False `unknown_member` in `elseif` after `instanceof` branch

[alexchexes]

PHPantom version

phpantom_lsp 0.8.0-dirty

Installation method

Pre-built binary from GitHub Releases

Operating system

Windows x86_64

Editor

VS Code

Bug description

PHPantom reports unknown_member inside an elseif branch guarded by is_callable([$value, 'getTime']), using the class type from the previous instanceof branch.

Expected: no diagnostic. The elseif branch only runs when $value is not the class checked in the previous if, and the method call is guarded by is_callable().

Actual: PHPantom reports Method 'getTime' not found on class 'Repro\KnownDateLike'.

Steps to reproduce

1. Use any supported PHP version.
2. Create a PHP file with:

<?php

namespace Repro;

final class KnownDateLike
{
    public function format(): string
    {
        return 'formatted';
    }
}

function formatDateLike(int|string|KnownDateLike|object|null $value): string
{
    if ($value === null) {
        return '';
    }

    if (is_object($value)) {
        if ($value instanceof KnownDateLike) {
            $value = $value->format();
        } elseif (is_callable([$value, 'getTime'])) {
            $value = (string) $value->getTime();
        }
    }

    return (string) $value;
}

3. Run diagnostics.

PHPantom reports:

31  Method 'getTime' not found on class 'Repro\KnownDateLike'
    unknown_member

Error output or panic trace

.phpantom.toml

Additional context

Binary source

Originally observed in the VS Code extension v0.5.0. Reproduced with the extension-cached GitHub Releases binary.