feat(7481): Operator to ensure an expression is contextually typed by, and satisfies, some type

src/compiler/checker.ts

@@ -27401,6 +27401,10 @@ namespace ts {
                 }
                 case SyntaxKind.NonNullExpression:
                     return getContextualType(parent as NonNullExpression, contextFlags);
+                case SyntaxKind.SatisfiesExpression:
+                    const assertedType = getTypeFromTypeNode((parent as SatisfiesExpression).type);
+                    const outerType = getContextualType(parent as SatisfiesExpression, contextFlags);
+                    return outerType === undefined ? assertedType : getIntersectionType([assertedType, outerType]);
                 case SyntaxKind.ExportAssignment:
                     return tryGetTypeFromEffectiveTypeNode(parent as ExportAssignment);
                 case SyntaxKind.JsxExpression:
@@ -32316,6 +32320,20 @@ namespace ts {
             }
         }
 
+        function checkSatisfiesExpression(node: SatisfiesExpression) {
+            checkSourceElement(node.type);
+
+            const targetType = getTypeFromTypeNode(node.type);
+            if (isErrorType(targetType)) {
+                return targetType;
+            }
+
+            const exprType = checkExpression(node.expression);
+            checkTypeAssignableToAndOptionallyElaborate(exprType, targetType, node.type, node.expression, Diagnostics.Type_0_does_not_satisfy_the_expected_type_1);
+
+            return exprType;
+        }
+
         function checkMetaProperty(node: MetaProperty): Type {
             checkGrammarMetaProperty(node);
 
@@ -35109,6 +35127,8 @@ namespace ts {
                     return checkNonNullAssertion(node as NonNullExpression);
                 case SyntaxKind.ExpressionWithTypeArguments:
                     return checkExpressionWithTypeArguments(node as ExpressionWithTypeArguments);
+                case SyntaxKind.SatisfiesExpression:
+                    return checkSatisfiesExpression(node as SatisfiesExpression);
                 case SyntaxKind.MetaProperty:
                     return checkMetaProperty(node as MetaProperty);
                 case SyntaxKind.DeleteExpression:

src/compiler/diagnosticMessages.json

@@ -1100,7 +1100,7 @@
         "category": "Error",
         "code": 1359
     },
-    "Class constructor may not be a generator.": {
+    "Type '{0}' does not satisfy the expected type '{1}'.": {
         "category": "Error",
         "code": 1360
     },
@@ -1132,6 +1132,10 @@
         "category": "Message",
         "code": 1367
     },
+    "Class constructor may not be a generator.": {
+        "category": "Error",
+        "code": 1368
+    },
     "Did you mean '{0}'?": {
         "category": "Message",
         "code": 1369
@@ -6328,6 +6332,10 @@
         "category": "Error",
         "code": 8036
     },
+    "Type satisfaction expressions can only be used in TypeScript files.": {
+        "category": "Error",
+        "code": 8037
+    },
 
     "Declaration emit for this file requires using private name '{0}'. An explicit type annotation may unblock declaration emit.": {
         "category": "Error",

src/compiler/emitter.ts

@@ -1764,6 +1764,8 @@ namespace ts {
                         return emitNonNullExpression(node as NonNullExpression);
                     case SyntaxKind.ExpressionWithTypeArguments:
                         return emitExpressionWithTypeArguments(node as ExpressionWithTypeArguments);
+                    case SyntaxKind.SatisfiesExpression:
+                        return emitSatisfiesExpression(node as SatisfiesExpression);
                     case SyntaxKind.MetaProperty:
                         return emitMetaProperty(node as MetaProperty);
                     case SyntaxKind.SyntheticExpression:
@@ -2847,6 +2849,16 @@ namespace ts {
             writeOperator("!");
         }
 
+        function emitSatisfiesExpression(node: SatisfiesExpression) {
+            emitExpression(node.expression, /*parenthesizerRules*/ undefined);
+            if (node.type) {
+                writeSpace();
+                writeKeyword("satisfies");
+                writeSpace();
+                emit(node.type);
+            }
+        }
+
         function emitMetaProperty(node: MetaProperty) {
             writeToken(node.keywordToken, node.pos, writePunctuation);
             writePunctuation(".");

src/compiler/factory/nodeFactory.ts

@@ -222,6 +222,8 @@ namespace ts {
             updateAsExpression,
             createNonNullExpression,
             updateNonNullExpression,
+            createSatisfiesExpression,
+            updateSatisfiesExpression,
             createNonNullChain,
             updateNonNullChain,
             createMetaProperty,
@@ -3139,6 +3141,26 @@ namespace ts {
                 : node;
         }
 
+        // @api
+        function createSatisfiesExpression(expression: Expression, type: TypeNode) {
+            const node = createBaseExpression<SatisfiesExpression>(SyntaxKind.SatisfiesExpression);
+            node.expression = expression;
+            node.type = type;
+            node.transformFlags |=
+                propagateChildFlags(node.expression) |
+                propagateChildFlags(node.type) |
+                TransformFlags.ContainsTypeScript;
+            return node;
+        }
+
+        // @api
+        function updateSatisfiesExpression(node: SatisfiesExpression, expression: Expression, type: TypeNode) {
+            return node.expression !== expression
+                || node.type !== type
+                ? update(createSatisfiesExpression(expression, type), node)
+                : node;
+        }
+
         // @api
         function createNonNullChain(expression: Expression) {
             const node = createBaseExpression<NonNullChain>(SyntaxKind.NonNullExpression);
@@ -5727,6 +5749,7 @@ namespace ts {
                 case SyntaxKind.ParenthesizedExpression: return updateParenthesizedExpression(outerExpression, expression);
                 case SyntaxKind.TypeAssertionExpression: return updateTypeAssertion(outerExpression, outerExpression.type, expression);
                 case SyntaxKind.AsExpression: return updateAsExpression(outerExpression, expression, outerExpression.type);
+                case SyntaxKind.SatisfiesExpression: return updateSatisfiesExpression(outerExpression, expression, outerExpression.type);
                 case SyntaxKind.NonNullExpression: return updateNonNullExpression(outerExpression, expression);
                 case SyntaxKind.PartiallyEmittedExpression: return updatePartiallyEmittedExpression(outerExpression, expression);
             }
@@ -6462,6 +6485,7 @@ namespace ts {
             case SyntaxKind.ArrayBindingPattern:
                 return TransformFlags.BindingPatternExcludes;
             case SyntaxKind.TypeAssertionExpression:
+            case SyntaxKind.SatisfiesExpression:
             case SyntaxKind.AsExpression:
             case SyntaxKind.PartiallyEmittedExpression:
             case SyntaxKind.ParenthesizedExpression:

src/compiler/factory/nodeTests.ts

@@ -438,6 +438,10 @@ namespace ts {
         return node.kind === SyntaxKind.AsExpression;
     }
 
+    export function isSatisfiesExpression(node: Node): node is SatisfiesExpression {
+        return node.kind === SyntaxKind.SatisfiesExpression;
+    }
+
     export function isNonNullExpression(node: Node): node is NonNullExpression {
         return node.kind === SyntaxKind.NonNullExpression;
     }

src/compiler/factory/utilities.ts

@@ -437,6 +437,7 @@ namespace ts {
                 return (kinds & OuterExpressionKinds.Parentheses) !== 0;
             case SyntaxKind.TypeAssertionExpression:
             case SyntaxKind.AsExpression:
+            case SyntaxKind.SatisfiesExpression:
                 return (kinds & OuterExpressionKinds.TypeAssertions) !== 0;
             case SyntaxKind.NonNullExpression:
                 return (kinds & OuterExpressionKinds.NonNullAssertions) !== 0;

src/compiler/parser.ts

@@ -365,6 +365,9 @@ namespace ts {
                     visitNode(cbNode, (node as AsExpression).type);
             case SyntaxKind.NonNullExpression:
                 return visitNode(cbNode, (node as NonNullExpression).expression);
+            case SyntaxKind.SatisfiesExpression:
+                return visitNode(cbNode, (node as SatisfiesExpression).expression) ||
+                    visitNode(cbNode, (node as SatisfiesExpression).type);
             case SyntaxKind.MetaProperty:
                 return visitNode(cbNode, (node as MetaProperty).name);
             case SyntaxKind.ConditionalExpression:
@@ -4928,7 +4931,7 @@ namespace ts {
                     break;
                 }
 
-                if (token() === SyntaxKind.AsKeyword) {
+                if (token() === SyntaxKind.AsKeyword || token() === SyntaxKind.SatisfiesKeyword) {
                     // Make sure we *do* perform ASI for constructs like this:
                     //    var x = foo
                     //    as (Bar)
@@ -4938,8 +4941,10 @@ namespace ts {
                         break;
                     }
                     else {
+                        const keywordKind = token();
                         nextToken();
-                        leftOperand = makeAsExpression(leftOperand, parseType());
+                        leftOperand = keywordKind === SyntaxKind.SatisfiesKeyword ? makeSatisfiesExpression(leftOperand, parseType()) :
+                            makeAsExpression(leftOperand, parseType());
                     }
                 }
                 else {
@@ -4958,6 +4963,10 @@ namespace ts {
             return getBinaryOperatorPrecedence(token()) > 0;
         }
 
+        function makeSatisfiesExpression(left: Expression, right: TypeNode): SatisfiesExpression {
+            return finishNode(factory.createSatisfiesExpression(left, right), left.pos);
+        }
+
         function makeBinaryExpression(left: Expression, operatorToken: BinaryOperatorToken, right: Expression, pos: number): BinaryExpression {
             return finishNode(factory.createBinaryExpression(left, operatorToken, right), pos);
         }

src/compiler/program.ts

@@ -2354,6 +2354,9 @@ namespace ts {
                         case SyntaxKind.AsExpression:
                             diagnostics.push(createDiagnosticForNode((node as AsExpression).type, Diagnostics.Type_assertion_expressions_can_only_be_used_in_TypeScript_files));
                             return "skip";
+                        case SyntaxKind.SatisfiesExpression:
+                            diagnostics.push(createDiagnosticForNode((node as SatisfiesExpression).type, Diagnostics.Type_satisfaction_expressions_can_only_be_used_in_TypeScript_files));
+                            return "skip";
                         case SyntaxKind.TypeAssertionExpression:
                             Debug.fail(); // Won't parse these in a JS file anyway, as they are interpreted as JSX.
                     }

src/compiler/scanner.ts

@@ -136,6 +136,7 @@ namespace ts {
         require: SyntaxKind.RequireKeyword,
         global: SyntaxKind.GlobalKeyword,
         return: SyntaxKind.ReturnKeyword,
+        satisfies: SyntaxKind.SatisfiesKeyword,
         set: SyntaxKind.SetKeyword,
         static: SyntaxKind.StaticKeyword,
         string: SyntaxKind.StringKeyword,

src/compiler/transformers/ts.ts

@@ -529,6 +529,9 @@ namespace ts {
                     // TypeScript type assertions are removed, but their subtrees are preserved.
                     return visitAssertionExpression(node as AssertionExpression);
 
+                case SyntaxKind.SatisfiesExpression:
+                    return visitSatisfiesExpression(node as SatisfiesExpression);
+
                 case SyntaxKind.CallExpression:
                     return visitCallExpression(node as CallExpression);
 
@@ -1421,6 +1424,11 @@ namespace ts {
             return factory.createPartiallyEmittedExpression(expression, node);
         }
 
+        function visitSatisfiesExpression(node: SatisfiesExpression): Expression {
+            const expression = visitNode(node.expression, visitor, isExpression);
+            return factory.createPartiallyEmittedExpression(expression, node);
+        }
+
         function visitCallExpression(node: CallExpression) {
             return factory.updateCallExpression(
                 node,

src/compiler/types.ts

@@ -181,6 +181,7 @@ namespace ts {
         RequireKeyword,
         NumberKeyword,
         ObjectKeyword,
+        SatisfiesKeyword,
         SetKeyword,
         StringKeyword,
         SymbolKeyword,
@@ -274,6 +275,7 @@ namespace ts {
         NonNullExpression,
         MetaProperty,
         SyntheticExpression,
+        SatisfiesExpression,
 
         // Misc
         TemplateSpan,
@@ -607,6 +609,7 @@ namespace ts {
         | SyntaxKind.OverrideKeyword
         | SyntaxKind.RequireKeyword
         | SyntaxKind.ReturnKeyword
+        | SyntaxKind.SatisfiesKeyword
         | SyntaxKind.SetKeyword
         | SyntaxKind.StaticKeyword
         | SyntaxKind.StringKeyword
@@ -2627,6 +2630,12 @@ namespace ts {
         readonly expression: UnaryExpression;
     }
 
+    export interface SatisfiesExpression extends Expression {
+        readonly kind: SyntaxKind.SatisfiesExpression;
+        readonly expression: Expression;
+        readonly type: TypeNode;
+    }
+
     export type AssertionExpression =
         | TypeAssertion
         | AsExpression
@@ -7323,6 +7332,7 @@ namespace ts {
     export type OuterExpression =
         | ParenthesizedExpression
         | TypeAssertion
+        | SatisfiesExpression
         | AsExpression
         | NonNullExpression
         | PartiallyEmittedExpression;
@@ -7659,6 +7669,8 @@ namespace ts {
         updateNonNullChain(node: NonNullChain, expression: Expression): NonNullChain;
         createMetaProperty(keywordToken: MetaProperty["keywordToken"], name: Identifier): MetaProperty;
         updateMetaProperty(node: MetaProperty, name: Identifier): MetaProperty;
+        createSatisfiesExpression(expression: Expression, type: TypeNode): SatisfiesExpression;
+        updateSatisfiesExpression(node: SatisfiesExpression, expression: Expression, type: TypeNode): SatisfiesExpression;
 
         //
         // Misc

src/compiler/utilities.ts

@@ -1995,6 +1995,7 @@ namespace ts {
             case SyntaxKind.TaggedTemplateExpression:
             case SyntaxKind.AsExpression:
             case SyntaxKind.TypeAssertionExpression:
+            case SyntaxKind.SatisfiesExpression:
             case SyntaxKind.NonNullExpression:
             case SyntaxKind.ParenthesizedExpression:
             case SyntaxKind.FunctionExpression:
@@ -2095,6 +2096,8 @@ namespace ts {
                 return (parent as ExpressionWithTypeArguments).expression === node && !isPartOfTypeNode(parent);
             case SyntaxKind.ShorthandPropertyAssignment:
                 return (parent as ShorthandPropertyAssignment).objectAssignmentInitializer === node;
+            case SyntaxKind.SatisfiesExpression:
+                return node === (parent as SatisfiesExpression).expression;
             default:
                 return isExpressionNode(parent);
         }
@@ -3801,6 +3804,7 @@ namespace ts {
                 return OperatorPrecedence.Member;
 
             case SyntaxKind.AsExpression:
+            case SyntaxKind.SatisfiesExpression:
                 return OperatorPrecedence.Relational;
 
             case SyntaxKind.ThisKeyword:
@@ -3859,6 +3863,7 @@ namespace ts {
             case SyntaxKind.InstanceOfKeyword:
             case SyntaxKind.InKeyword:
             case SyntaxKind.AsKeyword:
+            case SyntaxKind.SatisfiesKeyword:
                 return OperatorPrecedence.Relational;
             case SyntaxKind.LessThanLessThanToken:
             case SyntaxKind.GreaterThanGreaterThanToken:
@@ -5934,7 +5939,8 @@ namespace ts {
                 case SyntaxKind.PropertyAccessExpression:
                 case SyntaxKind.NonNullExpression:
                 case SyntaxKind.PartiallyEmittedExpression:
-                    node = (node as CallExpression | PropertyAccessExpression | ElementAccessExpression | AsExpression | NonNullExpression | PartiallyEmittedExpression).expression;
+                case SyntaxKind.SatisfiesExpression:
+                    node = (node as CallExpression | PropertyAccessExpression | ElementAccessExpression | AsExpression | NonNullExpression | PartiallyEmittedExpression | SatisfiesExpression).expression;
                     continue;
             }
 

src/compiler/utilitiesPublic.ts

@@ -1642,6 +1642,7 @@ namespace ts {
             case SyntaxKind.OmittedExpression:
             case SyntaxKind.CommaListExpression:
             case SyntaxKind.PartiallyEmittedExpression:
+            case SyntaxKind.SatisfiesExpression:
                 return true;
             default:
                 return isUnaryExpressionKind(kind);

src/compiler/visitorPublic.ts

@@ -880,6 +880,12 @@ namespace ts {
                     nodeVisitor(node.expression, visitor, isExpression),
                     nodeVisitor(node.type, visitor, isTypeNode));
 
+            case SyntaxKind.SatisfiesExpression:
+                Debug.type<SatisfiesExpression>(node);
+                return factory.updateSatisfiesExpression(node,
+                    nodeVisitor(node.expression, visitor, isExpression),
+                    nodeVisitor(node.type, visitor, isTypeNode));
+
             case SyntaxKind.NonNullExpression:
                 if (node.flags & NodeFlags.OptionalChain) {
                     Debug.type<NonNullChain>(node);