Stateless function components in JSX

src/compiler/checker.ts

@@ -140,9 +140,6 @@ namespace ts {
         let globalRegExpType: ObjectType;
         let globalTemplateStringsArrayType: ObjectType;
         let globalESSymbolType: ObjectType;
-        let jsxElementType: ObjectType;
-        /** Lazily loaded, use getJsxIntrinsicElementType() */
-        let jsxIntrinsicElementsType: ObjectType;
         let globalIterableType: GenericType;
         let globalIteratorType: GenericType;
         let globalIterableIteratorType: GenericType;
@@ -203,12 +200,17 @@ namespace ts {
             }
         };
 
+        let jsxElementType: ObjectType;
+        /** Things we lazy load from the JSX namespace */
+        const jsxTypes: {[name: string]: ObjectType} = {};
         const JsxNames = {
             JSX: "JSX",
             IntrinsicElements: "IntrinsicElements",
             ElementClass: "ElementClass",
             ElementAttributesPropertyNameContainer: "ElementAttributesProperty",
-            Element: "Element"
+            Element: "Element",
+            IntrinsicAttributes: "IntrinsicAttributes",
+            IntrinsicClassAttributes: "IntrinsicClassAttributes"
         };
 
         const subtypeRelation: Map<RelationComparisonResult> = {};
@@ -7714,12 +7716,11 @@ namespace ts {
             return type;
         }
 
-        /// Returns the type JSX.IntrinsicElements. May return `unknownType` if that type is not present.
-        function getJsxIntrinsicElementsType() {
-            if (!jsxIntrinsicElementsType) {
-                jsxIntrinsicElementsType = getExportedTypeFromNamespace(JsxNames.JSX, JsxNames.IntrinsicElements) || unknownType;
+        function getJsxType(name: string) {
+            if (jsxTypes[name] === undefined) {
+                return jsxTypes[name] = getExportedTypeFromNamespace(JsxNames.JSX, name) || unknownType;
             }
-            return jsxIntrinsicElementsType;
+            return jsxTypes[name];
         }
 
         /// Given a JSX opening element or self-closing element, return the symbol of the property that the tag name points to if
@@ -7742,7 +7743,7 @@ namespace ts {
             return links.resolvedSymbol;
 
             function lookupIntrinsicTag(node: JsxOpeningLikeElement | JsxClosingElement): Symbol {
-                const intrinsicElementsType = getJsxIntrinsicElementsType();
+                const intrinsicElementsType = getJsxType(JsxNames.IntrinsicElements);
                 if (intrinsicElementsType !== unknownType) {
                     // Property case
                     const intrinsicProp = getPropertyOfType(intrinsicElementsType, (<Identifier>node.tagName).text);
@@ -7774,7 +7775,7 @@ namespace ts {
 
                 // Look up the value in the current scope
                 if (valueSymbol && valueSymbol !== unknownSymbol) {
-                    links.jsxFlags |= JsxFlags.ClassElement;
+                    links.jsxFlags |= JsxFlags.ValueElement;
                     if (valueSymbol.flags & SymbolFlags.Alias) {
                         markAliasSymbolAsReferenced(valueSymbol);
                     }
@@ -7803,7 +7804,7 @@ namespace ts {
         function getJsxElementInstanceType(node: JsxOpeningLikeElement) {
             // There is no such thing as an instance type for a non-class element. This
             // line shouldn't be hit.
-            Debug.assert(!!(getNodeLinks(node).jsxFlags & JsxFlags.ClassElement), "Should not call getJsxElementInstanceType on non-class Element");
+            Debug.assert(!!(getNodeLinks(node).jsxFlags & JsxFlags.ValueElement), "Should not call getJsxElementInstanceType on non-class Element");
 
             const classSymbol = getJsxElementTagSymbol(node);
             if (classSymbol === unknownSymbol) {
@@ -7830,15 +7831,7 @@ namespace ts {
                 }
             }
 
-            const returnType = getUnionType(signatures.map(getReturnTypeOfSignature));
-
-            // Issue an error if this return type isn't assignable to JSX.ElementClass
-            const elemClassType = getJsxGlobalElementClassType();
-            if (elemClassType) {
-                checkTypeRelatedTo(returnType, elemClassType, assignableRelation, node, Diagnostics.JSX_element_type_0_is_not_a_constructor_function_for_JSX_elements);
-            }
-
-            return returnType;
+            return getUnionType(signatures.map(getReturnTypeOfSignature));
         }
 
         /// e.g. "props" for React.d.ts,
@@ -7887,9 +7880,31 @@ namespace ts {
             if (!links.resolvedJsxType) {
                 const sym = getJsxElementTagSymbol(node);
 
-                if (links.jsxFlags & JsxFlags.ClassElement) {
+                if (links.jsxFlags & JsxFlags.ValueElement) {
+                    // Get the element instance type (the result of newing or invoking this tag)
                     const elemInstanceType = getJsxElementInstanceType(node);
 
+                    // Is this is a stateless function component? See if its single signature is
+                    // assignable to the JSX Element Type
+                    const callSignature = getSingleCallSignature(getTypeOfSymbol(sym));
+                    const callReturnType = callSignature && getReturnTypeOfSignature(callSignature);
+                    let paramType = callReturnType && callSignature && (callSignature.parameters.length === 0 ? emptyObjectType : getTypeOfSymbol(callSignature.parameters[0]));
+                    if (callReturnType && isTypeAssignableTo(callReturnType, jsxElementType) && (paramType.flags & TypeFlags.ObjectType)) {
+                        // Intersect in JSX.IntrinsicAttributes if it exists
+                        const intrinsicAttributes = getJsxType(JsxNames.IntrinsicAttributes);
+                        if (intrinsicAttributes !== unknownType) {
+                            paramType = intersectTypes(intrinsicAttributes, paramType);
+                        }
+                        return paramType;
+                    }
+
+                    // Issue an error if this return type isn't assignable to JSX.ElementClass
+                    const elemClassType = getJsxGlobalElementClassType();
+                    if (elemClassType) {
+                        checkTypeRelatedTo(elemInstanceType, elemClassType, assignableRelation, node, Diagnostics.JSX_element_type_0_is_not_a_constructor_function_for_JSX_elements);
+                    }
+
+
                     if (isTypeAny(elemInstanceType)) {
                         return links.resolvedJsxType = elemInstanceType;
                     }
@@ -7911,14 +7926,36 @@ namespace ts {
                             return links.resolvedJsxType = emptyObjectType;
                         }
                         else if (isTypeAny(attributesType) || (attributesType === unknownType)) {
+                            // Props is of type 'any' or unknown
                             return links.resolvedJsxType = attributesType;
                         }
                         else if (!(attributesType.flags & TypeFlags.ObjectType)) {
+                            // Props is not an object type
                             error(node.tagName, Diagnostics.JSX_element_attributes_type_0_must_be_an_object_type, typeToString(attributesType));
                             return links.resolvedJsxType = anyType;
                         }
                         else {
-                            return links.resolvedJsxType = attributesType;
+                            // Normal case -- add in IntrinsicClassElements<T> and IntrinsicElements
+                            let apparentAttributesType = attributesType;
+                            const intrinsicClassAttribs = getJsxType(JsxNames.IntrinsicClassAttributes);
+                            if (intrinsicClassAttribs !== unknownType) {
+                                const typeParams = getLocalTypeParametersOfClassOrInterfaceOrTypeAlias(intrinsicClassAttribs.symbol);
+                                if (typeParams) {
+                                    if (typeParams.length === 1) {
+                                        apparentAttributesType = intersectTypes(createTypeReference(<GenericType>intrinsicClassAttribs, [elemInstanceType]), apparentAttributesType);
+                                    }
+                                }
+                                else {
+                                    apparentAttributesType = intersectTypes(attributesType, intrinsicClassAttribs);
+                                }
+                            }
+
+                            const intrinsicAttribs = getJsxType(JsxNames.IntrinsicAttributes);
+                            if (intrinsicAttribs !== unknownType) {
+                                apparentAttributesType = intersectTypes(intrinsicAttribs, apparentAttributesType);
+                            }
+
+                            return links.resolvedJsxType = apparentAttributesType;
                         }
                     }
                 }
@@ -7957,7 +7994,7 @@ namespace ts {
 
         /// Returns all the properties of the Jsx.IntrinsicElements interface
         function getJsxIntrinsicTagNames(): Symbol[] {
-            const intrinsics = getJsxIntrinsicElementsType();
+            const intrinsics = getJsxType(JsxNames.IntrinsicElements);
             return intrinsics ? getPropertiesOfType(intrinsics) : emptyArray;
         }
 

src/compiler/types.ts

@@ -437,12 +437,16 @@ namespace ts {
 
     export const enum JsxFlags {
         None = 0,
+        /** An element from a named property of the JSX.IntrinsicElements interface */
         IntrinsicNamedElement = 1 << 0,
+        /** An element inferred from the string index signature of the JSX.IntrinsicElements interface */
         IntrinsicIndexedElement = 1 << 1,
-        ClassElement = 1 << 2,
-        UnknownElement = 1 << 3,
+        /** An element backed by a class, class-like, or function value */
+        ValueElement = 1 << 2,
+        /** Element resolution failed */
+        UnknownElement = 1 << 4,
 
-        IntrinsicElement = IntrinsicNamedElement | IntrinsicIndexedElement
+        IntrinsicElement = IntrinsicNamedElement | IntrinsicIndexedElement,
     }
 
 

src/harness/harness.ts

@@ -975,6 +975,7 @@ namespace Harness {
             useCaseSensitiveFileNames?: boolean;
             includeBuiltFile?: string;
             baselineFile?: string;
+            libFiles?: string;
         }
 
         // Additional options not already in ts.optionDeclarations 
@@ -984,6 +985,7 @@ namespace Harness {
             { name: "baselineFile", type: "string" },
             { name: "includeBuiltFile", type: "string" },
             { name: "fileName", type: "string" },
+            { name: "libFiles", type: "string" },
             { name: "noErrorTruncation", type: "boolean" }
         ];
 
@@ -1115,6 +1117,15 @@ namespace Harness {
                     includeBuiltFiles.push({ unitName: builtFileName, content: normalizeLineEndings(IO.readFile(builtFileName), newLine) });
                 }
 
+                // Files from tests\lib that are requested by "@libFiles"
+                if (options.libFiles) {
+                    ts.forEach(options.libFiles.split(","), filename => {
+                        const libFileName = "tests/lib/" + filename;
+                        includeBuiltFiles.push({ unitName: libFileName, content: normalizeLineEndings(IO.readFile(libFileName), newLine) });
+                    });
+                }
+
+
                 const useCaseSensitiveFileNames = options.useCaseSensitiveFileNames !== undefined ? options.useCaseSensitiveFileNames : Harness.IO.useCaseSensitiveFileNames();
 
                 const fileOutputs: GeneratedFile[] = [];

tests/baselines/reference/tsxStatelessFunctionComponents1.errors.txt

@@ -0,0 +1,37 @@
+tests/cases/conformance/jsx/tsxStatelessFunctionComponents1.tsx(12,9): error TS2324: Property 'name' is missing in type 'IntrinsicAttributes & { name: string; }'.
+tests/cases/conformance/jsx/tsxStatelessFunctionComponents1.tsx(12,16): error TS2339: Property 'naaame' does not exist on type 'IntrinsicAttributes & { name: string; }'.
+tests/cases/conformance/jsx/tsxStatelessFunctionComponents1.tsx(19,15): error TS2322: Type 'number' is not assignable to type 'string'.
+tests/cases/conformance/jsx/tsxStatelessFunctionComponents1.tsx(21,15): error TS2339: Property 'naaaaaaame' does not exist on type 'IntrinsicAttributes & { name?: string; }'.
+
+
+==== tests/cases/conformance/jsx/tsxStatelessFunctionComponents1.tsx (4 errors) ====
+
+    function Greet(x: {name: string}) {
+    	return <div>Hello, {x}</div>;
+    }
+    function Meet({name = 'world'}) {
+    	return <div>Hello, {name}</div>;
+    }
+
+    // OK
+    let a = <Greet name='world' />;
+    // Error
+    let b = <Greet naaame='world' />;
+            ~~~~~~~~~~~~~~~~~~~~~~~~
+!!! error TS2324: Property 'name' is missing in type 'IntrinsicAttributes & { name: string; }'.
+                   ~~~~~~
+!!! error TS2339: Property 'naaame' does not exist on type 'IntrinsicAttributes & { name: string; }'.
+
+    // OK
+    let c = <Meet />;
+    // OK
+    let d = <Meet name='me' />;
+    // Error
+    let e = <Meet name={42} />;
+                  ~~~~~~~~~
+!!! error TS2322: Type 'number' is not assignable to type 'string'.
+    // Error
+    let f = <Meet naaaaaaame='no' />;
+                  ~~~~~~~~~~
+!!! error TS2339: Property 'naaaaaaame' does not exist on type 'IntrinsicAttributes & { name?: string; }'.
+

tests/baselines/reference/tsxStatelessFunctionComponents1.js

@@ -0,0 +1,44 @@
+//// [tsxStatelessFunctionComponents1.tsx]
+
+function Greet(x: {name: string}) {
+	return <div>Hello, {x}</div>;
+}
+function Meet({name = 'world'}) {
+	return <div>Hello, {name}</div>;
+}
+
+// OK
+let a = <Greet name='world' />;
+// Error
+let b = <Greet naaame='world' />;
+
+// OK
+let c = <Meet />;
+// OK
+let d = <Meet name='me' />;
+// Error
+let e = <Meet name={42} />;
+// Error
+let f = <Meet naaaaaaame='no' />;
+
+
+//// [tsxStatelessFunctionComponents1.jsx]
+function Greet(x) {
+    return <div>Hello, {x}</div>;
+}
+function Meet(_a) {
+    var _b = _a.name, name = _b === void 0 ? 'world' : _b;
+    return <div>Hello, {name}</div>;
+}
+// OK
+var a = <Greet name='world'/>;
+// Error
+var b = <Greet naaame='world'/>;
+// OK
+var c = <Meet />;
+// OK
+var d = <Meet name='me'/>;
+// Error
+var e = <Meet name={42}/>;
+// Error
+var f = <Meet naaaaaaame='no'/>;

tests/baselines/reference/tsxStatelessFunctionComponents2.errors.txt

@@ -0,0 +1,52 @@
+tests/cases/conformance/jsx/tsxStatelessFunctionComponents2.tsx(2,1): error TS1148: Cannot compile modules unless the '--module' flag is provided.
+tests/cases/conformance/jsx/tsxStatelessFunctionComponents2.tsx(20,16): error TS2339: Property 'ref' does not exist on type 'IntrinsicAttributes & { name?: string; }'.
+tests/cases/conformance/jsx/tsxStatelessFunctionComponents2.tsx(26,42): error TS2339: Property 'subtr' does not exist on type 'string'.
+tests/cases/conformance/jsx/tsxStatelessFunctionComponents2.tsx(28,5): error TS2451: Cannot redeclare block-scoped variable 'f'.
+tests/cases/conformance/jsx/tsxStatelessFunctionComponents2.tsx(28,33): error TS2339: Property 'notARealProperty' does not exist on type 'BigGreeter'.
+tests/cases/conformance/jsx/tsxStatelessFunctionComponents2.tsx(31,5): error TS2451: Cannot redeclare block-scoped variable 'f'.
+
+
+==== tests/cases/conformance/jsx/tsxStatelessFunctionComponents2.tsx (6 errors) ====
+
+    import React = require('react');
+    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+!!! error TS1148: Cannot compile modules unless the '--module' flag is provided.
+
+    function Greet(x: {name?: string}) {
+    	return <div>Hello, {x}</div>;
+    }
+
+    class BigGreeter extends React.Component<{ name?: string }, {}> {
+    	render() {
+    		return <div></div>;
+    	}
+    	greeting: string;
+    }
+
+    // OK
+    let a = <Greet />;
+    // OK
+    let b = <Greet key="k" />;
+    // Error
+    let c = <Greet ref="myRef" />;
+                   ~~~
+!!! error TS2339: Property 'ref' does not exist on type 'IntrinsicAttributes & { name?: string; }'.
+
+
+    // OK
+    let d = <BigGreeter ref={x => x.greeting.substr(10)} />;
+    // Error ('subtr')
+    let e = <BigGreeter ref={x => x.greeting.subtr(10)} />;
+                                             ~~~~~
+!!! error TS2339: Property 'subtr' does not exist on type 'string'.
+    // Error
+    let f = <BigGreeter ref={x => x.notARealProperty} />;
+        ~
+!!! error TS2451: Cannot redeclare block-scoped variable 'f'.
+                                    ~~~~~~~~~~~~~~~~
+!!! error TS2339: Property 'notARealProperty' does not exist on type 'BigGreeter'.
+
+    // OK
+    let f = <BigGreeter key={100} />;
+        ~
+!!! error TS2451: Cannot redeclare block-scoped variable 'f'.