Battle test with JSX PPX V4

[mununki]

• 1. You forgot to handle a possible case here, for example:

// original
@react.component
let make = (~height, ~width, ~fill, ~className=?) => body

// error message
You forgot to handle a possible case here, for example: 
  {height: _, width: _, fill: Some(_), className: None, _}
| {height: _, width: _, fill: None, className: Some(_), _}

• 2. The type variable name '_disabled is not allowed in programs

// original
@react.component
let make = (~_disabled=?, ()) => body

• 3. A type parameter occurs several times
• 4. Values do not match between intf and impl

let make: props<option<string>, 'a, 'b, 'c> => React.element
is not included in
let make: React.componentLike<
props<string, string, int, React.element>

• 5. At most one component definition per module or one gets an error of type props being defined multiple times "Multiple definition of the type name props".
• 6. Explicit type annotation for optional arg in definition
  This issue seems related to 4

let make = (~x: option<int>=?) => body
// generated
type props<'x> = {key?: string, x?: 'x}
let make = ({?x, _}: props<option<int>>) => body
// error type mismatch option<int> vs. option<option<int>>

• 7. Conversion for the alias

let make = (~x as y) => body

• 8. Backward compatibility for passing the optional expression to prop
  This expression seems not working with V4, should work in different expression.

x=?{a->returnOption} ❌ 

x=?{
  let _ = ()
  a->returnOption
} ⭕ 

• 9. Raise error with loc

• 10. If a component is calledfoo not make the ppx tries to call make.

• 11. Error without location when a required prop is not supplied.

[mununki]

WIP: #614

[mununki]

I've looked into each issue and finally make my company project build successfully.
I added some new issues and work left to do though, but it won't take a long time.

[mununki]

@cristianoc I have a question about the issue no. 8. I've investigated some and found this. I think it is a breaking change for users to have to change their code.

type x = {x?: int}
let x = Some(1)

let a = {x: ?x}
let b = {x: ?x->Option.map(x => x)} // error
//           ^^^^^^^^^^^^^^^^^^^^ This has type: option<int>
//                                Somewhere wanted: int
let c = {x: ?Option.map(x, x => x)} // ok

I guess it might be related to the operator precedence or just the wrong syntax usage by users. As V4 parses the props and value into the record, it causes a build error there. If users have their code base expressing let b way, then it causes a breaking change. Can we make a workaround to prevent a break?

[cristianoc]

Can you add examples with and without parens? Then we know what's going on.

Examples checked in as tests. So we can look at the generated code.

[cristianoc]

How can that be a breaking change if the syntax with ? did not exist before?

[mununki]

How can that be a breaking change if the syntax with ? did not exist before?

Ah! I meant that breaking between V3 -> V4 with V10 compiler. I'll add the example in tests right a way.

[cristianoc]

One more:

  @react.component
  let anotherComponent = (~b) => {
    React.string(b)
  }

  We've found a bug for you!
  /Users/cristianocalcagno/GitHub/rescript-compiler/jscomp/gentype_tests/typescript-react-example/src/Hooks.res

  The value make can't be found

[mununki]

ead4831 The example added

[mununki]

 @react.component
  let anotherComponent = (~b) => {
    React.string(b)
  }

It is correct. As long as the parser do parse the uppercase jsx to Foo.make, the make is only allowed for the react component. I think the error message should be polished.

EDIT: Plus, V4 allows only one react component per module.

[cristianoc]

```rescript
 @react.component
  let anotherComponent = (~b) => {
    React.string(b)
  }

It is correct. As long as the parser do parse the uppercase jsx to Foo.make, the make is only allowed for the react component. I think the error message should be polished.
EDIT: Plus, V4 allows only one react component per module.

The component does not need to be called make. This would be a very big breaking change.

[mununki]

@react.component
let make = (~b) => React.string(b)

It would be okay. Not sure I understand your point.

The component does not need to be called make.

Can you elaborate little more?

[cristianoc]

As in V3, the component can have any name. It can be called "default" to use file-level conventions for access from JS.
It could be called any name.

A direct <Foo ....> call, which obviously only works on components called make, is not the only way to consume a component.

[mununki]

I finally got your point, I verified the same error. It seems an unreasonable error even without actually calling the component from outside. I'll look at it.