Give a more helpful error message for certain decorators with too many arguments#18811
Give a more helpful error message for certain decorators with too many arguments#18811DanielRosenwasser merged 10 commits intomasterfrom
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…ressions that take no arguments.
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| tests/cases/conformance/decorators/class/method/decoratorOnClassMethod6.ts(4,5): error TS1241: Unable to resolve signature of method decorator when called as an expression. | |||
| tests/cases/conformance/decorators/class/method/decoratorOnClassMethod6.ts(4,5): error TS1329: This value has type '() => <T>(target: any, propertyKey: string, descriptor: TypedPropertyDescriptor<T>) => TypedPropertyDescriptor<T>' which accepts too few arguments to be used as a decorator here. Did you mean to call it first? | |||
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Would be nicer if you had the decorator name in the error message, e.g.:
Did you mean '@dec()' instead?
| * but is receiving too many arguments as part of the decorator invocation. | ||
| * In those cases, a user may have meant to *call* the expression before using it as a decorator. | ||
| */ | ||
| function isPotentiallyUncalledDecorator(decorator: Decorator, signatures: Signature[]) { |
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should you also check that the return type is callable/any to ensure your suggestion of calling it is warranted.
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any is accounted for - it's an uncalled function call. It also has no signatures.
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This should be marked as breaking change. the recommendation is to add rest args in the signature. |
src/compiler/checker.ts
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| if (isPotentiallyUncalledDecorator(node, callSignatures)) { | ||
| error(node, Diagnostics.This_value_has_type_0_which_accepts_too_few_arguments_to_be_used_as_a_decorator_here_Did_you_mean_to_call_it_first, typeToString(funcType)); |
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The type here seems weird. it might be long, and hides the main message. why not just say '${0}' expects too few arguments to be called as a decorator, did you mean @${0}()' instead?`
I think this should get the majority of the cases, for other ones we will fallback to unable to resolve decorator when called as a function message.
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Why? These decorators could never have succeeded as they would receive too many arguments. |
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Right now this only works for single-signature decorators that accept no arguments. We could improve this to cases wherethere are too many arguments from the decorated entity for every signature andthe min arg count is 0 for every signatureWe now give a more helpful error message when
This comes up for me all the time in Angular where I end up forgetting to invoke the decorator: