feat(ext-type-graph): implement reducible ast warning

Author: florius0

.formatter.exs

@@ -20,8 +20,8 @@ locals_without_parens = [
   ],
   locals_without_parens:
     [
-      inspect: 1,
-      inspect: 2
+      inspect: :*,
+      capture_io: :*
     ] ++ locals_without_parens,
   inputs: ["{mix,.formatter}.exs", "{config,lib,test}/**/*.{ex,exs}"],
   line_length: 200

lib/apix.schema.extensions/type_graph.ex

@@ -4,11 +4,15 @@ defmodule Apix.Schema.Extensions.TypeGraph do
   alias Apix.Schema.Ast
   alias Apix.Schema.Context
 
+  alias Apix.Schema.Warning
+
   alias Apix.Schema.Extensions.TypeGraph.Graph
 
   alias Apix.Schema.Extensions.TypeGraph.Errors.FullyRecursiveAstError
   alias Apix.Schema.Extensions.TypeGraph.Errors.UndefinedReferenceAstError
 
+  alias Apix.Schema.Extensions.TypeGraph.Warnings.ReducibleAstWarning
+
   @manifest %Extension{
     module: __MODULE__
   }
@@ -367,6 +371,11 @@ defmodule Apix.Schema.Extensions.TypeGraph do
   """
   @spec validate!() :: :ok | no_return()
   def validate! do
+    validate_undefined_reference!()
+    validate_fully_recursive!()
+  end
+
+  defp validate_undefined_reference! do
     Graph.vertices()
     |> Enum.each(fn hash ->
       {^hash, context_or_ast} = Graph.vertex(hash)
@@ -375,7 +384,9 @@ defmodule Apix.Schema.Extensions.TypeGraph do
         raise UndefinedReferenceAstError, context_or_ast
       end
     end)
+  end
 
+  defp validate_fully_recursive! do
     Graph.cyclic_strong_components_by(&(&1 == :references))
     |> Enum.each(fn [hash | _] = component ->
       component
@@ -409,6 +420,17 @@ defmodule Apix.Schema.Extensions.TypeGraph do
     end)
   end
 
+  defp validate_reducible!(context) do
+    ast = context.ast
+    reduced_ast = Context.normalize_ast!(context)
+
+    unless Ast.equals?(ast, reduced_ast) do
+      [ast: ast, reduced_ast: reduced_ast]
+      |> ReducibleAstWarning.exception()
+      |> Warning.print()
+    end
+  end
+
   @doc group: "Internal"
   @doc """
   Builds the sub/super-type relations in the graph.
@@ -592,6 +614,7 @@ defmodule Apix.Schema.Extensions.TypeGraph do
   @impl Extension
   def validate_ast!(context) do
     track!(context)
+    validate_reducible!(context)
     on_compilation!()
 
     context

lib/apix.schema.extensions/type_graph/warnings/reducible_ast_warning.ex

@@ -48,11 +48,7 @@ defmodule Apix.Schema.Extensions.TypeGraph.Warnings.ReducibleAstWarning do
 
     %__MODULE__{
       message: """
-      #{inspect ast} can be reduced to #{inspect reduced_ast} and remain equivalent.
-
-      If you intended that, rewrite it as #{inspect reduced_ast}.
-
-      #{ast.meta}
+      #{inspect ast} can be reduced to #{inspect reduced_ast} and remain equivalent. If you intended that, rewrite it as #{inspect reduced_ast}.
       """,
       ast: ast,
       reduced_ast: reduced_ast,

test/apix.schema.extensions/type_graph_test.exs

@@ -1,6 +1,8 @@
 defmodule Apix.Schema.Extensions.TypeGraphTest do
   use Apix.Schema.Case
 
+  import ExUnit.CaptureIO
+
   alias Apix.Schema.Extensions.TypeGraph
 
   alias Apix.Schema.Extensions.TypeGraph.Errors.FullyRecursiveAstError
@@ -611,11 +613,16 @@ defmodule Apix.Schema.Extensions.TypeGraphTest do
     end
 
     test "#{inspect ReducibleAstWarning}" do
-      defmodule TestSchema24 do
-        # use Apix.Schema
+      warning =
+        capture_io :stderr, fn ->
+          defmodule TestSchema24 do
+            use Apix.Schema
 
-        # schema a: Any.t() or Any.t()
-      end
+            schema a: Any.t() or Any.t()
+          end
+        end
+
+      assert warning =~ "can be reduced"
     end
   end
 end