Revert "Allow inout arguments that differ in optionality than the expected parameter."

This partially reverts commit 8685ee0.

The tests are still in place, but the code change is no longer necessary
now that IUOs are removed from the type system.

Fixes: rdar://problem/37013789

Author: rudkx

lib/AST/ASTVerifier.cpp

@@ -1069,17 +1069,8 @@ class Verifier : public ASTWalker {
       Type srcObj = checkLValue(E->getSubExpr()->getType(),
                                 "result of InOutExpr");
       auto DestTy = E->getType()->castTo<InOutType>()->getObjectType();
-
-      // HACK: Allow differences in optionality of the source and
-      // result types. When IUO is gone from the type system we'll no
-      // longer need this.
-      auto srcOptObjTy = srcObj->getAnyOptionalObjectType();
-      auto dstOptObjTy = DestTy->getAnyOptionalObjectType();
-      if (srcOptObjTy && dstOptObjTy) {
-        checkSameType(srcOptObjTy, dstOptObjTy, "object types for InOutExpr");
-      } else {
-        checkSameType(DestTy, srcObj, "object types for InOutExpr");
-      }
+      
+      checkSameType(DestTy, srcObj, "object types for InOutExpr");
       verifyCheckedBase(E);
     }
 

lib/Sema/CSApply.cpp

@@ -5544,38 +5544,6 @@ static unsigned computeCallLevel(ConstraintSystem &cs, ConcreteDeclRef callee,
   return 0;
 }
 
-// HACK: Support calling functions with inouts of differing kinds of
-// optionality so that we can warn about overloading by IUO vs. plain
-// Optional and allow users to correct the issue by removing an
-// overload and passing the differently-optional value to the
-// remaining overload.
-bool inOutOptionalityDifferenceHack(Expr *arg, Type paramType,
-                                    ConstraintSystem &cs) {
-  auto *inOutArgTy = cs.getType(arg)->getAs<InOutType>();
-  if (!inOutArgTy)
-    return false;
-
-  auto *inOutParamTy = paramType->getAs<InOutType>();
-  if (!inOutParamTy)
-    return false;
-
-  OptionalTypeKind argOTK;
-  OptionalTypeKind paramOTK;
-  auto argObjTy = inOutArgTy->getObjectType()->getAnyOptionalObjectType(argOTK);
-  auto paramObjTy =
-      inOutParamTy->getObjectType()->getAnyOptionalObjectType(paramOTK);
-
-  if (argOTK == paramOTK || argOTK == OTK_None || paramOTK == OTK_None)
-    return false;
-
-  if (!argObjTy->isEqual(paramObjTy))
-    return false;
-
-  // Hammer over the argument type with the expected parameter type.
-  cs.setType(arg, paramType);
-  return true;
-}
-
 Expr *ExprRewriter::coerceCallArguments(
     Expr *arg, AnyFunctionType *funcType,
     ApplyExpr *apply,
@@ -5806,16 +5774,11 @@ Expr *ExprRewriter::coerceCallArguments(
       continue;
     }
 
-    Expr *convertedArg;
-    if (inOutOptionalityDifferenceHack(arg, paramType, cs)) {
-      convertedArg = arg;
-    } else {
-      // Convert the argument.
-      convertedArg =
-          coerceToType(arg, paramType, getArgLocator(argIdx, paramIdx));
-      if (!convertedArg)
-        return nullptr;
-    }
+    // Convert the argument.
+    auto convertedArg = coerceToType(arg, paramType,
+                                     getArgLocator(argIdx, paramIdx));
+    if (!convertedArg)
+      return nullptr;
 
     // Add the converted argument.
     fromTupleExpr[argIdx] = convertedArg;

lib/Sema/CSRanking.cpp

@@ -80,8 +80,6 @@ void ConstraintSystem::increaseScore(ScoreKind kind, unsigned value) {
     case SK_ValueToPointerConversion:
       log << "value-to-pointer conversion";
       break;
-    case SK_InOutOptionalityConversion:
-      log << "inout optionality conversion";
     }
     log << ")\n";
   }

lib/Sema/CSSimplify.cpp

@@ -1863,32 +1863,16 @@ ConstraintSystem::matchTypes(Type type1, Type type2, ConstraintKind kind,
                         locator.withPathElement(
                           ConstraintLocator::ArrayElementType));
 
-    case TypeKind::InOut: {
+    case TypeKind::InOut:
       // If the RHS is an inout type, the LHS must be an @lvalue type.
       if (kind == ConstraintKind::BindParam ||
           kind >= ConstraintKind::OperatorArgumentConversion)
         return getTypeMatchFailure(locator);
-
-      auto inoutObjTy1 = cast<InOutType>(desugar1)->getObjectType();
-      auto inoutObjTy2 = cast<InOutType>(desugar2)->getObjectType();
-
-      OptionalTypeKind OTK1;
-      OptionalTypeKind OTK2;
-      auto optionalObjTy1 = inoutObjTy1->getAnyOptionalObjectType(OTK1);
-      auto optionalObjTy2 = inoutObjTy2->getAnyOptionalObjectType(OTK2);
-      if (OTK1 != OTK2 && optionalObjTy1 && optionalObjTy2) {
-        increaseScore(ScoreKind::SK_InOutOptionalityConversion);
-        return matchTypes(inoutObjTy1,
-                          inoutObjTy2,
-                          ConstraintKind::ArgumentConversion, subflags,
-                          locator.withPathElement(ConstraintLocator::ArrayElementType));
-      } else {
-        return matchTypes(inoutObjTy1,
-                          inoutObjTy2,
-                          ConstraintKind::Equal, subflags,
-                          locator.withPathElement(ConstraintLocator::ArrayElementType));
-      }
-    }
+      
+      return matchTypes(cast<InOutType>(desugar1)->getObjectType(),
+                        cast<InOutType>(desugar2)->getObjectType(),
+                        ConstraintKind::Equal, subflags,
+                  locator.withPathElement(ConstraintLocator::ArrayElementType));
 
     case TypeKind::UnboundGeneric:
       llvm_unreachable("Unbound generic type should have been opened");

lib/Sema/ConstraintSystem.h

@@ -462,12 +462,8 @@ enum ScoreKind {
   SK_KeyPathSubscript,
   /// A conversion from a string, array, or inout to a pointer.
   SK_ValueToPointerConversion,
-  /// A conversion from 'inout Optional<T>' to 'inout
-  /// ImplicitlyUnwrappedOptional<T>' or vice-versa.
-  /// FIXME: This goes away when IUO-as-a-type goes away.
-  SK_InOutOptionalityConversion,
 
-  SK_LastScoreKind = SK_InOutOptionalityConversion,
+  SK_LastScoreKind = SK_ValueToPointerConversion,
 };
 
 /// The number of score kinds.