Build scripts which build C++ or take arbitrary actions

Some crates use the cc crate to build and link C/C++ libraries. Other crates parse C/C++ using bindgen within their build scripts. These actions can’t be supported in a Chromium context — our gn, ninja and LLVM build system is very specific in expressing relationships between build actions.

So, your options are:

• Avoid these crates
• Apply a patch to the crate.

Patches should be kept in third_party/rust/chromium_crates_io/patches/<crate> - see for example the patches against the cxx crate - and will be applied automatically by gnrt each time it upgrades the crate.