A generation mode for -sys crates

[mzabaluev]

A smaller goal than #1 is to implement the generation mode to produce just the sys crates, to stop manually editing the currently maintained -sys crates and enable generation of many more linkage crates from GIR.

A list of existing -sys crates that could benefit from this:

• https://github.com/gi-rust/glib-sys
• https://github.com/gi-rust/gobject-sys
• https://github.com/crumblingstatue/rust-libnotify-sys

[gkoz]

To be clear, has any progress toward this goal been made so far?

[mzabaluev]

There is an old branch, 'codegen', with some preliminary groundwork in Python reusing the parser and AST from gobject-introspection.

[gkoz]

Some observations after playing with GIR... As mentioned in #1, typelibs alone are indeed inadequate for this purpose.

• Platform-dependent integers are already resolved to specific fixed-width ones.
• There are no version annotations so you need to process the definitions for each library version separately (extra fun with interdependencies expected).
• Variadic functions are completely ignored! Good luck creating a simple message dialog.

I'm sure there's more. So even this smaller goal requires kludges, possibly some manual overlay definitions.

[mzabaluev]

@gkoz GIR XML has none of those issues, and that is what I intend to use as the source format.

[gkoz]

Interesting. I've been making the XMLs out of typelibs assuming they're equivalent. I'll have to try generating them from sources then.

[gkoz]

You're right, the GIR definitions generated from source files are much more comprehensive, they should be workable.

[mzabaluev]

Development of the generator is underway in https://github.com/gi-rust/grust-gen.