Add a breakable space to the "missing rec" hint message

testsuite/tests/typing-core-bugs/missing_rec_hint.ml

@@ -10,7 +10,8 @@ Line _, characters 28-33:
      if n = 0 then 1 else n * facto (n-1)
                               ^^^^^
 Error: Unbound value facto
-Hint: If this is a recursive definition, you should add a 'rec' keyword on line 1
+Hint: If this is a recursive definition,
+you should add a 'rec' keyword on line 1
 |}];;
 
 let x = 3 in
@@ -22,7 +23,8 @@ Line _, characters 10-11:
   let f x = f x in
             ^
 Error: Unbound value f
-Hint: If this is a recursive definition, you should add a 'rec' keyword on line 2
+Hint: If this is a recursive definition,
+you should add a 'rec' keyword on line 2
 |}];;
 
 let f x = if x < 0 then x else h (x-1)
@@ -34,7 +36,8 @@ Line _, characters 31-32:
   let f x = if x < 0 then x else h (x-1)
                                  ^
 Error: Unbound value h
-Hint: If this is a recursive definition, you should add a 'rec' keyword on line 1
+Hint: If this is a recursive definition,
+you should add a 'rec' keyword on line 1
 |}];;
 
 let value1 = 3 in
@@ -59,5 +62,6 @@ Line _, characters 17-24:
                    ^^^^^^^
 Error: Unbound value foobar2
 Hint: Did you mean foobar1?
-Hint: If this is a recursive definition, you should add a 'rec' keyword on line 2
+Hint: If this is a recursive definition,
+you should add a 'rec' keyword on line 2
 |}];;

typing/typetexp.ml

@@ -1023,8 +1023,9 @@ let report_error env ppf = function
       spellcheck ppf fold_values env lid;
       let (_, line, _) = Location.get_pos_info loc.Location.loc_start in
       fprintf ppf
-        "@.@[%s %i@]"
-        "Hint: If this is a recursive definition, you should add a 'rec' keyword on line"
+        "@.@[%s@ %s %i@]"
+        "Hint: If this is a recursive definition,"
+        "you should add a 'rec' keyword on line"
         line
 
 let () =