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Equality comparisons for null/undefined in strict null checking mode

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This commit is contained in:
Anders Hejlsberg
2016-05-03 17:05:12 -07:00
parent 7f82bebb03
commit ccad31bf24
1 changed files with 10 additions and 4 deletions
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14
src/compiler/checker.ts
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@@ -12053,6 +12053,10 @@ namespace ts {
return sourceType;
}
function isTypeEqualityComparableTo(source: Type, target: Type) {
return (target.flags & TypeFlags.Nullable) !== 0 || isTypeComparableTo(source, target);
}
function checkBinaryExpression(node: BinaryExpression, contextualMapper?: TypeMapper) {
return checkBinaryLikeExpression(node.left, node.operatorToken, node.right, contextualMapper, node);
}
@@ -12166,15 +12170,17 @@ namespace ts {
case SyntaxKind.GreaterThanToken:
case SyntaxKind.LessThanEqualsToken:
case SyntaxKind.GreaterThanEqualsToken:
if (!checkForDisallowedESSymbolOperand(operator)) {
return booleanType;
if (checkForDisallowedESSymbolOperand(operator)) {
if (!isTypeComparableTo(leftType, rightType) && !isTypeComparableTo(rightType, leftType)) {
reportOperatorError();
}
}
// Fall through
return booleanType;
case SyntaxKind.EqualsEqualsToken:
case SyntaxKind.ExclamationEqualsToken:
case SyntaxKind.EqualsEqualsEqualsToken:
case SyntaxKind.ExclamationEqualsEqualsToken:
if (!isTypeComparableTo(leftType, rightType) && !isTypeComparableTo(rightType, leftType)) {
if (!isTypeEqualityComparableTo(leftType, rightType) && !isTypeEqualityComparableTo(rightType, leftType)) {
reportOperatorError();
}
return booleanType;