Follow-up on the raw-representable casting fixits, produce the fixit for optional destination types as well. (#2893)

* [sema] Follow-up on the raw-representable casting fixits, produce the fixit for optional destination types as well.

* [test] Add an extra test case for f60567e, per feedback by BenL.

Author: akyrtzi

lib/Sema/CSDiag.cpp

@@ -3158,6 +3158,9 @@ static void tryRawRepresentableFixIts(InFlightDiagnostic &diag,
                                       Type toType,
                                       KnownProtocolKind kind,
                                       Expr *expr) {
+  // The following fixes apply for optional destination types as well.
+  toType = toType->lookThroughAllAnyOptionalTypes();
+
   if (isLiteralConvertibleType(fromType, kind, CS)) {
     if (auto rawTy = isRawRepresentable(toType, kind, CS)) {
       // Produce before/after strings like 'Result(rawValue: RawType(<expr>))'
@@ -3821,9 +3824,7 @@ static bool diagnoseSingleCandidateFailures(CalleeCandidateInfo &CCI,
       candidate.getDecl() && isa<ConstructorDecl>(candidate.getDecl()) &&
       candidate.level == 1) {
     CallArgParam &arg = args[0];
-    auto resTy = candidate.getResultType();
-    if (auto unwrappedOpt = resTy->getOptionalObjectType())
-      resTy = unwrappedOpt;
+    auto resTy = candidate.getResultType()->lookThroughAllAnyOptionalTypes();
     auto rawTy = isRawRepresentable(resTy, CCI.CS);
     if (rawTy && resTy->getCanonicalType() == arg.Ty.getCanonicalTypeOrNull()) {
       auto getInnerExpr = [](Expr *E) -> Expr* {

test/FixCode/fixits-apply.swift

@@ -36,6 +36,8 @@ struct MyEventMask2 : OptionSet {
   var rawValue: UInt64 { return 0 }
 }
 func sendIt(_: MyEventMask2) {}
+func sendItOpt(_: MyEventMask2?) {}
+func sendItOpt3(_: MyEventMask2???) {}
 func testMask1(a: Int) {
   sendIt(a)
 }
@@ -48,6 +50,12 @@ func testMask3(a: MyEventMask2) {
 func testMask4(a: MyEventMask2) {
   testMask2(a: a)
 }
+func testMask5(a: Int) {
+  sendItOpt(a)
+}
+func testMask6(a: Int) {
+  sendItOpt(a)
+}
 
 enum MyEnumType : UInt32 {
   case invalid

test/FixCode/fixits-apply.swift.result

@@ -36,6 +36,8 @@ struct MyEventMask2 : OptionSet {
   var rawValue: UInt64 { return 0 }
 }
 func sendIt(_: MyEventMask2) {}
+func sendItOpt(_: MyEventMask2?) {}
+func sendItOpt3(_: MyEventMask2???) {}
 func testMask1(a: Int) {
   sendIt(MyEventMask2(rawValue: UInt64(a)))
 }
@@ -48,6 +50,12 @@ func testMask3(a: MyEventMask2) {
 func testMask4(a: MyEventMask2) {
   testMask2(a: a.rawValue)
 }
+func testMask5(a: Int) {
+  sendItOpt(MyEventMask2(rawValue: UInt64(a)))
+}
+func testMask6(a: Int) {
+  sendItOpt(MyEventMask2(rawValue: UInt64(a)))
+}
 
 enum MyEnumType : UInt32 {
   case invalid