Disallow partial uses in ReferenceUsedNamesOnly

[dereuromark]

Fixes #430.

Partial namespace references like Mockery\MockInterface (as opposed to the FQCN form \Mockery\MockInterface) were not flagged by SlevomatCodingStandard.Namespaces.ReferenceUsedNamesOnly because Slevomat's allowPartialUses property defaults to true.

Setting it to false makes the sniff flag such references so they must be imported via a use statement.

Before

namespace App\Test;

class FooTest {
    public function bar(Mockery\MockInterface $x): void {}  // not flagged
}

After

ERROR | Partial use statements are not allowed, but referencing Mockery\MockInterface found.

The FQCN form (\Mockery\MockInterface) was and remains flagged by the same sniff.

Note: this is a behavior-tightening change. Downstream code that intentionally uses partial imports would be affected - but I guess thats fair enough as they could change it back themselves.

[ADmad]

Won't this throw error for current usages like https://github.com/cakephp/cakephp/blob/d70712c983e6879bfcddd67d975d4b8ef3328aae/src/Database/TypeFactory.php#L33 ?

[dereuromark]

This goes into 6.x right now, we can backport it, but thats indeed a bit breaking.
Maybe for 5.next and a new minor?

[LordSimal]

technically nothing can break, its just a code style change. I'd say this can stay in 6.x

[dereuromark]

cakephp/cakephp#19391

[ADmad]

My point was this rule is a bit too pedantic for my liking.

[ADmad]

If the latest PER standard allows such partial usages then I would be in favor of keeping it.

[dereuromark]

Partials make the review much harder for humans IMO, as you need to scope in the context then always (you cannot directly see if this is root level or nested namespace).
For machines there is no difference of course.
But handling this manually is a bit more cumbersome.

Disallow partial uses

Pros

• One canonical form: every external class is in the use block. Easy to scan dependencies.
• Refactors and static analysis are more reliable.
• Enforces aliasing for real collisions, which is explicit rather than implicit.
• Matches the spirit of PSR-12 / most modern PHP style guides.

Cons

• Forces use ... as Alias for name clashes, which some find uglier than a short partial path.
• Loses the "namespace-as-context" readability in domain-heavy code.
• Migration cost when tightening the rule on an existing codebase.

[LordSimal]

I don't mind either way, i just thought its obvious to keep it more consistent.