attempt to fix #5557 #5743

Author: bobzhang

jscomp/ml/parmatch.ml

@@ -1037,7 +1037,7 @@ let build_other_constant proj make first next p env =
 
 let some_other_tag = "<some other tag>"
 
-let build_other ext env = match env with
+let build_other ext env : Typedtree.pattern = match env with
 | ({pat_desc = Tpat_construct (lid, {cstr_tag=Cstr_extension _},_)},_) :: _ ->
         (* let c = {c with cstr_name = "*extension*"} in *) (* PR#7330 *)
         make_pat (Tpat_var (Ident.create "*extension*",
@@ -1079,13 +1079,19 @@ let build_other ext env = match env with
             make_pat (Tpat_or (pat, p_res, None)) p.pat_type p.pat_env)
           pat other_pats
     end
-| ({pat_desc=(Tpat_constant (Const_int _ | Const_char _))} as p,_) :: _ ->
+| ({pat_desc=(Tpat_constant (Const_int _ ))} as p,_) :: _ ->
     build_other_constant
       (function Tpat_constant(Const_int i) -> i 
-      | Tpat_constant (Const_char i) -> Char.code i
       | _ -> assert false)
       (function i -> Tpat_constant(Const_int i))
       0 succ p env
+| ({pat_desc=(Tpat_constant (Const_char _ ))} as p,_) :: _ ->
+        build_other_constant
+          (function 
+          | Tpat_constant (Const_char i) -> Char.code i
+          | _ -> assert false)
+          (function i -> Tpat_constant(Const_char (Obj.magic (i:int) : char)))
+          0 succ p env      
 | ({pat_desc=(Tpat_constant (Const_int32 _))} as p,_) :: _ ->
     build_other_constant
       (function Tpat_constant(Const_int32 i) -> i | _ -> assert false)

jscomp/test/build.ninja

@@ -0,0 +1,12 @@
+'use strict';
+
+
+function isA(c) {
+  return true;
+}
+
+var h = /* 'a' */97;
+
+exports.isA = isA;
+exports.h = h;
+/* No side effect */

jscomp/test/gpr_5557.js

@@ -0,0 +1,6 @@
+let isA = c =>
+  switch c {
+  | 'a' => true
+  }
+
+let h : int = ('a' :> int)