adding ffi, not building enzyme yet

Author: ZuseZ4

compiler/rustc_codegen_llvm/src/lib.rs

@@ -29,6 +29,10 @@ use back::owned_target_machine::OwnedTargetMachine;
 use back::write::{create_informational_target_machine, create_target_machine};
 
 use errors::ParseTargetMachineConfig;
+
+#[allow(unused_imports)]
+use llvm::TypeTree;
+
 pub use llvm_util::target_features;
 use rustc_ast::expand::allocator::AllocatorKind;
 use rustc_codegen_ssa::back::lto::{LtoModuleCodegen, SerializedModule, ThinModule};