Fix crashing on autocompleting structs with runtime values (#14150)

Author: GuillaumeMilan

lib/iex/lib/iex/autocomplete.ex

@@ -363,7 +363,7 @@ defmodule IEx.Autocomplete do
       end)
 
     entries =
-      for {key, _value} <- pairs,
+      for key when key != :__struct__ <- Map.keys(pairs),
           name = Atom.to_string(key),
           if(hint == "",
             do: not String.starts_with?(name, "_"),

lib/iex/test/iex/autocomplete_test.exs

@@ -430,6 +430,19 @@ defmodule IEx.AutocompleteTest do
     assert {:yes, ~c"ry: ", []} = expand(~c"%URI{var | path: \"foo\", que")
     assert {:no, [], []} = expand(~c"%URI{var | path: \"foo\", unkno")
     assert {:no, [], []} = expand(~c"%Unknown{var | path: \"foo\", unkno")
+
+    eval("var = %URI{}")
+
+    assert {:yes, ~c"", entries} = expand(~c"%{var | ")
+    assert ~c"path:" in entries
+    assert ~c"query:" in entries
+
+    assert {:yes, ~c"", entries} = expand(~c"%{var | path: \"foo\",")
+    assert ~c"path:" not in entries
+    assert ~c"query:" in entries
+
+    assert {:yes, ~c"ry: ", []} = expand(~c"%{var | path: \"foo\", que")
+    assert {:no, [], []} = expand(~c"%URI{var | path: \"foo\", unkno")
   end
 
   test "completion for map keys in update syntax" do