[cfe,ddc,dart2js,vm] Add FutureOrType

This CL is the sum of the following 5 CLs:
* https://dart-review.googlesource.com/c/sdk/+/149297/
* https://dart-review.googlesource.com/c/sdk/+/149299/
* https://dart-review.googlesource.com/c/sdk/+/149320/
* https://dart-review.googlesource.com/c/sdk/+/149321/
* https://dart-review.googlesource.com/c/sdk/+/149323/

The reason for landing the 5 CLs as one CL is to prevent potential
troubles with bisecting over the branch because the change is fully
functional only with all 5 CLs.

Closes #40123.

Bug: #40123
Change-Id: Ice52250a98acfe455b1d7fa5bb0624c115ca5dac
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/150934
Commit-Queue: Dmitry Stefantsov <[email protected]>
Reviewed-by: Alexander Markov <[email protected]>
Reviewed-by: Johnni Winther <[email protected]>

Author: Dmitry Stefantsov

pkg/compiler/lib/src/ir/impact.dart

@@ -298,13 +298,11 @@ abstract class ImpactBuilderBase extends StaticTypeVisitor
 
       case ir.AsyncMarker.Async:
         ir.DartType elementType = const ir.DynamicType();
-        if (returnType is ir.InterfaceType) {
-          if (returnType.classNode == typeEnvironment.coreTypes.futureOrClass) {
-            elementType = returnType.typeArguments.first;
-          } else if (returnType.classNode ==
-              typeEnvironment.coreTypes.futureClass) {
-            elementType = returnType.typeArguments.first;
-          }
+        if (returnType is ir.InterfaceType &&
+            returnType.classNode == typeEnvironment.coreTypes.futureClass) {
+          elementType = returnType.typeArguments.first;
+        } else if (returnType is ir.FutureOrType) {
+          elementType = returnType.typeArgument;
         }
         registerAsync(elementType);
         break;

pkg/compiler/lib/src/ir/scope_visitor.dart

@@ -634,6 +634,11 @@ class ScopeModelBuilder extends ir.Visitor<InitializerComplexity>
     return visitNodes(node.typeArguments);
   }
 
+  @override
+  InitializerComplexity visitFutureOrType(ir.FutureOrType node) {
+    return visitNode(node.typeArgument);
+  }
+
   @override
   InitializerComplexity visitFunctionType(ir.FunctionType node) {
     InitializerComplexity complexity = visitNode(node.returnType);

pkg/compiler/lib/src/ir/static_type.dart

@@ -742,8 +742,7 @@ abstract class StaticTypeVisitor extends StaticTypeBase {
     assert(
         node.promotedType == null ||
             promotedType == typeEnvironment.nullType ||
-            promotedType is ir.InterfaceType &&
-                promotedType.classNode == typeEnvironment.futureOrClass ||
+            promotedType is ir.FutureOrType ||
             typeEnvironment.isSubtypeOf(promotedType, node.promotedType,
                 ir.SubtypeCheckMode.ignoringNullabilities),
         "Unexpected promotion of ${node.variable} in ${node.parent}. "

pkg/compiler/lib/src/ir/util.dart

@@ -204,6 +204,11 @@ class _FreeVariableVisitor implements ir.DartTypeVisitor<bool> {
     return visitList(node.typeArguments);
   }
 
+  @override
+  bool visitFutureOrType(ir.FutureOrType node) {
+    return visit(node.typeArgument);
+  }
+
   @override
   bool visitBottomType(ir.BottomType node) => false;
 

pkg/compiler/lib/src/ir/visitors.dart

@@ -148,17 +148,18 @@ class DartTypeConverter extends ir.DartTypeVisitor<DartType> {
   @override
   DartType visitInterfaceType(ir.InterfaceType node) {
     ClassEntity cls = elementMap.getClass(node.classNode);
-    if (cls.name == 'FutureOr' &&
-        cls.library == elementMap.commonElements.asyncLibrary) {
-      return _convertNullability(
-          _dartTypes.futureOrType(visitTypes(node.typeArguments).single),
-          node.nullability);
-    }
     return _convertNullability(
         _dartTypes.interfaceType(cls, visitTypes(node.typeArguments)),
         node.nullability);
   }
 
+  @override
+  DartType visitFutureOrType(ir.FutureOrType node) {
+    return _convertNullability(
+        _dartTypes.futureOrType(visitType(node.typeArgument)),
+        node.declaredNullability);
+  }
+
   @override
   DartType visitVoidType(ir.VoidType node) {
     return _dartTypes.voidType();

pkg/compiler/lib/src/kernel/kernel_impact.dart

@@ -137,10 +137,6 @@ abstract class KernelImpactRegistryMixin implements ImpactRegistry {
   Object _computeReceiverConstraint(
       ir.DartType receiverType, ClassRelation relation) {
     if (receiverType is ir.InterfaceType) {
-      if (receiverType.classNode == typeEnvironment.futureOrClass) {
-        // CFE encodes FutureOr as an interface type!
-        return null;
-      }
       return new StrongModeConstraint(commonElements, _nativeBasicData,
           elementMap.getClass(receiverType.classNode), relation);
     }

pkg/compiler/lib/src/serialization/abstract_source.dart

@@ -272,6 +272,10 @@ abstract class AbstractDataSource extends DataSourceMixin
         return new ir.TypedefType(typedef, nullability, typeArguments);
       case DartTypeNodeKind.dynamicType:
         return const ir.DynamicType();
+      case DartTypeNodeKind.futureOrType:
+        ir.Nullability nullability = readEnum(ir.Nullability.values);
+        ir.DartType typeArgument = _readDartTypeNode(functionTypeVariables);
+        return new ir.FutureOrType(typeArgument, nullability);
     }
     throw new UnsupportedError("Unexpected DartTypeKind $kind");
   }

pkg/compiler/lib/src/serialization/helpers.dart

@@ -119,6 +119,7 @@ enum DartTypeNodeKind {
   exactInterfaceType,
   doesNotComplete,
   neverType,
+  futureOrType,
 }
 
 const String functionTypeNodeTag = 'function-type-node';
@@ -194,6 +195,14 @@ class DartTypeNodeWriter
     visitTypes(node.typeArguments, functionTypeVariables);
   }
 
+  @override
+  void visitFutureOrType(
+      ir.FutureOrType node, List<ir.TypeParameter> functionTypeVariables) {
+    _sink.writeEnum(DartTypeNodeKind.futureOrType);
+    _sink.writeEnum(node.declaredNullability);
+    _sink._writeDartTypeNode(node.typeArgument, functionTypeVariables);
+  }
+
   @override
   void visitFunctionType(
       ir.FunctionType node, List<ir.TypeParameter> functionTypeVariables) {

pkg/compiler/lib/src/ssa/builder_kernel.dart

@@ -3257,7 +3257,8 @@ class KernelSsaGraphBuilder extends ir.Visitor {
     if (type is ir.InterfaceType ||
         type is ir.DynamicType ||
         type is ir.TypedefType ||
-        type is ir.FunctionType) {
+        type is ir.FunctionType ||
+        type is ir.FutureOrType) {
       ConstantValue constant =
           _elementMap.getConstantValue(_memberContextNode, node);
       stack.add(graph.addConstant(constant, closedWorld,

pkg/compiler/test/analyses/analysis_helper.dart

@@ -310,8 +310,7 @@ class DynamicVisitor extends StaticTypeVisitorBase {
     assert(
         node is! ir.Expression ||
             staticType == typeEnvironment.nullType ||
-            staticType is ir.InterfaceType &&
-                staticType.classNode == typeEnvironment.futureOrClass ||
+            staticType is ir.FutureOrType ||
             typeEnvironment.isSubtypeOf(
                 staticType,
                 _getStaticTypeFromExpression(node),