make some intrinsics safe.

src/librustc_typeck/check/intrinsic.rs

@@ -66,6 +66,17 @@ fn equate_intrinsic_type<'a, 'tcx>(
     require_same_types(tcx, &cause, tcx.mk_fn_ptr(tcx.fn_sig(def_id)), fty);
 }
 
+/// Returns whether the given intrinsic is unsafe to call or not.
+pub fn intrisic_operation_unsafety(intrinsic: &str) -> hir::Unsafety {
+    match intrinsic {
+        "size_of" | "min_align_of" | "needs_drop" |
+        "overflowing_add" | "overflowing_sub" | "overflowing_mul" |
+        "rotate_left" | "rotate_right"
+        => hir::Unsafety::Normal,
+        _ => hir::Unsafety::Unsafe,
+    }
+}
+
 /// Remember to add all intrinsics here, in librustc_codegen_llvm/intrinsic.rs,
 /// and in libcore/intrinsics.rs
 pub fn check_intrinsic_type<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
@@ -117,10 +128,7 @@ pub fn check_intrinsic_type<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
     } else if &name[..] == "abort" || &name[..] == "unreachable" {
         (0, Vec::new(), tcx.types.never, hir::Unsafety::Unsafe)
     } else {
-        let unsafety = match &name[..] {
-            "size_of" | "min_align_of" | "needs_drop" => hir::Unsafety::Normal,
-            _ => hir::Unsafety::Unsafe,
-        };
+        let unsafety = intrisic_operation_unsafety(&name[..]);
         let (n_tps, inputs, output) = match &name[..] {
             "breakpoint" => (0, Vec::new(), tcx.mk_unit()),
             "size_of" |

src/librustc_typeck/check/mod.rs

@@ -80,7 +80,7 @@ mod closure;
 mod callee;
 mod compare_method;
 mod generator_interior;
-mod intrinsic;
+pub mod intrinsic;
 mod op;
 
 use astconv::{AstConv, PathSeg};

src/librustc_typeck/collect.rs

@@ -16,6 +16,7 @@
 
 use astconv::{AstConv, Bounds};
 use constrained_type_params as ctp;
+use check::intrinsic::intrisic_operation_unsafety;
 use lint;
 use middle::lang_items::SizedTraitLangItem;
 use middle::resolve_lifetime as rl;
@@ -2076,10 +2077,7 @@ fn compute_sig_of_foreign_fn_decl<'a, 'tcx>(
     abi: abi::Abi,
 ) -> ty::PolyFnSig<'tcx> {
     let unsafety = if abi == abi::Abi::RustIntrinsic {
-        match &*tcx.item_name(def_id).as_str() {
-            "size_of" | "min_align_of" | "needs_drop" => hir::Unsafety::Normal,
-            _ => hir::Unsafety::Unsafe,
-        }
+        intrisic_operation_unsafety(&*tcx.item_name(def_id).as_str())
     } else {
         hir::Unsafety::Unsafe
     };