Move monomorphize code to its own crate.

compiler/rustc_monomorphize/src/lib.rs

@@ -0,0 +1,49 @@
+#![feature(array_windows)]
+#![feature(bool_to_option)]
+#![feature(crate_visibility_modifier)]
+#![feature(control_flow_enum)]
+#![feature(in_band_lifetimes)]
+
+#[macro_use]
+extern crate tracing;
+#[macro_use]
+extern crate rustc_middle;
+
+use rustc_hir::lang_items::LangItem;
+use rustc_middle::traits;
+use rustc_middle::ty::adjustment::CustomCoerceUnsized;
+use rustc_middle::ty::query::Providers;
+use rustc_middle::ty::{self, Ty, TyCtxt};
+
+mod collector;
+mod partitioning;
+mod polymorphize;
+mod util;
+
+fn custom_coerce_unsize_info<'tcx>(
+    tcx: TyCtxt<'tcx>,
+    source_ty: Ty<'tcx>,
+    target_ty: Ty<'tcx>,
+) -> CustomCoerceUnsized {
+    let def_id = tcx.require_lang_item(LangItem::CoerceUnsized, None);
+
+    let trait_ref = ty::Binder::dummy(ty::TraitRef {
+        def_id,
+        substs: tcx.mk_substs_trait(source_ty, &[target_ty.into()]),
+    });
+
+    match tcx.codegen_fulfill_obligation((ty::ParamEnv::reveal_all(), trait_ref)) {
+        Ok(traits::ImplSource::UserDefined(traits::ImplSourceUserDefinedData {
+            impl_def_id,
+            ..
+        })) => tcx.coerce_unsized_info(impl_def_id).custom_kind.unwrap(),
+        impl_source => {
+            bug!("invalid `CoerceUnsized` impl_source: {:?}", impl_source);
+        }
+    }
+}
+
+pub fn provide(providers: &mut Providers) {
+    partitioning::provide(providers);
+    polymorphize::provide(providers);
+}