Fix build error where aliasing argument to _ in make function with …

…jsx v4 (#720)

CHANGELOG.md

@@ -51,6 +51,7 @@
 - Fix issue where the JSX fragment without children build error https://github.com/rescript-lang/syntax/pull/704
 - Fix issue where async as an id cannot be used with application and labelled arguments https://github.com/rescript-lang/syntax/issues/707
 - Treat await as almost-unary operator weaker than pipe so `await foo->bar` means `await (foo->bar)` https://github.com/rescript-lang/syntax/pull/711
+- Fix build error where aliasing arguments to `_` in the make function with JSX V4. https://github.com/rescript-lang/syntax/pull/720
 
 #### :eyeglasses: Spec Compliance
 

cli/reactjs_jsx_v4.ml

@@ -1082,10 +1082,7 @@ let transformStructureItem ~config mapper item =
             | Pexp_fun
                 ( _arg_label,
                   _default,
-                  {
-                    ppat_desc =
-                      Ppat_construct ({txt = Lident "()"}, _) | Ppat_any;
-                  },
+                  {ppat_desc = Ppat_construct ({txt = Lident "()"}, _)},
                   expr ) ->
               (patternsWithLabel, patternsWithNolabel, expr)
             | Pexp_fun

tests/ppx/react/aliasProps.res

@@ -0,0 +1,11 @@
+@@jsxConfig({version: 4, mode: "automatic"})
+
+module C0 = {
+  @react.component
+  let make = (~priority as _, ~text="Test") => React.string(text)
+}
+
+module C1 = {
+  @react.component
+  let make = (~priority as p, ~text="Test") => React.string(p ++ text)
+}

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

@@ -0,0 +1,45 @@
+@@jsxConfig({version: 4, mode: "automatic"})
+
+module C0 = {
+  type props<'priority, 'text> = {
+    priority: 'priority,
+    text?: 'text,
+  }
+
+  @react.component
+  let make = ({priority: _, ?text, _}: props<'priority, 'text>) => {
+    let text = switch text {
+    | Some(text) => text
+    | None => "Test"
+    }
+
+    React.string(text)
+  }
+  let make = {
+    let \"AliasProps$C0" = (props: props<_>) => make(props)
+
+    \"AliasProps$C0"
+  }
+}
+
+module C1 = {
+  type props<'priority, 'text> = {
+    priority: 'priority,
+    text?: 'text,
+  }
+
+  @react.component
+  let make = ({priority: p, ?text, _}: props<'priority, 'text>) => {
+    let text = switch text {
+    | Some(text) => text
+    | None => "Test"
+    }
+
+    React.string(p ++ text)
+  }
+  let make = {
+    let \"AliasProps$C1" = (props: props<_>) => make(props)
+
+    \"AliasProps$C1"
+  }
+}