Remove support for -swift-version 3 from the expression type checker.

include/swift/AST/DiagnosticsSema.def

@@ -294,12 +294,6 @@ ERROR(err_noescape_param_call,none,
       "parameter %0 to a call to a non-escaping function parameter can allow "
       "re-entrant modification of a variable",
       (DeclName, unsigned))
-WARNING(warn_noescape_param_call,none,
-      "passing a %select{|closure which captures a }1non-escaping function "
-      "parameter %0 to a call to a non-escaping function parameter can allow "
-      "re-entrant modification of a variable and will be illegal in Swift 4",
-      (DeclName, unsigned))
-
 ERROR(cannot_call_function_value,none,
       "cannot invoke value of function type with argument list '%0'",
       (StringRef))
@@ -913,10 +907,6 @@ ERROR(missing_unwrap_optional_try,none,
 ERROR(missing_forced_downcast,none,
       "%0 is not convertible to %1; "
       "did you mean to use 'as!' to force downcast?", (Type, Type))
-WARNING(missing_forced_downcast_swift3_compat_warning,none,
-        "bridging %0 to %1 may fail at runtime and will become a checked "
-        "cast in Swift 4; did you mean to use 'as!' to force downcast?",
-        (Type, Type))
 ERROR(missing_explicit_conversion,none,
       "%0 is not implicitly convertible to %1; "
       "did you mean to use 'as' to explicitly convert?", (Type, Type))
@@ -2855,18 +2845,11 @@ WARNING(store_in_willset,none,
         "attempting to store to property %0 within its own willSet, which is "
         "about to be overwritten by the new value", (Identifier))
 
-ERROR(tuple_splat_use,none,
-      "passing %0 arguments to a callee as a single tuple value has been removed in Swift 3",
-        (unsigned))
-
-
 ERROR(value_of_module_type,none,
       "expected module member name after module name", ())
 
 ERROR(value_of_metatype_type,none,
       "expected member name or constructor call after type name", ())
-WARNING(warn_value_of_metatype_missing_self,none,
-      "missing '.self' for reference to metatype of type %0", (Type))
 
 NOTE(add_parens_to_type,none,
      "add arguments after the type to construct a value of the type", ())

include/swift/AST/Expr.h

@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2018 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -93,15 +93,8 @@ enum class CheckedCastKind : unsigned {
   SetDowncast,
   /// A bridging conversion that always succeeds.
   BridgingCoercion,
-  /// A bridging conversion that may fail, because there are multiple Swift
-  /// value types that bridge to the same Cocoa object type.
-  ///
-  /// This kind is only used for Swift 3 compatibility diagnostics and is
-  /// treated the same as 'BridgingCoercion' otherwise. In Swift 4 or later,
-  /// any conversions with this kind show up as ValueCasts.
-  Swift3BridgingDowncast,
 
-  Last_CheckedCastKind = Swift3BridgingDowncast,
+  Last_CheckedCastKind = BridgingCoercion,
 };
 
 /// What are the high-level semantics of this access?

lib/AST/ASTPrinter.cpp

@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2018 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -4009,8 +4009,6 @@ StringRef swift::getCheckedCastKindName(CheckedCastKind kind) {
     return "set_downcast";
   case CheckedCastKind::BridgingCoercion:
     return "bridging_coercion";
-  case CheckedCastKind::Swift3BridgingDowncast:
-    return "bridging_downcast";
   }
   llvm_unreachable("bad checked cast name");
 }

lib/SILOptimizer/FunctionSignatureTransforms/FunctionSignatureOpts.cpp

@@ -185,9 +185,8 @@ FunctionSignatureTransformDescriptor::createOptimizedSILFunctionName() {
     Mangler.setReturnValueOwnedToUnowned();
   }
 
-  SILModule &M = F->getModule();
   auto MangledName = Mangler.mangle();
-  assert(!M.hasFunction(MangledName));
+  assert(!F->getModule().hasFunction(MangledName));
 
   return MangledName;
 }

lib/Sema/CSApply.cpp

@@ -3299,7 +3299,6 @@ namespace {
         }
         expr->setCastKind(castKind);
         break;
-      case CheckedCastKind::Swift3BridgingDowncast:
       case CheckedCastKind::ArrayDowncast:
       case CheckedCastKind::DictionaryDowncast:
       case CheckedCastKind::SetDowncast:
@@ -3658,19 +3657,6 @@ namespace {
       Expr *sub = handleOptionalBindings(expr->getSubExpr(), toType,
                                          OptionalBindingsCastKind::Bridged,
                                          [&](Expr *sub, Type toInstanceType) {
-        // Warn about NSNumber and NSValue bridging coercions we accepted in
-        // Swift 3 but which can fail at runtime.
-        if (tc.Context.LangOpts.isSwiftVersion3()
-            && tc.typeCheckCheckedCast(cs.getType(sub), toInstanceType,
-                                       CheckedCastContextKind::None,
-                                       dc, SourceLoc(), sub, SourceRange())
-                 == CheckedCastKind::Swift3BridgingDowncast) {
-          tc.diagnose(expr->getLoc(),
-                      diag::missing_forced_downcast_swift3_compat_warning,
-                      cs.getType(sub), toInstanceType)
-            .fixItReplace(expr->getAsLoc(), "as!");
-        }
-
         return buildObjCBridgeExpr(sub, toInstanceType, locator);
       });
 
@@ -3736,7 +3722,6 @@ namespace {
       }
 
       // Valid casts.
-      case CheckedCastKind::Swift3BridgingDowncast:
       case CheckedCastKind::ArrayDowncast:
       case CheckedCastKind::DictionaryDowncast:
       case CheckedCastKind::SetDowncast:
@@ -3823,7 +3808,6 @@ namespace {
       }
 
       // Valid casts.
-      case CheckedCastKind::Swift3BridgingDowncast:
       case CheckedCastKind::ArrayDowncast:
       case CheckedCastKind::DictionaryDowncast:
       case CheckedCastKind::SetDowncast:
@@ -5703,34 +5687,6 @@ Expr *ExprRewriter::coerceCallArguments(
         return param.getType()->hasUnresolvedType();
       });
 
-  // If you value your sanity, ignore the body of this 'if' statement.
-  if (cs.getASTContext().isSwiftVersion3() && params.size() == 1) {
-    const auto &param = params.front();
-    auto paramType = param.getType();
-
-    // Total hack: In Swift 3 mode, we can end up with an arity mismatch due to
-    // loss of ParenType sugar.
-    if (isa<TupleExpr>(arg)) {
-      auto *tupleType = paramType->getAs<TupleType>();
-      if (!param.hasLabel() && !param.isVariadic() && tupleType) {
-        // Rebuild the function type.
-        funcType = FunctionType::get(tupleType, funcType->getResult(),
-                                     funcType->getExtInfo());
-        params = funcType->getParams();
-      }
-    }
-
-    // Total hack: In Swift 3 mode, argument labels are ignored when calling
-    // function type with a single Any parameter.
-    if (params.size() == 1 && params.front().getType()->isAny()) {
-      auto argType = cs.getType(arg);
-      if (auto *tupleArgType = dyn_cast<TupleType>(argType.getPointer())) {
-        if (tupleArgType->getNumElements() == 1)
-          matchCanFail = true;
-      }
-    }
-  }
-
   auto paramType = AnyFunctionType::composeInput(tc.Context, params, false);
   bool allParamsMatch = cs.getType(arg)->isEqual(paramType);
 
@@ -5781,6 +5737,7 @@ Expr *ExprRewriter::coerceCallArguments(
 
   assert((matchCanFail || !failed) && "Call arguments did not match up?");
   (void)failed;
+  (void)matchCanFail;
 
   // We should either have parentheses or a tuple.
   auto *argTuple = dyn_cast<TupleExpr>(arg);
@@ -6526,8 +6483,8 @@ Expr *ExprRewriter::coerceToType(Expr *expr, Type toType,
       if (toType->hasUnresolvedType())
         break;
 
-      // HACK: Fix problem related to Swift 3 mode (with assertions),
-      // since Swift 3 mode allows passing arguments with extra parens
+      // HACK: Fix problem related to Swift 4 mode (with assertions),
+      // since Swift 4 mode allows passing arguments with extra parens
       // to parameters which don't expect them, it should be supported
       // by "deep equality" type - Optional<T> e.g.
       // ```swift
@@ -6537,7 +6494,7 @@ Expr *ExprRewriter::coerceToType(Expr *expr, Type toType,
       // ```
       //
       // See also: https://bugs.swift.org/browse/SR-6796
-      if (cs.getASTContext().isSwiftVersionAtLeast(3) &&
+      if (cs.getASTContext().isSwiftVersionAtLeast(4) &&
           !cs.getASTContext().isSwiftVersionAtLeast(5)) {
         auto obj1 = fromType->getOptionalObjectType();
         auto obj2 = toType->getOptionalObjectType();
@@ -8067,24 +8024,6 @@ bool ConstraintSystem::applySolutionFix(Expr *expr,
         llvm_unreachable("Coercions handled in other disjunction branch");
 
       // Valid casts.
-      case CheckedCastKind::Swift3BridgingDowncast: {
-        // Swift 3 accepted coercions from NSNumber and NSValue to Swift
-        // value types, even though there are multiple Swift types that
-        // bridge to those classes, and the bridging operation back into Swift
-        // is type-checked. For compatibility, downgrade to a warning.
-        assert(TC.Context.LangOpts.isSwiftVersion3()
-               && "should only appear in Swift 3 compat mode");
-
-        TC.diagnose(coerceExpr->getLoc(),
-                    diag::missing_forced_downcast_swift3_compat_warning,
-                    fromType, toType)
-          .highlight(coerceExpr->getSourceRange())
-          .fixItReplace(coerceExpr->getLoc(), "as!");
-
-        // This is just a warning, so allow the expression to type-check.
-        return false;
-      }
-
       case CheckedCastKind::ArrayDowncast:
       case CheckedCastKind::DictionaryDowncast:
       case CheckedCastKind::SetDowncast:

lib/Sema/CSRanking.cpp

@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2018 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -613,12 +613,10 @@ static bool isDeclAsSpecializedAs(TypeChecker &tc, DeclContext *dc,
 
         // If they both have trailing closures, compare those separately.
         bool compareTrailingClosureParamsSeparately = false;
-        if (!tc.getLangOpts().isSwiftVersion3()) {
-          if (numParams1 > 0 && numParams2 > 0 &&
-              params1.back().getType()->is<AnyFunctionType>() &&
-              params2.back().getType()->is<AnyFunctionType>()) {
-            compareTrailingClosureParamsSeparately = true;
-          }
+        if (numParams1 > 0 && numParams2 > 0 &&
+            params1.back().getType()->is<AnyFunctionType>() &&
+            params2.back().getType()->is<AnyFunctionType>()) {
+          compareTrailingClosureParamsSeparately = true;
         }
 
         auto maybeAddSubtypeConstraint =

lib/Sema/CSSimplify.cpp

@@ -664,11 +664,8 @@ matchCallArguments(ConstraintSystem &cs, ConstraintKind kind,
     // Check if exactly one argument was passed to this function, otherwise
     // we obviously have a mismatch.
     if (auto tupleArgType = dyn_cast<TupleType>(argType.getPointer())) {
-      // Total hack: In Swift 3 mode, argument labels are ignored when calling
-      // function type with a single Any parameter.
       if (tupleArgType->getNumElements() != 1 ||
-          (!cs.getASTContext().isSwiftVersion3() &&
-           tupleArgType->getElement(0).hasName())) {
+          tupleArgType->getElement(0).hasName()) {
         return cs.getTypeMatchFailure(locator);
       }
     }
@@ -704,21 +701,6 @@ matchCallArguments(ConstraintSystem &cs, ConstraintKind kind,
   llvm::SmallBitVector defaultMap =
     computeDefaultMap(params, callee, calleeLevel);
 
-  if (callee && cs.getASTContext().isSwiftVersion3()
-      && argType->is<TupleType>()) {
-    // Hack: In Swift 3 mode, accept `foo(x, y)` for `foo((x, y))` when the
-    // callee is a function-typed property or an enum constructor whose
-    // argument is a single unlabeled type parameter.
-    if (auto *prop = dyn_cast<VarDecl>(callee)) {
-      auto *fnType = prop->getInterfaceType()->getAs<AnyFunctionType>();
-      if (fnType && fnType->getInput()->isTypeParameter())
-        argType = ParenType::get(cs.getASTContext(), argType);
-    } else if (auto *enumCtor = dyn_cast<EnumElementDecl>(callee)) {
-      if (enumCtor->getArgumentInterfaceType()->isTypeParameter())
-        argType = ParenType::get(cs.getASTContext(), argType);
-    }
-  }
-
   // Extract the arguments.
   auto args = decomposeArgType(argType, argLabels);
 
@@ -1154,7 +1136,7 @@ ConstraintSystem::matchFunctionTypes(FunctionType *func1, FunctionType *func2,
   // arity).
   auto func1Input = func1->getInput();
   auto func2Input = func2->getInput();
-  if (!getASTContext().isSwiftVersion3()) {
+  {
     SmallVector<LocatorPathElt, 4> path;
     locator.getLocatorParts(path);
 
@@ -1573,13 +1555,10 @@ ConstraintSystem::matchTypes(Type type1, Type type2, ConstraintKind kind,
   // types of two function types, we have to be careful to preserve
   // ParenType sugar.
   bool isArgumentTupleMatch = isArgumentTupleConversion;
-  bool isSwiftVersion3 = getASTContext().isSwiftVersion3();
 
-  // ... but not in Swift 3 mode, where this behavior was broken.
-  if (!isSwiftVersion3)
-    if (auto elt = locator.last())
-      if (elt->getKind() == ConstraintLocator::FunctionArgument)
-        isArgumentTupleMatch = true;
+  if (auto elt = locator.last())
+    if (elt->getKind() == ConstraintLocator::FunctionArgument)
+      isArgumentTupleMatch = true;
 
   // If we have type variables that have been bound to fixed types, look through
   // to the fixed type.
@@ -1591,8 +1570,7 @@ ConstraintSystem::matchTypes(Type type1, Type type2, ConstraintKind kind,
   auto desugar1 = type1->getDesugaredType();
   auto desugar2 = type2->getDesugaredType();
   TypeVariableType *typeVar1, *typeVar2;
-  if (isArgumentTupleMatch &&
-      !isSwiftVersion3) {
+  if (isArgumentTupleMatch) {
     typeVar1 = dyn_cast<TypeVariableType>(type1.getPointer());
     typeVar2 = dyn_cast<TypeVariableType>(type2.getPointer());
 
@@ -1777,8 +1755,7 @@ ConstraintSystem::matchTypes(Type type1, Type type2, ConstraintKind kind,
     return formUnsolvedResult();
   }
 
-  if (isArgumentTupleMatch &&
-      !isSwiftVersion3) {
+  if (isArgumentTupleMatch) {
     if (!typeVar1 && !typeVar2) {
       if (type1->hasParenSugar() != type2->hasParenSugar()) {
         return getTypeMatchFailure(locator);
@@ -2853,7 +2830,6 @@ ConstraintSystem::simplifyCheckedCastConstraint(
 
   case CheckedCastKind::Coercion:
   case CheckedCastKind::BridgingCoercion:
-  case CheckedCastKind::Swift3BridgingDowncast:
   case CheckedCastKind::Unresolved:
     llvm_unreachable("Not a valid result");
   }
@@ -3765,10 +3741,7 @@ ConstraintSystem::simplifyBridgingConstraint(Type type1,
       // Bridging NSNumber to NSValue is one-way, since there are multiple Swift
       // value types that bridge to those object types. It requires a checked
       // cast to get back.
-      // We accepted these coercions in Swift 3 mode, so we have to live with
-      // them (but give a warning) in that language mode.
-      if (!TC.Context.LangOpts.isSwiftVersion3()
-          && TC.Context.isObjCClassWithMultipleSwiftBridgedTypes(objcClass))
+      if (TC.Context.isObjCClassWithMultipleSwiftBridgedTypes(objcClass))
         return SolutionKind::Error;
 
       // If the bridged value type is generic, the generic arguments

lib/Sema/ConstraintSystem.cpp

@@ -893,10 +893,8 @@ static unsigned getNumRemovedArgumentLabels(TypeChecker &TC, ValueDecl *decl,
   // bar.map(E.foo)
   //
   // `E.foo` has to act as a regular function type passed as a value.
-  if (!TC.getLangOpts().isSwiftVersion3()) {
-    if (auto *EED = dyn_cast<EnumElementDecl>(decl)) {
-      numParameterLists = EED->hasAssociatedValues() ? 2 : 1;
-    }
+  if (auto *EED = dyn_cast<EnumElementDecl>(decl)) {
+    numParameterLists = EED->hasAssociatedValues() ? 2 : 1;
   }
 
   // Only applicable to functions. Nothing else should have argument labels in