I propose another two code actions that can be applied when we get either:

• a compile error because the struct is not defined
• a warning because we are calling a function from a module that is not known

Replacing modules

The first code action proposes replacing an unknown module with its full name. For example:

defmodule MyModule do
  def foo do
    %ExampleStruct{}
  end
end

will be replaced with

defmodule MyModule do
  def foo do
    %ElixirLS.LanguageServer.Fixtures.ExampleStruct{}
  end
end

if we have module ElixirLS.LanguageServer.Fixtures.ExampleStruct available. Similarly

defmodule MyModule do
  def foo do
    ExampleDefaultArgs.my_func("text")
  end
end

can be replaced with

defmodule MyModule do
  def foo do
    ElixirLS.LanguageServer.Fixtures.ExampleDefaultArgs.my_func("text")
  end
end

if ElixirLS.LanguageServer.Fixtures.ExampleDefaultArgs is available.

Adding an alias

The second code action adds an alias that is required to make the code work. For example:

defmodule MyModule do
  def foo do
    %ExampleStruct{}
  end
end

will be replaced with

defmodule MyModule do
  alias ElixirLS.LanguageServer.Fixtures.ExampleStruct

  def foo do
    %ExampleStruct{}
  end
end

and

defmodule MyModule do
  def foo do
    ExampleDefaultArgs.my_func("text")
  end
end

will be replaced with

defmodule MyModule do
  alias ElixirLS.LanguageServer.Fixtures.ExampleDefaultArgs

  def foo do
    ExampleDefaultArgs.my_func("text")
  end
end

Notes

• We always get 2 code actions (replacement and alias) for every suggested module
• There are at most 3 suggested modules (so at most 6 code actions)
• Suggested modules that are from the same namespace (first atom from full module name) as the module in which we are doing code action have priority
• To find a place for the alias I've used ElixirSense.Core.Metadata.get_position_to_insert_alias/2 function which has two limitations that may affect the usability of the code action:
  • if there are already aliases in the module, the new alias will be added as the first one so the aliases may stop being ordered alphabetically
  • if there are no aliases in the module, the new alias will be added as a first directive just below @moduledoc which may not be a perfect place