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feat(40750): add refactoring to infer a return type annotation to a function (microsoft#41052)
1 parent 3192754 commit 0904865

19 files changed

+367
-1
lines changed

‎src/compiler/diagnosticMessages.json

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"category": "Message",
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"code": 95147
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},
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"Infer function return type": {
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"category": "Message",
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"code": 95148
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},
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"No value exists in scope for the shorthand property '{0}'. Either declare one or provide an initializer.": {
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"category": "Error",

‎src/services/refactors/inferFunctionReturnType.ts

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/* @internal */
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namespace ts.refactor.inferFunctionReturnType {
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const refactorName = "Infer function return type";
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const refactorDescription = Diagnostics.Infer_function_return_type.message;
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registerRefactor(refactorName, { getEditsForAction, getAvailableActions });
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function getEditsForAction(context: RefactorContext): RefactorEditInfo | undefined {
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const info = getInfo(context);
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if (info) {
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const edits = textChanges.ChangeTracker.with(context, t =>
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t.tryInsertTypeAnnotation(context.file, info.declaration, info.returnTypeNode));
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return { renameFilename: undefined, renameLocation: undefined, edits };
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}
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return undefined;
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}
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function getAvailableActions(context: RefactorContext): readonly ApplicableRefactorInfo[] {
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const info = getInfo(context);
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if (info) {
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return [{
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name: refactorName,
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description: refactorDescription,
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actions: [{
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name: refactorName,
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description: refactorDescription
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}]
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}];
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}
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return emptyArray;
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}
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type ConvertibleDeclaration =
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| FunctionDeclaration
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| FunctionExpression
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| ArrowFunction
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| MethodDeclaration;
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interface Info {
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declaration: ConvertibleDeclaration;
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returnTypeNode: TypeNode;
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}
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function getInfo(context: RefactorContext): Info | undefined {
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if (isInJSFile(context.file)) return;
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const token = getTokenAtPosition(context.file, context.startPosition);
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const declaration = findAncestor(token, isConvertibleDeclaration);
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if (!declaration || !declaration.body || declaration.type) return;
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const typeChecker = context.program.getTypeChecker();
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const returnType = tryGetReturnType(typeChecker, declaration);
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if (!returnType) return;
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const returnTypeNode = typeChecker.typeToTypeNode(returnType, declaration, NodeBuilderFlags.NoTruncation);
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if (returnTypeNode) {
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return { declaration, returnTypeNode };
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}
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}
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function isConvertibleDeclaration(node: Node): node is ConvertibleDeclaration {
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switch (node.kind) {
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case SyntaxKind.FunctionDeclaration:
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case SyntaxKind.FunctionExpression:
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case SyntaxKind.ArrowFunction:
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case SyntaxKind.MethodDeclaration:
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return true;
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default:
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return false;
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}
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}
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function tryGetReturnType(typeChecker: TypeChecker, node: ConvertibleDeclaration): Type | undefined {
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if (typeChecker.isImplementationOfOverload(node)) {
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const signatures = typeChecker.getTypeAtLocation(node).getCallSignatures();
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if (signatures.length > 1) {
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return typeChecker.getUnionType(mapDefined(signatures, s => s.getReturnType()));
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}
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}
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const signature = typeChecker.getSignatureFromDeclaration(node);
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if (signature) {
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return typeChecker.getReturnTypeOfSignature(signature);
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}
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}
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}

‎src/services/tsconfig.json

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"refactors/convertParamsToDestructuredObject.ts",
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"refactors/convertStringOrTemplateLiteral.ts",
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"refactors/convertArrowFunctionOrFunctionExpression.ts",
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"refactors/inferFunctionReturnType.ts",
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"services.ts",
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"breakpoints.ts",
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"transform.ts",

‎tests/cases/fourslash/refactorConvertExport_namedToDefault_alreadyHasDefault.ts

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////export default function g() {}
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goTo.select("a", "b");
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verify.refactorsAvailable([]);
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verify.refactorsAvailable(["Infer function return type"]);

‎tests/cases/fourslash/refactorInferFunctionReturnType1.ts

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/// <reference path='fourslash.ts' />
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////function /*a*/foo/*b*/() {
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//// return { x: 1, y: 1 };
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////}
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goTo.select("a", "b");
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edit.applyRefactor({
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refactorName: "Infer function return type",
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actionName: "Infer function return type",
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actionDescription: "Infer function return type",
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newContent:
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`function foo(): { x: number; y: number; } {
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return { x: 1, y: 1 };
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}`
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});

‎tests/cases/fourslash/refactorInferFunctionReturnType10.ts

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/// <reference path='fourslash.ts' />
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////function /*a*/foo/*b*/(x: number) {
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//// return x ? x : x > 1;
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////}
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goTo.select("a", "b");
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edit.applyRefactor({
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refactorName: "Infer function return type",
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actionName: "Infer function return type",
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actionDescription: "Infer function return type",
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newContent:
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`function foo(x: number): number | boolean {
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return x ? x : x > 1;
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}`
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});

‎tests/cases/fourslash/refactorInferFunctionReturnType11.ts

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/// <reference path='fourslash.ts' />
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////interface F1 { x: number; y: number; }
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////type T1 = [number, number];
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////
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////function /*a*/foo/*b*/(num: number) {
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//// switch (num) {
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//// case 1:
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//// return { x: num, y: num } as F1;
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//// case 2:
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//// return [num, num] as T1;
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//// default:
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//// return num;
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//// }
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////}
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goTo.select("a", "b");
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edit.applyRefactor({
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refactorName: "Infer function return type",
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actionName: "Infer function return type",
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actionDescription: "Infer function return type",
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newContent:
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`interface F1 { x: number; y: number; }
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type T1 = [number, number];
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function foo(num: number): number | F1 | T1 {
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switch (num) {
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case 1:
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return { x: num, y: num } as F1;
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case 2:
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return [num, num] as T1;
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default:
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return num;
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}
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}`
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});

‎tests/cases/fourslash/refactorInferFunctionReturnType12.ts

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/// <reference path='fourslash.ts' />
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////function f(x: number) {
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//// return 1;
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////}
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////function /*a*/f/*b*/(x: number) {
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//// return "1";
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////}
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goTo.select("a", "b");
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edit.applyRefactor({
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refactorName: "Infer function return type",
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actionName: "Infer function return type",
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actionDescription: "Infer function return type",
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newContent:
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`function f(x: number) {
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return 1;
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}
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function f(x: number): string {
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return "1";
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}`
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});

‎tests/cases/fourslash/refactorInferFunctionReturnType13.ts

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/// <reference path='fourslash.ts' />
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////function /*a*/f/*b*/(x: string): number;
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////function f(x: string | number) {
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//// return 1;
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////}
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goTo.select("a", "b");
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verify.not.refactorAvailable("Infer function return type");

‎tests/cases/fourslash/refactorInferFunctionReturnType14.ts

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/// <reference path='fourslash.ts' />
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////function f(x: number): string;
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////function f(x: string): number;
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////function /*a*/f/*b*/(x: string | number) {
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//// return x === 1 ? 1 : "quit";
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////}
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goTo.select("a", "b");
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edit.applyRefactor({
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refactorName: "Infer function return type",
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actionName: "Infer function return type",
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actionDescription: "Infer function return type",
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newContent:
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`function f(x: number): string;
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function f(x: string): number;
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function f(x: string | number): string | number {
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return x === 1 ? 1 : "quit";
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}`
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});

‎tests/cases/fourslash/refactorInferFunctionReturnType15.ts

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/// <reference path='fourslash.ts' />
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////interface Foo {
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//// x: number;
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////}
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////function f(x: number): Foo;
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////function f(x: string): number;
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////function /*a*/f/*b*/(x: string | number) {
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//// return x === 1 ? 1 : { x };
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////}
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goTo.select("a", "b");
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edit.applyRefactor({
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refactorName: "Infer function return type",
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actionName: "Infer function return type",
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actionDescription: "Infer function return type",
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newContent:
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`interface Foo {
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x: number;
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}
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function f(x: number): Foo;
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function f(x: string): number;
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function f(x: string | number): number | Foo {
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return x === 1 ? 1 : { x };
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}`
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});

‎tests/cases/fourslash/refactorInferFunctionReturnType2.ts

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/// <reference path='fourslash.ts' />
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////class Foo {
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//// /*a*/method/*b*/() {
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//// return { x: 1, y: 1 };
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//// }
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////}
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goTo.select("a", "b");
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edit.applyRefactor({
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refactorName: "Infer function return type",
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actionName: "Infer function return type",
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actionDescription: "Infer function return type",
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newContent:
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`class Foo {
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method(): { x: number; y: number; } {
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return { x: 1, y: 1 };
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}
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}`
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});

‎tests/cases/fourslash/refactorInferFunctionReturnType3.ts

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/// <reference path='fourslash.ts' />
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////const foo = /*a*/function/*b*/() {
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//// return { x: 1, y: 1 };
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////}
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goTo.select("a", "b");
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edit.applyRefactor({
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refactorName: "Infer function return type",
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actionName: "Infer function return type",
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actionDescription: "Infer function return type",
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newContent:
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`const foo = function(): { x: number; y: number; } {
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return { x: 1, y: 1 };
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}`
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});

‎tests/cases/fourslash/refactorInferFunctionReturnType4.ts

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/// <reference path='fourslash.ts' />
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////const foo = /*a*/()/*b*/ => {
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//// return { x: 1, y: 1 };
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////}
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goTo.select("a", "b");
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edit.applyRefactor({
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refactorName: "Infer function return type",
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actionName: "Infer function return type",
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actionDescription: "Infer function return type",
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newContent:
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`const foo = (): { x: number; y: number; } => {
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return { x: 1, y: 1 };
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}`
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});

‎tests/cases/fourslash/refactorInferFunctionReturnType5.ts

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/// <reference path='fourslash.ts' />
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////function /*a*/foo/*b*/() {
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//// return 1;
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////}
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goTo.select("a", "b");
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edit.applyRefactor({
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refactorName: "Infer function return type",
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actionName: "Infer function return type",
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actionDescription: "Infer function return type",
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newContent:
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`function foo(): number {
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return 1;
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}`
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});

‎tests/cases/fourslash/refactorInferFunctionReturnType6.ts

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/// <reference path='fourslash.ts' />
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////function /*a*/foo/*b*/() {
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//// return "";
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////}
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goTo.select("a", "b");
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edit.applyRefactor({
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refactorName: "Infer function return type",
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actionName: "Infer function return type",
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actionDescription: "Infer function return type",
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newContent:
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`function foo(): string {
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return "";
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}`
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});

‎tests/cases/fourslash/refactorInferFunctionReturnType7.ts

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/// <reference path='fourslash.ts' />
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////function /*a*/foo/*b*/() {
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////}
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goTo.select("a", "b");
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edit.applyRefactor({
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refactorName: "Infer function return type",
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actionName: "Infer function return type",
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actionDescription: "Infer function return type",
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newContent:
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`function foo(): void {
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}`
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});

‎tests/cases/fourslash/refactorInferFunctionReturnType8.ts

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/// <reference path='fourslash.ts' />
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////function /*a*/foo/*b*/() {
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//// const bar = 1 as any;
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//// return bar;
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////}
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goTo.select("a", "b");
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edit.applyRefactor({
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refactorName: "Infer function return type",
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actionName: "Infer function return type",
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actionDescription: "Infer function return type",
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newContent:
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`function foo(): any {
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const bar = 1 as any;
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return bar;
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}`
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});

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