Each FIDL modifier has a specific set of declarations in which it can be used. Using the modifier in a prohibited declaration is not allowed:
{% include “docs/reference/fidl/language/error-catalog/label/_bad.md” %}
{% includecode gerrit_repo="fuchsia/fuchsia" gerrit_path="tools/fidl/fidlc/tests/fidl/bad/fi-0030.test.fidl" exclude_regexp="\/\/ (Copyright 20|Use of|found in).*" %}
The best course of action is to remove the offending modifier:
{% include “docs/reference/fidl/language/error-catalog/label/_good.md” %}
{% includecode gerrit_repo="fuchsia/fuchsia" gerrit_path="tools/fidl/fidlc/tests/fidl/good/fi-0030.test.fidl" exclude_regexp="\/\/ (Copyright 20|Use of|found in).*" %}