stabilize const_int_wrapping.

3 files changed, 32 insertions, 18 deletions

diff --git a/src/libcore/lib.rs b/src/libcore/lib.rs
index 5ea765d3585..a613c1afd09 100644
--- a/src/libcore/lib.rs
+++ b/src/libcore/lib.rs
@@ -114,7 +114,6 @@
 #![feature(const_str_as_bytes)]
 #![feature(const_str_len)]
 #![feature(const_int_rotate)]
-#![feature(const_int_wrapping)]
 #![feature(const_int_sign)]
 #![feature(const_int_conversion)]
 #![feature(const_transmute)]
diff --git a/src/libcore/num/mod.rs b/src/libcore/num/mod.rs
index 97bf582df5a..58ea651aa83 100644
--- a/src/libcore/num/mod.rs
+++ b/src/libcore/num/mod.rs
@@ -994,7 +994,7 @@ assert_eq!(", stringify!($SelfT), "::max_value().wrapping_add(2), ", stringify!(
 $EndFeature, "
 ```"),
             #[stable(feature = "rust1", since = "1.0.0")]
-            #[rustc_const_unstable(feature = "const_int_wrapping")]
+            #[cfg_attr(stage0, rustc_const_unstable(feature = "const_int_wrapping"))]
             #[inline]
             pub const fn wrapping_add(self, rhs: Self) -> Self {
                 unsafe {
@@ -1018,7 +1018,7 @@ stringify!($SelfT), "::max_value());",
 $EndFeature, "
 ```"),
             #[stable(feature = "rust1", since = "1.0.0")]
-            #[rustc_const_unstable(feature = "const_int_wrapping")]
+            #[cfg_attr(stage0, rustc_const_unstable(feature = "const_int_wrapping"))]
             #[inline]
             pub const fn wrapping_sub(self, rhs: Self) -> Self {
                 unsafe {
@@ -1041,7 +1041,7 @@ assert_eq!(11i8.wrapping_mul(12), -124);",
 $EndFeature, "
 ```"),
             #[stable(feature = "rust1", since = "1.0.0")]
-            #[rustc_const_unstable(feature = "const_int_wrapping")]
+            #[cfg_attr(stage0, rustc_const_unstable(feature = "const_int_wrapping"))]
             #[inline]
             pub const fn wrapping_mul(self, rhs: Self) -> Self {
                 unsafe {
@@ -1205,7 +1205,7 @@ assert_eq!((-1", stringify!($SelfT), ").wrapping_shl(128), -1);",
 $EndFeature, "
 ```"),
             #[stable(feature = "num_wrapping", since = "1.2.0")]
-            #[rustc_const_unstable(feature = "const_int_wrapping")]
+            #[cfg_attr(stage0, rustc_const_unstable(feature = "const_int_wrapping"))]
             #[inline]
             pub const fn wrapping_shl(self, rhs: u32) -> Self {
                 unsafe {
@@ -1233,7 +1233,7 @@ assert_eq!((-128i16).wrapping_shr(64), -128);",
 $EndFeature, "
 ```"),
             #[stable(feature = "num_wrapping", since = "1.2.0")]
-            #[rustc_const_unstable(feature = "const_int_wrapping")]
+            #[cfg_attr(stage0, rustc_const_unstable(feature = "const_int_wrapping"))]
             #[inline]
             pub const fn wrapping_shr(self, rhs: u32) -> Self {
                 unsafe {
@@ -2884,7 +2884,7 @@ assert_eq!(200", stringify!($SelfT), ".wrapping_add(", stringify!($SelfT), "::ma
 $EndFeature, "
 ```"),
             #[stable(feature = "rust1", since = "1.0.0")]
-            #[rustc_const_unstable(feature = "const_int_wrapping")]
+            #[cfg_attr(stage0, rustc_const_unstable(feature = "const_int_wrapping"))]
             #[inline]
             pub const fn wrapping_add(self, rhs: Self) -> Self {
                 unsafe {
@@ -2907,7 +2907,7 @@ assert_eq!(100", stringify!($SelfT), ".wrapping_sub(", stringify!($SelfT), "::ma
 $EndFeature, "
 ```"),
             #[stable(feature = "rust1", since = "1.0.0")]
-            #[rustc_const_unstable(feature = "const_int_wrapping")]
+            #[cfg_attr(stage0, rustc_const_unstable(feature = "const_int_wrapping"))]
             #[inline]
             pub const fn wrapping_sub(self, rhs: Self) -> Self {
                 unsafe {
@@ -2931,7 +2931,7 @@ $EndFeature, "
         /// assert_eq!(25u8.wrapping_mul(12), 44);
         /// ```
         #[stable(feature = "rust1", since = "1.0.0")]
-        #[rustc_const_unstable(feature = "const_int_wrapping")]
+        #[cfg_attr(stage0, rustc_const_unstable(feature = "const_int_wrapping"))]
         #[inline]
         pub const fn wrapping_mul(self, rhs: Self) -> Self {
             unsafe {
@@ -3081,7 +3081,7 @@ Basic usage:
 assert_eq!(1", stringify!($SelfT), ".wrapping_shl(128), 1);", $EndFeature, "
 ```"),
             #[stable(feature = "num_wrapping", since = "1.2.0")]
-            #[rustc_const_unstable(feature = "const_int_wrapping")]
+            #[cfg_attr(stage0, rustc_const_unstable(feature = "const_int_wrapping"))]
             #[inline]
             pub const fn wrapping_shl(self, rhs: u32) -> Self {
                 unsafe {
@@ -3111,7 +3111,7 @@ Basic usage:
 assert_eq!(128", stringify!($SelfT), ".wrapping_shr(128), 128);", $EndFeature, "
 ```"),
             #[stable(feature = "num_wrapping", since = "1.2.0")]
-            #[rustc_const_unstable(feature = "const_int_wrapping")]
+            #[cfg_attr(stage0, rustc_const_unstable(feature = "const_int_wrapping"))]
             #[inline]
             pub const fn wrapping_shr(self, rhs: u32) -> Self {
                 unsafe {
diff --git a/src/librustc_mir/transform/qualify_min_const_fn.rs b/src/librustc_mir/transform/qualify_min_const_fn.rs
index c1c5b18915a..f271fbaa55b 100644
--- a/src/librustc_mir/transform/qualify_min_const_fn.rs
+++ b/src/librustc_mir/transform/qualify_min_const_fn.rs
@@ -342,15 +342,11 @@ fn check_terminator(
                 // some intrinsics are waved through if called inside the
                 // standard library. Users never need to call them directly
                 match tcx.fn_sig(def_id).abi() {
-                    abi::Abi::RustIntrinsic => match &tcx.item_name(def_id).as_str()[..] {
-                        | "size_of"
-                        | "min_align_of"
-                        | "needs_drop"
-                        => {},
-                        _ => return Err((
+                    abi::Abi::RustIntrinsic => if !is_intrinsic_whitelisted(tcx, def_id) {
+                        return Err((
                             span,
                             "can only call a curated list of intrinsics in `min_const_fn`".into(),
-                        )),
+                        ))
                     },
                     abi::Abi::Rust if tcx.is_min_const_fn(def_id) => {},
                     abi::Abi::Rust => return Err((
@@ -390,3 +386,22 @@ fn check_terminator(
         },
     }
 }
+
+/// Returns true if the `def_id` refers to an intrisic which we've whitelisted.
+///
+/// Adding more intrinsics requires sign-off from @rust-lang/lang.
+fn is_intrinsic_whitelisted(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> bool {
+    match &tcx.item_name(def_id).as_str()[..] {
+        | "size_of"
+        | "min_align_of"
+        | "needs_drop"
+        // Arithmetic:
+        | "overflowing_add" // ~> wrapping_add
+        | "overflowing_sub" // ~> wrapping_sub
+        | "overflowing_mul" // ~> wrapping_mul
+        | "unchecked_shl" // ~> wrapping_shl
+        | "unchecked_shr" // ~> wrapping_shr
+        => true,
+        _ => false,
+    }
+}