jsx: allow locally abstract types and type constraints on @react.component definitions (#487)

* jsx: allow locally abstract types in @react.component definitions

* jsx: allow type constraints on @react.componenet definitions

Author: glennsl

src/reactjs_jsx_ppx_v3.ml

@@ -93,9 +93,10 @@ let otherAttrsPure (loc, _) = loc.txt <> "react.component"
 let hasAttrOnBinding { pvb_attributes } = find_opt hasAttr pvb_attributes <> None
 
 (* Finds the name of the variable the binding is assigned to, otherwise raises Invalid_argument *)
-let getFnName binding =
+let rec getFnName binding =
   match binding with
-  | { pvb_pat = { ppat_desc = Ppat_var { txt } } } -> txt
+  | { ppat_desc = Ppat_var { txt } } -> txt
+  | { ppat_desc = Ppat_constraint (pat, _) } -> getFnName pat
   | _ -> raise (Invalid_argument "react.component calls cannot be destructured.")
   [@@raises Invalid_argument]
 
@@ -487,7 +488,7 @@ let jsxMapper () =
             let bindingLoc = binding.pvb_loc in
             let bindingPatLoc = binding.pvb_pat.ppat_loc in
             let binding = { binding with pvb_pat = { binding.pvb_pat with ppat_loc = emptyLoc }; pvb_loc = emptyLoc } in
-            let fnName = getFnName binding in
+            let fnName = getFnName binding.pvb_pat in
             let internalFnName = fnName ^ "$Internal" in
             let fullModuleName = makeModuleName fileName !nestedModules fnName in
             let modifiedBindingOld binding =
@@ -506,6 +507,10 @@ let jsxMapper () =
                     spelunkForFunExpression innerFunctionExpression
                 | { pexp_desc = Pexp_sequence (_wrapperExpression, innerFunctionExpression) } ->
                     spelunkForFunExpression innerFunctionExpression
+                | { pexp_desc = Pexp_newtype (_label, innerFunctionExpression) } ->
+                    spelunkForFunExpression innerFunctionExpression
+                | { pexp_desc = Pexp_constraint (innerFunctionExpression, _typ) } ->
+                    spelunkForFunExpression innerFunctionExpression
                 | _ ->
                     raise
                       (Invalid_argument

tests/ppx/react/expected/newtype.res.txt

@@ -0,0 +1,6 @@
+@obj external makeProps: (~a: a, ~b: 'b, ~key: string=?, unit) => {"a": a, "b": 'b} = ""
+let make = (type a, ~a: a, ~b, _) => ReactDOMRe.createDOMElementVariadic("div", [])
+let make = {
+  let \"Newtype" = (\"Props": {"a": a, "b": 'b}) => make(~b=\"Props"["b"], ~a=\"Props"["a"])
+  \"Newtype"
+}

tests/ppx/react/expected/typeConstraint.res.txt

@@ -0,0 +1,8 @@
+@obj external makeProps: (~a: 'a, ~b: 'b, ~key: string=?, unit) => {"a": 'a, "b": 'b} = ""
+let make:
+  type a. (~a: a, ~b: a, a) => React.element =
+  (~a, ~b, _) => ReactDOMRe.createDOMElementVariadic("div", [])
+let make = {
+  let \"TypeConstraint" = (\"Props": {"a": 'a, "b": 'b}) => make(~b=\"Props"["b"], ~a=\"Props"["a"])
+  \"TypeConstraint"
+}

tests/ppx/react/newtype.res

@@ -0,0 +1,2 @@
+@react.component
+let make = (type a, ~a: a, ~b, _) => <div />

tests/ppx/react/typeConstraint.res

@@ -0,0 +1,2 @@
+@react.component
+let make: type a. (~a: a, ~b: a, a) => React.element = (~a, ~b, _) => <div />