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Fix narrowing of optional chains #36089

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Merged
merged 3 commits into from
Jan 8, 2020
Merged

Fix narrowing of optional chains #36089

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07b41e2
Check for definitely not undefined instead of maybe not undefined
ahejlsberg Jan 8, 2020
cf731d9
Fix comment
ahejlsberg Jan 8, 2020
bd53151
Add tests
ahejlsberg Jan 8, 2020
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23 changes: 16 additions & 7 deletions src/compiler/checker.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -19777,13 +19777,22 @@ namespace ts {
}

function narrowTypeByOptionalChainContainment(type: Type, operator: SyntaxKind, value: Expression, assumeTrue: boolean): Type {
// We are in a branch of obj?.foo === value or obj?.foo !== value. We remove undefined and null from
// the type of obj if (a) the operator is === and the type of value doesn't include undefined or (b) the
// operator is !== and the type of value is undefined.
const effectiveTrue = operator === SyntaxKind.EqualsEqualsToken || operator === SyntaxKind.EqualsEqualsEqualsToken ? assumeTrue : !assumeTrue;
const doubleEquals = operator === SyntaxKind.EqualsEqualsToken || operator === SyntaxKind.ExclamationEqualsToken;
const valueNonNullish = !(getTypeFacts(getTypeOfExpression(value)) & (doubleEquals ? TypeFacts.EQUndefinedOrNull : TypeFacts.EQUndefined));
return effectiveTrue === valueNonNullish ? getTypeWithFacts(type, TypeFacts.NEUndefinedOrNull) : type;
// We are in a branch of obj?.foo === value (or any one of the other equality operators). We narrow obj as follows:
// When operator is === and type of value excludes undefined, null and undefined is removed from type of obj in true branch.
// When operator is !== and type of value excludes undefined, null and undefined is removed from type of obj in false branch.
// When operator is == and type of value excludes null and undefined, null and undefined is removed from type of obj in true branch.
// When operator is != and type of value excludes null and undefined, null and undefined is removed from type of obj in false branch.
// When operator is === and type of value is undefined, null and undefined is removed from type of obj in false branch.
// When operator is !== and type of value is undefined, null and undefined is removed from type of obj in true branch.
// When operator is == and type of value is null or undefined, null and undefined is removed from type of obj in false branch.
// When operator is != and type of value is null or undefined, null and undefined is removed from type of obj in true branch.
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const equalsOperator = operator === SyntaxKind.EqualsEqualsToken || operator === SyntaxKind.EqualsEqualsEqualsToken;
const nullableFlags = operator === SyntaxKind.EqualsEqualsToken || operator === SyntaxKind.ExclamationEqualsToken ? TypeFlags.Nullable : TypeFlags.Undefined;
const valueType = getTypeOfExpression(value);
// Note that we include any and unknown in the exclusion test because their domain includes null and undefined.
const removeNullable = equalsOperator !== assumeTrue && everyType(valueType, t => !!(t.flags & nullableFlags)) ||
equalsOperator === assumeTrue && everyType(valueType, t => !(t.flags & (TypeFlags.AnyOrUnknown | nullableFlags)));
return removeNullable ? getTypeWithFacts(type, TypeFacts.NEUndefinedOrNull) : type;
}

function narrowTypeByEquality(type: Type, operator: SyntaxKind, value: Expression, assumeTrue: boolean): Type {
Expand Down
103 changes: 90 additions & 13 deletions tests/baselines/reference/controlFlowOptionalChain.errors.txt
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Expand Up @@ -36,24 +36,33 @@ tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(310,9): error TS
tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(319,9): error TS2532: Object is possibly 'undefined'.
tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(322,9): error TS2532: Object is possibly 'undefined'.
tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(331,9): error TS2532: Object is possibly 'undefined'.
tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(334,9): error TS2532: Object is possibly 'undefined'.
tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(337,9): error TS2532: Object is possibly 'undefined'.
tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(340,9): error TS2532: Object is possibly 'undefined'.
tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(343,9): error TS2532: Object is possibly 'undefined'.
tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(346,9): error TS2532: Object is possibly 'undefined'.
tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(349,9): error TS2532: Object is possibly 'undefined'.
tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(352,9): error TS2532: Object is possibly 'undefined'.
tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(391,9): error TS2532: Object is possibly 'undefined'.
tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(394,9): error TS2532: Object is possibly 'undefined'.
tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(403,9): error TS2532: Object is possibly 'undefined'.
tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(406,9): error TS2532: Object is possibly 'undefined'.
tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(415,9): error TS2532: Object is possibly 'undefined'.
tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(424,9): error TS2532: Object is possibly 'undefined'.
tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(427,9): error TS2532: Object is possibly 'undefined'.
tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(436,9): error TS2532: Object is possibly 'undefined'.
tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(471,13): error TS2532: Object is possibly 'undefined'.
tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(474,13): error TS2532: Object is possibly 'undefined'.
tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(488,13): error TS2532: Object is possibly 'undefined'.
tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(491,13): error TS2532: Object is possibly 'undefined'.
tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(358,9): error TS2532: Object is possibly 'undefined'.
tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(367,9): error TS2532: Object is possibly 'undefined'.
tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(370,9): error TS2532: Object is possibly 'undefined'.
tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(379,9): error TS2532: Object is possibly 'undefined'.
tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(418,9): error TS2532: Object is possibly 'undefined'.
tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(421,9): error TS2532: Object is possibly 'undefined'.
tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(430,9): error TS2532: Object is possibly 'undefined'.
tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(433,9): error TS2532: Object is possibly 'undefined'.
tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(442,9): error TS2532: Object is possibly 'undefined'.
tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(451,9): error TS2532: Object is possibly 'undefined'.
tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(454,9): error TS2532: Object is possibly 'undefined'.
tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(463,9): error TS2532: Object is possibly 'undefined'.
tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(498,13): error TS2532: Object is possibly 'undefined'.
tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(501,13): error TS2532: Object is possibly 'undefined'.
tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(515,13): error TS2532: Object is possibly 'undefined'.
tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(518,13): error TS2532: Object is possibly 'undefined'.
tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(567,21): error TS2532: Object is possibly 'undefined'.


==== tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts (53 errors) ====
==== tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts (62 errors) ====
// assignments in shortcutting chain
declare const o: undefined | {
[key: string]: any;
Expand Down Expand Up @@ -456,6 +465,49 @@ tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(491,13): error T
}
}

function f15a(o: Thing | undefined, value: unknown) {
if (o?.foo === value) {
o.foo; // Error
~
!!! error TS2532: Object is possibly 'undefined'.
}
else {
o.foo; // Error
~
!!! error TS2532: Object is possibly 'undefined'.
}
if (o?.foo !== value) {
o.foo; // Error
~
!!! error TS2532: Object is possibly 'undefined'.
}
else {
o.foo; // Error
~
!!! error TS2532: Object is possibly 'undefined'.
}
if (o?.foo == value) {
o.foo; // Error
~
!!! error TS2532: Object is possibly 'undefined'.
}
else {
o.foo; // Error
~
!!! error TS2532: Object is possibly 'undefined'.
}
if (o?.foo != value) {
o.foo; // Error
~
!!! error TS2532: Object is possibly 'undefined'.
}
else {
o.foo; // Error
~
!!! error TS2532: Object is possibly 'undefined'.
}
}

function f16(o: Thing | undefined) {
if (o?.foo === undefined) {
o.foo; // Error
Expand Down Expand Up @@ -687,4 +739,29 @@ tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(491,13): error T
}
return f.geometry.coordinates;
}

// Repro from #35842

interface SomeObject {
someProperty: unknown;
}

let lastSomeProperty: unknown | undefined;

function someFunction(someOptionalObject: SomeObject | undefined): void {
if (someOptionalObject?.someProperty !== lastSomeProperty) {
console.log(someOptionalObject);
console.log(someOptionalObject.someProperty); // Error
~~~~~~~~~~~~~~~~~~
!!! error TS2532: Object is possibly 'undefined'.
lastSomeProperty = someOptionalObject?.someProperty;
}
}

const someObject: SomeObject = {
someProperty: 42
};

someFunction(someObject);
someFunction(undefined);

89 changes: 89 additions & 0 deletions tests/baselines/reference/controlFlowOptionalChain.js
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Original file line number Diff line number Diff line change
Expand Up @@ -327,6 +327,33 @@ function f15(o: Thing | undefined, value: number) {
}
}

function f15a(o: Thing | undefined, value: unknown) {
if (o?.foo === value) {
o.foo; // Error
}
else {
o.foo; // Error
}
if (o?.foo !== value) {
o.foo; // Error
}
else {
o.foo; // Error
}
if (o?.foo == value) {
o.foo; // Error
}
else {
o.foo; // Error
}
if (o?.foo != value) {
o.foo; // Error
}
else {
o.foo; // Error
}
}

function f16(o: Thing | undefined) {
if (o?.foo === undefined) {
o.foo; // Error
Expand Down Expand Up @@ -526,6 +553,29 @@ function extractCoordinates(f: Feature): number[] {
}
return f.geometry.coordinates;
}

// Repro from #35842

interface SomeObject {
someProperty: unknown;
}

let lastSomeProperty: unknown | undefined;

function someFunction(someOptionalObject: SomeObject | undefined): void {
if (someOptionalObject?.someProperty !== lastSomeProperty) {
console.log(someOptionalObject);
console.log(someOptionalObject.someProperty); // Error
lastSomeProperty = someOptionalObject?.someProperty;
}
}

const someObject: SomeObject = {
someProperty: 42
};

someFunction(someObject);
someFunction(undefined);


//// [controlFlowOptionalChain.js]
Expand Down Expand Up @@ -809,6 +859,32 @@ function f15(o, value) {
o.foo;
}
}
function f15a(o, value) {
if ((o === null || o === void 0 ? void 0 : o.foo) === value) {
o.foo; // Error
}
else {
o.foo; // Error
}
if ((o === null || o === void 0 ? void 0 : o.foo) !== value) {
o.foo; // Error
}
else {
o.foo; // Error
}
if ((o === null || o === void 0 ? void 0 : o.foo) == value) {
o.foo; // Error
}
else {
o.foo; // Error
}
if ((o === null || o === void 0 ? void 0 : o.foo) != value) {
o.foo; // Error
}
else {
o.foo; // Error
}
}
function f16(o) {
if ((o === null || o === void 0 ? void 0 : o.foo) === undefined) {
o.foo; // Error
Expand Down Expand Up @@ -982,3 +1058,16 @@ function extractCoordinates(f) {
}
return f.geometry.coordinates;
}
var lastSomeProperty;
function someFunction(someOptionalObject) {
if ((someOptionalObject === null || someOptionalObject === void 0 ? void 0 : someOptionalObject.someProperty) !== lastSomeProperty) {
console.log(someOptionalObject);
console.log(someOptionalObject.someProperty); // Error
lastSomeProperty = someOptionalObject === null || someOptionalObject === void 0 ? void 0 : someOptionalObject.someProperty;
}
}
var someObject = {
someProperty: 42
};
someFunction(someObject);
someFunction(undefined);
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