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Enabling --warnings-as-errors flag?

/phoenix#debugging#mix
awful_waffle

awful_waffle

Enabling --warnings-as-errors flag?

Hello!

I recently discovered the --warnings-as-errors flag and strongly prefer the workflow of being blocked by compiler warnings. Warnings in Elixir seem to be much more important (i.e. calls to undefined functions) than what I typically see as warnings in my experience with other languages (i.e. lint errors, unused variables).

I’m currently working through a Phoenix project but found that mix phx.server --warnings-as-errors was unrecognized. Is there a way to tell mix/Elixir to use --warnings-as-errors under the hood when running phx.server?

Thank you for your help!

3 comments
/phoenix#debugging#mix
14 5454 3

Marked As Solved

hauleth

hauleth

If you want to enable that flag by default you can use:

elixirc_options: [
  :warnings_as_errors
]
9
Post #3

Also Liked

fuelen

fuelen

Hello!
--warnings-as-errors is a flag for mix compile.
What do you expect from --warnings-as-errors when running phx.server? Do not start server at all?
If so, then this command may help:

$ mix do compile --warnings-as-errors, phx.server
3
Post #2
awful_waffle

awful_waffle

Thanks for the responses!

Adding elixirc_options: [warnings_as_errors: true] to my project in mix.exs achieved my goal! Now warnings display as errors when I am working in Phoenix, which works great with live reload. If I start the server with an error, it fails to run - which is fine with me.

The only down side is that the warning itself is not printed to the browser - it just shows a generic compilation error screen. The console in which I ran mix phx.server still displays the rest of the information, at least. I assume there is a configuration setting somewhere to output those warnings to the web display, but for now I am happy.

Thank you again!

1
Post #4

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