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Allow assignments to readonly properties in constructors

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This commit is contained in:
Anders Hejlsberg 2016-01-18 16:58:09 -08:00
parent 13f763d33c
commit 2a20e915e8
1 changed files with 12 additions and 1 deletions
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13
src/compiler/checker.ts
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@ -10366,6 +10366,17 @@ namespace ts {
return true;
}
function isReferenceWithinOwnConstructor(expr: Expression, symbol: Symbol): boolean {
// Allow assignments to readonly properties or methods (but not readonly accessors) within constructors
// of the same class declaration.
if ((expr.kind === SyntaxKind.PropertyAccessExpression || expr.kind === SyntaxKind.ElementAccessExpression) &&
(expr as PropertyAccessExpression | ElementAccessExpression).expression.kind === SyntaxKind.ThisKeyword &&
symbol.flags & (SymbolFlags.Property | SymbolFlags.Method)) {
const func = getContainingFunction(expr);
return func && func.kind === SyntaxKind.Constructor && func.parent === symbol.valueDeclaration.parent;
}
}
function isReadonlySymbol(symbol: Symbol): boolean {
if (symbol.flags & (SymbolFlags.Property | SymbolFlags.Method)) {
return symbol === undefinedSymbol || (getDeclarationFlagsFromSymbol(symbol) & NodeFlags.Readonly) !== 0;
@ -10400,7 +10411,7 @@ namespace ts {
error(expr, invalidReferenceMessage);
return false;
}
if (isReadonlySymbol(symbol) || isConstantSymbol(symbol)) {
if (isConstantSymbol(symbol) || (isReadonlySymbol(symbol) && !isReferenceWithinOwnConstructor(expr, symbol))) {
error(expr, constantVariableMessage);
return false;
}