@do fails to complete

[axelson]

In ElixirLS typing @do above a function definition fails to return any completions and can result in an exception:

07:36:09.440 [error] Process #PID<0.400.0> raised an exception
** (CaseClauseError) no case clause matching: [{:hi, [line: 10, column: 7], nil}, [do: {:__block__, [], [{{:., [line: 16, column: 7], [{:__aliases__, [line: 16, column: 5], [:IO]}, :puts]}, [line: 16, column: 7], ["hihihibefesffesfasasd"]}, {{:., [line: 17, column: 9], [{:__aliases__, [line: 17, column: 5], [:Enum]}, :chunk_every]}, [line: 17, column: 9], [[], 3]}]}]]
    (elixir_sense 1.0.1) lib/elixir_sense/core/metadata_builder.ex:556: ElixirSense.Core.MetadataBuilder.pre/2
    (elixir 1.10.3) lib/macro.ex:430: anonymous fn/4 in Macro.do_traverse_args/4
    (elixir 1.10.3) lib/enum.ex:1520: Enum."-map_reduce/3-lists^mapfoldl/2-0-"/3
    (elixir 1.10.3) lib/enum.ex:1520: Enum."-map_reduce/3-lists^mapfoldl/2-0-"/3
    (elixir 1.10.3) lib/macro.ex:396: Macro.do_traverse/4
    (elixir 1.10.3) lib/macro.ex:411: Macro.do_traverse/4
    (elixir 1.10.3) lib/enum.ex:1520: Enum."-map_reduce/3-lists^mapfoldl/2-0-"/3
    (elixir 1.10.3) lib/macro.ex:416: Macro.do_traverse/4

Are there currently any tests of completion that involve a file that fails to compile?

[lukaszsamson]

Are there currently any tests of completion that involve a file that fails to compile?

There are some in test/elixir_sense/suggestion_test.exs

[lukaszsamson]

I hit some other similar errors lately, e.g.

add_call_to_line({Module.concat(module), call, length(params)}, {line, column + 1})
** (FunctionClauseError) no function clause matching in :elixir_aliases.do_concat/2
    (elixir 1.10.3) src/elixir_aliases.erl:120: :elixir_aliases.do_concat([{:state, [line: 50, column: 5], nil}, :Process], "Elixir")
    (elixir 1.10.3) src/elixir_aliases.erl:108: :elixir_aliases.concat/1
    (elixir_sense 1.0.1) lib/elixir_sense/core/metadata_builder.ex:990: ElixirSense.Core.MetadataBuilder.pre/2
    (elixir 1.10.3) lib/macro.ex:430: anonymous fn/4 in Macro.do_traverse_args/4
    (elixir 1.10.3) lib/enum.ex:1520: Enum."-map_reduce/3-lists^mapfoldl/2-0-"/3
    (elixir 1.10.3) lib/enum.ex:1520: Enum."-map_reduce/3-lists^mapfoldl/2-0-"/3
    (elixir 1.10.3) lib/macro.ex:396: Macro.do_traverse/4
    (elixir 1.10.3) lib/macro.ex:411: Macro.do_traverse/4


** (FunctionClauseError) no function clause matching in :elixir_aliases.do_concat/2
    (elixir 1.10.3) src/elixir_aliases.erl:120: :elixir_aliases.do_concat([{:|>, [line: 517, column: 5], [{:++, [line: 516, column: 28], [{:news, [line: 516, column: 23], nil}, {:modifys, [line: 516, column: 31], nil}]}, {{:., [line: 517, column: 12], [{:__aliases__, [line: 517, column: 8], [:Enum]}, :group_by]}, [line: 517, column: 12], [{:fn, [line: 517, column: 22], [{:->, [line: 517, column: 48], [[{:{}, [line: 517, column: 25], [{:side, [line: 517, column: 26], nil}, {:_price, [line: 517, column: 32], nil}, {:_order, [line: 517, column: 40], nil}]}], {:side, [line: 517, column: 51], nil}]}]}]}]}, :I], "Elixir")
    (elixir 1.10.3) src/elixir_aliases.erl:108: :elixir_aliases.concat/1
    (elixir_sense 1.0.1) lib/elixir_sense/core/state.ex:974: ElixirSense.Core.State.expand_alias/2
    (elixir_sense 1.0.1) lib/elixir_sense/core/metadata_builder.ex:1226: ElixirSense.Core.MetadataBuilder.get_binding_type/2
    (elixir_sense 1.0.1) lib/elixir_sense/core/metadata_builder.ex:753: ElixirSense.Core.MetadataBuilder.pre/2
    (elixir 1.10.3) lib/macro.ex:430: anonymous fn/4 in Macro.do_traverse_args/4
    (elixir 1.10.3) lib/enum.ex:1520: Enum."-map_reduce/3-lists^mapfoldl/2-0-"/3
    (elixir 1.10.3) lib/enum.ex:1520: Enum."-map_reduce/3-lists^mapfoldl/2-0-"/3
    (elixir 1.10.3) lib/macro.ex:396: Macro.do_traverse/4
    (elixir 1.10.3) lib/macro.ex:411: Macro.do_traverse/4
    (elixir 1.10.3) lib/enum.ex:1520: Enum."-map_reduce/3-lists^mapfoldl/2-0-"/3
    (elixir 1.10.3) lib/macro.ex:416: Macro.do_traverse/4
    (elixir 1.10.3) lib/enum.ex:1520: Enum."-map_reduce/3-lists^mapfoldl/2-0-"/3
    (elixir 1.10.3) lib/enum.ex:1520: Enum."-map_reduce/3-lists^mapfoldl/2-0-"/3
    (elixir 1.10.3) lib/macro.ex:396: Macro.do_traverse/4
    (elixir 1.10.3) lib/enum.ex:1520: Enum."-map_reduce/3-lists^mapfoldl/2-0-"/3
    (elixir 1.10.3) lib/enum.ex:1520: Enum."-map_reduce/3-lists^mapfoldl/2-0-"/3
    (elixir 1.10.3) lib/macro.ex:396: Macro.do_traverse/4
    (elixir 1.10.3) lib/macro.ex:411: Macro.do_traverse/4
    (elixir 1.10.3) lib/enum.ex:1520: Enum."-map_reduce/3-lists^mapfoldl/2-0-"/3

Unfortunately it is not worth fixing every one. Metadata builder makes assumptions that AST is relatively sane. In the case with @do ... the parser assumes that function block is the attribute value which is obviously illegal. The best we can do is catch the error and replace the faulty AST node with nil.

[axelson]

Thanks, that seems like a sane fix