generate-macro-bindings only works when generating bindings from C++ files

[GasInfinity]

Hello, I have been trying to use this project to generate bindings from the XCB library. However, I noticed that when generating bindings from C headers, no constants are generated from the macros.

I have dived into the code and I have found that the generator generates auto constants from the macros in a first pass and then translates the entire ast into C# in a second pass.

Currently, that only works for C++ files.

[tannergooding]

The easiest thing would be to parse the headers using C++. This works for most libraries (including xlib, xcb, etc).

C doesn't really provide any placeholder type specifier that I'm aware of (its auto keyword is a storage-class specifier). The closest thing is _Generic, but that doesn't do what's actually required to make things functional. Because of this limitation in the language and due to how macros work at the language/AST level, there isn't a good solution for allowing macros to be supported for pure C from ClangSharp.

If someone is familiar with a C specific alternative that allows for the compiler to determine the type instead, in a similar manner to how auto works in C++, then I'm all ears; but otherwise the best I can do here is ensure an error is reported if you try to -c generate-macro-bindings with the language set to C.

[GasInfinity]

That was what I was doing, it worked fine until it found invalid C++ code inside 'xkb.h' (a field in a struct was named 'explicit'). So, at least for now I don't think anything can be done unless I modify the headers directly.

If using compiler vendor extensions is allowed, we could use the 'typeof' extension that is also supported by clang.

const __typeof__(2) INTEGER_CONSTANT = 2;
const __typeof__(0xFFFF) OTHER_CONSTANT = 0xFFFF;

That should compile without any kind of problem in clang.

[tannergooding]

Using Clang specific extensions for this should be fine. I'll see if I can get __typeof__(...) working, might be a couple days as I have some other changes I'm also trying to wrap up as part of moving towards Clang v16

[GasInfinity]

I would like to add that If using clang specific behaviour is ok, instead of using __typeof__, we could use '__auto_type', it works exactly like 'auto'.

The gcc docs say that '__auto_type' is not supported when compiling C++ code. However, I've found this PR that added support for that extension in clang, but it differs in behaviour from gcc because it works for C and C++, even before C++11.

Maybe this is what you were looking for before I suggested using __typeof__.

[DeafMan1983]

@GasInfinity
PS Please do not use xcb library because xcb_get_setup() is very buggy for wrapper with C# = not good like I have already used wrapper but it seems crazy with C#. I have followed tutorial with XCB Getting Started
Example:

if I read since running dotnet's console
Output with Width and Height are wrong.
It happens:

Width: 16378
Height -107

That is why you need to write binding for c <-> c# communication/invocation.

I suggest you binding with xcb with pure files with c and h into custom-wrapper for xcb libraries.

...
typedef struct xcb_screen_t xcbsharp_screen_t
...
uint16_t xcbsharp_screen_width_in_pixels(xcbsharp_screen_t* screen);
...

and in source c: You should to add private function for xcb_screen_t and xcbsharp_screen_t conversion or static_cast() ...

I hope you understand cause I was worked before... :/

And sorry for my bad English!

[GasInfinity]

@DeafMan1983 Offtopic here but thanks for your warning, however, the xcb bindings I generated with ClangSharp work perfectly, even when combining it with EGL for OpenGL context creation and usage.

Maintaining a C library with the bindings for it is a lot more hassle than just maintaining a nuget package if it works.

Maybe that was an earlier bug or something?

[DeafMan1983]

You mean EGL with xcb? See EGL Support but you need to compile with whole X11 into static like ./configure--prefix=/YourDev --enable-static --enable-shared --host=x86_64-linux-gnu and XORG because EGL binding has with X11. If you get xcb from download then you should to configure, build and install to your directory 'YourDev' and you can copy all a files from /YourDev/lib/x86_64-linux-gnu to dotnet project's root directory and add

<Directinvoke Include="xcb" />
<NativeLibrary Include="-Wl,-Bstatic libxcb.a -Wl,-Bdynamic" /

Publish dotnet with -p:CppCompilerAndLinker=g++ if you want static with libgcc - you would like to add without libstdc++.

See gist

That is all for dotnet native executable without loading 2 libstc++.so.6 and libgcc_s.so.1

If you want to have static OpenGL then you need to pick up epoxy from LinuxFromScratch and build statical, too.

I hope that you know, how do you develop it?

EDIT I went wrong with xcb that is nice fixed from libxcb from gitlab is very latest and it was resolved problem since I told wrong width and height. Now xcb is successful with C# And happy coding! I have tested xcb and I am surprised because C# and c are same now.
Check my screenshot

That is result c and c#:

Thank you for great support! I will help you. :)