Rollup of 10 pull requests

src/libcore/intrinsics.rs

@@ -1007,6 +1007,16 @@ extern "rust-intrinsic" {
     /// This will statically either panic, or do nothing.
     pub fn panic_if_uninhabited<T>();
 
+    /// A guard for unsafe functions that cannot ever be executed if `T` does not permit
+    /// zero-initialization: This will statically either panic, or do nothing.
+    #[cfg(not(bootstrap))]
+    pub fn panic_if_zero_invalid<T>();
+
+    /// A guard for unsafe functions that cannot ever be executed if `T` has invalid
+    /// bit patterns: This will statically either panic, or do nothing.
+    #[cfg(not(bootstrap))]
+    pub fn panic_if_any_invalid<T>();
+
     /// Gets a reference to a static `Location` indicating where it was called.
     #[rustc_const_unstable(feature = "const_caller_location", issue = "47809")]
     pub fn caller_location() -> &'static crate::panic::Location<'static>;
@@ -1852,6 +1862,7 @@ extern "rust-intrinsic" {
     ///
     /// The stabilized version of this intrinsic is
     /// [`std::mem::discriminant`](../../std/mem/fn.discriminant.html)
+    #[rustc_const_unstable(feature = "const_discriminant", issue = "69821")]
     pub fn discriminant_value<T>(v: &T) -> u64;
 
     /// Rust's "try catch" construct which invokes the function pointer `f` with

src/libcore/lib.rs

@@ -72,6 +72,7 @@
 #![feature(concat_idents)]
 #![feature(const_ascii_ctype_on_intrinsics)]
 #![feature(const_alloc_layout)]
+#![feature(const_discriminant)]
 #![feature(const_if_match)]
 #![feature(const_loop)]
 #![feature(const_checked_int_methods)]
@@ -130,7 +131,6 @@
 #![feature(rtm_target_feature)]
 #![feature(f16c_target_feature)]
 #![feature(hexagon_target_feature)]
-#![feature(const_int_conversion)]
 #![feature(const_transmute)]
 #![feature(structural_match)]
 #![feature(abi_unadjusted)]

src/libcore/mem/mod.rs

@@ -496,6 +496,9 @@ pub const fn needs_drop<T>() -> bool {
 #[allow(deprecated)]
 #[rustc_diagnostic_item = "mem_zeroed"]
 pub unsafe fn zeroed<T>() -> T {
+    #[cfg(not(bootstrap))]
+    intrinsics::panic_if_zero_invalid::<T>();
+    #[cfg(bootstrap)]
     intrinsics::panic_if_uninhabited::<T>();
     intrinsics::init()
 }
@@ -529,6 +532,9 @@ pub unsafe fn zeroed<T>() -> T {
 #[allow(deprecated)]
 #[rustc_diagnostic_item = "mem_uninitialized"]
 pub unsafe fn uninitialized<T>() -> T {
+    #[cfg(not(bootstrap))]
+    intrinsics::panic_if_any_invalid::<T>();
+    #[cfg(bootstrap)]
     intrinsics::panic_if_uninhabited::<T>();
     intrinsics::uninit()
 }
@@ -864,6 +870,7 @@ impl<T> fmt::Debug for Discriminant<T> {
 /// assert_ne!(mem::discriminant(&Foo::B(3)), mem::discriminant(&Foo::C(3)));
 /// ```
 #[stable(feature = "discriminant_value", since = "1.21.0")]
-pub fn discriminant<T>(v: &T) -> Discriminant<T> {
+#[rustc_const_unstable(feature = "const_discriminant", issue = "69821")]
+pub const fn discriminant<T>(v: &T) -> Discriminant<T> {
     Discriminant(intrinsics::discriminant_value(v), PhantomData)
 }

src/libcore/num/mod.rs

@@ -2154,7 +2154,7 @@ let bytes = ", $swap_op, stringify!($SelfT), ".to_be_bytes();
 assert_eq!(bytes, ", $be_bytes, ");
 ```"),
             #[stable(feature = "int_to_from_bytes", since = "1.32.0")]
-            #[rustc_const_unstable(feature = "const_int_conversion", issue = "53718")]
+            #[rustc_const_stable(feature = "const_int_conversion", since = "1.43.0")]
             #[inline]
             pub const fn to_be_bytes(self) -> [u8; mem::size_of::<Self>()] {
                 self.to_be().to_ne_bytes()
@@ -2174,7 +2174,7 @@ let bytes = ", $swap_op, stringify!($SelfT), ".to_le_bytes();
 assert_eq!(bytes, ", $le_bytes, ");
 ```"),
             #[stable(feature = "int_to_from_bytes", since = "1.32.0")]
-            #[rustc_const_unstable(feature = "const_int_conversion", issue = "53718")]
+            #[rustc_const_stable(feature = "const_int_conversion", since = "1.43.0")]
             #[inline]
             pub const fn to_le_bytes(self) -> [u8; mem::size_of::<Self>()] {
                 self.to_le().to_ne_bytes()
@@ -2209,12 +2209,20 @@ assert_eq!(
 );
 ```"),
             #[stable(feature = "int_to_from_bytes", since = "1.32.0")]
-            #[rustc_const_unstable(feature = "const_int_conversion", issue = "53718")]
+            #[rustc_const_stable(feature = "const_int_conversion", since = "1.43.0")]
+            // SAFETY: const sound because integers are plain old datatypes so we can always
+            // transmute them to arrays of bytes
+            #[allow_internal_unstable(const_fn_union)]
             #[inline]
             pub const fn to_ne_bytes(self) -> [u8; mem::size_of::<Self>()] {
+                #[repr(C)]
+                union Bytes {
+                    val: $SelfT,
+                    bytes: [u8; mem::size_of::<$SelfT>()],
+                }
                 // SAFETY: integers are plain old datatypes so we can always transmute them to
                 // arrays of bytes
-                unsafe { mem::transmute(self) }
+                unsafe { Bytes { val: self }.bytes }
             }
         }
 
@@ -2243,7 +2251,7 @@ fn read_be_", stringify!($SelfT), "(input: &mut &[u8]) -> ", stringify!($SelfT),
 }
 ```"),
             #[stable(feature = "int_to_from_bytes", since = "1.32.0")]
-            #[rustc_const_unstable(feature = "const_int_conversion", issue = "53718")]
+            #[rustc_const_stable(feature = "const_int_conversion", since = "1.43.0")]
             #[inline]
             pub const fn from_be_bytes(bytes: [u8; mem::size_of::<Self>()]) -> Self {
                 Self::from_be(Self::from_ne_bytes(bytes))
@@ -2276,7 +2284,7 @@ fn read_le_", stringify!($SelfT), "(input: &mut &[u8]) -> ", stringify!($SelfT),
 }
 ```"),
             #[stable(feature = "int_to_from_bytes", since = "1.32.0")]
-            #[rustc_const_unstable(feature = "const_int_conversion", issue = "53718")]
+            #[rustc_const_stable(feature = "const_int_conversion", since = "1.43.0")]
             #[inline]
             pub const fn from_le_bytes(bytes: [u8; mem::size_of::<Self>()]) -> Self {
                 Self::from_le(Self::from_ne_bytes(bytes))
@@ -2319,11 +2327,19 @@ fn read_ne_", stringify!($SelfT), "(input: &mut &[u8]) -> ", stringify!($SelfT),
 }
 ```"),
             #[stable(feature = "int_to_from_bytes", since = "1.32.0")]
-            #[rustc_const_unstable(feature = "const_int_conversion", issue = "53718")]
+            #[rustc_const_stable(feature = "const_int_conversion", since = "1.43.0")]
+            // SAFETY: const sound because integers are plain old datatypes so we can always
+            // transmute to them
+            #[allow_internal_unstable(const_fn_union)]
             #[inline]
             pub const fn from_ne_bytes(bytes: [u8; mem::size_of::<Self>()]) -> Self {
+                #[repr(C)]
+                union Bytes {
+                    val: $SelfT,
+                    bytes: [u8; mem::size_of::<$SelfT>()],
+                }
                 // SAFETY: integers are plain old datatypes so we can always transmute to them
-                unsafe { mem::transmute(bytes) }
+                unsafe { Bytes { bytes }.val }
             }
         }
 
@@ -4099,7 +4115,7 @@ let bytes = ", $swap_op, stringify!($SelfT), ".to_be_bytes();
 assert_eq!(bytes, ", $be_bytes, ");
 ```"),
             #[stable(feature = "int_to_from_bytes", since = "1.32.0")]
-            #[rustc_const_unstable(feature = "const_int_conversion", issue = "53718")]
+            #[rustc_const_stable(feature = "const_int_conversion", since = "1.43.0")]
             #[inline]
             pub const fn to_be_bytes(self) -> [u8; mem::size_of::<Self>()] {
                 self.to_be().to_ne_bytes()
@@ -4119,7 +4135,7 @@ let bytes = ", $swap_op, stringify!($SelfT), ".to_le_bytes();
 assert_eq!(bytes, ", $le_bytes, ");
 ```"),
             #[stable(feature = "int_to_from_bytes", since = "1.32.0")]
-            #[rustc_const_unstable(feature = "const_int_conversion", issue = "53718")]
+            #[rustc_const_stable(feature = "const_int_conversion", since = "1.43.0")]
             #[inline]
             pub const fn to_le_bytes(self) -> [u8; mem::size_of::<Self>()] {
                 self.to_le().to_ne_bytes()
@@ -4154,12 +4170,20 @@ assert_eq!(
 );
 ```"),
             #[stable(feature = "int_to_from_bytes", since = "1.32.0")]
-            #[rustc_const_unstable(feature = "const_int_conversion", issue = "53718")]
+            #[rustc_const_stable(feature = "const_int_conversion", since = "1.43.0")]
+            // SAFETY: const sound because integers are plain old datatypes so we can always
+            // transmute them to arrays of bytes
+            #[allow_internal_unstable(const_fn_union)]
             #[inline]
             pub const fn to_ne_bytes(self) -> [u8; mem::size_of::<Self>()] {
+                #[repr(C)]
+                union Bytes {
+                    val: $SelfT,
+                    bytes: [u8; mem::size_of::<$SelfT>()],
+                }
                 // SAFETY: integers are plain old datatypes so we can always transmute them to
                 // arrays of bytes
-                unsafe { mem::transmute(self) }
+                unsafe { Bytes { val: self }.bytes }
             }
         }
 
@@ -4188,7 +4212,7 @@ fn read_be_", stringify!($SelfT), "(input: &mut &[u8]) -> ", stringify!($SelfT),
 }
 ```"),
             #[stable(feature = "int_to_from_bytes", since = "1.32.0")]
-            #[rustc_const_unstable(feature = "const_int_conversion", issue = "53718")]
+            #[rustc_const_stable(feature = "const_int_conversion", since = "1.43.0")]
             #[inline]
             pub const fn from_be_bytes(bytes: [u8; mem::size_of::<Self>()]) -> Self {
                 Self::from_be(Self::from_ne_bytes(bytes))
@@ -4221,7 +4245,7 @@ fn read_le_", stringify!($SelfT), "(input: &mut &[u8]) -> ", stringify!($SelfT),
 }
 ```"),
             #[stable(feature = "int_to_from_bytes", since = "1.32.0")]
-            #[rustc_const_unstable(feature = "const_int_conversion", issue = "53718")]
+            #[rustc_const_stable(feature = "const_int_conversion", since = "1.43.0")]
             #[inline]
             pub const fn from_le_bytes(bytes: [u8; mem::size_of::<Self>()]) -> Self {
                 Self::from_le(Self::from_ne_bytes(bytes))
@@ -4264,11 +4288,19 @@ fn read_ne_", stringify!($SelfT), "(input: &mut &[u8]) -> ", stringify!($SelfT),
 }
 ```"),
             #[stable(feature = "int_to_from_bytes", since = "1.32.0")]
-            #[rustc_const_unstable(feature = "const_int_conversion", issue = "53718")]
+            #[rustc_const_stable(feature = "const_int_conversion", since = "1.43.0")]
+            // SAFETY: const sound because integers are plain old datatypes so we can always
+            // transmute to them
+            #[allow_internal_unstable(const_fn_union)]
             #[inline]
             pub const fn from_ne_bytes(bytes: [u8; mem::size_of::<Self>()]) -> Self {
+                #[repr(C)]
+                union Bytes {
+                    val: $SelfT,
+                    bytes: [u8; mem::size_of::<$SelfT>()],
+                }
                 // SAFETY: integers are plain old datatypes so we can always transmute to them
-                unsafe { mem::transmute(bytes) }
+                unsafe { Bytes { bytes }.val }
             }
         }
 

src/libcore/ops/arith.rs

@@ -13,7 +13,7 @@
 /// ```
 /// use std::ops::Add;
 ///
-/// #[derive(Debug, PartialEq)]
+/// #[derive(Debug, Copy, Clone, PartialEq)]
 /// struct Point {
 ///     x: i32,
 ///     y: i32,
@@ -42,7 +42,7 @@
 /// ```
 /// use std::ops::Add;
 ///
-/// #[derive(Debug, PartialEq)]
+/// #[derive(Debug, Copy, Clone, PartialEq)]
 /// struct Point<T> {
 ///     x: T,
 ///     y: T,
@@ -115,7 +115,7 @@ add_impl! { usize u8 u16 u32 u64 u128 isize i8 i16 i32 i64 i128 f32 f64 }
 /// ```
 /// use std::ops::Sub;
 ///
-/// #[derive(Debug, PartialEq)]
+/// #[derive(Debug, Copy, Clone, PartialEq)]
 /// struct Point {
 ///     x: i32,
 ///     y: i32,
@@ -657,7 +657,7 @@ neg_impl_numeric! { isize i8 i16 i32 i64 i128 f32 f64 }
 /// ```
 /// use std::ops::AddAssign;
 ///
-/// #[derive(Debug, PartialEq)]
+/// #[derive(Debug, Copy, Clone, PartialEq)]
 /// struct Point {
 ///     x: i32,
 ///     y: i32,
@@ -715,7 +715,7 @@ add_assign_impl! { usize u8 u16 u32 u64 u128 isize i8 i16 i32 i64 i128 f32 f64 }
 /// ```
 /// use std::ops::SubAssign;
 ///
-/// #[derive(Debug, PartialEq)]
+/// #[derive(Debug, Copy, Clone, PartialEq)]
 /// struct Point {
 ///     x: i32,
 ///     y: i32,

src/libcore/ops/mod.rs

@@ -42,7 +42,7 @@
 //! ```rust
 //! use std::ops::{Add, Sub};
 //!
-//! #[derive(Debug, PartialEq)]
+//! #[derive(Debug, Copy, Clone, PartialEq)]
 //! struct Point {
 //!     x: i32,
 //!     y: i32,

src/libcore/tests/lib.rs

@@ -41,6 +41,7 @@
 #![feature(never_type)]
 #![feature(unwrap_infallible)]
 #![feature(leading_trailing_ones)]
+#![feature(const_forget)]
 
 extern crate test;
 

src/libcore/tests/mem.rs

@@ -129,3 +129,21 @@ fn test_discriminant_send_sync() {
     is_send_sync::<Discriminant<Regular>>();
     is_send_sync::<Discriminant<NotSendSync>>();
 }
+
+#[test]
+fn test_const_forget() {
+    const _: () = forget(0i32);
+    const _: () = forget(Vec::<Vec<Box<i32>>>::new());
+
+    // Writing this function signature without const-forget
+    // triggers compiler errors:
+    // 1) That we use a non-const fn inside a const fn
+    // 2) without the forget, it complains about the destructor of Box
+    const fn const_forget_box<T>(x: Box<T>) {
+        forget(x);
+    }
+
+    // Call the forget_box at runtime,
+    // as we can't const-construct a box yet.
+    const_forget_box(Box::new(0i32));
+}

src/librustc/ty/layout.rs

@@ -1904,36 +1904,6 @@ impl<'tcx, T: HasTyCtxt<'tcx>> HasTyCtxt<'tcx> for LayoutCx<'tcx, T> {
     }
 }
 
-pub trait MaybeResult<T> {
-    type Error;
-
-    fn from(x: Result<T, Self::Error>) -> Self;
-    fn to_result(self) -> Result<T, Self::Error>;
-}
-
-impl<T> MaybeResult<T> for T {
-    type Error = !;
-
-    fn from(x: Result<T, Self::Error>) -> Self {
-        let Ok(x) = x;
-        x
-    }
-    fn to_result(self) -> Result<T, Self::Error> {
-        Ok(self)
-    }
-}
-
-impl<T, E> MaybeResult<T> for Result<T, E> {
-    type Error = E;
-
-    fn from(x: Result<T, Self::Error>) -> Self {
-        x
-    }
-    fn to_result(self) -> Result<T, Self::Error> {
-        self
-    }
-}
-
 pub type TyLayout<'tcx> = ::rustc_target::abi::TyLayout<'tcx, Ty<'tcx>>;
 
 impl<'tcx> LayoutOf for LayoutCx<'tcx, TyCtxt<'tcx>> {

src/librustc_codegen_ssa/mir/block.rs

@@ -434,6 +434,89 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
         helper.do_call(self, &mut bx, fn_abi, llfn, &args, None, cleanup);
     }
 
+    /// Returns `true` if this is indeed a panic intrinsic and codegen is done.
+    fn codegen_panic_intrinsic(
+        &mut self,
+        helper: &TerminatorCodegenHelper<'tcx>,
+        bx: &mut Bx,
+        intrinsic: Option<&str>,
+        instance: Option<Instance<'tcx>>,
+        span: Span,
+        destination: &Option<(mir::Place<'tcx>, mir::BasicBlock)>,
+        cleanup: Option<mir::BasicBlock>,
+    ) -> bool {
+        // Emit a panic or a no-op for `panic_if_uninhabited`.
+        // These are intrinsics that compile to panics so that we can get a message
+        // which mentions the offending type, even from a const context.
+        #[derive(Debug, PartialEq)]
+        enum PanicIntrinsic {
+            IfUninhabited,
+            IfZeroInvalid,
+            IfAnyInvalid,
+        };
+        let panic_intrinsic = intrinsic.and_then(|i| match i {
+            // FIXME: Move to symbols instead of strings.
+            "panic_if_uninhabited" => Some(PanicIntrinsic::IfUninhabited),
+            "panic_if_zero_invalid" => Some(PanicIntrinsic::IfZeroInvalid),
+            "panic_if_any_invalid" => Some(PanicIntrinsic::IfAnyInvalid),
+            _ => None,
+        });
+        if let Some(intrinsic) = panic_intrinsic {
+            use PanicIntrinsic::*;
+            let ty = instance.unwrap().substs.type_at(0);
+            let layout = bx.layout_of(ty);
+            let do_panic = match intrinsic {
+                IfUninhabited => layout.abi.is_uninhabited(),
+                // We unwrap as the error type is `!`.
+                IfZeroInvalid => !layout.might_permit_raw_init(bx, /*zero:*/ true).unwrap(),
+                // We unwrap as the error type is `!`.
+                IfAnyInvalid => !layout.might_permit_raw_init(bx, /*zero:*/ false).unwrap(),
+            };
+            if do_panic {
+                let msg_str = if layout.abi.is_uninhabited() {
+                    // Use this error even for the other intrinsics as it is more precise.
+                    format!("attempted to instantiate uninhabited type `{}`", ty)
+                } else if intrinsic == IfZeroInvalid {
+                    format!("attempted to zero-initialize type `{}`, which is invalid", ty)
+                } else {
+                    format!("attempted to leave type `{}` uninitialized, which is invalid", ty)
+                };
+                let msg = bx.const_str(Symbol::intern(&msg_str));
+                let location = self.get_caller_location(bx, span).immediate();
+
+                // Obtain the panic entry point.
+                // FIXME: dedup this with `codegen_assert_terminator` above.
+                let def_id =
+                    common::langcall(bx.tcx(), Some(span), "", lang_items::PanicFnLangItem);
+                let instance = ty::Instance::mono(bx.tcx(), def_id);
+                let fn_abi = FnAbi::of_instance(bx, instance, &[]);
+                let llfn = bx.get_fn_addr(instance);
+
+                if let Some((_, target)) = destination.as_ref() {
+                    helper.maybe_sideeffect(self.mir, bx, &[*target]);
+                }
+                // Codegen the actual panic invoke/call.
+                helper.do_call(
+                    self,
+                    bx,
+                    fn_abi,
+                    llfn,
+                    &[msg.0, msg.1, location],
+                    destination.as_ref().map(|(_, bb)| (ReturnDest::Nothing, *bb)),
+                    cleanup,
+                );
+            } else {
+                // a NOP
+                let target = destination.as_ref().unwrap().1;
+                helper.maybe_sideeffect(self.mir, bx, &[target]);
+                helper.funclet_br(self, bx, target)
+            }
+            true
+        } else {
+            false
+        }
+    }
+
     fn codegen_call_terminator(
         &mut self,
         helper: TerminatorCodegenHelper<'tcx>,
@@ -520,41 +603,15 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
             bug!("`miri_start_panic` should never end up in compiled code");
         }
 
-        // Emit a panic or a no-op for `panic_if_uninhabited`.
-        if intrinsic == Some("panic_if_uninhabited") {
-            let ty = instance.unwrap().substs.type_at(0);
-            let layout = bx.layout_of(ty);
-            if layout.abi.is_uninhabited() {
-                let msg_str = format!("Attempted to instantiate uninhabited type {}", ty);
-                let msg = bx.const_str(Symbol::intern(&msg_str));
-                let location = self.get_caller_location(&mut bx, span).immediate();
-
-                // Obtain the panic entry point.
-                let def_id =
-                    common::langcall(bx.tcx(), Some(span), "", lang_items::PanicFnLangItem);
-                let instance = ty::Instance::mono(bx.tcx(), def_id);
-                let fn_abi = FnAbi::of_instance(&bx, instance, &[]);
-                let llfn = bx.get_fn_addr(instance);
-
-                if let Some((_, target)) = destination.as_ref() {
-                    helper.maybe_sideeffect(self.mir, &mut bx, &[*target]);
-                }
-                // Codegen the actual panic invoke/call.
-                helper.do_call(
-                    self,
-                    &mut bx,
-                    fn_abi,
-                    llfn,
-                    &[msg.0, msg.1, location],
-                    destination.as_ref().map(|(_, bb)| (ReturnDest::Nothing, *bb)),
-                    cleanup,
-                );
-            } else {
-                // a NOP
-                let target = destination.as_ref().unwrap().1;
-                helper.maybe_sideeffect(self.mir, &mut bx, &[target]);
-                helper.funclet_br(self, &mut bx, target)
-            }
+        if self.codegen_panic_intrinsic(
+            &helper,
+            &mut bx,
+            intrinsic,
+            instance,
+            span,
+            destination,
+            cleanup,
+        ) {
             return;
         }
 

src/librustc_index/vec.rs

@@ -196,7 +196,7 @@ macro_rules! newtype_index {
 
             #[inline]
             fn index(self) -> usize {
-                usize::from(self)
+                self.as_usize()
             }
         }
 

src/librustc_infer/infer/canonical/query_response.rs

@@ -12,14 +12,15 @@ use crate::infer::canonical::{
     Canonical, CanonicalVarValues, CanonicalizedQueryResponse, Certainty, OriginalQueryValues,
     QueryOutlivesConstraint, QueryRegionConstraints, QueryResponse,
 };
+use crate::infer::nll_relate::{NormalizationStrategy, TypeRelating, TypeRelatingDelegate};
 use crate::infer::region_constraints::{Constraint, RegionConstraintData};
-use crate::infer::InferCtxtBuilder;
-use crate::infer::{InferCtxt, InferOk, InferResult};
+use crate::infer::{InferCtxt, InferCtxtBuilder, InferOk, InferResult, NLLRegionVariableOrigin};
 use crate::traits::query::{Fallible, NoSolution};
-use crate::traits::TraitEngine;
+use crate::traits::{DomainGoal, TraitEngine};
 use crate::traits::{Obligation, ObligationCause, PredicateObligation};
 use rustc::arena::ArenaAllocatable;
 use rustc::ty::fold::TypeFoldable;
+use rustc::ty::relate::TypeRelation;
 use rustc::ty::subst::{GenericArg, GenericArgKind};
 use rustc::ty::{self, BoundVar, Ty, TyCtxt};
 use rustc_data_structures::captures::Captures;
@@ -304,13 +305,31 @@ impl<'cx, 'tcx> InferCtxt<'cx, 'tcx> {
                 }
 
                 (GenericArgKind::Type(v1), GenericArgKind::Type(v2)) => {
-                    let ok = self.at(cause, param_env).eq(v1, v2)?;
-                    obligations.extend(ok.into_obligations());
+                    TypeRelating::new(
+                        self,
+                        QueryTypeRelatingDelegate {
+                            infcx: self,
+                            param_env,
+                            cause,
+                            obligations: &mut obligations,
+                        },
+                        ty::Variance::Invariant,
+                    )
+                    .relate(&v1, &v2)?;
                 }
 
                 (GenericArgKind::Const(v1), GenericArgKind::Const(v2)) => {
-                    let ok = self.at(cause, param_env).eq(v1, v2)?;
-                    obligations.extend(ok.into_obligations());
+                    TypeRelating::new(
+                        self,
+                        QueryTypeRelatingDelegate {
+                            infcx: self,
+                            param_env,
+                            cause,
+                            obligations: &mut obligations,
+                        },
+                        ty::Variance::Invariant,
+                    )
+                    .relate(&v1, &v2)?;
                 }
 
                 _ => {
@@ -656,3 +675,55 @@ pub fn make_query_region_constraints<'tcx>(
 
     QueryRegionConstraints { outlives, member_constraints: member_constraints.clone() }
 }
+
+struct QueryTypeRelatingDelegate<'a, 'tcx> {
+    infcx: &'a InferCtxt<'a, 'tcx>,
+    obligations: &'a mut Vec<PredicateObligation<'tcx>>,
+    param_env: ty::ParamEnv<'tcx>,
+    cause: &'a ObligationCause<'tcx>,
+}
+
+impl<'tcx> TypeRelatingDelegate<'tcx> for QueryTypeRelatingDelegate<'_, 'tcx> {
+    fn create_next_universe(&mut self) -> ty::UniverseIndex {
+        self.infcx.create_next_universe()
+    }
+
+    fn next_existential_region_var(&mut self, from_forall: bool) -> ty::Region<'tcx> {
+        let origin = NLLRegionVariableOrigin::Existential { from_forall };
+        self.infcx.next_nll_region_var(origin)
+    }
+
+    fn next_placeholder_region(&mut self, placeholder: ty::PlaceholderRegion) -> ty::Region<'tcx> {
+        self.infcx.tcx.mk_region(ty::RePlaceholder(placeholder))
+    }
+
+    fn generalize_existential(&mut self, universe: ty::UniverseIndex) -> ty::Region<'tcx> {
+        self.infcx.next_nll_region_var_in_universe(
+            NLLRegionVariableOrigin::Existential { from_forall: false },
+            universe,
+        )
+    }
+
+    fn push_outlives(&mut self, sup: ty::Region<'tcx>, sub: ty::Region<'tcx>) {
+        self.obligations.push(Obligation {
+            cause: self.cause.clone(),
+            param_env: self.param_env,
+            predicate: ty::Predicate::RegionOutlives(ty::Binder::dummy(ty::OutlivesPredicate(
+                sup, sub,
+            ))),
+            recursion_depth: 0,
+        });
+    }
+
+    fn push_domain_goal(&mut self, _: DomainGoal<'tcx>) {
+        bug!("should never be invoked with eager normalization")
+    }
+
+    fn normalization() -> NormalizationStrategy {
+        NormalizationStrategy::Eager
+    }
+
+    fn forbid_inference_vars() -> bool {
+        true
+    }
+}

src/librustc_lint/types.rs

@@ -998,10 +998,8 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for VariantSizeDifferences {
             let ty = cx.tcx.erase_regions(&t);
             let layout = match cx.layout_of(ty) {
                 Ok(layout) => layout,
-                Err(ty::layout::LayoutError::Unknown(_)) => return,
-                Err(err @ ty::layout::LayoutError::SizeOverflow(_)) => {
-                    bug!("failed to get layout for `{}`: {}", t, err);
-                }
+                Err(ty::layout::LayoutError::Unknown(_))
+                | Err(ty::layout::LayoutError::SizeOverflow(_)) => return,
             };
             let (variants, tag) = match layout.variants {
                 layout::Variants::Multiple {

src/librustc_mir/interpret/intrinsics.rs

@@ -216,6 +216,11 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                 };
                 self.write_scalar(val, dest)?;
             }
+            sym::discriminant_value => {
+                let place = self.deref_operand(args[0])?;
+                let discr_val = self.read_discriminant(place.into())?.0;
+                self.write_scalar(Scalar::from_uint(discr_val, dest.layout.size), dest)?;
+            }
             sym::unchecked_shl
             | sym::unchecked_shr
             | sym::unchecked_add

src/librustc_mir_build/hair/pattern/_match.rs

@@ -480,7 +480,11 @@ impl<'p, 'tcx> Matrix<'p, 'tcx> {
     /// Pushes a new row to the matrix. If the row starts with an or-pattern, this expands it.
     crate fn push(&mut self, row: PatStack<'p, 'tcx>) {
         if let Some(rows) = row.expand_or_pat() {
-            self.0.extend(rows);
+            for row in rows {
+                // We recursively expand the or-patterns of the new rows.
+                // This is necessary as we might have `0 | (1 | 2)` or e.g., `x @ 0 | x @ (1 | 2)`.
+                self.push(row)
+            }
         } else {
             self.0.push(row);
         }

src/librustc_parse/parser/item.rs

@@ -1544,9 +1544,7 @@ impl<'a> Parser<'a> {
 
         let is_name_required = match self.token.kind {
             token::DotDotDot => false,
-            // FIXME: Consider using interpolated token for this edition check,
-            // it should match the intent of edition hygiene better.
-            _ => req_name(self.token.uninterpolate().span.edition()),
+            _ => req_name(self.token.span.edition()),
         };
         let (pat, ty) = if is_name_required || self.is_named_param() {
             debug!("parse_param_general parse_pat (is_name_required:{})", is_name_required);

src/librustc_span/symbol.rs

@@ -265,6 +265,7 @@ symbols! {
         derive,
         diagnostic,
         direct,
+        discriminant_value,
         doc,
         doc_alias,
         doc_cfg,

src/librustc_target/abi/mod.rs

@@ -937,6 +937,7 @@ impl<'a, Ty> Deref for TyLayout<'a, Ty> {
     }
 }
 
+/// Trait for context types that can compute layouts of things.
 pub trait LayoutOf {
     type Ty;
     type TyLayout;
@@ -947,6 +948,38 @@ pub trait LayoutOf {
     }
 }
 
+/// The `TyLayout` above will always be a `MaybeResult<TyLayout<'_, Self>>`.
+/// We can't add the bound due to the lifetime, but this trait is still useful when
+/// writing code that's generic over the `LayoutOf` impl.
+pub trait MaybeResult<T> {
+    type Error;
+
+    fn from(x: Result<T, Self::Error>) -> Self;
+    fn to_result(self) -> Result<T, Self::Error>;
+}
+
+impl<T> MaybeResult<T> for T {
+    type Error = !;
+
+    fn from(Ok(x): Result<T, Self::Error>) -> Self {
+        x
+    }
+    fn to_result(self) -> Result<T, Self::Error> {
+        Ok(self)
+    }
+}
+
+impl<T, E> MaybeResult<T> for Result<T, E> {
+    type Error = E;
+
+    fn from(x: Result<T, Self::Error>) -> Self {
+        x
+    }
+    fn to_result(self) -> Result<T, Self::Error> {
+        self
+    }
+}
+
 #[derive(Copy, Clone, PartialEq, Eq)]
 pub enum PointerKind {
     /// Most general case, we know no restrictions to tell LLVM.
@@ -987,13 +1020,17 @@ impl<'a, Ty> TyLayout<'a, Ty> {
     {
         Ty::for_variant(self, cx, variant_index)
     }
+
+    /// Callers might want to use `C: LayoutOf<Ty=Ty, TyLayout: MaybeResult<Self>>`
+    /// to allow recursion (see `might_permit_zero_init` below for an example).
     pub fn field<C>(self, cx: &C, i: usize) -> C::TyLayout
     where
         Ty: TyLayoutMethods<'a, C>,
         C: LayoutOf<Ty = Ty>,
     {
         Ty::field(self, cx, i)
     }
+
     pub fn pointee_info_at<C>(self, cx: &C, offset: Size) -> Option<PointeeInfo>
     where
         Ty: TyLayoutMethods<'a, C>,
@@ -1017,4 +1054,52 @@ impl<'a, Ty> TyLayout<'a, Ty> {
             Abi::Aggregate { sized } => sized && self.size.bytes() == 0,
         }
     }
+
+    /// Determines if this type permits "raw" initialization by just transmuting some
+    /// memory into an instance of `T`.
+    /// `zero` indicates if the memory is zero-initialized, or alternatively
+    /// left entirely uninitialized.
+    /// This is conservative: in doubt, it will answer `true`.
+    ///
+    /// FIXME: Once we removed all the conservatism, we could alternatively
+    /// create an all-0/all-undef constant and run the const value validator to see if
+    /// this is a valid value for the given type.
+    pub fn might_permit_raw_init<C, E>(self, cx: &C, zero: bool) -> Result<bool, E>
+    where
+        Self: Copy,
+        Ty: TyLayoutMethods<'a, C>,
+        C: LayoutOf<Ty = Ty, TyLayout: MaybeResult<Self, Error = E>> + HasDataLayout,
+    {
+        let scalar_allows_raw_init = move |s: &Scalar| -> bool {
+            if zero {
+                let range = &s.valid_range;
+                // The range must contain 0.
+                range.contains(&0) || (*range.start() > *range.end()) // wrap-around allows 0
+            } else {
+                // The range must include all values. `valid_range_exclusive` handles
+                // the wrap-around using target arithmetic; with wrap-around then the full
+                // range is one where `start == end`.
+                let range = s.valid_range_exclusive(cx);
+                range.start == range.end
+            }
+        };
+
+        // Check the ABI.
+        let valid = match &self.abi {
+            Abi::Uninhabited => false, // definitely UB
+            Abi::Scalar(s) => scalar_allows_raw_init(s),
+            Abi::ScalarPair(s1, s2) => scalar_allows_raw_init(s1) && scalar_allows_raw_init(s2),
+            Abi::Vector { element: s, count } => *count == 0 || scalar_allows_raw_init(s),
+            Abi::Aggregate { .. } => true, // Cannot be excluded *right now*.
+        };
+        if !valid {
+            // This is definitely not okay.
+            trace!("might_permit_raw_init({:?}, zero={}): not valid", self.details, zero);
+            return Ok(false);
+        }
+
+        // If we have not found an error yet, we need to recursively descend.
+        // FIXME(#66151): For now, we are conservative and do not do this.
+        Ok(true)
+    }
 }

src/librustc_target/lib.rs

@@ -10,6 +10,9 @@
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/")]
 #![feature(bool_to_option)]
 #![feature(nll)]
+#![feature(never_type)]
+#![feature(associated_type_bounds)]
+#![feature(exhaustive_patterns)]
 
 #[macro_use]
 extern crate log;

src/librustc_typeck/check/expr.rs

@@ -18,6 +18,7 @@ use crate::type_error_struct;
 use crate::util::common::ErrorReported;
 
 use rustc::middle::lang_items;
+use rustc::mir::interpret::ErrorHandled;
 use rustc::ty;
 use rustc::ty::adjustment::{Adjust, Adjustment, AllowTwoPhase, AutoBorrow, AutoBorrowMutability};
 use rustc::ty::Ty;
@@ -1039,11 +1040,18 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         };
 
         if element_ty.references_error() {
-            tcx.types.err
-        } else if let Ok(count) = count {
-            tcx.mk_ty(ty::Array(t, count))
-        } else {
-            tcx.types.err
+            return tcx.types.err;
+        }
+        match count {
+            Ok(count) => tcx.mk_ty(ty::Array(t, count)),
+            Err(ErrorHandled::TooGeneric) => {
+                self.tcx.sess.span_err(
+                    tcx.def_span(count_def_id),
+                    "array lengths can't depend on generic parameters",
+                );
+                tcx.types.err
+            }
+            Err(ErrorHandled::Reported) => tcx.types.err,
         }
     }
 

src/librustc_typeck/check/intrinsic.rs

@@ -147,7 +147,9 @@ pub fn check_intrinsic_type(tcx: TyCtxt<'_>, it: &hir::ForeignItem<'_>) {
             ),
             "rustc_peek" => (1, vec![param(0)], param(0)),
             "caller_location" => (0, vec![], tcx.caller_location_ty()),
-            "panic_if_uninhabited" => (1, Vec::new(), tcx.mk_unit()),
+            "panic_if_uninhabited" | "panic_if_zero_invalid" | "panic_if_any_invalid" => {
+                (1, Vec::new(), tcx.mk_unit())
+            }
             "init" => (1, Vec::new(), param(0)),
             "uninit" => (1, Vec::new(), param(0)),
             "forget" => (1, vec![param(0)], tcx.mk_unit()),

src/test/ui/anon-params/anon-params-edition-hygiene.rs

@@ -0,0 +1,10 @@
+// check-pass
+// edition:2018
+// aux-build:anon-params-edition-hygiene.rs
+
+#[macro_use]
+extern crate anon_params_edition_hygiene;
+
+generate_trait_2015!(u8);
+
+fn main() {}

src/test/ui/anon-params/auxiliary/anon-params-edition-hygiene.rs

@@ -0,0 +1,12 @@
+// edition:2015
+
+#[macro_export]
+macro_rules! generate_trait_2015 {
+    ($Type: ident) => {
+        trait Trait {
+            fn method($Type) {}
+        }
+    };
+}
+
+fn main() {}

src/test/ui/const-generics/issues/issue-62456.rs

@@ -0,0 +1,9 @@
+#![feature(const_generics)]
+//~^ WARN the feature `const_generics` is incomplete and may cause the compiler to crash
+
+fn foo<const N: usize>() {
+    let _ = [0u64; N + 1];
+    //~^ ERROR array lengths can't depend on generic parameters
+}
+
+fn main() {}

src/test/ui/const-generics/issues/issue-62456.stderr

@@ -0,0 +1,16 @@
+warning: the feature `const_generics` is incomplete and may cause the compiler to crash
+  --> $DIR/issue-62456.rs:1:12
+   |
+LL | #![feature(const_generics)]
+   |            ^^^^^^^^^^^^^^
+   |
+   = note: `#[warn(incomplete_features)]` on by default
+
+error: array lengths can't depend on generic parameters
+  --> $DIR/issue-62456.rs:5:20
+   |
+LL |     let _ = [0u64; N + 1];
+   |                    ^^^^^
+
+error: aborting due to previous error
+

src/test/ui/consts/const-int-conversion-rpass.rs

@@ -1,7 +1,5 @@
 // run-pass
 
-#![feature(const_int_conversion)]
-
 const REVERSE: u32 = 0x12345678_u32.reverse_bits();
 const FROM_BE_BYTES: i32 = i32::from_be_bytes([0x12, 0x34, 0x56, 0x78]);
 const FROM_LE_BYTES: i32 = i32::from_le_bytes([0x12, 0x34, 0x56, 0x78]);

src/test/ui/consts/const_discriminant.rs

@@ -0,0 +1,40 @@
+// run-pass
+#![feature(const_discriminant)]
+#![allow(dead_code)]
+
+use std::mem::{discriminant, Discriminant};
+
+// `discriminant(const_expr)` may get const-propagated.
+// As we want to check that const-eval is equal to ordinary exection,
+// we wrap `const_expr` with a function which is not const to prevent this.
+#[inline(never)]
+fn identity<T>(x: T) -> T { x }
+
+enum Test {
+    A(u8),
+    B,
+    C { a: u8, b: u8 },
+}
+
+const TEST_A: Discriminant<Test> = discriminant(&Test::A(5));
+const TEST_A_OTHER: Discriminant<Test> = discriminant(&Test::A(17));
+const TEST_B: Discriminant<Test> = discriminant(&Test::B);
+
+enum Void {}
+
+enum SingleVariant {
+    V,
+    Never(Void),
+}
+
+const TEST_V: Discriminant<SingleVariant> = discriminant(&SingleVariant::V);
+
+fn main() {
+    assert_eq!(TEST_A, TEST_A_OTHER);
+    assert_eq!(TEST_A, discriminant(identity(&Test::A(17))));
+    assert_eq!(TEST_B, discriminant(identity(&Test::B)));
+    assert_ne!(TEST_A, TEST_B);
+    assert_ne!(TEST_B, discriminant(identity(&Test::C { a: 42, b: 7 })));
+
+    assert_eq!(TEST_V, discriminant(identity(&SingleVariant::V)));
+}

src/test/ui/intrinsics/panic-uninitialized-zeroed.rs

@@ -0,0 +1,170 @@
+// run-pass
+// ignore-wasm32-bare compiled with panic=abort by default
+
+// This test checks panic emitted from `mem::{uninitialized,zeroed}`.
+
+#![feature(never_type)]
+#![allow(deprecated, invalid_value)]
+
+use std::{
+    mem::{self, MaybeUninit, ManuallyDrop},
+    panic,
+    ptr::NonNull,
+    num,
+};
+
+#[allow(dead_code)]
+struct Foo {
+    x: u8,
+    y: !,
+}
+
+enum Bar {}
+
+#[allow(dead_code)]
+enum OneVariant { Variant(i32) }
+
+// An enum with ScalarPair layout
+#[allow(dead_code)]
+enum LR {
+    Left(i64),
+    Right(i64),
+}
+#[allow(dead_code, non_camel_case_types)]
+enum LR_NonZero {
+    Left(num::NonZeroI64),
+    Right(num::NonZeroI64),
+}
+
+fn test_panic_msg<T>(op: impl (FnOnce() -> T) + panic::UnwindSafe, msg: &str) {
+    let err = panic::catch_unwind(op).err();
+    assert_eq!(
+        err.as_ref().and_then(|a| a.downcast_ref::<String>()).map(|s| &**s),
+        Some(msg)
+    );
+}
+
+fn main() {
+    unsafe {
+        // Uninhabited types
+        test_panic_msg(
+            || mem::uninitialized::<!>(),
+            "attempted to instantiate uninhabited type `!`"
+        );
+        test_panic_msg(
+            || mem::zeroed::<!>(),
+            "attempted to instantiate uninhabited type `!`"
+        );
+        test_panic_msg(
+            || MaybeUninit::<!>::uninit().assume_init(),
+            "attempted to instantiate uninhabited type `!`"
+        );
+
+        test_panic_msg(
+            || mem::uninitialized::<Foo>(),
+            "attempted to instantiate uninhabited type `Foo`"
+        );
+        test_panic_msg(
+            || mem::zeroed::<Foo>(),
+            "attempted to instantiate uninhabited type `Foo`"
+        );
+        test_panic_msg(
+            || MaybeUninit::<Foo>::uninit().assume_init(),
+            "attempted to instantiate uninhabited type `Foo`"
+        );
+
+        test_panic_msg(
+            || mem::uninitialized::<Bar>(),
+            "attempted to instantiate uninhabited type `Bar`"
+        );
+        test_panic_msg(
+            || mem::zeroed::<Bar>(),
+            "attempted to instantiate uninhabited type `Bar`"
+        );
+        test_panic_msg(
+            || MaybeUninit::<Bar>::uninit().assume_init(),
+            "attempted to instantiate uninhabited type `Bar`"
+        );
+
+        // Types that do not like zero-initialziation
+        test_panic_msg(
+            || mem::uninitialized::<fn()>(),
+            "attempted to leave type `fn()` uninitialized, which is invalid"
+        );
+        test_panic_msg(
+            || mem::zeroed::<fn()>(),
+            "attempted to zero-initialize type `fn()`, which is invalid"
+        );
+
+        test_panic_msg(
+            || mem::uninitialized::<*const dyn Send>(),
+            "attempted to leave type `*const dyn std::marker::Send` uninitialized, which is invalid"
+        );
+        test_panic_msg(
+            || mem::zeroed::<*const dyn Send>(),
+            "attempted to zero-initialize type `*const dyn std::marker::Send`, which is invalid"
+        );
+
+        /* FIXME(#66151) we conservatively do not error here yet.
+        test_panic_msg(
+            || mem::uninitialized::<LR_NonZero>(),
+            "attempted to leave type `LR_NonZero` uninitialized, which is invalid"
+        );
+        test_panic_msg(
+            || mem::zeroed::<LR_NonZero>(),
+            "attempted to zero-initialize type `LR_NonZero`, which is invalid"
+        );
+
+        test_panic_msg(
+            || mem::uninitialized::<ManuallyDrop<LR_NonZero>>(),
+            "attempted to leave type `std::mem::ManuallyDrop<LR_NonZero>` uninitialized, \
+             which is invalid"
+        );
+        test_panic_msg(
+            || mem::zeroed::<ManuallyDrop<LR_NonZero>>(),
+            "attempted to zero-initialize type `std::mem::ManuallyDrop<LR_NonZero>`, \
+             which is invalid"
+        );
+
+        test_panic_msg(
+            || mem::uninitialized::<(NonNull<u32>, u32, u32)>(),
+            "attempted to leave type `(std::ptr::NonNull<u32>, u32, u32)` uninitialized, \
+                which is invalid"
+        );
+        test_panic_msg(
+            || mem::zeroed::<(NonNull<u32>, u32, u32)>(),
+            "attempted to zero-initialize type `(std::ptr::NonNull<u32>, u32, u32)`, \
+                which is invalid"
+        );
+        */
+
+        // Types that can be zero, but not uninit.
+        test_panic_msg(
+            || mem::uninitialized::<bool>(),
+            "attempted to leave type `bool` uninitialized, which is invalid"
+        );
+        test_panic_msg(
+            || mem::uninitialized::<LR>(),
+            "attempted to leave type `LR` uninitialized, which is invalid"
+        );
+        test_panic_msg(
+            || mem::uninitialized::<ManuallyDrop<LR>>(),
+            "attempted to leave type `std::mem::ManuallyDrop<LR>` uninitialized, which is invalid"
+        );
+
+        // Some things that should work.
+        let _val = mem::zeroed::<bool>();
+        let _val = mem::zeroed::<LR>();
+        let _val = mem::zeroed::<ManuallyDrop<LR>>();
+        let _val = mem::zeroed::<OneVariant>();
+        let _val = mem::zeroed::<Option<&'static i32>>();
+        let _val = mem::zeroed::<MaybeUninit<NonNull<u32>>>();
+        let _val = mem::uninitialized::<MaybeUninit<bool>>();
+
+        // These are UB because they have not been officially blessed, but we await the resolution
+        // of <https://github.com/rust-lang/unsafe-code-guidelines/issues/71> before doing
+        // anything about that.
+        let _val = mem::uninitialized::<i32>();
+        let _val = mem::uninitialized::<*const ()>();
+    }
+}

src/test/ui/issues/issue-69602-type-err-during-codegen-ice.rs

@@ -19,4 +19,5 @@ impl TraitB for B { //~ ERROR not all trait items implemented, missing: `MyA`
 
 fn main() {
     let _ = [0; B::VALUE];
+    //~^ ERROR array lengths can't depend on generic parameters
 }

src/test/ui/issues/issue-69602-type-err-during-codegen-ice.stderr

@@ -13,7 +13,13 @@ LL |     type MyA: TraitA;
 LL | impl TraitB for B {
    | ^^^^^^^^^^^^^^^^^ missing `MyA` in implementation
 
-error: aborting due to 2 previous errors
+error: array lengths can't depend on generic parameters
+  --> $DIR/issue-69602-type-err-during-codegen-ice.rs:21:17
+   |
+LL |     let _ = [0; B::VALUE];
+   |                 ^^^^^^^^
+
+error: aborting due to 3 previous errors
 
 Some errors have detailed explanations: E0046, E0437.
 For more information about an error, try `rustc --explain E0046`.

src/test/ui/lint/issue-69485-var-size-diffs-too-large.rs

@@ -0,0 +1,9 @@
+// build-fail
+
+fn main() {
+    Bug::V([0; !0]); //~ ERROR is too big for the current
+}
+
+enum Bug {
+    V([u8; !0]),
+}

src/test/ui/lint/issue-69485-var-size-diffs-too-large.stderr

@@ -0,0 +1,8 @@
+error: the type `[u8; 18446744073709551615]` is too big for the current architecture
+  --> $DIR/issue-69485-var-size-diffs-too-large.rs:4:12
+   |
+LL |     Bug::V([0; !0]);
+   |            ^^^^^^^
+
+error: aborting due to previous error
+

src/test/ui/nll/user-annotations/type-annotation-with-hrtb.rs

@@ -0,0 +1,33 @@
+// Regression test for issue #69490
+
+// check-pass
+
+pub trait Trait<T> {
+    const S: &'static str;
+}
+
+impl<T> Trait<()> for T
+where
+    T: for<'a> Trait<&'a ()>,
+{
+    // Use of `T::S` here caused an ICE
+    const S: &'static str = T::S;
+}
+
+// Some similar cases that didn't ICE:
+
+impl<'a, T> Trait<()> for (T,)
+where
+    T: Trait<&'a ()>,
+{
+    const S: &'static str = T::S;
+}
+
+impl<T> Trait<()> for [T; 1]
+where
+    T: Trait<for<'a> fn(&'a ())>,
+{
+    const S: &'static str = T::S;
+}
+
+fn main() {}

src/test/ui/or-patterns/issue-69875-should-have-been-expanded-earlier-non-exhaustive.rs

@@ -0,0 +1,9 @@
+#![feature(or_patterns)]
+
+fn main() {
+    let 0 | (1 | 2) = 0; //~ ERROR refutable pattern in local binding
+    match 0 {
+        //~^ ERROR non-exhaustive patterns
+        0 | (1 | 2) => {}
+    }
+}

src/test/ui/or-patterns/issue-69875-should-have-been-expanded-earlier-non-exhaustive.stderr

@@ -0,0 +1,25 @@
+error[E0005]: refutable pattern in local binding: `std::i32::MIN..=-1i32` and `3i32..=std::i32::MAX` not covered
+  --> $DIR/issue-69875-should-have-been-expanded-earlier-non-exhaustive.rs:4:9
+   |
+LL |     let 0 | (1 | 2) = 0;
+   |         ^^^^^^^^^^^ patterns `std::i32::MIN..=-1i32` and `3i32..=std::i32::MAX` not covered
+   |
+   = note: `let` bindings require an "irrefutable pattern", like a `struct` or an `enum` with only one variant
+   = note: for more information, visit https://doc.rust-lang.org/book/ch18-02-refutability.html
+help: you might want to use `if let` to ignore the variant that isn't matched
+   |
+LL |     if let 0 | (1 | 2) = 0 { /* */ }
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error[E0004]: non-exhaustive patterns: `std::i32::MIN..=-1i32` and `3i32..=std::i32::MAX` not covered
+  --> $DIR/issue-69875-should-have-been-expanded-earlier-non-exhaustive.rs:5:11
+   |
+LL |     match 0 {
+   |           ^ patterns `std::i32::MIN..=-1i32` and `3i32..=std::i32::MAX` not covered
+   |
+   = help: ensure that all possible cases are being handled, possibly by adding wildcards or more match arms
+
+error: aborting due to 2 previous errors
+
+Some errors have detailed explanations: E0004, E0005.
+For more information about an error, try `rustc --explain E0004`.

src/test/ui/or-patterns/issue-69875-should-have-been-expanded-earlier.rs

@@ -0,0 +1,9 @@
+// check-pass
+
+#![feature(or_patterns)]
+
+fn main() {
+    let 0 | (1 | _) = 0;
+    if let 0 | (1 | 2) = 0 {}
+    if let x @ 0 | x @ (1 | 2) = 0 {}
+}