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fix(48166): Checking module.exports should not yield a This condition will always return true since this function is always defined error#48337

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Merged
Nathan Shively-Sanders (sandersn) merged 1 commit into from
Mar 28, 2022
Merged

fix(48166): Checking module.exports should not yield a This condition will always return true since this function is always defined error #48337

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1 change: 1 addition & 0 deletions src/compiler/checker.ts
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Original file line numberDiff line numberDiff line change
Expand Up@@ -37599,6 +37599,7 @@ namespace ts {
(condExpr.operatorToken.kind === SyntaxKind.BarBarToken || condExpr.operatorToken.kind === SyntaxKind.AmpersandAmpersandToken)
? condExpr.right
: condExpr;
if (isModuleExportsAccessExpression(location)) return;
const type = checkTruthinessExpression(location);
const isPropertyExpressionCast = isPropertyAccessExpression(location) && isTypeAssertion(location.expression);
if (getFalsyFlags(type) || isPropertyExpressionCast) return;
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17 changes: 17 additions & 0 deletions tests/baselines/reference/truthinessCallExpressionCoercion4.symbols
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@@ -0,0 +1,17 @@
=== tests/cases/compiler/a.js ===
function fn() {}
>fn : Symbol(fn, Decl(a.js, 0, 0))

if (typeof module === 'object' && module.exports) {
>module : Symbol(module, Decl(a.js, 2, 51))
>module.exports : Symbol(module.exports, Decl(a.js, 0, 0))
>module : Symbol(module, Decl(a.js, 2, 51))
>exports : Symbol(module.exports, Decl(a.js, 0, 0))

module.exports = fn;
>module.exports : Symbol(module.exports, Decl(a.js, 0, 0))
>module : Symbol(export=, Decl(a.js, 2, 51))
>exports : Symbol(export=, Decl(a.js, 2, 51))
>fn : Symbol(fn, Decl(a.js, 0, 0))
}

22 changes: 22 additions & 0 deletions tests/baselines/reference/truthinessCallExpressionCoercion4.types
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@@ -0,0 +1,22 @@
=== tests/cases/compiler/a.js ===
function fn() {}
>fn : () => void

if (typeof module === 'object' && module.exports) {
>typeof module === 'object' && module.exports : false | (() => void)
>typeof module === 'object' : boolean
>typeof module : "string" | "number" | "bigint" | "boolean" | "symbol" | "undefined" | "object" | "function"
>module : { exports: () => void; }
>'object' : "object"
>module.exports : () => void
>module : { exports: () => void; }
>exports : () => void

module.exports = fn;
>module.exports = fn : () => void
>module.exports : () => void
>module : { exports: () => void; }
>exports : () => void
>fn : () => void
}

11 changes: 11 additions & 0 deletions tests/cases/compiler/truthinessCallExpressionCoercion4.ts
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@@ -0,0 +1,11 @@
// @checkJs: true
// @allowJs: true
// @strict: true
// @noEmit: true
// @filename: a.js

function fn() {}

if (typeof module === 'object' && module.exports) {
module.exports = fn;
}