Thanks for the confirmation. I’m not that confident with macros, but I’ll take a look in the code in Phoenix LiveView
That would be most likely an Elixir bug. I did a quick attempt to reproduce it and failed, so if you can isolate it into a small app, it would help a lot!
As with all things in life, the situation turned out more complex than expected.
Basically we have multiple themes and in order to ensure that each theme implements the same components and interfaces we created a file lib/themes/impl.ex where we defined function headers and attribute for the components. For example.
# themes/impl.ex
defmodule Themes.Impl do
defmacro __using__(_) do
quote do
use Phoenix.Component
attr :total_pages, :string, default: nil
attr :current_page, :string, default: nil
slot :inner_block
def pagination(assigns)
end
end
end
# themes/theme_name.ex
defmodule Themes.ThemeName do
use Themes.Impl
embed_templates("theme_name/*")
end
I invested the issue with help from claude and found out the root cause is that elixir only considers the file (@file) of the first function clause.
write this into a .exs file and run it
defmodule Bug do
def render(x)
@file "template.heex"
def render(x) do
label = describe(x)
_ = label == :only
x
end
defp describe(_), do: "page"
end
warning: comparison between distinct types found:
label == :only
given types:
binary() == :only
where "label" was given the type:
# type: binary()
# from: repro.exs:16:11
label = describe(x)
While Elixir can compare across all types, you are comparing across types which are always disjoint, and the result is either always true or always false
typing violation found at:
│
17 │ _ = label == :only
│ ~
│
└─ repro.exs:17:15: Bug.render/1 # Should have been template.heex
Note: This is also reproducible in 1.19.5