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Disallow assigments to exported variables from external modules

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This commit is contained in:
Anders Hejlsberg 2016-01-22 10:32:17 -08:00
parent b6f43e6cae
commit fac1bf6eef
1 changed files with 37 additions and 17 deletions
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54
src/compiler/checker.ts
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@ -10400,25 +10400,44 @@ 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 {
return symbol.flags & SymbolFlags.Property && (getDeclarationFlagsFromSymbol(symbol) & NodeFlags.Readonly) !== 0;
}
function isConstantSymbol(symbol: Symbol): boolean {
return symbol === undefinedSymbol ||
symbol.flags & SymbolFlags.Variable && (getDeclarationFlagsFromSymbol(symbol) & NodeFlags.Const) !== 0 ||
symbol.flags & SymbolFlags.Accessor && !(symbol.flags & SymbolFlags.SetAccessor);
function isReferenceToConstant(expr: Expression, symbol: Symbol): boolean {
if (symbol.flags & SymbolFlags.Variable) {
// A variable declared with 'const' is considered constant.
if (getDeclarationFlagsFromSymbol(symbol) & NodeFlags.Const) {
return true;
}
// An exported variable declared in an external module and accessed through a property
// or element access is considered constant.
if (expr.kind === SyntaxKind.PropertyAccessExpression || expr.kind === SyntaxKind.ElementAccessExpression) {
if (symbol.parent && symbol.parent.flags & SymbolFlags.ValueModule) {
const declaration = symbol.parent.valueDeclaration;
return declaration && (declaration.kind === SyntaxKind.SourceFile ||
declaration.kind === SyntaxKind.ModuleDeclaration && (<ModuleDeclaration>declaration).name.kind === SyntaxKind.StringLiteral);
}
}
}
if (symbol.flags & SymbolFlags.Accessor) {
// An get accessor with no corresponding set accessor is considered constant.
return !(symbol.flags & SymbolFlags.SetAccessor);
}
return false;
}
function isReferenceToReadonlyProperty(expr: Expression, symbol: Symbol): boolean {
if (isReadonlySymbol(symbol)) {
// Allow assignments to readonly properties within constructors of the same class declaration.
if ((expr.kind === SyntaxKind.PropertyAccessExpression || expr.kind === SyntaxKind.ElementAccessExpression) &&
(expr as PropertyAccessExpression | ElementAccessExpression).expression.kind === SyntaxKind.ThisKeyword) {
const func = getContainingFunction(expr);
return !(func && func.kind === SyntaxKind.Constructor && func.parent === symbol.valueDeclaration.parent);
}
return true;
}
return false;
}
function checkReferenceExpression(expr: Expression, invalidReferenceMessage: DiagnosticMessage, constantVariableMessage: DiagnosticMessage): boolean {
@ -10435,11 +10454,12 @@ namespace ts {
const symbol = getExportSymbolOfValueSymbolIfExported(links.resolvedSymbol);
if (symbol) {
if (symbol !== unknownSymbol && symbol !== argumentsSymbol) {
if (symbol === undefinedSymbol || !(symbol.flags & (SymbolFlags.Variable | SymbolFlags.Property | SymbolFlags.Method | SymbolFlags.Accessor))) {
if (symbol === undefinedSymbol ||
!(symbol.flags & (SymbolFlags.Variable | SymbolFlags.Property | SymbolFlags.Method | SymbolFlags.Accessor))) {
error(expr, invalidReferenceMessage);
return false;
}
if (isConstantSymbol(symbol) || (isReadonlySymbol(symbol) && !isReferenceWithinOwnConstructor(expr, symbol))) {
if (isReferenceToConstant(node, symbol) || isReferenceToReadonlyProperty(node, symbol)) {
error(expr, constantVariableMessage);
return false;
}