[typechecker] look through all optionals

Author: Suyash Srijan

lib/Sema/TypeCheckPattern.cpp

@@ -1391,9 +1391,10 @@ bool TypeChecker::coercePatternToType(Pattern *&P, TypeResolution resolution,
           // If we have an optional type, let's try to see if the case
           // exists in its base type and if it does then synthesize an
           // OptionalSomePattern that wraps the case.
-          if (auto baseType = type->getOptionalObjectType()) {
-            if (lookupEnumMemberElement(*this, dc, baseType, EEP->getName(),
-                                        EEP->getLoc())) {
+          if (type->getOptionalObjectType()) {
+            if (lookupEnumMemberElement(*this, dc,
+                                        type->lookThroughAllOptionalTypes(),
+                                        EEP->getName(), EEP->getLoc())) {
               P = new (Context)
                   OptionalSomePattern(EEP, EEP->getEndLoc(), /*implicit*/true);
               return coercePatternToType(P, resolution, type, options);

test/Constraints/patterns.swift

@@ -418,3 +418,14 @@ switch sr7799 {
  case .baz: break // Ok
  default: break
 }
+
+let sr7799_1: SR_7799?? = .baz
+
+switch sr7799_1 {
+ case .bar?: break // Ok
+ case .baz: break // Ok
+ default: break
+}
+
+if case .baz = sr7799_1 {} // Ok
+if case .bar? = sr7799_1 {} // Ok