Godot C# Parser Fails to Parse Namespace Alias Qualifiers

[sethdmoore]

Godot version:
v3.1.mono.official

OS/device including version:
Windows 10

Issue description:
Cannot compile C# script with namespace alias qualifier.
Using Visual Studio 2019 MSBUILD.

Minimal reproduction project:
Build with following script

using shorthand = System.Collections.Generic;

public class KeyExtension : shorthand::KeyNotFoundException {}

Result

 modules/mono/editor/csharp_project.cpp:183 - Parse error: Unexpected token: :
 Failed to determine namespace and class for script: res://Scripts/Card.cs
 modules/mono/editor/mono_bottom_panel.cpp:168 - Condition ' metadata_err != OK ' is true

Sanity
The above script compiles in Visual Studio Community 2019.
If I change the script from using '::' to a '.', it will compile in Godot.
EG:

using shorthand = System.Collections.Generic;

public class KeyExtension : shorthand.KeyNotFoundException {}

Use Case
We are using protoc (Google's Protobuf) to generate C# files for our Godot project. It generates fine on the Golang backend, but the generated C# code will not compile due to it generating namespace aliases.
EG (partial generated code):

using pb = global::Google.Protobuf;
namespace Card {
  public sealed partial class Card : pb::IMessage<Card> {}
}

[sethdmoore]

In the off chance that someone else encounters this issue with protobufs and Godot (or they really like namespace alias qualifiers), I've written a python script to alter scripts to satisfy Godot's parser peculiarities.

It's a hack, but it unblocks me for now.

fix_namespace_alias_qualifiers.py�

[sethdmoore]

Is there any movement on this? We depend on protoc to generate code for C# protobufs, so I find it important to not rely on python hacks.

[jonathancm]

I can confirm that this is still the case in Godot v3.2.1.

We have a similar setup where we also use Google Protocol Buffer and the generated files contain namespace alias qualifiers. It works fine when we run, but it fails to build.

[Calinou]

cc @neikeq

[sylv256]

I'm also encountering a similar issue in Godot v3.2.1. It seems that not all of the components of the Protobuf library are available. I've installed the NuGet package and everything, but no luck. It can't find my compiled protobuf files for some reason.

[Sslaxx]

This appears to be the case in 3.3 still, if the README for https://github.com/HaxeGodot/godot/ is accurate. @ibilon

[ibilon]

Yes I still have that issue in 3.3.
modules/mono/glue/gd_glue.cpp:250 - Failed to determine namespace and class for script: res://build/src/Main.cs. Parse error: Unexpected token: :
with the Haxe generated c# code public class Main : global::Godot.Spatial { (...)
I'll try on godot 4 to see if that's already fixed there.

[ibilon]

Testing on Godot 4, with the class public partial class MyNode : global::Godot.Node2D or the code from the first post, building doesn't show any warning.
I'll take a look if I can make a fix for the parser on 3.3.

[neikeq]

We switched to source generators to collect qualified names in Godot 4.
I don't think it's a good idea to keep patching our simple parser in Godot 3.2. If we want to fix those bugs, it may be a better idea to replace it with roslyn there.