Support includeDeclaration in references

apps/language_server/lib/language_server/providers/references.ex

@@ -3,8 +3,7 @@ defmodule ElixirLS.LanguageServer.Providers.References do
   This module provides textDocument/references support. Currently its able to find references to
   functions, macros, variables and module attributes
 
-  Does not support configuring "includeDeclaration" and assumes it is always
-  `true`
+  Supports configuring "includeDeclaration" as defined by the LSP.
 
   https://microsoft.github.io//language-server-protocol/specifications/specification-3-14/#textDocument_references
   """
@@ -13,29 +12,59 @@ defmodule ElixirLS.LanguageServer.Providers.References do
   alias ElixirLS.LanguageServer.Providers.References.Locator
   require Logger
 
+  alias ElixirLS.LanguageServer.Providers.{Definition, Declaration}
+
   def references(
-        %Parser.Context{source_file: source_file, metadata: metadata},
+        parser_context = %Parser.Context{source_file: source_file, metadata: metadata},
         uri,
         line,
         character,
-        _include_declaration,
+        include_declaration,
         project_dir
       ) do
     Build.with_build_lock(fn ->
       trace = ElixirLS.LanguageServer.Tracer.get_trace()
 
-      Locator.references(source_file.text, line, character, trace, metadata: metadata)
-      |> Enum.map(fn elixir_sense_reference ->
-        elixir_sense_reference
-        |> build_reference(uri, source_file.text, project_dir)
-      end)
-      |> Enum.filter(&(not is_nil(&1)))
-      # Returned references come from both compile tracer and current buffer
-      # There may be duplicates
-      |> Enum.uniq()
+      base_refs =
+        Locator.references(source_file.text, line, character, trace, metadata: metadata)
+        |> Enum.map(fn elixir_sense_reference ->
+          elixir_sense_reference
+          |> build_reference(uri, source_file.text, project_dir)
+        end)
+        |> Enum.filter(&(not is_nil(&1)))
+
+      {definition_locations, declaration_locations} =
+        definition_and_declaration_locations(uri, parser_context, line, character, project_dir)
+
+      references =
+        if include_declaration do
+          base_refs ++ definition_locations ++ declaration_locations
+        else
+          locations_to_exclude = MapSet.new(definition_locations ++ declaration_locations)
+          Enum.reject(base_refs, fn ref -> ref in locations_to_exclude end)
+        end
+        |> Enum.uniq()
+
+      references
     end)
   end
 
+  defp definition_and_declaration_locations(uri, parser_context, line, character, project_dir) do
+    definition_locations =
+      case Definition.definition(uri, parser_context, line, character, project_dir) do
+        {:ok, def_loc} -> List.wrap(def_loc || [])
+        _ -> []
+      end
+
+    declaration_locations =
+      case Declaration.declaration(uri, parser_context, line, character, project_dir) do
+        {:ok, decl_loc} -> List.wrap(decl_loc || [])
+        _ -> []
+      end
+
+    {definition_locations, declaration_locations}
+  end
+
   defp build_reference(ref, current_file_uri, current_file_text, project_dir) do
     case get_text(ref, current_file_text) do
       {:ok, text} ->

apps/language_server/test/providers/references_test.exs

@@ -156,6 +156,28 @@ defmodule ElixirLS.LanguageServer.Providers.ReferencesTest do
            ]
   end
 
+  test "respects includeDeclaration flag for variables" do
+    file_path = FixtureHelpers.get_path("references_referenced.ex")
+    parser_context = ParserContextBuilder.from_path(file_path)
+    uri = SourceFile.Path.to_uri(file_path)
+    {line, char} = {4, 14}
+
+    ElixirLS.Test.TextLoc.annotate_assert(file_path, line, char, """
+        IO.puts(referenced_variable + 1)
+                  ^
+    """)
+
+    {line, char} =
+      SourceFile.lsp_position_to_elixir(parser_context.source_file.text, {line, char})
+
+    assert References.references(parser_context, uri, line, char, false, File.cwd!()) == [
+             %GenLSP.Structures.Location{
+               range: range(4, 12, 4, 31),
+               uri: uri
+             }
+           ]
+  end
+
   test "finds references to an attribute" do
     file_path = FixtureHelpers.get_path("references_referenced.ex")
     parser_context = ParserContextBuilder.from_path(file_path)