Properly format functions without the Tfun type.

Summary: There are some functions (like `idx`) which are special-cased by the typechecker, which means that even though its type is Function it doesn't have a Tfun. Right now we fall back to displaying these as if they were class members, due to a faulty match expression.

Differential Revision: D7418540

fbshipit-source-id: 01ff338788230187be2203deebdccecdcd2aed3e

hphp/hack/src/typing/typing_print.ml

@@ -595,30 +595,27 @@ module Full = struct
     in
     let body =
       let open SymbolOccurrence in
-      match occurrence with
-      | { type_ = Class; name; _ } -> Concat [text "class "; text_strip_ns name]
-
-      | { type_ = Function; name; _ }
-      | { type_ = Method (_, name); _ }
-      | { type_ = Property (_, name); _ }
-      | { type_ = ClassConst (_, name); _ }
-      | { type_ = GConst; name; _ } ->
+      match occurrence, x with
+      | { type_ = Class; name; _ }, _ -> Concat [text "class "; text_strip_ns name]
+
+      | { type_ = Function; name; _ }, (_, Tfun ft)
+      | { type_ = Method (_, name); _ }, (_, Tfun ft) ->
         (* Use short names for function types since they display a lot more
            information to the user. *)
-        begin match x with
-        | (_, Tfun ft) ->
-          Concat [
-            text "function ";
-            text_strip_ns name;
-            fun_type text_strip_ns ISet.empty env ft;
-          ]
-        | _ ->
-          Concat [
-            ty text_strip_ns ISet.empty env x;
-            Space;
-            text_strip_ns (occurrence.name);
-          ]
-        end
+         Concat [
+           text "function ";
+           text_strip_ns name;
+           fun_type text_strip_ns ISet.empty env ft;
+         ]
+
+      | { type_ = Property _; name; _ }, _
+      | { type_ = ClassConst _; name; _ }, _
+      | { type_ = GConst; name; _ }, _ ->
+        Concat [
+          ty text_strip_ns ISet.empty env x;
+          Space;
+          text_strip_ns name;
+        ]
 
       | _ -> ty text_strip_ns ISet.empty env x
     in

hphp/hack/test/integration_ml/test_server_hover.ml

@@ -19,8 +19,13 @@ let pos_at (line1, column1) (line2, column2) =
     (File_pos.of_line_column_offset line1 (column1 - 1) 0)
     (File_pos.of_line_column_offset line2 column2 0))
 
-let builtins = "<?hh // strict
-class Awaitable<T> {}"
+let builtins = "<?hh // decl
+class Awaitable<T> {}
+interface Traversable<+Tv> {}
+interface KeyedTraversable<+Tk, +Tv> extends Traversable<Tv> {}
+interface Container<+Tv> extends Traversable<Tv> {}
+interface KeyedContainer<+Tk, +Tv> extends Container<Tv>, KeyedTraversable<Tk, Tv> {}
+function idx<Tk, Tv>(?KeyedContainer<Tk, Tv> $collection, Tk $index, $default = null): ?Tv {}"
 
 let class_members = "<?hh // strict
 abstract class ClassMembers {
@@ -424,17 +429,38 @@ the other stars."; "Full name: `DocBlock::leadingStarsAndMDList`"];
   ]
 ]
 
+let special_cases = "<?hh // strict
+function special_cases(): void {
+  idx(array(1, 2, 3), 1);
+//^3:3
+}
+"
+
+let special_cases_cases = [
+  ("special_cases.php", 3, 3), [
+    {
+      (* Without the `ft` corresponding to the `Tfun`, we can't give any useful
+         information here :/ *)
+      snippet = "?int";
+      addendum = [];
+      pos = pos_at (3, 3) (3, 24);
+    }
+  ]
+]
+
 let files = [
   "builtins.php", builtins;
   "class_members.php", class_members;
   "classname_call.php", classname_call;
   "chained_calls.php", chained_calls;
   "classname_variable.php", classname_variable;
   "docblock.php", docblock;
+  "special_cases.php", special_cases;
 ]
 
 let cases =
-  docblockCases
+  special_cases_cases
+  @ docblockCases
   @ class_members_cases
   @ classname_call_cases
   @ chained_calls_cases