feat(compiler): support unary operators for more accurate type checking (#37918)
Prior to this change, the unary + and - operators would be parsed as `x - 0`
and `0 - x` respectively. The runtime semantics of these expressions are
equivalent, however they may introduce inaccurate template type checking
errors as the literal type is lost, for example:
```ts
@Component({
template: `<button [disabled]="isAdjacent(-1)"></button>`
})
export class Example {
isAdjacent(direction: -1 | 1): boolean { return false; }
}
```
would incorrectly report a type-check error:
> error TS2345: Argument of type 'number' is not assignable to parameter
of type '-1 | 1'.
Additionally, the translated expression for the unary + operator would be
considered as arithmetic expression with an incompatible left-hand side:
> error TS2362: The left-hand side of an arithmetic operation must be of
type 'any', 'number', 'bigint' or an enum type.
To resolve this issues, the implicit transformation should be avoided.
This commit adds a new unary AST node to represent these expressions,
allowing for more accurate type-checking.
Fixes #20845
Fixes #36178
PR Close #37918
This commit is contained in:
@@ -6,7 +6,7 @@
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* found in the LICENSE file at https://angular.io/license
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*/
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import {AbsoluteSourceSpan, AST, AstVisitor, ASTWithSource, Binary, BindingPipe, Chain, Conditional, FunctionCall, ImplicitReceiver, Interpolation, KeyedRead, KeyedWrite, LiteralArray, LiteralMap, LiteralPrimitive, MethodCall, NonNullAssert, ParseSpan, PrefixNot, PropertyRead, PropertyWrite, Quote, RecursiveAstVisitor, SafeMethodCall, SafePropertyRead} from '../../../src/expression_parser/ast';
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import {AST, AstVisitor, ASTWithSource, Binary, BindingPipe, Chain, Conditional, FunctionCall, ImplicitReceiver, Interpolation, KeyedRead, KeyedWrite, LiteralArray, LiteralMap, LiteralPrimitive, MethodCall, NonNullAssert, ParseSpan, PrefixNot, PropertyRead, PropertyWrite, Quote, RecursiveAstVisitor, SafeMethodCall, SafePropertyRead, Unary} from '../../../src/expression_parser/ast';
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import {DEFAULT_INTERPOLATION_CONFIG, InterpolationConfig} from '../../../src/ml_parser/interpolation_config';
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class Unparser implements AstVisitor {
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@@ -35,6 +35,11 @@ class Unparser implements AstVisitor {
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this._visit(ast.value);
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}
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visitUnary(ast: Unary, context: any) {
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this._expression += ast.operator;
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this._visit(ast.expr);
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}
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visitBinary(ast: Binary, context: any) {
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this._visit(ast.left);
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this._expression += ` ${ast.operation} `;
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