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Support assignments in truthiness type guards

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This commit is contained in:
Anders Hejlsberg
2016-04-21 13:02:52 -07:00
parent 06928b669e
commit 8a0bc3b992
2 changed files with 4 additions and 0 deletions
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2
src/compiler/binder.ts
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@@ -617,6 +617,8 @@ namespace ts {
function isNarrowingBinaryExpression(expr: BinaryExpression) {
switch (expr.operatorToken.kind) {
case SyntaxKind.EqualsToken:
return isNarrowableReference(expr.left);
case SyntaxKind.EqualsEqualsToken:
case SyntaxKind.ExclamationEqualsToken:
case SyntaxKind.EqualsEqualsEqualsToken:

2
src/compiler/checker.ts
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@@ -7671,6 +7671,8 @@ namespace ts {
function narrowTypeByBinaryExpression(type: Type, expr: BinaryExpression, assumeTrue: boolean): Type {
switch (expr.operatorToken.kind) {
case SyntaxKind.EqualsToken:
return narrowTypeByTruthiness(type, expr.left, assumeTrue);
case SyntaxKind.EqualsEqualsToken:
case SyntaxKind.ExclamationEqualsToken:
case SyntaxKind.EqualsEqualsEqualsToken: