Every bug below must be fixed at its root cause. "Detect the symptom and suppress the diagnostic" is not an acceptable fix. If the type resolution pipeline produces wrong data, fix the pipeline so it produces correct data. Downstream consumers (diagnostics, hover, completion, definition) should never need to second-guess upstream output.
Blocked on: phpstorm-stubs#1882
PDOStatement::fetch() and PDOStatement::fetchAll() return
different types depending on the fetch mode constant passed as
the first argument. Once the upstream PR is merged and we update
our stubs, the existing conditional return type support should
handle this automatically.
Tests: Assertion lines were removed from
tests/psalm_assertions/method_call.php (out of scope until
upstream stubs land).