9.6 -error() and -warning() directives

The directive -error(Term) causes a compilation error.

Example:

-module(t).
-export([version/0]).
 
-ifdef(VERSION).
version() -> ?VERSION.
-else.
-error("Macro VERSION must be defined.").
version() -> "".
-endif.

The error message will look like this:

% erlc t.erl
t.erl:7: -error("Macro VERSION must be defined.").

The directive -warning(Term) causes a compilation warning.

Example:

-module(t).
-export([version/0]).
 
-ifndef(VERSION).
-warning("Macro VERSION not defined -- using default version.").
-define(VERSION, "0").
-endif.
version() -> ?VERSION.

The warning message will look like this:

% erlc t.erl
t.erl:5: Warning: -warning("Macro VERSION not defined -- using default version.").

The -error() and -warning() directives were added in OTP 19.