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Fix GH-32798: Allow == null to narrow unknown to null | undefined #45853

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Merged
merged 4 commits into from
Sep 22, 2021
Merged

Fix GH-32798: Allow == null to narrow unknown to null | undefined #45853

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007547d
Fix GH-32798
hahmadia Sep 13, 2021
ef67e5d
add assume true
hahmadia Sep 14, 2021
f2bd3bc
Address Gabby comments
hahmadia Sep 21, 2021
b1a6e5f
Address Gabby comments by adding Else branch
hahmadia Sep 22, 2021
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3 changes: 3 additions & 0 deletions src/compiler/checker.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -23895,6 +23895,9 @@ namespace ts {
assumeTrue = !assumeTrue;
}
const valueType = getTypeOfExpression(value);
if (assumeTrue && (type.flags & TypeFlags.Unknown) && (operator === SyntaxKind.EqualsEqualsToken || operator === SyntaxKind.ExclamationEqualsToken) && (valueType.flags & TypeFlags.Null)) {
return getUnionType([nullType, undefinedType]);
}
if ((type.flags & TypeFlags.Unknown) && assumeTrue && (operator === SyntaxKind.EqualsEqualsEqualsToken || operator === SyntaxKind.ExclamationEqualsEqualsToken)) {
if (valueType.flags & (TypeFlags.Primitive | TypeFlags.NonPrimitive)) {
return valueType;
Expand Down
19 changes: 17 additions & 2 deletions tests/baselines/reference/narrowByEquality.errors.txt
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Original file line number Diff line number Diff line change
@@ -1,6 +1,6 @@
tests/cases/compiler/narrowByEquality.ts(53,15): error TS2322: Type 'string | number' is not assignable to type 'number'.
tests/cases/compiler/narrowByEquality.ts(54,15): error TS2322: Type 'string | number' is not assignable to type 'number'.
Type 'string' is not assignable to type 'number'.
tests/cases/compiler/narrowByEquality.ts(54,9): error TS2322: Type 'string | number' is not assignable to type 'number'.
tests/cases/compiler/narrowByEquality.ts(55,9): error TS2322: Type 'string | number' is not assignable to type 'number'.
Type 'string' is not assignable to type 'number'.


Expand All @@ -9,6 +9,7 @@ tests/cases/compiler/narrowByEquality.ts(54,9): error TS2322: Type 'string | num
declare let n: number;
declare let s: string;
declare let b: boolean;
declare let xUnknown: unknown;

if (x == n) {
x;
Expand Down Expand Up @@ -68,4 +69,18 @@ tests/cases/compiler/narrowByEquality.ts(54,9): error TS2322: Type 'string | num
}
return 0;
}

// From issue #32798
if (xUnknown == null) {
xUnknown;
} else {
xUnknown
}

if (xUnknown != null) {
xUnknown;
} else {
xUnknown;
}


28 changes: 28 additions & 0 deletions tests/baselines/reference/narrowByEquality.js
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Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,7 @@ declare let x: number | string | boolean
declare let n: number;
declare let s: string;
declare let b: boolean;
declare let xUnknown: unknown;

if (x == n) {
x;
Expand Down Expand Up @@ -56,6 +57,20 @@ function test(level: number | string):number {
}
return 0;
}

// From issue #32798
if (xUnknown == null) {
xUnknown;
} else {
xUnknown
}

if (xUnknown != null) {
xUnknown;
} else {
xUnknown;
}



//// [narrowByEquality.js]
Expand Down Expand Up @@ -99,3 +114,16 @@ function test(level) {
}
return 0;
}
// From issue #32798
if (xUnknown == null) {
xUnknown;
}
else {
xUnknown;
}
if (xUnknown != null) {
xUnknown;
}
else {
xUnknown;
}
51 changes: 39 additions & 12 deletions tests/baselines/reference/narrowByEquality.symbols
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Original file line number Diff line number Diff line change
Expand Up @@ -11,6 +11,9 @@ declare let s: string;
declare let b: boolean;
>b : Symbol(b, Decl(narrowByEquality.ts, 3, 11))

declare let xUnknown: unknown;
>xUnknown : Symbol(xUnknown, Decl(narrowByEquality.ts, 4, 11))

if (x == n) {
>x : Symbol(x, Decl(narrowByEquality.ts, 0, 11))
>n : Symbol(n, Decl(narrowByEquality.ts, 1, 11))
Expand Down Expand Up @@ -71,43 +74,67 @@ if (x == false) {
}

declare let xAndObj: number | string | boolean | object
>xAndObj : Symbol(xAndObj, Decl(narrowByEquality.ts, 37, 11))
>xAndObj : Symbol(xAndObj, Decl(narrowByEquality.ts, 38, 11))

if (xAndObj == {}) {
>xAndObj : Symbol(xAndObj, Decl(narrowByEquality.ts, 37, 11))
>xAndObj : Symbol(xAndObj, Decl(narrowByEquality.ts, 38, 11))

xAndObj;
>xAndObj : Symbol(xAndObj, Decl(narrowByEquality.ts, 37, 11))
>xAndObj : Symbol(xAndObj, Decl(narrowByEquality.ts, 38, 11))
}

if (x == xAndObj) {
>x : Symbol(x, Decl(narrowByEquality.ts, 0, 11))
>xAndObj : Symbol(xAndObj, Decl(narrowByEquality.ts, 37, 11))
>xAndObj : Symbol(xAndObj, Decl(narrowByEquality.ts, 38, 11))

x;
>x : Symbol(x, Decl(narrowByEquality.ts, 0, 11))

xAndObj;
>xAndObj : Symbol(xAndObj, Decl(narrowByEquality.ts, 37, 11))
>xAndObj : Symbol(xAndObj, Decl(narrowByEquality.ts, 38, 11))
}

// Repro from #24991

function test(level: number | string):number {
>test : Symbol(test, Decl(narrowByEquality.ts, 46, 1))
>level : Symbol(level, Decl(narrowByEquality.ts, 50, 14))
>test : Symbol(test, Decl(narrowByEquality.ts, 47, 1))
>level : Symbol(level, Decl(narrowByEquality.ts, 51, 14))

if (level == +level) {
>level : Symbol(level, Decl(narrowByEquality.ts, 50, 14))
>level : Symbol(level, Decl(narrowByEquality.ts, 50, 14))
>level : Symbol(level, Decl(narrowByEquality.ts, 51, 14))
>level : Symbol(level, Decl(narrowByEquality.ts, 51, 14))

const q2: number = level; // error
>q2 : Symbol(q2, Decl(narrowByEquality.ts, 52, 13))
>level : Symbol(level, Decl(narrowByEquality.ts, 50, 14))
>q2 : Symbol(q2, Decl(narrowByEquality.ts, 53, 13))
>level : Symbol(level, Decl(narrowByEquality.ts, 51, 14))

return level;
>level : Symbol(level, Decl(narrowByEquality.ts, 50, 14))
>level : Symbol(level, Decl(narrowByEquality.ts, 51, 14))
}
return 0;
}

// From issue #32798
if (xUnknown == null) {
>xUnknown : Symbol(xUnknown, Decl(narrowByEquality.ts, 4, 11))

xUnknown;
>xUnknown : Symbol(xUnknown, Decl(narrowByEquality.ts, 4, 11))

} else {
xUnknown
>xUnknown : Symbol(xUnknown, Decl(narrowByEquality.ts, 4, 11))
}

if (xUnknown != null) {
>xUnknown : Symbol(xUnknown, Decl(narrowByEquality.ts, 4, 11))

xUnknown;
>xUnknown : Symbol(xUnknown, Decl(narrowByEquality.ts, 4, 11))

} else {
xUnknown;
>xUnknown : Symbol(xUnknown, Decl(narrowByEquality.ts, 4, 11))
}


31 changes: 31 additions & 0 deletions tests/baselines/reference/narrowByEquality.types
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Original file line number Diff line number Diff line change
Expand Up @@ -11,6 +11,9 @@ declare let s: string;
declare let b: boolean;
>b : boolean

declare let xUnknown: unknown;
>xUnknown : unknown

if (x == n) {
>x == n : boolean
>x : string | number | boolean
Expand Down Expand Up @@ -130,3 +133,31 @@ function test(level: number | string):number {
>0 : 0
}

// From issue #32798
if (xUnknown == null) {
>xUnknown == null : boolean
>xUnknown : unknown
>null : null

xUnknown;
>xUnknown : null | undefined

} else {
xUnknown
>xUnknown : unknown
}

if (xUnknown != null) {
>xUnknown != null : boolean
>xUnknown : unknown
>null : null

xUnknown;
>xUnknown : unknown

} else {
xUnknown;
>xUnknown : null | undefined
}


15 changes: 15 additions & 0 deletions tests/cases/compiler/narrowByEquality.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -4,6 +4,7 @@ declare let x: number | string | boolean
declare let n: number;
declare let s: string;
declare let b: boolean;
declare let xUnknown: unknown;

if (x == n) {
x;
Expand Down Expand Up @@ -57,3 +58,17 @@ function test(level: number | string):number {
}
return 0;
}

// From issue #32798
if (xUnknown == null) {
xUnknown;
} else {
xUnknown
}

if (xUnknown != null) {
xUnknown;
} else {
xUnknown;
}