[Bug rust/122888] rust/ast/rust-fmt.h: templates through extern "C" linkage ?

[schwab--- via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=122888

--- Comment #1 from Andreas Schwab <sch...@linux-m68k.org> ---
// TODO: Should we instead make an FFIVector struct?
type PieceVec<'a> = ffi::FFIVec<ffi::Piece<'a>>;