Use imported library with prefix (remove hide/add show) adds new prefix to use

[FMorschel]

After #54786 was closed, we now have a bug in the following code when using the assist:

file.dart:

class A {}

main.dart

import 'file.dart' as f hide A;

void foo(l.A a) {} // <-- Use imported library with prefix...

Currently adds a new prefix so at that line we end up with void foo(l.l.A a) {}.

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Also, prefix-related, I think this could probably be fixed together. If the code was instead:

import 'file.dart' as f hide A; // Unneded for the explanation but a reason for the prefix later in the file
import 'file.dart' hide A;

void foo(l.A a) {} // <-- Update library import

It removes the hide A but it doesn't look whether there is a prefix on the element. I'm unsure if this suggestion should be suppressed or if we should remove the prefix (preferred) in that case (there is no suggestion if the hide A or a show is not present at the import).

[dart-github-bot]

Summary: The "Use imported library with prefix" assist incorrectly adds a new prefix when the import already has a prefix, resulting in a double prefix. Additionally, the assist removes hide A from imports without considering existing prefixes, potentially leading to incorrect code.