Optional case lowercase cleanups

- Use == operator for identifier comparison
- Add a test where the Optional isn't the top-level type

rdar://problem/26481304

Author: bitjammer

lib/Sema/TypeCheckPattern.cpp

@@ -1396,9 +1396,14 @@ bool TypeChecker::coercePatternToType(Pattern *&P, DeclContext *dc, Type type,
       }
       if (!elt) {
         if (!type->is<ErrorType>()) {
+          // Lowercasing of Swift.Optional's cases is handled in the
+          // standard library itself, not through the clang importer,
+          // so we have to do this check here. Additionally, .Some
+          // isn't a static VarDecl, so the existing mechanics in
+          // extractEnumElement won't work.
           if (type->getAnyNominal() == Context.getOptionalDecl()) {
-            if (EEP->getName().str().compare("None") == 0 ||
-                EEP->getName().str().compare("Some") == 0) {
+            if (EEP->getName().str() == "None" ||
+                EEP->getName().str() == "Some") {
               SmallString<4> Rename;
               camel_case::toLowercaseWord(EEP->getName().str(), Rename);
               diagnose(EEP->getLoc(), diag::availability_decl_unavailable_rename,

test/1_stdlib/OptionalRenames.swift

@@ -14,3 +14,13 @@ switch x {
   case .Some(let x): print(x) // expected-error {{'Some' has been renamed to 'some'}} {{9-13=some}}
 }
 
+let optionals: (Int?, Int?) = (Optional.Some(1), .None)
+// expected-error@-1 {{'Some' has been renamed to 'some'}} {{41-45=some}}
+// expected-error@-2 {{'None' has been renamed to 'none'}} {{51-55=none}}
+
+switch optionals {
+  case (.None, .none): break // expected-error {{'None' has been renamed to 'none'}} {{10-14=none}}
+  case (.Some(let left), .some(let right)): break // expected-error {{'Some' has been renamed to 'some'}} {{10-14=some}}
+  default: break
+}
+