Fix type check for async function with alias return type. #5429
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| @@ -28,7 +28,7 @@ tests/cases/conformance/async/es6/functionDeclarations/asyncFunctionDeclaration1 | |||
| !!! error TS1055: Type 'number' is not a valid async function return type. | |||
| async function fn5(): PromiseLike<void> { } // error | |||
| ~~~ | |||
| !!! error TS1055: Type 'PromiseLike<void>' is not a valid async function return type. | |||
| !!! error TS1055: Type 'PromiseLike' is not a valid async function return type. | |||
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Is this the alias case that the change is meant to fix?
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OK, thanks for the the in-person explanation -- |
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👍 |
rbuckton
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Oct 28, 2015
Fix type check for async function with alias return type.
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Switched to resolvedSymbol from NodeLinks instead of mergedSymbol from the type. When the return type is a type alias, we eagerly resolve the actual type. This resuls in a false positive for a type that exists as a value.
There is a minor change to the error reporting here, as I want to report the error using the name of the alias used in the return type, not the name of the resolved type of the alias. This is so you don't see an error like
"Type 'Promise' is not a valid async function return type"when you use an alias for Promise. This has the side effect of not including the type arguments in the error message, but I think that's acceptable.Fixes #5333.