microsoft / microsoft/TypeScript
Confusing error when destructuring and overwriting with a wrong type
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Descripción
Bug Report
I noticed it because I put the spread at the bottom instead of top, but I had a hard time finding my mistake because of this. It's easy to spot if the object is small like in this example, but in my case the error and the spread was separated by multiple lines. Any other suggested error would be much clearer, but this confused me very much.
🔎 Search Terms
destructuring, spread, error reporting
🕗 Version & Regression Information
- This is the behavior in every version I tried, and I reviewed the FAQ for entries about destructuring, spread, error reporting
⏯ Playground Link
Playground link with relevant code
💻 Code
interface Test {
foo: boolean;
}
interface LesserTest {
foo?: boolean | null;
}
const bar: LesserTest = {
foo: null
}
const barWrong: Test = {
foo: true, // Type 'boolean | null' is not assignable to type 'boolean'.
...bar
}
// Type '{ foo?: boolean | null | undefined; }' is not assignable to type 'Test'. - such error would be much better
const barRight: Test = {
...bar
}
🙁 Actual behavior
The same property will be overwritten with a wrong type, but the error is reported in a wrong place, where the type is correct.
🙂 Expected behavior
The error should be reported on the destructured variable where the type is wrong or in the main variable barWrong.
I also noticed that if those types would match we get an error 'foo' is specified more than once, so this usage will be overwritten. which is also much better.
Guía de contribución
Primeros pasos
- Lee el issue completo y luego la guía de contribución del proyecto.
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- Abre un pull request que haga referencia al número del issue.
Línea de trabajo
Comienza con el ejemplo enlazado de TypeScript Playground y reproduce el diagnóstico para barWrong, comparándolo con barRight. Sigue el recorrido del checker para object spread y las propiedades sobrescritas; se considera terminado cuando el diagnóstico señala la propiedad con el tipo incorrecto o barWrong y explica claramente la incompatibilidad de tipos resultante.
Escrito por el modelo de indexación a partir del texto del issue.
Evaluación
- Stack tecnológico
- typescript
- Área
- compilers
- Tipo de issue
- Error
- Dificultad
- 4/5
- Tiempo estimado
- 3-5 días
- Estado de actividad
- Estancado
- Claridad
- Bastante claro
- Aptitud para principiantes
- 35/100