Get quickInfo from a contextual type if possible (#18119)

src/compiler/types.ts

@@ -744,6 +744,7 @@ namespace ts {
         ;
 
     export interface PropertyAssignment extends ObjectLiteralElement {
+        parent: ObjectLiteralExpression;
         kind: SyntaxKind.PropertyAssignment;
         name: PropertyName;
         questionToken?: QuestionToken;
@@ -751,6 +752,7 @@ namespace ts {
     }
 
     export interface ShorthandPropertyAssignment extends ObjectLiteralElement {
+        parent: ObjectLiteralExpression;
         kind: SyntaxKind.ShorthandPropertyAssignment;
         name: Identifier;
         questionToken?: QuestionToken;
@@ -761,6 +763,7 @@ namespace ts {
     }
 
     export interface SpreadAssignment extends ObjectLiteralElement {
+        parent: ObjectLiteralExpression;
         kind: SyntaxKind.SpreadAssignment;
         expression: Expression;
     }

src/services/services.ts

@@ -1398,7 +1398,7 @@ namespace ts {
             }
 
             const typeChecker = program.getTypeChecker();
-            const symbol = typeChecker.getSymbolAtLocation(node);
+            const symbol = getSymbolAtLocationForQuickInfo(node, typeChecker);
 
             if (!symbol || typeChecker.isUnknownSymbol(symbol)) {
                 // Try getting just type at this position and show
@@ -1437,6 +1437,21 @@ namespace ts {
             };
         }
 
+        function getSymbolAtLocationForQuickInfo(node: Node, checker: TypeChecker): Symbol | undefined {
+            if ((isIdentifier(node) || isStringLiteral(node))
+                && isPropertyAssignment(node.parent)
+                && node.parent.name === node) {
+                const type = checker.getContextualType(node.parent.parent);
+                if (type) {
+                    const property = checker.getPropertyOfType(type, getTextOfIdentifierOrLiteral(node));
+                    if (property) {
+                        return property;
+                    }
+                }
+            }
+            return checker.getSymbolAtLocation(node);
+        }
+
         /// Goto definition
         function getDefinitionAtPosition(fileName: string, position: number): DefinitionInfo[] {
             synchronizeHostData();

tests/cases/fourslash/contextualTyping.ts

@@ -32,7 +32,7 @@
 ////var /*13*/c3t5: (n: number) => IFoo = function(/*14*/n) { return <IFoo>({}) };
 ////var /*15*/c3t6: (n: number, s: string) => IFoo = function(/*16*/n, /*17*/s) { return <IFoo>({}) };
 ////var /*18*/c3t7: {
-////    (n: number): number;    
+////    (n: number): number;
 ////    (s1: string): number;
 ////};
 ////var /*20*/c3t8: (n: number, s: string) => number = function(/*21*/n) { return n; };
@@ -79,7 +79,7 @@
 ////    t5: (n: number) => IFoo;
 ////    t6: (n: number, s: string) => IFoo;
 ////    t7: {
-////            (n: number, s: string): number;    
+////            (n: number, s: string): number;
 ////            //(s1: string, s2: string): number;
 ////        };
 ////    t8: (n: number, s: string) => number;
@@ -98,7 +98,7 @@
 ////    t5: (n: number) => IFoo;
 ////    t6: (n: number, s: string) => IFoo;
 ////    t7: {
-////            (n: number, s: string): number;    
+////            (n: number, s: string): number;
 ////            //(s1: string, s2: string): number;
 ////        };
 ////    t8: (n: number, s: string) => number;
@@ -152,7 +152,7 @@
 ////var /*80*/c12t5 = <(n: number) => IFoo> function(/*81*/n) { return <IFoo>({}) };
 ////var /*82*/c12t6 = <(n: number, s: string) => IFoo> function(/*83*/n, /*84*/s) { return <IFoo>({}) };
 ////var /*85*/c12t7 = <{
-////    (n: number, s: string): number;    
+////    (n: number, s: string): number;
 ////    //(s1: string, s2: string): number;
 ////}> function(n:number) { return n };
 ////var /*86*/c12t8 = <(n: number, s: string) => number> function (/*87*/n) { return n; };
@@ -221,13 +221,13 @@ verify.quickInfos({
     25: "(parameter) n: number",
     26: "(parameter) s: string",
     27: "var c3t12: IBar",
-    28: "(property) foo: IFoo",
+    28: "(property) IBar.foo: IFoo",
     29: "var c3t13: IFoo",
-    30: "(property) f: (i: number, s: string) => string",
+    30: "(method) IFoo.f(i: number, s: string): string",
     31: "(parameter) i: number",
     32: "(parameter) s: string",
     33: "var c3t14: IFoo",
-    34: "(property) a: undefined[]",
+    34: "(property) IFoo.a: number[]",
     35: "(property) C4T5.foo: (i: number, s: string) => string",
     36: "(parameter) i: number",
     37: "(parameter) s: string",
@@ -257,13 +257,13 @@ verify.quickInfos({
     61: "(parameter) n: number",
     62: "(parameter) s: string",
     63: "(property) t12: IBar",
-    64: "(property) foo: IFoo",
+    64: "(property) IBar.foo: IFoo",
     65: "(property) t13: IFoo",
-    66: "(property) f: (i: number, s: string) => string",
+    66: "(method) IFoo.f(i: number, s: string): string",
     67: "(parameter) i: number",
     68: "(parameter) s: string",
     69: "(property) t14: IFoo",
-    70: "(property) a: undefined[]",
+    70: "(property) IFoo.a: number[]",
     71: "(parameter) n: number",
     72: "var c10t5: () => (n: number) => IFoo",
     73: "(parameter) n: number",
@@ -287,13 +287,13 @@ verify.quickInfos({
     91: "(parameter) n: number",
     92: "(parameter) s: string",
     93: "var c12t12: IBar",
-    94: "(property) foo: IFoo",
+    94: "(property) IBar.foo: IFoo",
     95: "var c12t13: IFoo",
-    96: "(property) f: (i: number, s: string) => string",
+    96: "(method) IFoo.f(i: number, s: string): string",
     97: "(parameter) i: number",
     98: "(parameter) s: string",
     99: "var c12t14: IFoo",
-    100: "(property) a: undefined[]",
+    100: "(property) IFoo.a: number[]",
     101: "function EF1(a: number, b: number): number",
     102: "(parameter) a: any",
     103: "(parameter) b: any",
@@ -302,7 +302,7 @@ verify.quickInfos({
     112: "(method) Point.add(dx: number, dy: number): Point",
     113: "(parameter) dx: number",
     114: "(parameter) dy: number",
-    115: "(property) add: (dx: number, dy: number) => Point",
+    115: "(method) Point.add(dx: number, dy: number): Point",
     116: "(parameter) dx: number",
     117: "(parameter) dy: number"
 });

tests/cases/fourslash/quickInfoFromContextualType.ts

@@ -0,0 +1,10 @@
+/// <reference path='fourslash.ts' />
+
+// @Filename: quickInfoExportAssignmentOfGenericInterface_0.ts
+////interface I {
+////    /** Documentation */
+////    x: number;
+////}
+////const i: I = { /**/x: 0 };
+
+verify.quickInfoAt("", "(property) I.x: number", "Documentation ");

tests/cases/fourslash/quickInfoOnClassMergedWithFunction.ts

@@ -1,16 +1,16 @@
 /// <reference path="fourslash.ts" />
 
 ////module Test {
-//// class Mocked {
-//// myProp: string;
-//// }
-//// class Tester {
-//// willThrowError() {
-//// Mocked = Mocked || function () { // => Error: Invalid left-hand side of assignment expression.
-//// return { /**/myProp: "test" };
-//// };
-//// }
-//// }
+////    class Mocked {
+////        myProp: string;
+////    }
+////    class Tester {
+////        willThrowError() {
+////            Mocked = Mocked || function () { // => Error: Invalid left-hand side of assignment expression.
+////                return { /**/myProp: "test" };
+////            };
+////        }
+////    }
 ////}
 
-verify.quickInfoAt("", "(property) myProp: string");
+verify.quickInfoAt("", "(property) myProp: string");

tests/cases/fourslash/quickInfoTypeError.ts

@@ -5,6 +5,6 @@
 ////    f() {}
 ////});
 
-// The symbol indicates that this is a funciton, but the type is `any`.
+// The symbol indicates that this is a function, but the type is `any`.
 // Regression test that we don't crash (by trying to get signatures from `any`).
-verify.quickInfoAt("", "(method) f");
+verify.quickInfoAt("", "(method) f(): void");