fix: babel-plugin-proposal-function-bind: ts-ignore

[coderaiser]

Q	A
Fixed Issues?	Fixes #1, Fixes #2
Patch: Bug Fix?	ts-ignore
Major: Breaking Change?
Minor: New Feature?
Tests Added + Pass?	Yes
Documentation PR Link
Any Dependency Changes?
License	MIT

Get rid of ts-ignore in babel-plugin-proposal-function-bind. Added isMemberExpression check, since when there is no object, callee of BindExpression is Always MemberExpression, otherwise we see:

Binding should be performed on object property. (1:2)

for such code:

::console

So it should always used as MemberExpression:

::console.log

And produce:

BindExpression {
    callee: MemberExpression
}

In cases when we have object:

console::log

We have such signature:

BindExpression {
    callee: Expression,
    object: Expression
}

And both callee and object can be any Expression.

[babel-bot]

Build successful! You can test your changes in the REPL here: https://babeljs.io/repl/build/52429/

[liuxingbaoyu]

Could you add a test?

[coderaiser]

Could you add a test?

Test for what exactly? This is more like refactoring to fix TypeScript errors, this cases already tested in fixture directory.

[liuxingbaoyu]

Ah, I mistakenly thought this was a bug fix.

[JLHwung]

Q: Does Babel parser ensures that bind.callee is always a member expression? If so we can remove the runtime assertion and just cast bind.callee as a member expression. Or we refine the AST types so that bind.callee must be a member expression.

[coderaiser]

Yes, babel-parser ensures that, if no bind.object exists, this is expression like:

::console.log

And it cannot contain any other Expression or Babel parser throws:

Binding should be performed on object property. (1:2)

This check is needed for TypeScript, since it can infer types without it.
If you just remove the comment line:

// @ts-ignore Fixme: should check bind.callee type first

You will see the message:

So the purpose of PR is making TypeScript happy and removing a Fixme comment :). I agree that everything works good without this check either but, additional check makes code little bit more clear since function bind has two cases of work that supported by Babel (according to current implementation), as I wrote on the beginning.

[liuxingbaoyu]

Looks good, I'm in favor of changing the definition of ast, as long as it doesn't compromise compatibility.