Improve contextual types and return type checking

Author: rbuckton

src/compiler/checker.ts

@@ -2620,20 +2620,19 @@ namespace ts {
         });
     }
 
-    /** Get the type annotation for the value parameter. */
-    export function getSetAccessorTypeAnnotationNode(accessor: SetAccessorDeclaration, includeJSDocType?: boolean): TypeNode {
+    function getSetAccessorValueParameter(accessor: SetAccessorDeclaration): ParameterDeclaration | undefined {
         if (accessor && accessor.parameters.length > 0) {
             const hasThis = accessor.parameters.length === 2 && parameterIsThisKeyword(accessor.parameters[0]);
-            const parameter = accessor.parameters[hasThis ? 1 : 0];
-            if (parameter.type) {
-                return parameter.type;
-            }
-            if (includeJSDocType && parameter.flags & NodeFlags.JavaScriptFile) {
-                return getJSDocType(parameter);
-            }
+            return accessor.parameters[hasThis ? 1 : 0];
         }
     }
 
+    /** Get the type annotation for the value parameter. */
+    export function getSetAccessorTypeAnnotationNode(accessor: SetAccessorDeclaration): TypeNode {
+        const parameter = getSetAccessorValueParameter(accessor);
+        return parameter && parameter.type;
+    }
+
     export function getThisParameter(signature: SignatureDeclaration): ParameterDeclaration | undefined {
         if (signature.parameters.length) {
             const thisParameter = signature.parameters[0];
@@ -2712,6 +2711,41 @@ namespace ts {
         };
     }
 
+    /**
+     * Gets the effective type annotation of a variable, parameter, or property. If the node was
+     * parsed in a JavaScript file, gets the type annotation from JSDoc.
+     */
+    export function getEffectiveTypeAnnotationNode(node: VariableLikeDeclaration): TypeNode {
+        if (node.type) {
+            return node.type;
+        }
+        if (node.flags & NodeFlags.JavaScriptFile) {
+            return getJSDocType(node);
+        }
+    }
+
+    /**
+     * Gets the effective return type annotation of a signature. If the node was parsed in a
+     * JavaScript file, gets the return type annotation from JSDoc.
+     */
+    export function getEffectiveReturnTypeNode(node: SignatureDeclaration): TypeNode {
+        if (node.type) {
+            return node.type;
+        }
+        if (node.flags & NodeFlags.JavaScriptFile) {
+            return getJSDocReturnType(node);
+        }
+    }
+
+    /**
+     * Gets the effective type annotation of the value parameter of a set accessor. If the node
+     * was parsed in a JavaScript file, gets the type annotation from JSDoc.
+     */
+    export function getEffectiveSetAccessorTypeAnnotationNode(node: SetAccessorDeclaration): TypeNode {
+        const parameter = getSetAccessorValueParameter(node);
+        return parameter && getEffectiveTypeAnnotationNode(parameter);
+    }
+
     export function emitNewLineBeforeLeadingComments(lineMap: number[], writer: EmitTextWriter, node: TextRange, leadingComments: CommentRange[]) {
         emitNewLineBeforeLeadingCommentsOfPosition(lineMap, writer, node.pos, leadingComments);
     }

src/compiler/utilities.ts

@@ -0,0 +1,25 @@
+tests/cases/conformance/jsdoc/returns.js(6,5): error TS2322: Type '5' is not assignable to type 'string'.
+tests/cases/conformance/jsdoc/returns.js(13,5): error TS2322: Type 'true | 5' is not assignable to type 'string | number'.
+  Type 'true' is not assignable to type 'string | number'.
+
+
+==== tests/cases/conformance/jsdoc/returns.js (2 errors) ====
+    // @ts-check
+    /**
+     * @returns {string} This comment is not currently exposed
+     */
+    function f() {
+        return 5;
+        ~~~~~~~~~
+!!! error TS2322: Type '5' is not assignable to type 'string'.
+    }
+    
+    /**
+     * @returns {string | number} This comment is not currently exposed
+     */
+    function f1() {
+        return 5 || true;
+        ~~~~~~~~~~~~~~~~~
+!!! error TS2322: Type 'true | 5' is not assignable to type 'string | number'.
+!!! error TS2322:   Type 'true' is not assignable to type 'string | number'.
+    }

tests/baselines/reference/checkJsdocReturnTag2.errors.txt

@@ -1,13 +1,13 @@
 tests/cases/conformance/jsdoc/0.js(3,5): error TS2322: Type 'true' is not assignable to type 'string'.
 tests/cases/conformance/jsdoc/0.js(6,5): error TS2322: Type '"hello"' is not assignable to type 'number'.
 tests/cases/conformance/jsdoc/0.js(10,4): error TS2345: Argument of type '"string"' is not assignable to parameter of type 'number'.
-tests/cases/conformance/jsdoc/0.js(13,7): error TS2451: Cannot redeclare block-scoped variable 'x2'.
 tests/cases/conformance/jsdoc/0.js(17,1): error TS2322: Type 'number' is not assignable to type 'string'.
-tests/cases/conformance/jsdoc/0.js(20,7): error TS2451: Cannot redeclare block-scoped variable 'x2'.
 tests/cases/conformance/jsdoc/0.js(20,21): error TS2339: Property 'concat' does not exist on type 'number'.
+tests/cases/conformance/jsdoc/0.js(24,7): error TS2322: Type '(a: number) => number' is not assignable to type '(arg0: number) => string'.
+  Type 'number' is not assignable to type 'string'.
 
 
-==== tests/cases/conformance/jsdoc/0.js (7 errors) ====
+==== tests/cases/conformance/jsdoc/0.js (6 errors) ====
     // @ts-check
     /** @type {String} */
     var S = true;
@@ -27,8 +27,6 @@ tests/cases/conformance/jsdoc/0.js(20,21): error TS2339: Property 'concat' does
 
     /** @type {function (number): number} */
     const x2 = (a) => a + 1;
-          ~~
-!!! error TS2451: Cannot redeclare block-scoped variable 'x2'.
 
     /** @type {string} */
     var a;
@@ -37,9 +35,14 @@ tests/cases/conformance/jsdoc/0.js(20,21): error TS2339: Property 'concat' does
 !!! error TS2322: Type 'number' is not assignable to type 'string'.
 
     /** @type {function (number): number} */
-    const x2 = (a) => a.concat("hi");
-          ~~
-!!! error TS2451: Cannot redeclare block-scoped variable 'x2'.
+    const x3 = (a) => a.concat("hi");
                         ~~~~~~
 !!! error TS2339: Property 'concat' does not exist on type 'number'.
-    x2(0);
+    x3(0);
+    
+    /** @type {function (number): string} */
+    const x4 = (a) => a + 1;
+          ~~
+!!! error TS2322: Type '(a: number) => number' is not assignable to type '(arg0: number) => string'.
+!!! error TS2322:   Type 'number' is not assignable to type 'string'.
+    x4(0);

tests/baselines/reference/checkJsdocTypeTag2.errors.txt

@@ -18,8 +18,12 @@ var a;
 a = x2(0);
 
 /** @type {function (number): number} */
-const x2 = (a) => a.concat("hi");
-x2(0);
+const x3 = (a) => a.concat("hi");
+x3(0);
+
+/** @type {function (number): string} */
+const x4 = (a) => a + 1;
+x4(0);
 
 //// [0.js]
 // @ts-check
@@ -36,5 +40,8 @@ var x2 = function (a) { return a + 1; };
 var a;
 a = x2(0);
 /** @type {function (number): number} */
-var x2 = function (a) { return a.concat("hi"); };
-x2(0);
+var x3 = function (a) { return a.concat("hi"); };
+x3(0);
+/** @type {function (number): string} */
+var x4 = function (a) { return a + 1; };
+x4(0);

tests/baselines/reference/checkJsdocTypeTag2.js

@@ -11,7 +11,7 @@ const arr = [
 
 ];
 
-/** @return {function(): Array<[string, {x?:number, y?:number}]>} */
+/** @return {Array<[string, {x?:number, y?:number}]>} */
 function f() {
 >f : Symbol(f, Decl(index.js, 4, 2))
 
@@ -28,13 +28,13 @@ function f() {
 class C {
 >C : Symbol(C, Decl(index.js, 12, 1))
 
-    /** @param {function(): Array<[string, {x?:number, y?:number}]>} value */
+    /** @param {Array<[string, {x?:number, y?:number}]>} value */
     set x(value) { }
->x : Symbol(C.x, Decl(index.js, 14, 9))
+>x : Symbol(C.x, Decl(index.js, 14, 9), Decl(index.js, 16, 20))
 >value : Symbol(value, Decl(index.js, 16, 10))
 
-    get () {
->get : Symbol(C.get, Decl(index.js, 16, 20))
+    get x() {
+>x : Symbol(C.x, Decl(index.js, 14, 9), Decl(index.js, 16, 20))
 
         return [
             ['a', { x: 1 }],

tests/baselines/reference/contextualTypeFromJSDoc.symbols

@@ -20,24 +20,24 @@ const arr = [
 
 ];
 
-/** @return {function(): Array<[string, {x?:number, y?:number}]>} */
+/** @return {Array<[string, {x?:number, y?:number}]>} */
 function f() {
->f : () => () => [string, { x?: number; y?: number; }][]
+>f : () => [string, { x?: number; y?: number; }][]
 
     return [
->[        ['a', { x: 1 }],        ['b', { y: 2 }]    ] : ((string | { [x: string]: any; x: number; })[] | (string | { [x: string]: any; y: number; })[])[]
+>[        ['a', { x: 1 }],        ['b', { y: 2 }]    ] : ([string, { x: number; }] | [string, { y: number; }])[]
 
         ['a', { x: 1 }],
->['a', { x: 1 }] : (string | { [x: string]: any; x: number; })[]
+>['a', { x: 1 }] : [string, { x: number; }]
 >'a' : "a"
->{ x: 1 } : { [x: string]: any; x: number; }
+>{ x: 1 } : { x: number; }
 >x : number
 >1 : 1
 
         ['b', { y: 2 }]
->['b', { y: 2 }] : (string | { [x: string]: any; y: number; })[]
+>['b', { y: 2 }] : [string, { y: number; }]
 >'b' : "b"
->{ y: 2 } : { [x: string]: any; y: number; }
+>{ y: 2 } : { y: number; }
 >y : number
 >2 : 2
 
@@ -47,28 +47,28 @@ function f() {
 class C {
 >C : C
 
-    /** @param {function(): Array<[string, {x?:number, y?:number}]>} value */
+    /** @param {Array<[string, {x?:number, y?:number}]>} value */
     set x(value) { }
->x : any
->value : () => [string, { x?: number; y?: number; }][]
+>x : [string, { x?: number; y?: number; }][]
+>value : [string, { x?: number; y?: number; }][]
 
-    get () {
->get : () => ((string | { [x: string]: any; x: number; })[] | (string | { [x: string]: any; y: number; })[])[]
+    get x() {
+>x : [string, { x?: number; y?: number; }][]
 
         return [
->[            ['a', { x: 1 }],            ['b', { y: 2 }]        ] : ((string | { [x: string]: any; x: number; })[] | (string | { [x: string]: any; y: number; })[])[]
+>[            ['a', { x: 1 }],            ['b', { y: 2 }]        ] : ([string, { x: number; }] | [string, { y: number; }])[]
 
             ['a', { x: 1 }],
->['a', { x: 1 }] : (string | { [x: string]: any; x: number; })[]
+>['a', { x: 1 }] : [string, { x: number; }]
 >'a' : "a"
->{ x: 1 } : { [x: string]: any; x: number; }
+>{ x: 1 } : { x: number; }
 >x : number
 >1 : 1
 
             ['b', { y: 2 }]
->['b', { y: 2 }] : (string | { [x: string]: any; y: number; })[]
+>['b', { y: 2 }] : [string, { y: number; }]
 >'b' : "b"
->{ y: 2 } : { [x: string]: any; y: number; }
+>{ y: 2 } : { y: number; }
 >y : number
 >2 : 2
 

tests/baselines/reference/contextualTypeFromJSDoc.types

@@ -21,5 +21,9 @@ var a;
 a = x2(0);
 
 /** @type {function (number): number} */
-const x2 = (a) => a.concat("hi");
-x2(0);
+const x3 = (a) => a.concat("hi");
+x3(0);
+
+/** @type {function (number): string} */
+const x4 = (a) => a + 1;
+x4(0);

tests/cases/conformance/jsdoc/checkJsdocTypeTag2.ts

@@ -10,7 +10,7 @@ const arr = [
     ['b', { y: 2 }]
 ];
 
-/** @return {function(): Array<[string, {x?:number, y?:number}]>} */
+/** @return {Array<[string, {x?:number, y?:number}]>} */
 function f() {
     return [
         ['a', { x: 1 }],
@@ -19,9 +19,9 @@ function f() {
 }
 
 class C {
-    /** @param {function(): Array<[string, {x?:number, y?:number}]>} value */
+    /** @param {Array<[string, {x?:number, y?:number}]>} value */
     set x(value) { }
-    get () {
+    get x() {
         return [
             ['a', { x: 1 }],
             ['b', { y: 2 }]