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Fix narrowing by typeof applied to discriminant property #51720

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Merged
merged 3 commits into from
Dec 5, 2022
Merged

Fix narrowing by typeof applied to discriminant property #51720

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40bbce3
Fix narrowing by typeof applied to discriminant property
ahejlsberg Dec 1, 2022
0685cd8
Include effects of getReferenceCandidate
ahejlsberg Dec 1, 2022
acfc111
Add tests
ahejlsberg Dec 2, 2022
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8 changes: 4 additions & 4 deletions src/compiler/checker.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -26514,13 +26514,13 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
}
const target = getReferenceCandidate(typeOfExpr.expression);
if (!isMatchingReference(reference, target)) {
const propertyAccess = getDiscriminantPropertyAccess(typeOfExpr.expression, type);
if (strictNullChecks && optionalChainContainsReference(target, reference) && assumeTrue === (literal.text !== "undefined")) {
type = getAdjustedTypeWithFacts(type, TypeFacts.NEUndefinedOrNull);
}
const propertyAccess = getDiscriminantPropertyAccess(target, type);
if (propertyAccess) {
return narrowTypeByDiscriminant(type, propertyAccess, t => narrowTypeByLiteralExpression(t, literal, assumeTrue));
}
if (strictNullChecks && optionalChainContainsReference(target, reference) && assumeTrue === (literal.text !== "undefined")) {
return getAdjustedTypeWithFacts(type, TypeFacts.NEUndefinedOrNull);
}
return type;
}
return narrowTypeByLiteralExpression(type, literal, assumeTrue);
Expand Down
81 changes: 81 additions & 0 deletions tests/baselines/reference/narrowingTypeofDiscriminant.js
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@@ -0,0 +1,81 @@
//// [narrowingTypeofDiscriminant.ts]
function f1(obj: { kind: 'a', data: string } | { kind: 1, data: number }) {
if (typeof obj.kind === "string") {
obj; // { kind: 'a', data: string }
}
else {
obj; // { kind: 1, data: number }
}
}

function f2(obj: { kind: 'a', data: string } | { kind: 1, data: number } | undefined) {
if (typeof obj?.kind === "string") {
obj; // { kind: 'a', data: string }
}
else {
obj; // { kind: 1, data: number } | undefined
}
}

// Repro from #51700

type WrappedStringOr<T> = { value?: string } | { value?: T };

function numberOk(wrapped: WrappedStringOr<number> | null) {
if (typeof wrapped?.value !== 'string') {
return null;
}
return wrapped.value;
}

function booleanBad(wrapped: WrappedStringOr<boolean> | null) {
if (typeof wrapped?.value !== 'string') {
return null;
}
return wrapped.value;
}

function booleanFixed(wrapped: WrappedStringOr<boolean> | null) {
if (typeof (wrapped?.value) !== 'string') {
return null;
}
return wrapped.value;
}


//// [narrowingTypeofDiscriminant.js]
"use strict";
function f1(obj) {
if (typeof obj.kind === "string") {
obj; // { kind: 'a', data: string }
}
else {
obj; // { kind: 1, data: number }
}
}
function f2(obj) {
if (typeof (obj === null || obj === void 0 ? void 0 : obj.kind) === "string") {
obj; // { kind: 'a', data: string }
}
else {
obj; // { kind: 1, data: number } | undefined
}
}
function numberOk(wrapped) {
if (typeof (wrapped === null || wrapped === void 0 ? void 0 : wrapped.value) !== 'string') {
return null;
}
return wrapped.value;
}
function booleanBad(wrapped) {
if (typeof (wrapped === null || wrapped === void 0 ? void 0 : wrapped.value) !== 'string') {
return null;
}
return wrapped.value;
}
function booleanFixed(wrapped) {
if (typeof (wrapped === null || wrapped === void 0 ? void 0 : wrapped.value) !== 'string') {
return null;
}
return wrapped.value;
}
108 changes: 108 additions & 0 deletions tests/baselines/reference/narrowingTypeofDiscriminant.symbols
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@@ -0,0 +1,108 @@
=== tests/cases/compiler/narrowingTypeofDiscriminant.ts ===
function f1(obj: { kind: 'a', data: string } | { kind: 1, data: number }) {
>f1 : Symbol(f1, Decl(narrowingTypeofDiscriminant.ts, 0, 0))
>obj : Symbol(obj, Decl(narrowingTypeofDiscriminant.ts, 0, 12))
>kind : Symbol(kind, Decl(narrowingTypeofDiscriminant.ts, 0, 18))
>data : Symbol(data, Decl(narrowingTypeofDiscriminant.ts, 0, 29))
>kind : Symbol(kind, Decl(narrowingTypeofDiscriminant.ts, 0, 48))
>data : Symbol(data, Decl(narrowingTypeofDiscriminant.ts, 0, 57))

if (typeof obj.kind === "string") {
>obj.kind : Symbol(kind, Decl(narrowingTypeofDiscriminant.ts, 0, 18), Decl(narrowingTypeofDiscriminant.ts, 0, 48))
>obj : Symbol(obj, Decl(narrowingTypeofDiscriminant.ts, 0, 12))
>kind : Symbol(kind, Decl(narrowingTypeofDiscriminant.ts, 0, 18), Decl(narrowingTypeofDiscriminant.ts, 0, 48))

obj; // { kind: 'a', data: string }
>obj : Symbol(obj, Decl(narrowingTypeofDiscriminant.ts, 0, 12))
}
else {
obj; // { kind: 1, data: number }
>obj : Symbol(obj, Decl(narrowingTypeofDiscriminant.ts, 0, 12))
}
}

function f2(obj: { kind: 'a', data: string } | { kind: 1, data: number } | undefined) {
>f2 : Symbol(f2, Decl(narrowingTypeofDiscriminant.ts, 7, 1))
>obj : Symbol(obj, Decl(narrowingTypeofDiscriminant.ts, 9, 12))
>kind : Symbol(kind, Decl(narrowingTypeofDiscriminant.ts, 9, 18))
>data : Symbol(data, Decl(narrowingTypeofDiscriminant.ts, 9, 29))
>kind : Symbol(kind, Decl(narrowingTypeofDiscriminant.ts, 9, 48))
>data : Symbol(data, Decl(narrowingTypeofDiscriminant.ts, 9, 57))

if (typeof obj?.kind === "string") {
>obj?.kind : Symbol(kind, Decl(narrowingTypeofDiscriminant.ts, 9, 18), Decl(narrowingTypeofDiscriminant.ts, 9, 48))
>obj : Symbol(obj, Decl(narrowingTypeofDiscriminant.ts, 9, 12))
>kind : Symbol(kind, Decl(narrowingTypeofDiscriminant.ts, 9, 18), Decl(narrowingTypeofDiscriminant.ts, 9, 48))

obj; // { kind: 'a', data: string }
>obj : Symbol(obj, Decl(narrowingTypeofDiscriminant.ts, 9, 12))
}
else {
obj; // { kind: 1, data: number } | undefined
>obj : Symbol(obj, Decl(narrowingTypeofDiscriminant.ts, 9, 12))
}
}

// Repro from #51700

type WrappedStringOr<T> = { value?: string } | { value?: T };
>WrappedStringOr : Symbol(WrappedStringOr, Decl(narrowingTypeofDiscriminant.ts, 16, 1))
>T : Symbol(T, Decl(narrowingTypeofDiscriminant.ts, 20, 21))
>value : Symbol(value, Decl(narrowingTypeofDiscriminant.ts, 20, 27))
>value : Symbol(value, Decl(narrowingTypeofDiscriminant.ts, 20, 48))
>T : Symbol(T, Decl(narrowingTypeofDiscriminant.ts, 20, 21))

function numberOk(wrapped: WrappedStringOr<number> | null) {
>numberOk : Symbol(numberOk, Decl(narrowingTypeofDiscriminant.ts, 20, 61))
>wrapped : Symbol(wrapped, Decl(narrowingTypeofDiscriminant.ts, 22, 18))
>WrappedStringOr : Symbol(WrappedStringOr, Decl(narrowingTypeofDiscriminant.ts, 16, 1))

if (typeof wrapped?.value !== 'string') {
>wrapped?.value : Symbol(value, Decl(narrowingTypeofDiscriminant.ts, 20, 27), Decl(narrowingTypeofDiscriminant.ts, 20, 48))
>wrapped : Symbol(wrapped, Decl(narrowingTypeofDiscriminant.ts, 22, 18))
>value : Symbol(value, Decl(narrowingTypeofDiscriminant.ts, 20, 27), Decl(narrowingTypeofDiscriminant.ts, 20, 48))

return null;
}
return wrapped.value;
>wrapped.value : Symbol(value, Decl(narrowingTypeofDiscriminant.ts, 20, 27), Decl(narrowingTypeofDiscriminant.ts, 20, 48))
>wrapped : Symbol(wrapped, Decl(narrowingTypeofDiscriminant.ts, 22, 18))
>value : Symbol(value, Decl(narrowingTypeofDiscriminant.ts, 20, 27), Decl(narrowingTypeofDiscriminant.ts, 20, 48))
}

function booleanBad(wrapped: WrappedStringOr<boolean> | null) {
>booleanBad : Symbol(booleanBad, Decl(narrowingTypeofDiscriminant.ts, 27, 1))
>wrapped : Symbol(wrapped, Decl(narrowingTypeofDiscriminant.ts, 29, 20))
>WrappedStringOr : Symbol(WrappedStringOr, Decl(narrowingTypeofDiscriminant.ts, 16, 1))

if (typeof wrapped?.value !== 'string') {
>wrapped?.value : Symbol(value, Decl(narrowingTypeofDiscriminant.ts, 20, 27), Decl(narrowingTypeofDiscriminant.ts, 20, 48))
>wrapped : Symbol(wrapped, Decl(narrowingTypeofDiscriminant.ts, 29, 20))
>value : Symbol(value, Decl(narrowingTypeofDiscriminant.ts, 20, 27), Decl(narrowingTypeofDiscriminant.ts, 20, 48))

return null;
}
return wrapped.value;
>wrapped.value : Symbol(value, Decl(narrowingTypeofDiscriminant.ts, 20, 27))
>wrapped : Symbol(wrapped, Decl(narrowingTypeofDiscriminant.ts, 29, 20))
>value : Symbol(value, Decl(narrowingTypeofDiscriminant.ts, 20, 27))
}

function booleanFixed(wrapped: WrappedStringOr<boolean> | null) {
>booleanFixed : Symbol(booleanFixed, Decl(narrowingTypeofDiscriminant.ts, 34, 1))
>wrapped : Symbol(wrapped, Decl(narrowingTypeofDiscriminant.ts, 36, 22))
>WrappedStringOr : Symbol(WrappedStringOr, Decl(narrowingTypeofDiscriminant.ts, 16, 1))

if (typeof (wrapped?.value) !== 'string') {
>wrapped?.value : Symbol(value, Decl(narrowingTypeofDiscriminant.ts, 20, 27), Decl(narrowingTypeofDiscriminant.ts, 20, 48))
>wrapped : Symbol(wrapped, Decl(narrowingTypeofDiscriminant.ts, 36, 22))
>value : Symbol(value, Decl(narrowingTypeofDiscriminant.ts, 20, 27), Decl(narrowingTypeofDiscriminant.ts, 20, 48))

return null;
}
return wrapped.value;
>wrapped.value : Symbol(value, Decl(narrowingTypeofDiscriminant.ts, 20, 27))
>wrapped : Symbol(wrapped, Decl(narrowingTypeofDiscriminant.ts, 36, 22))
>value : Symbol(value, Decl(narrowingTypeofDiscriminant.ts, 20, 27))
}

125 changes: 125 additions & 0 deletions tests/baselines/reference/narrowingTypeofDiscriminant.types
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@@ -0,0 +1,125 @@
=== tests/cases/compiler/narrowingTypeofDiscriminant.ts ===
function f1(obj: { kind: 'a', data: string } | { kind: 1, data: number }) {
>f1 : (obj: { kind: 'a'; data: string;} | { kind: 1; data: number;}) => void
>obj : { kind: 'a'; data: string; } | { kind: 1; data: number; }
>kind : "a"
>data : string
>kind : 1
>data : number

if (typeof obj.kind === "string") {
>typeof obj.kind === "string" : boolean
>typeof obj.kind : "string" | "number" | "bigint" | "boolean" | "symbol" | "undefined" | "object" | "function"
>obj.kind : "a" | 1
>obj : { kind: "a"; data: string; } | { kind: 1; data: number; }
>kind : "a" | 1
>"string" : "string"

obj; // { kind: 'a', data: string }
>obj : { kind: "a"; data: string; }
}
else {
obj; // { kind: 1, data: number }
>obj : { kind: 1; data: number; }
}
}

function f2(obj: { kind: 'a', data: string } | { kind: 1, data: number } | undefined) {
>f2 : (obj: { kind: 'a'; data: string;} | { kind: 1; data: number;} | undefined) => void
>obj : { kind: 'a'; data: string; } | { kind: 1; data: number; } | undefined
>kind : "a"
>data : string
>kind : 1
>data : number

if (typeof obj?.kind === "string") {
>typeof obj?.kind === "string" : boolean
>typeof obj?.kind : "string" | "number" | "bigint" | "boolean" | "symbol" | "undefined" | "object" | "function"
>obj?.kind : "a" | 1 | undefined
>obj : { kind: "a"; data: string; } | { kind: 1; data: number; } | undefined
>kind : "a" | 1 | undefined
>"string" : "string"

obj; // { kind: 'a', data: string }
>obj : { kind: "a"; data: string; }
}
else {
obj; // { kind: 1, data: number } | undefined
>obj : { kind: 1; data: number; } | undefined
}
}

// Repro from #51700

type WrappedStringOr<T> = { value?: string } | { value?: T };
>WrappedStringOr : WrappedStringOr<T>
>value : string | undefined
>value : T | undefined

function numberOk(wrapped: WrappedStringOr<number> | null) {
>numberOk : (wrapped: WrappedStringOr<number> | null) => string | null
>wrapped : WrappedStringOr<number> | null
>null : null

if (typeof wrapped?.value !== 'string') {
>typeof wrapped?.value !== 'string' : boolean
>typeof wrapped?.value : "string" | "number" | "bigint" | "boolean" | "symbol" | "undefined" | "object" | "function"
>wrapped?.value : string | number | undefined
>wrapped : WrappedStringOr<number> | null
>value : string | number | undefined
>'string' : "string"

return null;
>null : null
}
return wrapped.value;
>wrapped.value : string
>wrapped : WrappedStringOr<number>
>value : string
}

function booleanBad(wrapped: WrappedStringOr<boolean> | null) {
>booleanBad : (wrapped: WrappedStringOr<boolean> | null) => string | null
>wrapped : WrappedStringOr<boolean> | null
>null : null

if (typeof wrapped?.value !== 'string') {
>typeof wrapped?.value !== 'string' : boolean
>typeof wrapped?.value : "string" | "number" | "bigint" | "boolean" | "symbol" | "undefined" | "object" | "function"
>wrapped?.value : string | boolean | undefined
>wrapped : WrappedStringOr<boolean> | null
>value : string | boolean | undefined
>'string' : "string"

return null;
>null : null
}
return wrapped.value;
>wrapped.value : string
>wrapped : { value?: string | undefined; }
>value : string
}

function booleanFixed(wrapped: WrappedStringOr<boolean> | null) {
>booleanFixed : (wrapped: WrappedStringOr<boolean> | null) => string | null
>wrapped : WrappedStringOr<boolean> | null
>null : null

if (typeof (wrapped?.value) !== 'string') {
>typeof (wrapped?.value) !== 'string' : boolean
>typeof (wrapped?.value) : "string" | "number" | "bigint" | "boolean" | "symbol" | "undefined" | "object" | "function"
>(wrapped?.value) : string | boolean | undefined
>wrapped?.value : string | boolean | undefined
>wrapped : WrappedStringOr<boolean> | null
>value : string | boolean | undefined
>'string' : "string"

return null;
>null : null
}
return wrapped.value;
>wrapped.value : string
>wrapped : { value?: string | undefined; }
>value : string
}

44 changes: 44 additions & 0 deletions tests/cases/compiler/narrowingTypeofDiscriminant.ts
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@@ -0,0 +1,44 @@
// @strict: true

function f1(obj: { kind: 'a', data: string } | { kind: 1, data: number }) {
if (typeof obj.kind === "string") {
obj; // { kind: 'a', data: string }
}
else {
obj; // { kind: 1, data: number }
}
}

function f2(obj: { kind: 'a', data: string } | { kind: 1, data: number } | undefined) {
if (typeof obj?.kind === "string") {
obj; // { kind: 'a', data: string }
}
else {
obj; // { kind: 1, data: number } | undefined
}
}

// Repro from #51700

type WrappedStringOr<T> = { value?: string } | { value?: T };

function numberOk(wrapped: WrappedStringOr<number> | null) {
if (typeof wrapped?.value !== 'string') {
return null;
}
return wrapped.value;
}

function booleanBad(wrapped: WrappedStringOr<boolean> | null) {
if (typeof wrapped?.value !== 'string') {
return null;
}
return wrapped.value;
}

function booleanFixed(wrapped: WrappedStringOr<boolean> | null) {
if (typeof (wrapped?.value) !== 'string') {
return null;
}
return wrapped.value;
}