References broken on elixir 1.10

[lukaszsamson]

Mix.Tasks.Xref.calls/0 is deprecated now and does not seem to work correctly. We should probably migrate to compiler tracing

[josevalim]

Can you please expand on what "does not seem to work correctly" means? We kept a shim for users where it should work for functions (but not macros).

[lukaszsamson]

@josevalim in https://github.com/lukaszsamson/elixir_xfer_repro repo I created a few modules to test xref behavior.
Below is the result of calling Mix.Tasks.Xref.calls/0 on 1.9 and 1.10

1.9.4

iex(1)> Mix.Tasks.Xref.calls() |> Enum.filter(fn %{callee: callee} -> callee == {XrefCalls.Callee, :hello, 0} end)                                   
[
  %{
    callee: {XrefCalls.Callee, :hello, 0},
    caller_module: XrefCalls,
    file: "lib/callee.ex",
    line: 19
  },
  %{
    callee: {XrefCalls.Callee, :hello, 0},
    caller_module: XrefCalls,
    file: "lib/callee.ex",
    line: 15
  },
  %{
    callee: {XrefCalls.Callee, :hello, 0},
    caller_module: XrefCalls,
    file: "lib/callee.ex",
    line: 14
  },
  %{
    callee: {XrefCalls.Callee, :hello, 0},
    caller_module: XrefCalls,
    file: "lib/callee.ex",
    line: 13
  },
  %{
    callee: {XrefCalls.Callee, :hello, 0},
    caller_module: XrefCalls.SubmoduleCaller,
    file: "lib/callee.ex",
    line: 19
  },
  %{
    callee: {XrefCalls.Callee, :hello, 0},
    caller_module: XrefCalls.SubmoduleCaller,
    file: "lib/callee.ex",
    line: 15
  },
  %{
    callee: {XrefCalls.Callee, :hello, 0},
    caller_module: XrefCalls.SubmoduleCaller,
    file: "lib/callee.ex",
    line: 14
  },
  %{
    callee: {XrefCalls.Callee, :hello, 0},
    caller_module: XrefCalls.SubmoduleCaller,
    file: "lib/callee.ex",
    line: 13
  },
  %{
    callee: {XrefCalls.Callee, :hello, 0},
    caller_module: XrefCalls.CaptureCaller,
    file: "lib/capture_caller.ex",
    line: 7
  },
  %{
    callee: {XrefCalls.Callee, :hello, 0},
    caller_module: XrefCalls.ImportedCaller,
    file: "lib/imported_caller.ex",
    line: 9
  },
  %{
    callee: {XrefCalls.Callee, :hello, 0},
    caller_module: XrefCalls.ImportedCaller,
    file: "lib/imported_caller.ex",
    line: 8
  },
  %{
    callee: {XrefCalls.Callee, :hello, 0},
    caller_module: XrefCalls.ImportedCaller,
    file: "lib/imported_caller.ex",
    line: 7
  },
  %{
    callee: {XrefCalls.Callee, :hello, 0},
    caller_module: XrefCalls.Callee,
    file: "lib/callee.ex",
    line: 19
  },
  %{
    callee: {XrefCalls.Callee, :hello, 0},
    caller_module: XrefCalls.Callee,
    file: "lib/callee.ex",
    line: 15
  },
  %{
    callee: {XrefCalls.Callee, :hello, 0},
    caller_module: XrefCalls.Callee,
    file: "lib/callee.ex",
    line: 14
  },
  %{
    callee: {XrefCalls.Callee, :hello, 0},
    caller_module: XrefCalls.Callee,
    file: "lib/callee.ex",
    line: 13
  },
  %{
    callee: {XrefCalls.Callee, :hello, 0},
    caller_module: XrefCalls.DifferentLineCaller,
    file: "lib/different_line_caller.ex",
    line: 7
  },
  %{
    callee: {XrefCalls.Callee, :hello, 0},
    caller_module: XrefCalls.AliasedCaller,
    file: "lib/aliased_caller.ex",
    line: 9
  },
  %{
    callee: {XrefCalls.Callee, :hello, 0},
    caller_module: XrefCalls.AliasedCaller,
    file: "lib/aliased_caller.ex",
    line: 8
  },
  %{
    callee: {XrefCalls.Callee, :hello, 0},
    caller_module: XrefCalls.AliasedCaller,
    file: "lib/aliased_caller.ex",
    line: 7
  }
]

1.10-rc.0

iex(1)> Mix.Tasks.Xref.calls() |> Enum.filter(fn %{callee: callee} -> callee == {XrefCalls.Callee, :hello, 0} end)
[
  %{
    callee: {XrefCalls.Callee, :hello, 0},
    caller_module: XrefCalls.SubmoduleCaller,
    file: "lib/callee.ex",
    line: 14
  },
  %{
    callee: {XrefCalls.Callee, :hello, 0},
    caller_module: XrefCalls.SubmoduleCaller,
    file: "lib/callee.ex",
    line: 13
  },
  %{
    callee: {XrefCalls.Callee, :hello, 0},
    caller_module: XrefCalls.SubmoduleCaller,
    file: "lib/callee.ex",
    line: 19
  },
  %{
    callee: {XrefCalls.Callee, :hello, 0},
    caller_module: XrefCalls.ImportedCaller,
    file: "lib/imported_caller.ex",
    line: nil
  },
  %{
    callee: {XrefCalls.Callee, :hello, 0},
    caller_module: XrefCalls.ImportedCaller,
    file: "lib/imported_caller.ex",
    line: nil
  },
  %{
    callee: {XrefCalls.Callee, :hello, 0},
    caller_module: XrefCalls.DifferentLineCaller,
    file: "lib/different_line_caller.ex",
    line: 7
  },
  %{
    callee: {XrefCalls.Callee, :hello, 0},
    caller_module: XrefCalls.AliasedCaller,
    file: "lib/aliased_caller.ex",
    line: 8
  },
  %{
    callee: {XrefCalls.Callee, :hello, 0},
    caller_module: XrefCalls.AliasedCaller,
    file: "lib/aliased_caller.ex",
    line: 7
  }
]

As you can see on 1.10

• capture tracking no longer works
• imported function call does not register line number (might be related to String interpolation emits duplicate :imported_function trace events elixir-lang/elixir#9709)
• calls inside string interpolation are not registered
• duplicated entries for calls from sibling module are no longer returned (that's an improvement)

[josevalim]

Thanks, I have fixed those. Although note macros and others still won't show up, but calls/0 is at least a bit more accurate now!

[lukaszsamson]

Works again on elixir@9814a4cd61b9b054e4594c1b225d7939a9eb5add. I'm closing this now but #80 still remains relevant