`RuntimesFolderResolver` fails on Ubuntu

[xen2]

Summary

RuntimesFolderResolver fails on Ubuntu (and other distros missing from hardcoded _linuxRiDs list)

Problem

DefaultPathResolver.RuntimesFolderResolver fails to find native libraries in runtimes/linux-x64/native/ when running on Ubuntu because ubuntu is missing from the hardcoded _linuxRiDs array:

private static readonly string[] _linuxRiDs =
{
    "alpine", "android", "arch", "centos", "debian", "exherbo", "fedora", "freebsd", "gentoo", "linux",
    "opensuse", "rhel", "sles", "tizen", "pop"
};

GuessFallbackRid uses this list to decide whether to fall back from a distro-specific RID (e.g. ubuntu.24.04-x64) to linux-x64. Since ubuntu is not in the list, the method returns null and the resolver only searches runtimes/ubuntu.24.04-x64/native/ — which doesn't exist — and never reaches runtimes/linux-x64/native/.

Windows is unaffected because win has its own hardcoded fallback path (line 394-397) that doesn't depend on this list.

Reproduction

# On Ubuntu 24.04, build a project referencing Silk.NET.SDL (without -r)
dotnet build

# Run via dotnet vstest
dotnet vstest bin/Debug/net10.0/MyTests.dll
# -> FileNotFoundException: Could not load from any of the possible library names!

The native library exists at runtimes/linux-x64/native/libSDL2-2.0.so but is never found.

Suggested Fixes

Quick fix (fragile): Add missing distros (ubuntu, linuxmint, rocky, ol, amzn, ...) to _linuxRiDs. This will break again for any new distro not in the list.

Robust fix ideas:

if (OperatingSystem.IsLinux())
{
    // Check with linux-x64/x86/arm/arm64 depending on RuntimeInformation.OSArchitecture
}

Environment

• Silk.NET 2.22.0
• .NET 10.0
• Ubuntu 24.04 (RID: ubuntu.24.04-x64)
• Running via dotnet vstest