Make external... = "" optional in reason syntax

formatTest/errorTests/expected_output/reservedRecordPunned.re

@@ -1,2 +1,2 @@
 File "reservedRecordPunned.re", line 1, characters 22-26:
-Error: 3411: type is a reserved keyword, it cannot be used as an identifier. Try `type_` or `_type` instead
+Error: 3417: type is a reserved keyword, it cannot be used as an identifier. Try `type_` or `_type` instead

formatTest/errorTests/expected_output/reservedRecordPunned.re.4.08.0

@@ -1,5 +1,5 @@
 File "reservedRecordPunned.re", line 1, characters 22-26:
 1 | let foo = { ...other, type };
                           ^^^^
-Error: 3411: type is a reserved keyword, it cannot be used as an identifier. Try `type_` or `_type` instead
+Error: 3417: type is a reserved keyword, it cannot be used as an identifier. Try `type_` or `_type` instead
 

formatTest/errorTests/expected_output/reservedRecordPunned.re.4.09.0

@@ -1,5 +1,5 @@
 File "reservedRecordPunned.re", line 1, characters 22-26:
 1 | let foo = { ...other, type };
                           ^^^^
-Error: 3411: type is a reserved keyword, it cannot be used as an identifier. Try `type_` or `_type` instead
+Error: 3417: type is a reserved keyword, it cannot be used as an identifier. Try `type_` or `_type` instead
 

formatTest/typeCheckedTests/expected_output/attributes.re

@@ -427,7 +427,7 @@ external add_nat: (int, int) => int =
 [@ocaml.deprecated
   "Use bar instead. It's a much cooler function. This string needs to be a little long"
 ]
-external foo: bool => bool = "";
+external foo: bool => bool;
 
 /* Attributes on an entire polymorphic variant leaf */
 [@bs.module "fs"]
@@ -439,8 +439,7 @@ external readFileSync:
       | [@bs.as "ascii"] `my_name
     ]
   ) =>
-  string =
-  "";
+  string;
 
 [@bs.module "fs"]
 external readFileSync2:
@@ -451,35 +450,34 @@ external readFileSync2:
       | [@bs.as "ascii"] `my_name
     ]
   ) =>
-  string =
-  "";
+  string;
 
 /* Ensure that attributes on extensions are printed */
 [@test
   [@attr]
   [%%extension]
 ];
 
-external debounce: (int, [@bs.meth] unit) => unit =
-  "";
+external debounce:
+  (int, [@bs.meth] unit) => unit;
+
+external debounce:
+  (int, [@bs.meth] unit) => unit;
 
 external debounce:
-  int => [@bs.meth] (unit => unit) =
-  "";
+  int => [@bs.meth] (unit => unit);
 
 external debounce:
   (int, [@bs.meth] (unit => unit)) =>
-  [@bs.meth] (unit => unit) =
-  "";
+  [@bs.meth] (unit => unit);
 
 external debounce:
   (
     int,
     [@bs.meth] (unit => unit),
     [@bs.meth] (unit => unit)
   ) =>
-  [@bs.meth] (unit => unit) =
-  "";
+  [@bs.meth] (unit => unit);
 
 external debounce:
   (
@@ -489,8 +487,7 @@ external debounce:
       unit => [@bs.meth] (unit => unit)
     )
   ) =>
-  [@bs.meth] (unit => unit) =
-  "";
+  [@bs.meth] (unit => unit);
 
 let x = "hi";
 

formatTest/typeCheckedTests/expected_output/attributes.rei

@@ -29,7 +29,7 @@ external createClassInternalHack:
   "createClass";
 
 [@bs.send.pipe: array('a)]
-external map: (. ('a => 'b)) => array('b) = "";
+external map: (. ('a => 'b)) => array('b);
 
 [@bs.val] [@bs.module "react"]
 external createClassInternalHack:

formatTest/typeCheckedTests/expected_output/mlSyntax.re

@@ -108,8 +108,8 @@ let pub__ = "method";
 let pri_ = "private";
 let pri__ = "private";
 
-external private: unit => unit = "";
-external pri_: unit => unit = "";
+external private: unit => unit;
+external pri_: unit => unit;
 
 type pub_ = int;
 type pub__ = int;

formatTest/typeCheckedTests/expected_output/mlSyntax.re.4.02.3

@@ -108,8 +108,8 @@ let pub__ = "method";
 let pri_ = "private";
 let pri__ = "private";
 
-external private: unit => unit = "";
-external pri_: unit => unit = "";
+external private: unit => unit;
+external pri_: unit => unit;
 
 type pub_ = int;
 type pub__ = int;

formatTest/typeCheckedTests/expected_output/reasonComments.re

@@ -731,20 +731,20 @@ let r = {
 
 /** doc comment */
 [@bs.send]
-external url: t => string = "";
+external url: t => string;
 
 /**
  * Short multiline doc comment
  */
 [@bs.send]
-external url: t => string = "";
+external url: t => string;
 
 /** Longer doc comment before an attribute on an external. */
 [@bs.send]
-external url: t => string = "";
+external url: t => string;
 
 /* normal comment */
-[@bs.send] external url: t => string = "";
+[@bs.send] external url: t => string;
 
 /** doc type */
 type q = {

formatTest/typeCheckedTests/input/attributes.re

@@ -360,6 +360,8 @@ external readFileSync2 : (
 /* Ensure that attributes on extensions are printed */
 [@test [@attr] [%%extension]];
 
+external debounce : (int, [@bs.meth] unit) => unit;
+
 external debounce : (int, [@bs.meth] unit) => unit = "";
 
 external debounce : int => ([@bs.meth] (unit => unit)) = "";

formatTest/typeCheckedTests/input/attributes.rei

@@ -27,7 +27,7 @@ type reactElement;
 [@bs.val] [@bs.module "React"]
 external createClassInternalHack : (t('classSpec)) => reactClass = "createClass";
 
-[@bs.send.pipe : array('a)] external map : [@bs] (('a) => 'b) => array('b) = "";
+[@bs.send.pipe : array('a)] external map: [@bs] (('a) => 'b) => array('b) = "";
 
 [@bs.val] [@bs.module "react"]
 external createClassInternalHack : (t('classSpec)) => reactClass =

src/reason-parser/reason_parser.mly

@@ -1705,6 +1705,10 @@ structure_item:
       EXTERNAL as_loc(val_ident) COLON core_type EQUAL primitive_declaration
       { let loc = mklocation $symbolstartpos $endpos in
         mkstr (Pstr_primitive (Val.mk $3 $5 ~prim:$7 ~attrs:$1 ~loc)) }
+    | item_attributes
+      EXTERNAL as_loc(val_ident) COLON core_type SEMI
+      { let loc = mklocation $symbolstartpos $endpos in
+        mkstr (Pstr_primitive (Val.mk $3 $5 ~prim:[""] ~attrs:$1 ~loc)) }
     | type_declarations
       { let (nonrec_flag, tyl) = $1 in mkstr(Pstr_type (nonrec_flag, tyl)) }
     | str_type_extension
@@ -1912,6 +1916,11 @@ signature_item:
     { let loc = mklocation $symbolstartpos $endpos in
       Psig_value (Val.mk $3 $5 ~prim:$7 ~attrs:$1 ~loc)
     }
+  | item_attributes
+    EXTERNAL as_loc(val_ident) COLON core_type SEMI
+    { let loc = mklocation $symbolstartpos $endpos in
+      Psig_value (Val.mk $3 $5 ~prim:[""] ~attrs:$1 ~loc)
+    }
   | type_declarations
     { let (nonrec_flag, tyl) = $1 in Psig_type (nonrec_flag, tyl) }
   | sig_type_extension

src/reason-parser/reason_pprint_ast.ml

@@ -6487,9 +6487,13 @@ let printer = object(self:'self)
            [(makeList ~postSpace:true [atom "external"; protectIdentifier vd.pval_name.txt]); (atom ":")])
         (self#core_type vd.pval_type)
     in
-    let frstHalf = makeList ~postSpace:true [lblBefore; atom "="] in
-    let sndHalf = makeSpacedBreakableInlineList (List.map self#constant_string vd.pval_prim) in
-    let primDecl = label ~space:true frstHalf sndHalf in
+    let primDecl = match vd.pval_prim with
+      | [""] -> lblBefore
+      | _ ->
+        let frstHalf = makeList ~postSpace:true [lblBefore; atom "="] in
+        let sndHalf = makeSpacedBreakableInlineList (List.map self#constant_string vd.pval_prim) in
+        label ~space:true frstHalf sndHalf
+    in
     match vd.pval_attributes with
     | [] -> primDecl
     | attrs ->