mirror of
https://github.com/angular/angular.git
synced 2026-09-14 13:54:52 +08:00
JoostK
874792dc43
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
Angular
Angular is a development platform for building mobile and desktop web applications using TypeScript/JavaScript and other languages.
Quickstart
Changelog
Learn about the latest improvements.
Want to help?
Want to file a bug, contribute some code, or improve documentation? Excellent! Read up on our guidelines for contributing and then check out one of our issues in the hotlist: community-help.