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Adds 'symbol constraints' for easier checking of assignments. #5170

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Adds 'symbol constraints' for easier checking of assignments. #5170

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16 changes: 16 additions & 0 deletions src/compiler/binder.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -242,6 +242,22 @@ namespace ts {
addDeclarationToSymbol(symbol, node, includes);
symbol.parent = parent;

if (node.flags & NodeFlags.Const ||
(node.kind === SyntaxKind.VariableDeclaration && node.parent.flags & NodeFlags.Const)) {
if (symbol.flags & SymbolFlags.ConstEnum) {
symbol.constraints |= SymbolConstraints.Immutable;
}
else {
symbol.constraints |= SymbolConstraints.notWritable;
}
}

// Only true for 'const enum' which its members are implicitly not writable
// Note: Immutable class/container could exist iff all its members are notWritable/const
if(symbol.parent && symbol.parent.constraints & SymbolConstraints.Immutable) {
symbol.constraints |= SymbolConstraints.notWritable;
}

return symbol;
}

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12 changes: 6 additions & 6 deletions src/compiler/checker.ts
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Expand Up @@ -9744,7 +9744,7 @@ namespace ts {
return !symbol || symbol === unknownSymbol || (symbol.flags & ~SymbolFlags.EnumMember) !== 0;
}
case SyntaxKind.ElementAccessExpression:
// old compiler doesn't check indexed assess
// old compiler doesn't check indexed access
return true;
case SyntaxKind.ParenthesizedExpression:
return isReferenceOrErrorExpression((<ParenthesizedExpression>n).expression);
Expand All @@ -9753,25 +9753,25 @@ namespace ts {
}
}

function isConstVariableReference(n: Node): boolean {
function isNotWritableVariableReference(n: Node): boolean {
switch (n.kind) {
case SyntaxKind.Identifier:
case SyntaxKind.PropertyAccessExpression: {
let symbol = findSymbol(n);
return symbol && (symbol.flags & SymbolFlags.Variable) !== 0 && (getDeclarationFlagsFromSymbol(symbol) & NodeFlags.Const) !== 0;
return symbol && (symbol.constraints & SymbolConstraints.notWritable) !== 0;
}
case SyntaxKind.ElementAccessExpression: {
let index = (<ElementAccessExpression>n).argumentExpression;
let symbol = findSymbol((<ElementAccessExpression>n).expression);
if (symbol && index && index.kind === SyntaxKind.StringLiteral) {
let name = (<LiteralExpression>index).text;
let prop = getPropertyOfType(getTypeOfSymbol(symbol), name);
return prop && (prop.flags & SymbolFlags.Variable) !== 0 && (getDeclarationFlagsFromSymbol(prop) & NodeFlags.Const) !== 0;
return prop && (prop.constraints & SymbolConstraints.notWritable) !== 0;
}
return false;
}
case SyntaxKind.ParenthesizedExpression:
return isConstVariableReference((<ParenthesizedExpression>n).expression);
return isNotWritableVariableReference((<ParenthesizedExpression>n).expression);
default:
return false;
}
Expand All @@ -9782,7 +9782,7 @@ namespace ts {
return false;
}

if (isConstVariableReference(n)) {
if (isNotWritableVariableReference(n)) {
error(n, constantVariableMessage);
return false;
}
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18 changes: 12 additions & 6 deletions src/compiler/parser.ts
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Expand Up @@ -955,8 +955,11 @@ namespace ts {
createMissingNode(t, reportAtCurrentPosition, diagnosticMessage, arg0);
}

function parseTokenNode<T extends Node>(): T {
function parseTokenNode<T extends Node>(flags?: NodeFlags): T {
let node = <T>createNode(token);
if (flags) {
node.flags = flags;
}
nextToken();
return finishNode(node);
}
Expand Down Expand Up @@ -1849,7 +1852,7 @@ namespace ts {
function parseTemplateExpression(): TemplateExpression {
let template = <TemplateExpression>createNode(SyntaxKind.TemplateExpression);

template.head = parseLiteralNode();
template.head = parseLiteralNode(/*internName*/ false, NodeFlags.ConstValue);
Debug.assert(template.head.kind === SyntaxKind.TemplateHead, "Template head has wrong token kind");

let templateSpans = <NodeArray<TemplateSpan>>[];
Expand Down Expand Up @@ -1884,11 +1887,13 @@ namespace ts {
return finishNode(span);
}

function parseLiteralNode(internName?: boolean): LiteralExpression {
function parseLiteralNode(internName?: boolean, flags?: NodeFlags): LiteralExpression {
let node = <LiteralExpression>createNode(token);
let text = scanner.getTokenValue();
node.text = internName ? internIdentifier(text) : text;

if (flags) {
node.flags = flags;
}
if (scanner.hasExtendedUnicodeEscape()) {
node.hasExtendedUnicodeEscape = true;
}
Expand Down Expand Up @@ -3651,13 +3656,14 @@ namespace ts {
case SyntaxKind.NumericLiteral:
case SyntaxKind.StringLiteral:
case SyntaxKind.NoSubstitutionTemplateLiteral:
return parseLiteralNode();
return parseLiteralNode(/* internName */ false, NodeFlags.ConstValue);
case SyntaxKind.ThisKeyword:
case SyntaxKind.SuperKeyword:
return parseTokenNode<PrimaryExpression>();
case SyntaxKind.NullKeyword:
case SyntaxKind.TrueKeyword:
case SyntaxKind.FalseKeyword:
return parseTokenNode<PrimaryExpression>();
return parseTokenNode<PrimaryExpression>(NodeFlags.ConstValue);
case SyntaxKind.OpenParenToken:
return parseParenthesizedExpression();
case SyntaxKind.OpenBracketToken:
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11 changes: 10 additions & 1 deletion src/compiler/types.ts
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Expand Up @@ -377,10 +377,12 @@ namespace ts {
Namespace = 0x00020000, // Namespace declaration
ExportContext = 0x00040000, // Export context (initialized by binding)
ContainsThis = 0x00080000, // Interface contains references to "this"
ConstValue = 0x00100000, // Node that represents a constant value (1, "a", true/false, null)

Modifier = Export | Ambient | Public | Private | Protected | Static | Abstract | Default | Async,
AccessibilityModifier = Public | Private | Protected,
BlockScoped = Let | Const
BlockScoped = Let | Const,
Constant = Const | ConstValue
}

/* @internal */
Expand Down Expand Up @@ -1693,6 +1695,7 @@ namespace ts {
name: string; // Name of symbol
declarations?: Declaration[]; // Declarations associated with this symbol
valueDeclaration?: Declaration; // First value declaration of the symbol
constraints?: SymbolConstraints; // Symbol constraints

members?: SymbolTable; // Class, interface or literal instance members
exports?: SymbolTable; // Module exports
Expand All @@ -1703,6 +1706,12 @@ namespace ts {
/* @internal */ constEnumOnlyModule?: boolean; // True if module contains only const enums or other modules with only const enums
}

export const enum SymbolConstraints {
notWritable = 1,
notMutable,
Immutable = notWritable | notMutable,
}

/* @internal */
export interface SymbolLinks {
target?: Symbol; // Resolved (non-alias) target of an alias
Expand Down