This patch introduces a new Rust crate called `static_prefs`.
It also changes generate_static_pref_list.py to generate two new files.
- StaticPrefsCGetters.cpp: contains C getters, which are just wrappers around
the C++ getters. This is included into Preferences.cpp.
- static_prefs.rs: contains declarations for the C getters, plus the `pref!`
macro which provides nice syntax for calling the C getters. This is included
into static_prefs/src/lib.rs.
The new code is only generated for prefs marked with the new `rust` field in
the YAML. It's opt-in because there's no point generating additional code for
900+ static prefs when only about 20 are currently used from Rust.
This patch only marks a single pref (`browser.display.document_color_use`) with
`rust: true`. That pref isn't accessed from Rust code in this patch, but it's
necessary because the generated Rust code is invalid if there are zero
Rust-accessed prefs. (The next patch will access that pref and others from Rust
code.
Differential Revision: https://phabricator.services.mozilla.com/D40791
--HG--
extra : moz-landing-system : lando
Kristen Wright
Nicholas Nethercote
Tom Ritter