Add mix help Mod, mix help :mod, mix help Mod.fun and mix help Mod.fun/arity

lib/iex/lib/iex/helpers.ex

@@ -333,7 +333,7 @@ defmodule IEx.Helpers do
   """
   defmacro open(term) do
     quote do
-      IEx.Introspection.open(unquote(IEx.Introspection.decompose(term, __CALLER__)))
+      IEx.Introspection.open(unquote(decompose(term, __CALLER__)))
     end
   end
 
@@ -362,7 +362,7 @@ defmodule IEx.Helpers do
   """
   defmacro h(term) do
     quote do
-      IEx.Introspection.h(unquote(IEx.Introspection.decompose(term, __CALLER__)))
+      IEx.Introspection.h(unquote(decompose(term, __CALLER__)))
     end
   end
 
@@ -381,7 +381,7 @@ defmodule IEx.Helpers do
   """
   defmacro b(term) do
     quote do
-      IEx.Introspection.b(unquote(IEx.Introspection.decompose(term, __CALLER__)))
+      IEx.Introspection.b(unquote(decompose(term, __CALLER__)))
     end
   end
 
@@ -406,7 +406,7 @@ defmodule IEx.Helpers do
   """
   defmacro t(term) do
     quote do
-      IEx.Introspection.t(unquote(IEx.Introspection.decompose(term, __CALLER__)))
+      IEx.Introspection.t(unquote(decompose(term, __CALLER__)))
     end
   end
 
@@ -553,6 +553,13 @@ defmodule IEx.Helpers do
     dont_display_result()
   end
 
+  defp decompose(term, context) do
+    case IEx.Introspection.decompose(term, context) do
+      :error -> term
+      m_mf_mfa -> Macro.escape(m_mf_mfa)
+    end
+  end
+
   # Given any "term", this function returns all the protocols in
   # :code.get_path() implemented by the data structure of such term, in the form
   # of a binary like "Protocol1, Protocol2, Protocol3".

lib/iex/lib/iex/introspection.ex

@@ -11,44 +11,50 @@ defmodule IEx.Introspection do
   Decomposes an introspection call into `{mod, fun, arity}`,
   `{mod, fun}` or `mod`.
   """
-  def decompose({:/, _, [call, arity]} = term, context) do
+  def decompose(atom, _context) when is_atom(atom), do: atom
+
+  def decompose({:__aliases__, _, _} = module, context) do
+    Macro.expand(module, context)
+  end
+
+  def decompose({:/, _, [call, arity]}, context) do
     case Macro.decompose_call(call) do
       {_mod, :__info__, []} when arity == 1 ->
-        {:{}, [], [Module, :__info__, 1]}
+        {Module, :__info__, 1}
 
       {mod, fun, []} ->
-        {:{}, [], [mod, fun, arity]}
+        {Macro.expand(mod, context), fun, arity}
 
       {fun, []} ->
-        {:{}, [], [find_decompose_fun_arity(fun, arity, context), fun, arity]}
+        {find_decompose_fun_arity(fun, arity, context), fun, arity}
 
       _ ->
-        term
+        :error
     end
   end
 
   def decompose(call, context) do
     case Macro.decompose_call(call) do
       {_mod, :__info__, []} ->
-        Macro.escape({Module, :__info__, 1})
-
-      {mod, fun, []} ->
-        {mod, fun}
+        {Module, :__info__, 1}
 
       {maybe_sigil, [_, _]} ->
         case Atom.to_string(maybe_sigil) do
           "sigil_" <> _ ->
-            {:{}, [], [find_decompose_fun_arity(maybe_sigil, 2, context), maybe_sigil, 2]}
+            {find_decompose_fun_arity(maybe_sigil, 2, context), maybe_sigil, 2}
 
           _ ->
-            call
+            :error
         end
 
+      {mod, fun, []} ->
+        {Macro.expand(mod, context), fun}
+
       {fun, []} ->
         {find_decompose_fun(fun, context), fun}
 
       _ ->
-        call
+        :error
     end
   end
 

lib/mix/lib/mix/tasks/help.ex

@@ -94,6 +94,28 @@ defmodule Mix.Tasks.Help do
     Mix.raise("Unexpected arguments, expected \"mix help --search PATTERN\"")
   end
 
+  def run([module = <<first, _::binary>>]) when first in ?A..?Z or first == ?: do
+    loadpaths!()
+
+    iex_colors = Application.get_env(:iex, :colors, [])
+    mix_colors = Application.get_env(:mix, :colors, [])
+
+    try do
+      Application.put_env(:iex, :colors, mix_colors)
+
+      module
+      |> Code.string_to_quoted!()
+      |> IEx.Introspection.decompose(__ENV__)
+      |> case do
+        :error -> Mix.raise("Invalid expression: #{module}")
+        decomposition -> decomposition
+      end
+      |> IEx.Introspection.h()
+    after
+      Application.put_env(:iex, :colors, iex_colors)
+    end
+  end
+
   def run([task]) do
     loadpaths!()
     opts = Application.get_env(:mix, :colors)

lib/mix/test/mix/tasks/help_test.exs

@@ -191,6 +191,86 @@ defmodule Mix.Tasks.HelpTest do
     end)
   end
 
+  test "help Elixir MODULE", context do
+    in_tmp(context.test, fn ->
+      output =
+        capture_io(fn ->
+          Mix.Tasks.Help.run(["Mix"])
+        end)
+
+      assert output =~
+               "Mix is a build tool that provides tasks for creating, compiling, and testing\nElixir projects, managing its dependencies, and more."
+    end)
+  end
+
+  test "help Elixir NESTED MODULE", context do
+    in_tmp(context.test, fn ->
+      output =
+        capture_io(fn ->
+          Mix.Tasks.Help.run(["IO.ANSI"])
+        end)
+
+      assert output =~ "Functionality to render ANSI escape sequences."
+    end)
+  end
+
+  test "help Erlang MODULE", context do
+    otp_docs? = match?({:docs_v1, _, _, _, _, _, _}, Code.fetch_docs(:math))
+
+    in_tmp(context.test, fn ->
+      output =
+        capture_io(fn ->
+          Mix.Tasks.Help.run([":math"])
+        end)
+
+      if otp_docs? do
+        assert output =~
+                 "This module provides an interface to a number of mathematical"
+      else
+        assert output =~ ":math was not compiled with docs"
+      end
+    end)
+  end
+
+  test "help FUNCTION/0", context do
+    in_tmp(context.test, fn ->
+      output =
+        capture_io(fn ->
+          Mix.Tasks.Help.run(["DateTime.utc_now()"])
+        end)
+
+      assert output =~ "Returns the current datetime in UTC"
+    end)
+  end
+
+  test "help FUNCTION/1", context do
+    in_tmp(context.test, fn ->
+      output =
+        capture_io(fn ->
+          Mix.Tasks.Help.run(["Enum.all?/1"])
+        end)
+
+      assert output =~ "Returns `true` if all elements in `enumerable` are truthy."
+    end)
+  end
+
+  test "help NESTED MODULE FUNCTION/3", context do
+    in_tmp(context.test, fn ->
+      output =
+        capture_io(fn ->
+          Mix.Tasks.Help.run(["IO.ANSI.color/3"])
+        end)
+
+      assert output =~ "Sets the foreground color from individual RGB values"
+    end)
+  end
+
+  test "help ERROR" do
+    assert_raise Mix.Error, "Invalid expression: Foo.bar(~s[baz])", fn ->
+      Mix.Tasks.Help.run(["Foo.bar(~s[baz])"])
+    end
+  end
+
   test "help --search PATTERN", context do
     in_tmp(context.test, fn ->
       Mix.Tasks.Help.run(["--search", "deps"])