175 lines
4.5 KiB
TypeScript
175 lines
4.5 KiB
TypeScript
//// [literalTypeWidening.ts]
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// Widening vs. non-widening literal types
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function f1() {
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const c1 = "hello"; // Widening type "hello"
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let v1 = c1; // Type string
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const c2 = c1; // Widening type "hello"
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let v2 = c2; // Type string
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const c3: "hello" = "hello"; // Type "hello"
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let v3 = c3; // Type "hello"
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const c4: "hello" = c1; // Type "hello"
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let v4 = c4; // Type "hello"
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}
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function f2(cond: boolean) {
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const c1 = cond ? "foo" : "bar"; // widening "foo" | widening "bar"
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const c2: "foo" | "bar" = c1; // "foo" | "bar"
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const c3 = cond ? c1 : c2; // "foo" | "bar"
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const c4 = cond ? c3 : "baz"; // "foo" | "bar" | widening "baz"
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const c5: "foo" | "bar" | "baz" = c4; // "foo" | "bar" | "baz"
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let v1 = c1; // string
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let v2 = c2; // "foo" | "bar"
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let v3 = c3; // "foo" | "bar"
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let v4 = c4; // string
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let v5 = c5; // "foo" | "bar" | "baz"
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}
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function f3() {
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const c1 = 123; // Widening type 123
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let v1 = c1; // Type number
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const c2 = c1; // Widening type 123
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let v2 = c2; // Type number
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const c3: 123 = 123; // Type 123
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let v3 = c3; // Type 123
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const c4: 123 = c1; // Type 123
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let v4 = c4; // Type 123
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}
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function f4(cond: boolean) {
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const c1 = cond ? 123 : 456; // widening 123 | widening 456
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const c2: 123 | 456 = c1; // 123 | 456
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const c3 = cond ? c1 : c2; // 123 | 456
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const c4 = cond ? c3 : 789; // 123 | 456 | widening 789
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const c5: 123 | 456 | 789 = c4; // 123 | 456 | 789
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let v1 = c1; // number
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let v2 = c2; // 123 | 456
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let v3 = c3; // 123 | 456
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let v4 = c4; // number
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let v5 = c5; // 123 | 456 | 789
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}
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function f5() {
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const c1 = "foo";
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let v1 = c1;
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const c2: "foo" = "foo";
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let v2 = c2;
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const c3 = "foo" as "foo";
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let v3 = c3;
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const c4 = <"foo">"foo";
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let v4 = c4;
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}
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// Repro from #10898
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type FAILURE = "FAILURE";
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const FAILURE = "FAILURE";
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type Result<T> = T | FAILURE;
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function doWork<T>(): Result<T> {
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return FAILURE;
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}
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function isSuccess<T>(result: Result<T>): result is T {
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return !isFailure(result);
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}
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function isFailure<T>(result: Result<T>): result is FAILURE {
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return result === FAILURE;
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}
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function increment(x: number): number {
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return x + 1;
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}
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let result = doWork<number>();
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if (isSuccess(result)) {
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increment(result);
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}
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// Repro from #10898
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type TestEvent = "onmouseover" | "onmouseout";
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function onMouseOver(): TestEvent { return "onmouseover"; }
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let x = onMouseOver();
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//// [literalTypeWidening.js]
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// Widening vs. non-widening literal types
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function f1() {
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var c1 = "hello"; // Widening type "hello"
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var v1 = c1; // Type string
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var c2 = c1; // Widening type "hello"
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var v2 = c2; // Type string
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var c3 = "hello"; // Type "hello"
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var v3 = c3; // Type "hello"
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var c4 = c1; // Type "hello"
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var v4 = c4; // Type "hello"
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}
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function f2(cond) {
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var c1 = cond ? "foo" : "bar"; // widening "foo" | widening "bar"
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var c2 = c1; // "foo" | "bar"
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var c3 = cond ? c1 : c2; // "foo" | "bar"
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var c4 = cond ? c3 : "baz"; // "foo" | "bar" | widening "baz"
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var c5 = c4; // "foo" | "bar" | "baz"
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var v1 = c1; // string
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var v2 = c2; // "foo" | "bar"
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var v3 = c3; // "foo" | "bar"
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var v4 = c4; // string
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var v5 = c5; // "foo" | "bar" | "baz"
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}
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function f3() {
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var c1 = 123; // Widening type 123
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var v1 = c1; // Type number
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var c2 = c1; // Widening type 123
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var v2 = c2; // Type number
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var c3 = 123; // Type 123
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var v3 = c3; // Type 123
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var c4 = c1; // Type 123
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var v4 = c4; // Type 123
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}
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function f4(cond) {
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var c1 = cond ? 123 : 456; // widening 123 | widening 456
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var c2 = c1; // 123 | 456
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var c3 = cond ? c1 : c2; // 123 | 456
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var c4 = cond ? c3 : 789; // 123 | 456 | widening 789
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var c5 = c4; // 123 | 456 | 789
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var v1 = c1; // number
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var v2 = c2; // 123 | 456
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var v3 = c3; // 123 | 456
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var v4 = c4; // number
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var v5 = c5; // 123 | 456 | 789
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}
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function f5() {
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var c1 = "foo";
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var v1 = c1;
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var c2 = "foo";
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var v2 = c2;
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var c3 = "foo";
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var v3 = c3;
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var c4 = "foo";
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var v4 = c4;
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}
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var FAILURE = "FAILURE";
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function doWork() {
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return FAILURE;
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}
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function isSuccess(result) {
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return !isFailure(result);
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}
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function isFailure(result) {
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return result === FAILURE;
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}
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function increment(x) {
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return x + 1;
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}
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var result = doWork();
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if (isSuccess(result)) {
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increment(result);
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}
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function onMouseOver() { return "onmouseover"; }
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var x = onMouseOver();
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