1 extern crate autocfg; 2 main()3fn main() { 4 // Normally, cargo will set `OUT_DIR` for build scripts. 5 let ac = autocfg::AutoCfg::with_dir("target").unwrap(); 6 7 // since ancient times... 8 ac.emit_has_trait("std::ops::Add"); 9 ac.emit_trait_cfg("std::ops::Add", "has_ops"); 10 11 // trait parameters have to be provided 12 ac.emit_has_trait("std::borrow::Borrow<str>"); 13 ac.emit_trait_cfg("std::borrow::Borrow<str>", "has_borrow"); 14 15 // rustc 1.8.0 16 ac.emit_has_trait("std::ops::AddAssign"); 17 ac.emit_trait_cfg("std::ops::AddAssign", "has_assign_ops"); 18 19 // rustc 1.12.0 20 ac.emit_has_trait("std::iter::Sum"); 21 ac.emit_trait_cfg("std::iter::Sum", "has_sum"); 22 23 // rustc 1.28.0 24 ac.emit_has_trait("std::alloc::GlobalAlloc"); 25 ac.emit_trait_cfg("std::alloc::GlobalAlloc", "has_global_alloc"); 26 } 27