In JSDoc, parse postfix-? below conditional types/tuple types #39123
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Outside of JSDoc comments, postfix-? is parsed at lower precedence than the `?` of conditional types, and a postfix-? inside a tuple type results in the type being marked optional. This PR changes JSDoc parsing to behave the same way, which means that 1. Conditional types are allowed in JSDoc. Fixes #37166. 2. Tuple types' postfix-? syntax is interpreted correctly in JSDoc. Fixes #38747. The breaking change is that a postfix-? type followed by another postfix type, like `[]` or `!`, is parsed as a conditional type. [Postfix-? is not common](#37166 (comment)), so this is an acceptable breaking change. A postfix-? type `T?` is still parsed everywhere else and treated as `T | null`.
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@typescript-bot user test this -- let's see if any of Google's open source uses postfix-? |
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@DanielRosenwasser pretty sure this is not going to break anyone -- think it should go into 4.0? |
RyanCavanaugh
approved these changes
Jun 17, 2020
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The user suite test run you requested has finished and failed. I've opened a PR with the baseline diff from master. |
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No changes to user tests! I think this is safe for 4.0. |
| @@ -3356,7 +3356,7 @@ namespace ts { | |||
| break; | |||
| case SyntaxKind.QuestionToken: | |||
| // If not in JSDoc and next token is start of a type we have a conditional type | |||
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Outside of JSDoc comments, postfix-? is parsed at lower precedence than the
?of conditional types, and a postfix-? inside a tuple type results in the type being marked optional.This PR changes JSDoc parsing to behave the same way, which means that
The breaking change is that a postfix-? type followed by another postfix type, like
[]or!, is parsed as a conditional type. Postfix-? is not common, so this is an acceptable breaking change.A postfix-? type
T?is still parsed everywhere else and treated asT | null.