skip ~ or ? in the location of named arguments

Fixes #244

Author: cristianoc

analysis/src/ProcessCmt.ml

@@ -1076,8 +1076,23 @@ struct
     | Texp_let (_, _, _) ->
       (* TODO this scope tracking won't work for recursive *)
       addScopeExtent expression.exp_loc
-    | Texp_function {cases} -> (
-      match cases with [{c_rhs}] -> addScopeExtent c_rhs.exp_loc | _ -> ())
+    | Texp_function {arg_label; cases} -> (
+      match cases with
+      | [{c_lhs = {pat_desc = Tpat_var (ident, name)} as c_lhs; c_rhs}] ->
+        (match arg_label with
+        | Labelled _ | Optional _ ->
+          let loc_start = name.loc.loc_start in
+          (* skip `~` or `?` in the location of labeled arguments *)
+          let loc_start = {loc_start with pos_cnum = loc_start.pos_cnum + 1} in
+          let loc = {name.loc with loc_start} in
+          let name = {name with loc} in
+          let c_lhs = {c_lhs with pat_desc = Tpat_var (ident, name)} in
+          (* Force an earlier enter_pattern to control the location. *)
+          enter_pattern c_lhs
+        | Nolabel -> ());
+
+        addScopeExtent c_rhs.exp_loc
+      | _ -> ())
     | _ -> ()
 
   let leave_expression expression =

analysis/tests/src/References.res

@@ -7,5 +7,5 @@ let b = a
 
 let c = x
 
-let foo = (~x) => x + 1
-//                ^ref
+let foo = (~xx) => xx + 1
+//                 ^ref

analysis/tests/src/expected/References.res.txt

@@ -6,9 +6,9 @@ References tests/src/References.res 0:4
 {"uri": "References.res", "range": {"start": {"line": 0, "character": 4}, "end": {"line": 0, "character": 5}}}
 ]
 
-References tests/src/References.res 9:18
+References tests/src/References.res 9:19
 [
-{"uri": "References.res", "range": {"start": {"line": 9, "character": 18}, "end": {"line": 9, "character": 19}}},
-{"uri": "References.res", "range": {"start": {"line": 9, "character": 11}, "end": {"line": 9, "character": 13}}}
+{"uri": "References.res", "range": {"start": {"line": 9, "character": 19}, "end": {"line": 9, "character": 21}}},
+{"uri": "References.res", "range": {"start": {"line": 9, "character": 12}, "end": {"line": 9, "character": 14}}}
 ]