Sema: Look through inout when mapping IUOs to Optionals.

include/swift/AST/DiagnosticsSema.def

@@ -613,6 +613,12 @@ ERROR(invalid_redecl,none,"invalid redeclaration of %0", (DeclName))
 NOTE(invalid_redecl_prev,none,
      "%0 previously declared here", (DeclName))
 
+WARNING(deprecated_redecl_by_optionality, none,
+        "invalid redeclaration of %0 which differs only by the kind of optional passed as an inout argument (%1 vs. %2)",
+        (DeclName, Type, Type))
+NOTE(deprecated_redecl_by_optionality_note, none,
+     "overloading by kind of optional is deprecated and will be removed in a future release", ())
+
 ERROR(ambiguous_type_base,none,
       "%0 is ambiguous for type lookup in this context", (Identifier))
 ERROR(invalid_member_type,none,

lib/AST/Decl.cpp

@@ -1696,8 +1696,15 @@ static Type mapSignatureType(ASTContext &ctx, Type type) {
 
 /// Map a signature type for a parameter.
 static Type mapSignatureParamType(ASTContext &ctx, Type type) {
-  /// Translate implicitly unwrapped optionals into strict optionals.
-  if (auto uncheckedOptOf = type->getImplicitlyUnwrappedOptionalObjectType()) {
+  // Translate implicitly unwrapped optionals into strict optionals.
+  if (auto inOutTy = type->getAs<InOutType>()) {
+    if (auto uncheckedOptOf =
+            inOutTy->getObjectType()
+                ->getImplicitlyUnwrappedOptionalObjectType()) {
+      type = InOutType::get(OptionalType::get(uncheckedOptOf));
+    }
+  } else if (auto uncheckedOptOf =
+                 type->getImplicitlyUnwrappedOptionalObjectType()) {
     type = OptionalType::get(uncheckedOptOf);
   }
 
@@ -1739,16 +1746,17 @@ static Type mapSignatureFunctionType(ASTContext &ctx, Type type,
   if (curryLevels == 0) {
     // In an initializer, ignore optionality.
     if (isInitializer) {
-      if (auto objectType = type->getAnyOptionalObjectType())
+      if (auto inOutTy = type->getAs<InOutType>()) {
+        if (auto objectType =
+                inOutTy->getObjectType()->getAnyOptionalObjectType()) {
+          type = InOutType::get(objectType);
+        }
+      } else if (auto objectType = type->getAnyOptionalObjectType()) {
         type = objectType;
+      }
     }
 
-    // Translate implicitly unwrapped optionals into strict optionals.
-    if (auto uncheckedOptOf = type->getImplicitlyUnwrappedOptionalObjectType()) {
-      type = OptionalType::get(uncheckedOptOf);
-    }
-
-    return mapSignatureType(ctx, type);
+    return mapSignatureParamType(ctx, type);
   }
 
   auto funcTy = type->castTo<AnyFunctionType>();

lib/Sema/TypeCheckDecl.cpp

@@ -971,6 +971,63 @@ static void checkRedeclaration(TypeChecker &tc, ValueDecl *current) {
           continue;
       }
 
+      // Signatures are the same, but interface types are not. We must
+      // have a type that we've massaged as part of signature
+      // interface type generation. If it's a result of remapping a
+      // function parameter from 'inout T!' to 'inout T?', emit a
+      // warning that these overloads are deprecated and will no
+      // longer be supported in the future.
+      if (!current->getInterfaceType()->isEqual(other->getInterfaceType())) {
+        if (currentDC->isTypeContext() == other->getDeclContext()->isTypeContext()) {
+          auto currFnTy = current->getInterfaceType()->getAs<AnyFunctionType>();
+          auto otherFnTy = other->getInterfaceType()->getAs<AnyFunctionType>();
+          if (currFnTy && otherFnTy && currentDC->isTypeContext()) {
+            currFnTy = currFnTy->getResult()->getAs<AnyFunctionType>();
+            otherFnTy = otherFnTy->getResult()->getAs<AnyFunctionType>();
+          }
+
+          if (currFnTy && otherFnTy) {
+            ArrayRef<AnyFunctionType::Param> currParams = currFnTy->getParams();
+            ArrayRef<AnyFunctionType::Param> otherParams = otherFnTy->getParams();
+
+            if (currParams.size() == otherParams.size()) {
+              auto diagnosed = false;
+              for (unsigned i : indices(currParams)) {
+                if (currParams[i].isInOut() && otherParams[i].isInOut()) {
+                  auto currParamTy = currParams[i]
+                    .getType()
+                    ->getAs<InOutType>()
+                    ->getObjectType();
+                  auto otherParamTy = otherParams[i]
+                    .getType()
+                    ->getAs<InOutType>()
+                    ->getObjectType();
+                  OptionalTypeKind currOTK;
+                  OptionalTypeKind otherOTK;
+                  (void)currParamTy->getAnyOptionalObjectType(currOTK);
+                  (void)otherParamTy->getAnyOptionalObjectType(otherOTK);
+                  if (currOTK != OTK_None && otherOTK != OTK_None &&
+                      currOTK != otherOTK) {
+                    tc.diagnose(current, diag::deprecated_redecl_by_optionality,
+                                current->getFullName(), currParamTy,
+                                otherParamTy);
+                    tc.diagnose(other, diag::invalid_redecl_prev,
+                                other->getFullName());
+                    tc.diagnose(current,
+                                diag::deprecated_redecl_by_optionality_note);
+                    diagnosed = true;
+                    break;
+                  }
+                }
+              }
+
+              if (diagnosed)
+                break;
+            }
+          }
+        }
+      }
+
       // If the conflicting declarations have non-overlapping availability and,
       // we allow the redeclaration to proceed if...
       //

test/decl/overload.swift

@@ -261,6 +261,29 @@ func inout2(x: inout Int) { }
 func optional(x: Int?) { } // expected-note{{previously declared}}
 func optional(x: Int!) { } // expected-error{{invalid redeclaration of 'optional(x:)'}}
 
+func optionalInOut(x: inout Int?) { } // expected-note{{previously declared}}
+// expected-note@-1 {{previously declared}}
+func optionalInOut(x: inout Int!) { } // expected-warning{{invalid redeclaration of 'optionalInOut(x:)' which differs only by the kind of optional passed as an inout argument ('Int!' vs. 'Int?')}}
+  // expected-note@-1 {{overloading by kind of optional is deprecated and will be removed in a future release}}
+  // expected-warning@-2 {{invalid redeclaration of 'optionalInOut(x:)' which differs only by the kind of optional passed as an inout argument ('Int!' vs. 'Int?')}}
+  // expected-note@-3 {{overloading by kind of optional is deprecated and will be removed in a future release}}
+
+class optionalOverloads {
+  class func optionalInOut(x: inout Int?) { } // expected-note{{previously declared}}
+  // expected-note@-1 {{previously declared}}
+  class func optionalInOut(x: inout Int!) { } // expected-warning{{invalid redeclaration of 'optionalInOut(x:)' which differs only by the kind of optional passed as an inout argument ('Int!' vs. 'Int?')}}
+  // expected-note@-1 {{overloading by kind of optional is deprecated and will be removed in a future release}}
+  // expected-warning@-2 {{invalid redeclaration of 'optionalInOut(x:)' which differs only by the kind of optional passed as an inout argument ('Int!' vs. 'Int?')}}
+  // expected-note@-3 {{overloading by kind of optional is deprecated and will be removed in a future release}}
+
+  func optionalInOut(x: inout Int?) { } // expected-note{{previously declared}}
+  // expected-note@-1 {{previously declared}}
+  func optionalInOut(x: inout Int!) { } // expected-warning{{invalid redeclaration of 'optionalInOut(x:)' which differs only by the kind of optional passed as an inout argument ('Int!' vs. 'Int?')}}
+  // expected-note@-1 {{overloading by kind of optional is deprecated and will be removed in a future release}}
+  // expected-warning@-2 {{invalid redeclaration of 'optionalInOut(x:)' which differs only by the kind of optional passed as an inout argument ('Int!' vs. 'Int?')}}
+  // expected-note@-3 {{overloading by kind of optional is deprecated and will be removed in a future release}}
+}
+
 func optional_3() -> Int? { } // expected-note{{previously declared}}
 func optional_3() -> Int! { } // expected-error{{invalid redeclaration of 'optional_3()'}}