Namespace completion not triggered after `new \` or any backslash

[osrec]

Namespace completion not triggered after new \ or \

Environment

• Intelephense version: 1.17.3
• VS Code version: 1.112.0
• OS: Ubuntu Linux (UK keyboard layout)

Description
Typing \ does not trigger namespace completion suggestions, despite \ being registered as a trigger character in Intelephense's capabilities. The completion request is sent correctly with triggerKind: 2 and triggerCharacter: "\\", but Intelephense returns an empty result set immediately (within ~4ms, suggesting it is rejecting the context rather than searching).

Steps to reproduce

1. Open any PHP file with a namespace declared
2. Inside a method body, type $x = new \ or just \
3. Observe that no completion suggestions appear
4. Typing a class name however does work, and will also import in the fully qualified name in a use statement at the top of the file.

Expected behaviour
A list of available namespaces and classes should appear, e.g. \App\, \Illuminate\, allowing the user to browse and select a fully qualified class name.

Actual behaviour
No suggestions are returned. The LSP trace shows:

{
    "context": {
        "triggerKind": 2,
        "triggerCharacter": "\\"
    }
}

{
    "items": [],
    "isIncomplete": false
}

Additional context

• Typing use \ correctly triggers namespace suggestions — the bug is specific to the new \ context
• Typing a partial class name after new (without \) works correctly and triggers class suggestions with auto-import
• The \ trigger character is present in the server's initialize response:

"triggerCharacters": ["$", ">", ":", "\\", "/", "'", "\"", "*", ".", "<"]

• On a UK keyboard layout, VS Code identifies the \ key as IntlBackslash rather than Backslash, meaning triggerKind: 2 was not firing at all without a custom keybinding workaround — however even after fixing the trigger kind, the completion result remains empty

[bmewburn]

If the prompt is an empty string, nothing is deliberately returned because it would be just a dump of all known symbols. Would it be useful to have such a large list returned?

[osrec]

It seems to be the functionality in other IDEs. I would say it's definitely useful. Maybe just return the first few options to begin with, and narrow it down as the user types more chars.