prefix instead of suffix

jscomp/syntax/src/reactjs_jsx_v4.ml

@@ -858,7 +858,7 @@ let vbMatch ~expr (name, default, _, alias, loc, _) =
       Vb.mk
         (Pat.var (Location.mkloc alias loc))
         (Exp.match_
-           (Exp.ident {txt = Lident (alias ^ "__"); loc = Location.none})
+           (Exp.ident {txt = Lident ("__" ^ alias); loc = Location.none})
            [
              Exp.case
                (Pat.construct
@@ -987,9 +987,9 @@ let mapBinding ~config ~emptyLoc ~pstr_loc ~fileName ~recFlag binding =
     let safePatternLabel pattern =
       match pattern with
       | {ppat_desc = Ppat_var {txt; loc}} ->
-        {pattern with ppat_desc = Ppat_var {txt = txt ^ "__"; loc}}
+        {pattern with ppat_desc = Ppat_var {txt = "__" ^ txt; loc}}
       | {ppat_desc = Ppat_alias (p, {txt; loc})} ->
-        {pattern with ppat_desc = Ppat_alias (p, {txt = txt ^ "__"; loc})}
+        {pattern with ppat_desc = Ppat_alias (p, {txt = "__" ^ txt; loc})}
       | _ -> pattern
     in
     let rec returnedExpression patternsWithLabel patternsWithNolabel
@@ -1013,7 +1013,7 @@ let mapBinding ~config ~emptyLoc ~pstr_loc ~fileName ~recFlag binding =
         (*
            If prop has the default value as Ident, it will get a build error
            when the referenced Ident value and the prop have the same name.
-           So we add a "__" after label to resolve the build error.
+           So we add a "__" to label to resolve the build error.
         *)
         let patternWithSafeLabel =
           match default with

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

@@ -3,8 +3,8 @@
 module C0 = {
   type props<'priority, 'text> = {priority: 'priority, text?: 'text}
 
-  let make = ({priority: _, text: ?text__, _}: props<_, _>) => {
-    let text = switch text__ {
+  let make = ({priority: _, text: ?__text, _}: props<_, _>) => {
+    let text = switch __text {
     | Some(text) => text
     | None => "Test"
     }
@@ -21,8 +21,8 @@ module C0 = {
 module C1 = {
   type props<'priority, 'text> = {priority: 'priority, text?: 'text}
 
-  let make = ({priority: p, text: ?text__, _}: props<_, _>) => {
-    let text = switch text__ {
+  let make = ({priority: p, text: ?__text, _}: props<_, _>) => {
+    let text = switch __text {
     | Some(text) => text
     | None => "Test"
     }
@@ -39,8 +39,8 @@ module C1 = {
 module C2 = {
   type props<'foo> = {foo?: 'foo}
 
-  let make = ({foo: ?bar__, _}: props<_>) => {
-    let bar = switch bar__ {
+  let make = ({foo: ?__bar, _}: props<_>) => {
+    let bar = switch __bar {
     | Some(foo) => foo
     | None => ""
     }
@@ -57,12 +57,12 @@ module C2 = {
 module C3 = {
   type props<'foo, 'a, 'b> = {foo?: 'foo, a?: 'a, b: 'b}
 
-  let make = ({foo: ?bar__, a: ?a__, b, _}: props<_, _, _>) => {
-    let bar = switch bar__ {
+  let make = ({foo: ?__bar, a: ?__a, b, _}: props<_, _, _>) => {
+    let bar = switch __bar {
     | Some(foo) => foo
     | None => ""
     }
-    let a = switch a__ {
+    let a = switch __a {
     | Some(a) => a
     | None => bar
     }
@@ -81,8 +81,8 @@ module C3 = {
 module C4 = {
   type props<'a, 'x> = {a: 'a, x?: 'x}
 
-  let make = ({a: b, x: ?x__, _}: props<_, _>) => {
-    let x = switch x__ {
+  let make = ({a: b, x: ?__x, _}: props<_, _>) => {
+    let x = switch __x {
     | Some(x) => x
     | None => true
     }
@@ -99,8 +99,8 @@ module C4 = {
 module C5 = {
   type props<'a, 'z> = {a: 'a, z?: 'z}
 
-  let make = ({a: (x, y), z: ?z__, _}: props<_, _>) => {
-    let z = switch z__ {
+  let make = ({a: (x, y), z: ?__z, _}: props<_, _>) => {
+    let z = switch __z {
     | Some(z) => z
     | None => 3
     }

jscomp/syntax/tests/ppx/react/expected/defaultValueProp.res.txt

@@ -1,11 +1,11 @@
 module C0 = {
   type props<'a, 'b> = {a?: 'a, b?: 'b}
-  let make = ({a: ?a__, b: ?b__, _}: props<_, _>) => {
-    let a = switch a__ {
+  let make = ({a: ?__a, b: ?__b, _}: props<_, _>) => {
+    let a = switch __a {
     | Some(a) => a
     | None => 2
     }
-    let b = switch b__ {
+    let b = switch __b {
     | Some(b) => b
     | None => a * 2
     }
@@ -21,8 +21,8 @@ module C0 = {
 module C1 = {
   type props<'a, 'b> = {a?: 'a, b: 'b}
 
-  let make = ({a: ?a__, b, _}: props<_, _>) => {
-    let a = switch a__ {
+  let make = ({a: ?__a, b, _}: props<_, _>) => {
+    let a = switch __a {
     | Some(a) => a
     | None => 2
     }
@@ -40,8 +40,8 @@ module C2 = {
   let a = "foo"
   type props<'a> = {a?: 'a}
 
-  let make = ({a: ?a__, _}: props<_>) => {
-    let a = switch a__ {
+  let make = ({a: ?__a, _}: props<_>) => {
+    let a = switch __a {
     | Some(a) => a
     | None => a
     }
@@ -58,8 +58,8 @@ module C2 = {
 module C3 = {
   type props<'disabled> = {disabled?: 'disabled}
 
-  let make = ({disabled: ?everythingDisabled__, _}: props<bool>) => {
-    let everythingDisabled = switch everythingDisabled__ {
+  let make = ({disabled: ?__everythingDisabled, _}: props<bool>) => {
+    let everythingDisabled = switch __everythingDisabled {
     | Some(disabled) => disabled
     | None => false
     }

jscomp/syntax/tests/ppx/react/expected/uncurriedProps.res.txt

@@ -1,8 +1,8 @@
 @@jsxConfig({version: 4})
 type props<'a> = {a?: 'a}
 
-let make = ({a: ?a__, _}: props<(. unit) => unit>) => {
-  let a = switch a__ {
+let make = ({a: ?__a, _}: props<(. unit) => unit>) => {
+  let a = switch __a {
   | Some(a) => a
   | None => (. ()) => ()
   }
@@ -28,8 +28,8 @@ func(~callback=(. str, a, b) => {
 module Foo = {
   type props<'callback> = {callback?: 'callback}
 
-  let make = ({callback: ?callback__, _}: props<(. string, bool, bool) => unit>) => {
-    let callback = switch callback__ {
+  let make = ({callback: ?__callback, _}: props<(. string, bool, bool) => unit>) => {
+    let callback = switch __callback {
     | Some(callback) => callback
     | None => (. _, _, _) => ()
     }