Don't panic on intrinsics

example.rs

@@ -1,4 +1,4 @@
-#![feature(no_core, lang_items)]
+#![feature(no_core, lang_items, intrinsics)]
 #![no_core]
 #![allow(dead_code)]
 
@@ -68,6 +68,10 @@ unsafe fn drop_in_place<T: ?Sized>(to_drop: *mut T) {
     drop_in_place(to_drop);
 }
 
+extern "rust-intrinsic" {
+    fn copy<T>(src: *const T, dst: *mut T, count: usize);
+}
+
 fn abc(a: u8) -> u8 {
     a * 2
 }
@@ -144,3 +148,12 @@ struct DebugTuple(());
 fn debug_tuple() -> DebugTuple {
     DebugTuple(())
 }
+
+unsafe fn use_copy_intrinsic(src: *const u8, dst: *mut u8) {
+    copy::<u8>(src, dst, 1);
+}
+
+/*unsafe fn use_copy_intrinsic_ref(src: *const u8, dst: *mut u8) {
+    let copy2 = &copy::<u8>;
+    copy2(src, dst, 1);
+}*/

src/abi.rs

@@ -15,6 +15,8 @@ pub fn cton_sig_from_fn_ty<'a, 'tcx: 'a>(tcx: TyCtxt<'a, 'tcx, 'tcx>, fn_ty: Ty<
             unimplemented!();
         }
         Abi::System => bug!("system abi should be selected elsewhere"),
+        // TODO: properly implement intrinsics
+        Abi::RustIntrinsic => (CallConv::SystemV, sig.inputs().to_vec(), sig.output()),
         _ => unimplemented!("unsupported abi {:?}", sig.abi),
     };
     Signature {

src/base.rs

@@ -322,7 +322,7 @@ fn trans_stmt<'a, 'tcx: 'a>(fx: &mut FunctionCx<'a, 'tcx>, cur_ebb: Ebb, stmt: &
                     }
                 },
                 Rvalue::Cast(CastKind::ClosureFnPointer, operand, ty) => unimplemented!("rval closure_fn_ptr {:?} {:?}", operand, ty),
-                Rvalue::Cast(CastKind::Unsize, operand, ty) => unimplemented!("rval unsize {:?} {:?}", operand, ty),
+                Rvalue::Cast(CastKind::Unsize, operand, ty) => return Err(format!("rval unsize {:?} {:?}", operand, ty)),
                 Rvalue::Discriminant(place) => {
                     let place = trans_place(fx, place);
                     let dest_cton_ty = fx.cton_type(dest_layout.ty).unwrap();

src/constant.rs

@@ -14,6 +14,7 @@ pub fn trans_constant<'a, 'tcx: 'a>(fx: &mut FunctionCx<'a, 'tcx>, const_: &Cons
             }))
             .unwrap(),
     };
+    fx.tcx.sess.warn(&format!("const: {:?}", value));
 
     let ty = fx.monomorphize(&const_.ty);
     let layout = fx.layout_of(ty);