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Fix instanceof with type variable constrained to class #20142

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2 changes: 2 additions & 0 deletions src/compiler/checker.ts
Original file line number Diff line number Diff line change
Expand Up @@ -8868,13 +8868,15 @@ namespace ts {
// An object type S is considered to be derived from an object type T if
// S is a union type and every constituent of S is derived from T,
// T is a union type and S is derived from at least one constituent of T, or
// S is a type variable with a base constraint that is derived from T,
// T is one of the global types Object and Function and S is a subtype of T, or
// T occurs directly or indirectly in an 'extends' clause of S.
// Note that this check ignores type parameters and only considers the
// inheritance hierarchy.
function isTypeDerivedFrom(source: Type, target: Type): boolean {
return source.flags & TypeFlags.Union ? every((<UnionType>source).types, t => isTypeDerivedFrom(t, target)) :
target.flags & TypeFlags.Union ? some((<UnionType>target).types, t => isTypeDerivedFrom(source, t)) :
source.flags & TypeFlags.TypeVariable ? isTypeDerivedFrom(getBaseConstraintOfType(source) || emptyObjectType, target) :
target === globalObjectType || target === globalFunctionType ? isTypeSubtypeOf(source, target) :
hasBaseType(source, getTargetType(target));
}
Expand Down
79 changes: 79 additions & 0 deletions tests/baselines/reference/narrowingConstrainedTypeVariable.js
Original file line number Diff line number Diff line change
@@ -0,0 +1,79 @@
//// [narrowingConstrainedTypeVariable.ts]
// Repro from #20138

class C { }

function f1<T extends C>(v: T | string): void {
if (v instanceof C) {
const x: T = v;
}
else {
const s: string = v;
}
}

class D { }

function f2<T extends C, U extends D>(v: T | U) {
if (v instanceof C) {
const x: T = v;
}
else {
const y: U = v;
}
}

class E { x: string }

function f3<T extends E>(v: T | { x: string }) {
if (v instanceof E) {
const x: T = v;
}
else {
const y: { x: string } = v;
}
}


//// [narrowingConstrainedTypeVariable.js]
"use strict";
// Repro from #20138
var C = /** @class */ (function () {
function C() {
}
return C;
}());
function f1(v) {
if (v instanceof C) {
var x = v;
}
else {
var s = v;
}
}
var D = /** @class */ (function () {
function D() {
}
return D;
}());
function f2(v) {
if (v instanceof C) {
var x = v;
}
else {
var y = v;
}
}
var E = /** @class */ (function () {
function E() {
}
return E;
}());
function f3(v) {
if (v instanceof E) {
var x = v;
}
else {
var y = v;
}
}
88 changes: 88 additions & 0 deletions tests/baselines/reference/narrowingConstrainedTypeVariable.symbols
Original file line number Diff line number Diff line change
@@ -0,0 +1,88 @@
=== tests/cases/conformance/types/typeRelationships/instanceOf/narrowingConstrainedTypeVariable.ts ===
// Repro from #20138

class C { }
>C : Symbol(C, Decl(narrowingConstrainedTypeVariable.ts, 0, 0))

function f1<T extends C>(v: T | string): void {
>f1 : Symbol(f1, Decl(narrowingConstrainedTypeVariable.ts, 2, 11))
>T : Symbol(T, Decl(narrowingConstrainedTypeVariable.ts, 4, 12))
>C : Symbol(C, Decl(narrowingConstrainedTypeVariable.ts, 0, 0))
>v : Symbol(v, Decl(narrowingConstrainedTypeVariable.ts, 4, 25))
>T : Symbol(T, Decl(narrowingConstrainedTypeVariable.ts, 4, 12))

if (v instanceof C) {
>v : Symbol(v, Decl(narrowingConstrainedTypeVariable.ts, 4, 25))
>C : Symbol(C, Decl(narrowingConstrainedTypeVariable.ts, 0, 0))

const x: T = v;
>x : Symbol(x, Decl(narrowingConstrainedTypeVariable.ts, 6, 13))
>T : Symbol(T, Decl(narrowingConstrainedTypeVariable.ts, 4, 12))
>v : Symbol(v, Decl(narrowingConstrainedTypeVariable.ts, 4, 25))
}
else {
const s: string = v;
>s : Symbol(s, Decl(narrowingConstrainedTypeVariable.ts, 9, 13))
>v : Symbol(v, Decl(narrowingConstrainedTypeVariable.ts, 4, 25))
}
}

class D { }
>D : Symbol(D, Decl(narrowingConstrainedTypeVariable.ts, 11, 1))

function f2<T extends C, U extends D>(v: T | U) {
>f2 : Symbol(f2, Decl(narrowingConstrainedTypeVariable.ts, 13, 11))
>T : Symbol(T, Decl(narrowingConstrainedTypeVariable.ts, 15, 12))
>C : Symbol(C, Decl(narrowingConstrainedTypeVariable.ts, 0, 0))
>U : Symbol(U, Decl(narrowingConstrainedTypeVariable.ts, 15, 24))
>D : Symbol(D, Decl(narrowingConstrainedTypeVariable.ts, 11, 1))
>v : Symbol(v, Decl(narrowingConstrainedTypeVariable.ts, 15, 38))
>T : Symbol(T, Decl(narrowingConstrainedTypeVariable.ts, 15, 12))
>U : Symbol(U, Decl(narrowingConstrainedTypeVariable.ts, 15, 24))

if (v instanceof C) {
>v : Symbol(v, Decl(narrowingConstrainedTypeVariable.ts, 15, 38))
>C : Symbol(C, Decl(narrowingConstrainedTypeVariable.ts, 0, 0))

const x: T = v;
>x : Symbol(x, Decl(narrowingConstrainedTypeVariable.ts, 17, 13))
>T : Symbol(T, Decl(narrowingConstrainedTypeVariable.ts, 15, 12))
>v : Symbol(v, Decl(narrowingConstrainedTypeVariable.ts, 15, 38))
}
else {
const y: U = v;
>y : Symbol(y, Decl(narrowingConstrainedTypeVariable.ts, 20, 13))
>U : Symbol(U, Decl(narrowingConstrainedTypeVariable.ts, 15, 24))
>v : Symbol(v, Decl(narrowingConstrainedTypeVariable.ts, 15, 38))
}
}

class E { x: string }
>E : Symbol(E, Decl(narrowingConstrainedTypeVariable.ts, 22, 1))
>x : Symbol(E.x, Decl(narrowingConstrainedTypeVariable.ts, 24, 9))

function f3<T extends E>(v: T | { x: string }) {
>f3 : Symbol(f3, Decl(narrowingConstrainedTypeVariable.ts, 24, 21))
>T : Symbol(T, Decl(narrowingConstrainedTypeVariable.ts, 26, 12))
>E : Symbol(E, Decl(narrowingConstrainedTypeVariable.ts, 22, 1))
>v : Symbol(v, Decl(narrowingConstrainedTypeVariable.ts, 26, 25))
>T : Symbol(T, Decl(narrowingConstrainedTypeVariable.ts, 26, 12))
>x : Symbol(x, Decl(narrowingConstrainedTypeVariable.ts, 26, 33))

if (v instanceof E) {
>v : Symbol(v, Decl(narrowingConstrainedTypeVariable.ts, 26, 25))
>E : Symbol(E, Decl(narrowingConstrainedTypeVariable.ts, 22, 1))

const x: T = v;
>x : Symbol(x, Decl(narrowingConstrainedTypeVariable.ts, 28, 13))
>T : Symbol(T, Decl(narrowingConstrainedTypeVariable.ts, 26, 12))
>v : Symbol(v, Decl(narrowingConstrainedTypeVariable.ts, 26, 25))
}
else {
const y: { x: string } = v;
>y : Symbol(y, Decl(narrowingConstrainedTypeVariable.ts, 31, 13))
>x : Symbol(x, Decl(narrowingConstrainedTypeVariable.ts, 31, 18))
>v : Symbol(v, Decl(narrowingConstrainedTypeVariable.ts, 26, 25))
}
}

91 changes: 91 additions & 0 deletions tests/baselines/reference/narrowingConstrainedTypeVariable.types
Original file line number Diff line number Diff line change
@@ -0,0 +1,91 @@
=== tests/cases/conformance/types/typeRelationships/instanceOf/narrowingConstrainedTypeVariable.ts ===
// Repro from #20138

class C { }
>C : C

function f1<T extends C>(v: T | string): void {
>f1 : <T extends C>(v: string | T) => void
>T : T
>C : C
>v : string | T
>T : T

if (v instanceof C) {
>v instanceof C : boolean
>v : string | T
>C : typeof C

const x: T = v;
>x : T
>T : T
>v : T
}
else {
const s: string = v;
>s : string
>v : string
}
}

class D { }
>D : D

function f2<T extends C, U extends D>(v: T | U) {
>f2 : <T extends C, U extends D>(v: T | U) => void
>T : T
>C : C
>U : U
>D : D
>v : T | U
>T : T
>U : U

if (v instanceof C) {
>v instanceof C : boolean
>v : T | U
>C : typeof C

const x: T = v;
>x : T
>T : T
>v : T
}
else {
const y: U = v;
>y : U
>U : U
>v : U
}
}

class E { x: string }
>E : E
>x : string

function f3<T extends E>(v: T | { x: string }) {
>f3 : <T extends E>(v: T | { x: string; }) => void
>T : T
>E : E
>v : T | { x: string; }
>T : T
>x : string

if (v instanceof E) {
>v instanceof E : boolean
>v : T | { x: string; }
>E : typeof E

const x: T = v;
>x : T
>T : T
>v : T
}
else {
const y: { x: string } = v;
>y : { x: string; }
>x : string
>v : { x: string; }
}
}

Original file line number Diff line number Diff line change
@@ -0,0 +1,36 @@
// @strict: true

// Repro from #20138

class C { }

function f1<T extends C>(v: T | string): void {
if (v instanceof C) {
const x: T = v;
}
else {
const s: string = v;
}
}

class D { }

function f2<T extends C, U extends D>(v: T | U) {
if (v instanceof C) {
const x: T = v;
}
else {
const y: U = v;
}
}

class E { x: string }

function f3<T extends E>(v: T | { x: string }) {
if (v instanceof E) {
const x: T = v;
}
else {
const y: { x: string } = v;
}
}