Support intersection types

[chancancode]

Motivation

When using TypeScript with JSDoc, the types can be (almost) anything TypeScript supports. This seems to be mostly true already, however, the following doesn't work and give a syntax error:

/**
 * @typedef {object} Foo
 * @property {boolean} isFoo
 *
 * @typedef {object} Bar
 * @property {boolean} isBar
 *
 * @typedef {Foo & Bar} FooAndBar
 *           ~~~~~~~~~ Syntax error in type: Foo & Bar  jsdoc/valid-types
 * 
 * @typedef {Foo | Bar} FooOrBar
 *           ~~~~~~~~~ Ok: union types works
 */

This is not as simple as disabling jsdoc/valid-types. Fundamentally, if this ESLint plugin doesn't understand the intersection type syntax, it will do other things incorrectly. For example, it wouldn't be able to error when Foo or Bar doesn't refer to valid types (e.g. typos), and it can't mark the Foo and Bar values as used to disable the no-unused-vars warning from ESLint.

Current behavior

Syntax error on intersection types X & Y.

Desired behavior

No syntax error on intersection types X & Y, and it understand both X and Y here are type symbols.

Alternatives considered

???

[chancancode]

I understand this is not an official JSDoc feature, so it would have to be opt-in. But it would be nice if there is a configuration option in the parser to allow this.

[brettz9]

Good write-up, thank you. This should become available if the intersection types component of jsdoctypeparser/jsdoctypeparser#50 (comment) can be implemented. You may subscribe there (we tend to update the dependencies of eslint-plugin-jsdoc fairly frequently, but if that issue gets merged and we need a reminder, feel free to file a new issue here to remind us to update; I'd like to avoid tracking type-specific issues if possible). Thanks again!

[chancancode]

Thank you for the pointer and the quick response!

[brettz9]

This should now be working as of 96dcdce (v29.0.0 -- though latest is now at v29.1.0)