IO.warn

You're seeing just the function warn, go back to IO module for more information.

Specs

warn(chardata() | String.Chars.t()) :: :ok

Writes a message to stderr, along with the current stacktrace.

It returns :ok if it succeeds.

Do not call this function at the tail of another function. Due to tail call optimization, a stacktrace entry would not be added and the stacktrace would be incorrectly trimmed. Therefore make sure at least one expression (or an atom such as :ok) follows the IO.warn/1 call.

Examples

IO.warn("variable bar is unused")
#=> warning: variable bar is unused
#=>   (iex) evaluator.ex:108: IEx.Evaluator.eval/4
Link to this function

warn(message, stacktrace)

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Specs

Writes a message to stderr, along with the given stacktrace.

This function also notifies the compiler a warning was printed (in case --warnings-as-errors was enabled). It returns :ok if it succeeds.

An empty list can be passed to avoid stacktrace printing.

Examples

stacktrace = [{MyApp, :main, 1, [file: 'my_app.ex', line: 4]}]
IO.warn("variable bar is unused", stacktrace)
#=> warning: variable bar is unused
#=>   my_app.ex:4: MyApp.main/1