This error occurs when you use a symbol that's from an unknown library.
{% include “docs/reference/fidl/language/error-catalog/label/_bad.md” %}
{% includecode gerrit_repo="fuchsia/fuchsia" gerrit_path="tools/fidl/fidlc/tests/fidl/bad/fi-0051.test.fidl" exclude_regexp="\/\/ (Copyright 20|Use of|found in).*" %}
To fix this, import the missing dependent library with a using declaration.
{% include “docs/reference/fidl/language/error-catalog/label/_good.md” %}
{% includecode gerrit_repo="fuchsia/fuchsia" gerrit_path="tools/fidl/fidlc/tests/fidl/good/fi-0051-a.test.fidl" exclude_regexp="\/\/ (Copyright 20|Use of|found in).*" %}
{% includecode gerrit_repo="fuchsia/fuchsia" gerrit_path="tools/fidl/fidlc/tests/fidl/good/fi-0051-b.test.fidl" exclude_regexp="\/\/ (Copyright 20|Use of|found in).*" %}
This error commonly occurs when the fidlc command line invocation is improperly formed. If you are confident that the unknown library exists and should be resolvable, make sure you are passing the dependent library's files correctly via a space-separated list passed to the --files flag.
