I have a bunch of classes in src/Controller, src/Entity, src/Form etc. For each of them Netbeans tells me that "namespace declaration name doesn't correspond to current directory structure". My namespaces:
namespace App\Controller;
namespace App\Entity;
namespace App\Form;
Is it Symfony or Netbeans issue? Is it something to be worried about?
There is no problem with Symfony, and there is nothing to be worried about. The contradiction is as follow:
Symfony4 structure is based in namespaces but still is under src/ directory the default namespace is App and netbeans expects your namespace to be something like src/Controller/MyController or any other pattern that matches with the folder structure.
Also the standard used by Symfony to autoload files is psr-4, to check this you may take a look at composer.json or under composer installation directory.
Try to check the netbeans configuration under Tools->Options->Editor->Hints->PHP->PSR and select the proper autoload configuration
You can check the diferences of psr-0 and psr-4 to understand why netbeans is throwing those warnings.
Hope it helps!