Include a hint for defimpl type checking

Author: josevalim

lib/elixir/lib/module/types.ex

@@ -49,8 +49,8 @@ defmodule Module.Types do
  finder =
  fn fun_arity ->
  case :lists.keyfind(fun_arity, 1, defs) do
- {_, kind, _, _} = clause ->
- {infer_mode(kind, infer_signatures?), clause, default_domain(fun_arity, impl)}
+ {_, kind, _, _} = def ->
+ default_domain(infer_mode(kind, infer_signatures?), def, fun_arity, impl)
 
  false ->
  false
@@ -82,7 +82,7 @@ defmodule Module.Types do
  {types, context} ->
  # Optimized version of finder, since we already the definition
  finder = fn _ ->
- {infer_mode(kind, infer_signatures?), def, default_domain(fun_arity, impl)}
+ default_domain(infer_mode(kind, infer_signatures?), def, fun_arity, impl)
  end
 
  {_kind, inferred, context} = local_handler(meta, fun_arity, stack, context, finder)
@@ -146,12 +146,24 @@ defmodule Module.Types do
  end
  end
 
- defp default_domain({_, arity} = fun_arity, impl) do
+ defp default_domain(mode, def, {_, arity} = fun_arity, impl) do
  with {for, callbacks} <- impl,
  true <- fun_arity in callbacks do
- [Descr.dynamic(Module.Types.Of.impl(for)) | List.duplicate(Descr.dynamic(), arity - 1)]
+ args = [
+ Descr.dynamic(Module.Types.Of.impl(for))
+ | List.duplicate(Descr.dynamic(), arity - 1)
+ ]
+
+ {fun_arity, kind, meta, clauses} = def
+
+ clauses =
+ for {meta, args, guards, body} <- clauses do
+ {[type_check: {:impl, for}] ++ meta, args, guards, body}
+ end
+
+ {mode, {fun_arity, kind, meta, clauses}, args}
  else
- _ -> List.duplicate(Descr.dynamic(), arity)
+ _ -> {mode, def, List.duplicate(Descr.dynamic(), arity)}
  end
  end
 
@@ -208,7 +220,7 @@ defmodule Module.Types do
 
  finder = fn fun_arity ->
  case :lists.keyfind(fun_arity, 1, defs) do
- {_, _, _, _} = clause -> {:dynamic, clause, default_domain(fun_arity, impl)}
+ {_, _, _, _} = def -> default_domain(:dynamic, def, fun_arity, impl)
  false -> false
  end
  end
@@ -219,7 +231,7 @@ defmodule Module.Types do
  context =
  Enum.reduce(defs, context(), fn {fun_arity, _kind, meta, _clauses} = def, context ->
  # Optimized version of finder, since we already the definition
- finder = fn _ -> {:dynamic, def, default_domain(fun_arity, impl)} end
+ finder = fn _ -> default_domain(:dynamic, def, fun_arity, impl) end
  {_kind, _inferred, context} = local_handler(meta, fun_arity, stack, context, finder)
  context
  end)

lib/elixir/lib/module/types/helpers.ex

@@ -132,6 +132,20 @@ defmodule Module.Types.Helpers do
  the union (which may be none)
  """
 
+ {:impl, for} ->
+ # Get the type without dynamic for better pretty printing
+ type =
+ for
+ |> Module.Types.Of.impl()
+ |> Module.Types.Descr.dynamic()
+ |> Map.fetch!(:dynamic)
+ |> Module.Types.Descr.to_quoted_string(collapse_structs: true)
+
+ """
+
+ #{hint()} defimpl for #{inspect(for)} requires its callbacks to match exclusively on #{type}
+ """
+
  :empty_domain ->
  """
 

lib/elixir/lib/module/types/pattern.ex

@@ -259,12 +259,12 @@ defmodule Module.Types.Pattern do
  defp badpattern_error(expr, index, tag, stack, context) do
  meta =
  if meta = get_meta(expr) do
- meta ++ Keyword.take(stack.meta, [:generated, :line])
+ meta ++ Keyword.take(stack.meta, [:generated, :line, :type_check])
  else
  stack.meta
  end
 
- error(__MODULE__, {:badpattern, expr, index, tag, context}, meta, stack, context)
+ error(__MODULE__, {:badpattern, meta, expr, index, tag, context}, meta, stack, context)
  end
 
  defp of_pattern_intersect(tree, expected, expr, index, tag, stack, context) do
@@ -803,13 +803,19 @@ defmodule Module.Types.Pattern do
  #
  # The match pattern ones have the whole expression instead
  # of a single pattern.
- def format_diagnostic({:badpattern, pattern_or_expr, index, tag, context}) do
+ def format_diagnostic({:badpattern, meta, pattern_or_expr, index, tag, context}) do
  {to_trace, message} = badpattern(tag, pattern_or_expr, index)
  traces = collect_traces(to_trace, context)
 
+ hints =
+ case Keyword.get(meta, :type_check) do
+ {:impl, _} = impl -> [impl]
+ _ -> []
+ end
+
  %{
  details: %{typing_traces: traces},
- message: IO.iodata_to_binary([message, format_traces(traces)])
+ message: IO.iodata_to_binary([message, format_traces(traces), format_hints(hints)])
  }
  end
 

lib/elixir/test/elixir/module/types/integration_test.exs

@@ -479,6 +479,8 @@ defmodule Module.Types.IntegrationTest do
 
  dynamic(%Range{})
 
+ hint: defimpl for Range requires its callbacks to match exclusively on %Range{}
+
  typing violation found at:
  │
  6 │ def itself(nil), do: nil