The unknown target name error is generated for implicit ReST targets, even though they build correctly, and the output links correctly as well.
Example:
#!rest
Some text that refers to `$this->foo->bar()`_ generates the following error
when building: *ERROR: Unknown target name: "$this->foo->bar()"*
$this->foo->bar()
=================
Lorem ipsum...
The unknown target name error is generated for implicit ReST targets, even though they build correctly, and the output links correctly as well.
Example: