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Control flow analysis of aliased conditional expressions and discriminants (#44730)
* CFA inlining of conditional expressions referenced by const variables * Accept new baselines * Add tests * Accept new baselines * Increase inlining limit to 5 levels per design meeting discussion
1 parent 906cbd2 commit 8058619

10 files changed

+2398
-40
lines changed

‎src/compiler/checker.ts

+91-35
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‎tests/baselines/reference/controlFlowAliasing.errors.txt

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tests/cases/conformance/controlFlow/controlFlowAliasing.ts(61,13): error TS2339: Property 'foo' does not exist on type '{ kind: "foo"; foo: string; } | { kind: "bar"; bar: number; }'.
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Property 'foo' does not exist on type '{ kind: "bar"; bar: number; }'.
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tests/cases/conformance/controlFlow/controlFlowAliasing.ts(64,13): error TS2339: Property 'bar' does not exist on type '{ kind: "foo"; foo: string; } | { kind: "bar"; bar: number; }'.
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Property 'bar' does not exist on type '{ kind: "foo"; foo: string; }'.
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tests/cases/conformance/controlFlow/controlFlowAliasing.ts(71,13): error TS2339: Property 'foo' does not exist on type '{ kind: "foo"; foo: string; } | { kind: "bar"; bar: number; }'.
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Property 'foo' does not exist on type '{ kind: "bar"; bar: number; }'.
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tests/cases/conformance/controlFlow/controlFlowAliasing.ts(74,13): error TS2339: Property 'bar' does not exist on type '{ kind: "foo"; foo: string; } | { kind: "bar"; bar: number; }'.
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Property 'bar' does not exist on type '{ kind: "foo"; foo: string; }'.
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tests/cases/conformance/controlFlow/controlFlowAliasing.ts(82,13): error TS2339: Property 'foo' does not exist on type '{ kind: "foo"; foo: string; } | { kind: "bar"; bar: number; }'.
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Property 'foo' does not exist on type '{ kind: "bar"; bar: number; }'.
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tests/cases/conformance/controlFlow/controlFlowAliasing.ts(85,13): error TS2339: Property 'bar' does not exist on type '{ kind: "foo"; foo: string; } | { kind: "bar"; bar: number; }'.
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Property 'bar' does not exist on type '{ kind: "foo"; foo: string; }'.
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tests/cases/conformance/controlFlow/controlFlowAliasing.ts(104,13): error TS2339: Property 'foo' does not exist on type '{ kind: "foo"; foo: string; } | { kind: "bar"; bar: number; }'.
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Property 'foo' does not exist on type '{ kind: "bar"; bar: number; }'.
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tests/cases/conformance/controlFlow/controlFlowAliasing.ts(107,13): error TS2339: Property 'bar' does not exist on type '{ kind: "foo"; foo: string; } | { kind: "bar"; bar: number; }'.
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Property 'bar' does not exist on type '{ kind: "foo"; foo: string; }'.
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tests/cases/conformance/controlFlow/controlFlowAliasing.ts(124,19): error TS2339: Property 'foo' does not exist on type '{ kind: "foo"; foo: string; } | { kind: "bar"; bar: number; }'.
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Property 'foo' does not exist on type '{ kind: "bar"; bar: number; }'.
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tests/cases/conformance/controlFlow/controlFlowAliasing.ts(127,19): error TS2339: Property 'bar' does not exist on type '{ kind: "foo"; foo: string; } | { kind: "bar"; bar: number; }'.
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Property 'bar' does not exist on type '{ kind: "foo"; foo: string; }'.
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tests/cases/conformance/controlFlow/controlFlowAliasing.ts(207,13): error TS2322: Type 'string | number' is not assignable to type 'string'.
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Type 'number' is not assignable to type 'string'.
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tests/cases/conformance/controlFlow/controlFlowAliasing.ts(210,13): error TS2322: Type 'string | number' is not assignable to type 'number'.
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Type 'string' is not assignable to type 'number'.
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==== tests/cases/conformance/controlFlow/controlFlowAliasing.ts (12 errors) ====
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// Narrowing by aliased conditional expressions
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function f10(x: string | number) {
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const isString = typeof x === "string";
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if (isString) {
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let t: string = x;
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}
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else {
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let t: number = x;
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}
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}
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function f11(x: unknown) {
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const isString = typeof x === "string";
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if (isString) {
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let t: string = x;
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}
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}
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function f12(x: string | number | boolean) {
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const isString = typeof x === "string";
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const isNumber = typeof x === "number";
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if (isString || isNumber) {
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let t: string | number = x;
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}
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else {
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let t: boolean = x;
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}
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}
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function f13(x: string | number | boolean) {
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const isString = typeof x === "string";
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const isNumber = typeof x === "number";
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const isStringOrNumber = isString || isNumber;
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if (isStringOrNumber) {
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let t: string | number = x;
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}
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else {
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let t: boolean = x;
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}
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}
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function f14(x: number | null | undefined): number | null {
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const notUndefined = x !== undefined;
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return notUndefined ? x : 0;
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}
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function f20(obj: { kind: 'foo', foo: string } | { kind: 'bar', bar: number }) {
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const isFoo = obj.kind === 'foo';
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if (isFoo) {
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obj.foo;
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}
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else {
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obj.bar;
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}
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}
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function f21(obj: { kind: 'foo', foo: string } | { kind: 'bar', bar: number }) {
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const isFoo: boolean = obj.kind === 'foo';
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if (isFoo) {
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obj.foo; // Not narrowed because isFoo has type annotation
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~~~
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!!! error TS2339: Property 'foo' does not exist on type '{ kind: "foo"; foo: string; } | { kind: "bar"; bar: number; }'.
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!!! error TS2339: Property 'foo' does not exist on type '{ kind: "bar"; bar: number; }'.
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}
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else {
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obj.bar; // Not narrowed because isFoo has type annotation
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~~~
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!!! error TS2339: Property 'bar' does not exist on type '{ kind: "foo"; foo: string; } | { kind: "bar"; bar: number; }'.
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!!! error TS2339: Property 'bar' does not exist on type '{ kind: "foo"; foo: string; }'.
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}
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}
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function f22(obj: { kind: 'foo', foo: string } | { kind: 'bar', bar: number }) {
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let isFoo = obj.kind === 'foo';
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if (isFoo) {
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obj.foo; // Not narrowed because isFoo is mutable
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~~~
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!!! error TS2339: Property 'foo' does not exist on type '{ kind: "foo"; foo: string; } | { kind: "bar"; bar: number; }'.
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!!! error TS2339: Property 'foo' does not exist on type '{ kind: "bar"; bar: number; }'.
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}
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else {
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obj.bar; // Not narrowed because isFoo is mutable
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~~~
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!!! error TS2339: Property 'bar' does not exist on type '{ kind: "foo"; foo: string; } | { kind: "bar"; bar: number; }'.
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!!! error TS2339: Property 'bar' does not exist on type '{ kind: "foo"; foo: string; }'.
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}
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}
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function f23(obj: { kind: 'foo', foo: string } | { kind: 'bar', bar: number }) {
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const isFoo = obj.kind === 'foo';
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obj = obj;
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if (isFoo) {
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obj.foo; // Not narrowed because obj is assigned in function body
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~~~
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!!! error TS2339: Property 'foo' does not exist on type '{ kind: "foo"; foo: string; } | { kind: "bar"; bar: number; }'.
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!!! error TS2339: Property 'foo' does not exist on type '{ kind: "bar"; bar: number; }'.
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}
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else {
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obj.bar; // Not narrowed because obj is assigned in function body
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~~~
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!!! error TS2339: Property 'bar' does not exist on type '{ kind: "foo"; foo: string; } | { kind: "bar"; bar: number; }'.
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!!! error TS2339: Property 'bar' does not exist on type '{ kind: "foo"; foo: string; }'.
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}
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}
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function f24(arg: { kind: 'foo', foo: string } | { kind: 'bar', bar: number }) {
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const obj = arg;
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const isFoo = obj.kind === 'foo';
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if (isFoo) {
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obj.foo;
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}
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else {
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obj.bar;
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}
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}
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function f25(arg: { kind: 'foo', foo: string } | { kind: 'bar', bar: number }) {
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let obj = arg;
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const isFoo = obj.kind === 'foo';
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if (isFoo) {
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obj.foo; // Not narrowed because obj is mutable
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~~~
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!!! error TS2339: Property 'foo' does not exist on type '{ kind: "foo"; foo: string; } | { kind: "bar"; bar: number; }'.
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!!! error TS2339: Property 'foo' does not exist on type '{ kind: "bar"; bar: number; }'.
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}
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else {
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obj.bar; // Not narrowed because obj is mutable
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~~~
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!!! error TS2339: Property 'bar' does not exist on type '{ kind: "foo"; foo: string; } | { kind: "bar"; bar: number; }'.
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!!! error TS2339: Property 'bar' does not exist on type '{ kind: "foo"; foo: string; }'.
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}
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}
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function f26(outer: { readonly obj: { kind: 'foo', foo: string } | { kind: 'bar', bar: number } }) {
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const isFoo = outer.obj.kind === 'foo';
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if (isFoo) {
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outer.obj.foo;
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}
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else {
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outer.obj.bar;
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}
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}
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function f27(outer: { obj: { kind: 'foo', foo: string } | { kind: 'bar', bar: number } }) {
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const isFoo = outer.obj.kind === 'foo';
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if (isFoo) {
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outer.obj.foo; // Not narrowed because obj is mutable
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~~~
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!!! error TS2339: Property 'foo' does not exist on type '{ kind: "foo"; foo: string; } | { kind: "bar"; bar: number; }'.
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!!! error TS2339: Property 'foo' does not exist on type '{ kind: "bar"; bar: number; }'.
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}
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else {
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outer.obj.bar; // Not narrowed because obj is mutable
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~~~
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!!! error TS2339: Property 'bar' does not exist on type '{ kind: "foo"; foo: string; } | { kind: "bar"; bar: number; }'.
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!!! error TS2339: Property 'bar' does not exist on type '{ kind: "foo"; foo: string; }'.
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}
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}
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function f28(obj?: { kind: 'foo', foo: string } | { kind: 'bar', bar: number }) {
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const isFoo = obj && obj.kind === 'foo';
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const isBar = obj && obj.kind === 'bar';
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if (isFoo) {
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obj.foo;
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}
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if (isBar) {
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obj.bar;
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}
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}
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// Narrowing by aliased discriminant property access
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function f30(obj: { kind: 'foo', foo: string } | { kind: 'bar', bar: number }) {
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const kind = obj.kind;
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if (kind === 'foo') {
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obj.foo;
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}
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else {
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obj.bar;
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}
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}
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function f31(obj: { kind: 'foo', foo: string } | { kind: 'bar', bar: number }) {
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const { kind } = obj;
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if (kind === 'foo') {
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obj.foo;
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}
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else {
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obj.bar;
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}
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}
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function f32(obj: { kind: 'foo', foo: string } | { kind: 'bar', bar: number }) {
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const { kind: k } = obj;
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if (k === 'foo') {
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obj.foo;
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}
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else {
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obj.bar;
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}
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}
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function f33(obj: { kind: 'foo', foo: string } | { kind: 'bar', bar: number }) {
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const { kind } = obj;
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switch (kind) {
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case 'foo': obj.foo; break;
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case 'bar': obj.bar; break;
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}
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}
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// Mixing of aliased discriminants and conditionals
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function f40(obj: { kind: 'foo', foo?: string } | { kind: 'bar', bar?: number }) {
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const { kind } = obj;
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const isFoo = kind == 'foo';
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if (isFoo && obj.foo) {
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let t: string = obj.foo;
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}
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}
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// Unsupported narrowing of destructured payload by destructured discriminant
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type Data = { kind: 'str', payload: string } | { kind: 'num', payload: number };
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function gg2(obj: Data) {
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if (obj.kind === 'str') {
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let t: string = obj.payload;
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}
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else {
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let t: number = obj.payload;
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}
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}
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function foo({ kind, payload }: Data) {
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if (kind === 'str') {
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let t: string = payload;
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~
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!!! error TS2322: Type 'string | number' is not assignable to type 'string'.
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!!! error TS2322: Type 'number' is not assignable to type 'string'.
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}
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else {
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let t: number = payload;
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~
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!!! error TS2322: Type 'string | number' is not assignable to type 'number'.
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!!! error TS2322: Type 'string' is not assignable to type 'number'.
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}
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}
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