provide_deprecation_message

Provide a deprecation message, via @Deprecated("message").

DO specify a deprecation message (with migration instructions and/or a removal schedule) in the Deprecated constructor.

BAD:

@deprecated
void oldFunction(arg1, arg2) {}

GOOD:

@Deprecated("""
[oldFunction] is being deprecated in favor of [newFunction] (with slightly
different parameters; see [newFunction] for more information). [oldFunction]
will be removed on or after the 4.0.0 release.
""")
void oldFunction(arg1, arg2) {}

To enable the provide_deprecation_message rule, add provide_deprecation_message under linter > rules in your analysis_options.yaml file:

linter:
  rules:
    - provide_deprecation_message

If you're instead using the YAML map syntax to configure linter rules, add provide_deprecation_message: true under linter > rules:

linter:
  rules:
    provide_deprecation_message: true