G_LIKELY doesn’t appear in gi-docgen documentation
See https://docs.gtk.org/glib/func.LIKELY.html. Do note that function macros can be documented, e.g. https://gnome.pages.gitlab.gnome.org/libadwaita/doc/main/func.CHECK_VERSION.html.
The file docs.c contains
/**
* G_LIKELY:
* @expr: the expression
*
* Hints the compiler that the expression is likely to evaluate to
* a true value. The compiler may use this information for optimizations.
*
* |[<!-- language="C" -->
* if (G_LIKELY (random () != 1))
* g_print ("not one");
* ]|
*
* Returns: the value of @expr
*
* Since: 2.2
*/
since 2011. With the exception of the code block (maybe this is OK though?) it should be OK. Is this file being parsed by gi-docgen?