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Use same literal comparison rules for switch/===

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switch was missing the rule for converting literal types to the literal
base type if needed.
This commit is contained in:
Nathan Shively-Sanders
2016-10-13 16:26:44 -07:00
parent 31a55e6452
commit 00ebf59b50
1 changed files with 8 additions and 2 deletions
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10
src/compiler/checker.ts
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@@ -16584,7 +16584,7 @@ namespace ts {
let firstDefaultClause: CaseOrDefaultClause;
let hasDuplicateDefaultClause = false;
const expressionType = checkExpression(node.expression);
let expressionType = checkExpression(node.expression);
forEach(node.caseBlock.clauses, clause => {
// Grammar check for duplicate default clauses, skip if we already report duplicate default clause
if (clause.kind === SyntaxKind.DefaultClause && !hasDuplicateDefaultClause) {
@@ -16605,7 +16605,13 @@ namespace ts {
// TypeScript 1.0 spec (April 2014): 5.9
// In a 'switch' statement, each 'case' expression must be of a type that is comparable
// to or from the type of the 'switch' expression.
const caseType = checkExpression(caseClause.expression);
let caseType = checkExpression(caseClause.expression);
const expressionIsLiteral = isLiteralType(expressionType);
const caseIsLiteral = isLiteralType(caseType);
if (!expressionIsLiteral || !caseIsLiteral) {
expressionType = expressionIsLiteral ? getBaseTypeOfLiteralType(expressionType) : expressionType;
caseType = caseIsLiteral ? getBaseTypeOfLiteralType(caseType) : caseType;
}
if (!isTypeEqualityComparableTo(expressionType, caseType)) {
// expressionType is not comparable to caseType, try the reversed check and report errors if it fails
checkTypeComparableTo(caseType, expressionType, caseClause.expression, /*headMessage*/ undefined);