memberLocator &&
+      memberLocator->isLastElement<LocatorPathElt::PatternMatch>() &&
+      instanceTy->getOptionalObjectType() &&
+      baseObjTy->is<AnyMetatypeType>()) {
+    SmallVector<Type, 2> optionals;
+    Type instanceObjectTy = instanceTy->lookThroughAllOptionalTypes(optionals);
+    Type metaObjectType = MetatypeType::get(instanceObjectTy);
+    auto result = performMemberLookup(
+        constraintKind, memberName, metaObjectType,
+        functionRefKind, memberLocator, includeInaccessibleMembers);
+    result.numImplicitOptionalUnwraps = optionals.size();
+    result.actualBaseType = metaObjectType;
+    return result;
+  }
+
   // If we're looking into a metatype for an unresolved member lookup, look
   // through optional types.
   //
-  // FIXME: The short-circuit here is lame.
+  // FIXME: Unify with the above code path.
   if (result.ViableCandidates.empty() &&
       baseObjTy->is<AnyMetatypeType>() &&
       constraintKind == ConstraintKind::UnresolvedValueMember) {
@@ -6097,25 +6116,6 @@ performMemberLookup(ConstraintKind constraintKind, DeclNameRef memberName,
     }
   }
 
-  // If we have candidates, and we're doing a member lookup for a pattern
-  // match, unwrap optionals and try again to allow implicit creation of
-  // optional "some" patterns (spelled "?").
-  if (result.ViableCandidates.empty() && result.UnviableCandidates.empty() &&
-      memberLocator &&
-      memberLocator->isLastElement<LocatorPathElt::PatternMatch>() &&
-      instanceTy->getOptionalObjectType() &&
-      baseObjTy->is<AnyMetatypeType>()) {
-    SmallVector<Type, 2> optionals;
-    Type instanceObjectTy = instanceTy->lookThroughAllOptionalTypes(optionals);
-    Type metaObjectType = MetatypeType::get(instanceObjectTy);
-    auto result = performMemberLookup(
-        constraintKind, memberName, metaObjectType,
-        functionRefKind, memberLocator, includeInaccessibleMembers);
-    result.numImplicitOptionalUnwraps = optionals.size();
-    result.actualBaseType = metaObjectType;
-    return result;
-  }
-
   // If we have no viable or unviable candidates, and we're generating,
   // diagnostics, rerun the query with inaccessible members included, so we can
   // include them in the unviable candidates list.

test/stmt/if_while_var.swift

@@ -219,3 +219,22 @@ enum CaseStaticAmbiguity {
 
   static func C(_: Int) -> CaseStaticAmbiguity { return .C(true) }
 }
+
+// Case name/static member ambiguity along with implicit optional unwrapping.
+enum HasPayload {
+  case payload(Int, Bool)
+
+  static func payload(_ bool: Bool, int: Int) -> HasPayload {
+    .payload(int, bool)
+  }
+}
+
+class UsesPayload {
+  private var eOpt: HasPayload? = nil
+
+  deinit {
+    if case .payload(_, let x) = eOpt {
+      _ = x
+    }
+  }
+}