Improve context detection for package types (#1608)

from voodoos/issue-1607

Author: voodoos

CHANGES.md

@@ -15,6 +15,7 @@ unreleased
       (#1609, fixes #1529 and ocaml-lsp#1032)
     - Fix `construct` results ordering for sum types sand poly variants (#1603)
     - Fix object method completion not working (#1606, fixes #1575)
+    - Improve context detection for package types (#1608, fixes #1607)
   + editor modes
     - emacs: call the user's configured completion UI in
       `merlin-construct` (#1598)

src/analysis/context.ml

@@ -148,6 +148,7 @@ let inspect_browse_tree ~cursor lid browse : t option =
     | Module_expr _
     | Open_description _ -> Some Module_path
     | Module_type _ -> Some Module_type
+    | Core_type { ctyp_desc = Ttyp_package _; _ } -> Some Module_type
     | Core_type _ -> Some Type
     | Record_field (_, lbl, _) when (Longident.last lid) = lbl.lbl_name ->
       (* if we stopped here, then we're on the label itself, and whether or

tests/test-dirs/type-enclosing/issue1607.t

@@ -0,0 +1,59 @@
+  $ cat >main.ml <<EOF
+  > module type Empty = sig end
+  > 
+  > module Foo = struct
+  >   module type S = Empty
+  > 
+  >   let x = ()
+  > end
+  > 
+  > module type Foo = Foo.S
+  > 
+  > let f (module M : Foo) = ()
+  > 
+  > module S : sig
+  >   val f : (module Foo) -> unit
+  > end = struct
+  >   let f (module M : Foo) = ()
+  > end
+  > EOF
+
+  $ $MERLIN single errors -filename main.ml <main.ml
+  {
+    "class": "return",
+    "value": [],
+    "notifications": []
+  }
+
+That Foo is the module type Foo.S, not the module Foo
+  $ $MERLIN single type-enclosing -position 11:21 \
+  > -filename main.ml <main.ml | jq '.value[0]'
+  {
+    "start": {
+      "line": 11,
+      "col": 18
+    },
+    "end": {
+      "line": 11,
+      "col": 21
+    },
+    "type": "Foo.S",
+    "tail": "no"
+  }
+
+
+That Foo is the module type Foo.S, not the module Foo
+  $ $MERLIN single type-enclosing -position 14:19 \
+  > -filename main.ml <main.ml | jq '.value[0]'
+  {
+    "start": {
+      "line": 14,
+      "col": 18
+    },
+    "end": {
+      "line": 14,
+      "col": 21
+    },
+    "type": "Foo.S",
+    "tail": "no"
+  }