IEx.Introspection.decompose/2 return :error on invalid expressions

And write a helper function on iex to Macro.espace

Author: renanroberto

lib/iex/lib/iex/helpers.ex

@@ -333,7 +333,7 @@ defmodule IEx.Helpers do
   """
   defmacro open(term) do
     quote do
-      IEx.Introspection.open(unquote(Macro.escape(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(Macro.escape(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(Macro.escape(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(Macro.escape(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

@@ -17,7 +17,7 @@ defmodule IEx.Introspection do
     Macro.expand(module, context)
   end
 
-  def decompose({:/, _, [call, arity]} = term, context) do
+  def decompose({:/, _, [call, arity]}, context) do
     case Macro.decompose_call(call) do
       {_mod, :__info__, []} when arity == 1 ->
         {Module, :__info__, 1}
@@ -29,7 +29,7 @@ defmodule IEx.Introspection do
         {find_decompose_fun_arity(fun, arity, context), fun, arity}
 
       _ ->
-        term
+        :error
     end
   end
 
@@ -44,7 +44,7 @@ defmodule IEx.Introspection do
             {find_decompose_fun_arity(maybe_sigil, 2, context), maybe_sigil, 2}
 
           _ ->
-            call
+            :error
         end
 
       {mod, fun, []} ->
@@ -54,7 +54,7 @@ defmodule IEx.Introspection do
         {find_decompose_fun(fun, context), fun}
 
       _ ->
-        call
+        :error
     end
   end
 

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

@@ -106,6 +106,10 @@ defmodule Mix.Tasks.Help do
       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)

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

@@ -265,6 +265,12 @@ defmodule Mix.Tasks.HelpTest do
     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"])