Rollup of 4 pull requests

src/libcore/iter/adapters/fuse.rs

@@ -0,0 +1,342 @@
+use crate::intrinsics;
+use crate::iter::{
+    DoubleEndedIterator, ExactSizeIterator, FusedIterator, Iterator, TrustedRandomAccess,
+};
+use crate::ops::Try;
+
+/// An iterator that yields `None` forever after the underlying iterator
+/// yields `None` once.
+///
+/// This `struct` is created by the [`fuse`] method on [`Iterator`]. See its
+/// documentation for more.
+///
+/// [`fuse`]: trait.Iterator.html#method.fuse
+/// [`Iterator`]: trait.Iterator.html
+#[derive(Clone, Debug)]
+#[must_use = "iterators are lazy and do nothing unless consumed"]
+#[stable(feature = "rust1", since = "1.0.0")]
+pub struct Fuse<I> {
+    // NOTE: for `I: FusedIterator`, this is always assumed `Some`!
+    iter: Option<I>,
+}
+impl<I> Fuse<I> {
+    pub(in crate::iter) fn new(iter: I) -> Fuse<I> {
+        Fuse { iter: Some(iter) }
+    }
+}
+
+#[stable(feature = "fused", since = "1.26.0")]
+impl<I> FusedIterator for Fuse<I> where I: Iterator {}
+
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<I> Iterator for Fuse<I>
+where
+    I: Iterator,
+{
+    type Item = <I as Iterator>::Item;
+
+    #[inline]
+    default fn next(&mut self) -> Option<<I as Iterator>::Item> {
+        let next = self.iter.as_mut()?.next();
+        if next.is_none() {
+            self.iter = None;
+        }
+        next
+    }
+
+    #[inline]
+    default fn nth(&mut self, n: usize) -> Option<I::Item> {
+        let nth = self.iter.as_mut()?.nth(n);
+        if nth.is_none() {
+            self.iter = None;
+        }
+        nth
+    }
+
+    #[inline]
+    default fn last(self) -> Option<I::Item> {
+        self.iter?.last()
+    }
+
+    #[inline]
+    default fn count(self) -> usize {
+        self.iter.map_or(0, I::count)
+    }
+
+    #[inline]
+    default fn size_hint(&self) -> (usize, Option<usize>) {
+        self.iter.as_ref().map_or((0, Some(0)), I::size_hint)
+    }
+
+    #[inline]
+    default fn try_fold<Acc, Fold, R>(&mut self, mut acc: Acc, fold: Fold) -> R
+    where
+        Self: Sized,
+        Fold: FnMut(Acc, Self::Item) -> R,
+        R: Try<Ok = Acc>,
+    {
+        if let Some(ref mut iter) = self.iter {
+            acc = iter.try_fold(acc, fold)?;
+            self.iter = None;
+        }
+        Try::from_ok(acc)
+    }
+
+    #[inline]
+    default fn fold<Acc, Fold>(self, mut acc: Acc, fold: Fold) -> Acc
+    where
+        Fold: FnMut(Acc, Self::Item) -> Acc,
+    {
+        if let Some(iter) = self.iter {
+            acc = iter.fold(acc, fold);
+        }
+        acc
+    }
+
+    #[inline]
+    default fn find<P>(&mut self, predicate: P) -> Option<Self::Item>
+    where
+        P: FnMut(&Self::Item) -> bool,
+    {
+        let found = self.iter.as_mut()?.find(predicate);
+        if found.is_none() {
+            self.iter = None;
+        }
+        found
+    }
+}
+
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<I> DoubleEndedIterator for Fuse<I>
+where
+    I: DoubleEndedIterator,
+{
+    #[inline]
+    default fn next_back(&mut self) -> Option<<I as Iterator>::Item> {
+        let next = self.iter.as_mut()?.next_back();
+        if next.is_none() {
+            self.iter = None;
+        }
+        next
+    }
+
+    #[inline]
+    default fn nth_back(&mut self, n: usize) -> Option<<I as Iterator>::Item> {
+        let nth = self.iter.as_mut()?.nth_back(n);
+        if nth.is_none() {
+            self.iter = None;
+        }
+        nth
+    }
+
+    #[inline]
+    default fn try_rfold<Acc, Fold, R>(&mut self, mut acc: Acc, fold: Fold) -> R
+    where
+        Self: Sized,
+        Fold: FnMut(Acc, Self::Item) -> R,
+        R: Try<Ok = Acc>,
+    {
+        if let Some(ref mut iter) = self.iter {
+            acc = iter.try_rfold(acc, fold)?;
+            self.iter = None;
+        }
+        Try::from_ok(acc)
+    }
+
+    #[inline]
+    default fn rfold<Acc, Fold>(self, mut acc: Acc, fold: Fold) -> Acc
+    where
+        Fold: FnMut(Acc, Self::Item) -> Acc,
+    {
+        if let Some(iter) = self.iter {
+            acc = iter.rfold(acc, fold);
+        }
+        acc
+    }
+
+    #[inline]
+    default fn rfind<P>(&mut self, predicate: P) -> Option<Self::Item>
+    where
+        P: FnMut(&Self::Item) -> bool,
+    {
+        let found = self.iter.as_mut()?.rfind(predicate);
+        if found.is_none() {
+            self.iter = None;
+        }
+        found
+    }
+}
+
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<I> ExactSizeIterator for Fuse<I>
+where
+    I: ExactSizeIterator,
+{
+    default fn len(&self) -> usize {
+        self.iter.as_ref().map_or(0, I::len)
+    }
+
+    default fn is_empty(&self) -> bool {
+        self.iter.as_ref().map_or(true, I::is_empty)
+    }
+}
+
+// NOTE: for `I: FusedIterator`, we assume that the iterator is always `Some`
+impl<I: FusedIterator> Fuse<I> {
+    #[inline(always)]
+    fn as_inner(&self) -> &I {
+        match self.iter {
+            Some(ref iter) => iter,
+            // SAFETY: the specialized iterator never sets `None`
+            None => unsafe { intrinsics::unreachable() },
+        }
+    }
+
+    #[inline(always)]
+    fn as_inner_mut(&mut self) -> &mut I {
+        match self.iter {
+            Some(ref mut iter) => iter,
+            // SAFETY: the specialized iterator never sets `None`
+            None => unsafe { intrinsics::unreachable() },
+        }
+    }
+
+    #[inline(always)]
+    fn into_inner(self) -> I {
+        match self.iter {
+            Some(iter) => iter,
+            // SAFETY: the specialized iterator never sets `None`
+            None => unsafe { intrinsics::unreachable() },
+        }
+    }
+}
+
+#[stable(feature = "fused", since = "1.26.0")]
+impl<I> Iterator for Fuse<I>
+where
+    I: FusedIterator,
+{
+    #[inline]
+    fn next(&mut self) -> Option<<I as Iterator>::Item> {
+        self.as_inner_mut().next()
+    }
+
+    #[inline]
+    fn nth(&mut self, n: usize) -> Option<I::Item> {
+        self.as_inner_mut().nth(n)
+    }
+
+    #[inline]
+    fn last(self) -> Option<I::Item> {
+        self.into_inner().last()
+    }
+
+    #[inline]
+    fn count(self) -> usize {
+        self.into_inner().count()
+    }
+
+    #[inline]
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        self.as_inner().size_hint()
+    }
+
+    #[inline]
+    fn try_fold<Acc, Fold, R>(&mut self, init: Acc, fold: Fold) -> R
+    where
+        Self: Sized,
+        Fold: FnMut(Acc, Self::Item) -> R,
+        R: Try<Ok = Acc>,
+    {
+        self.as_inner_mut().try_fold(init, fold)
+    }
+
+    #[inline]
+    fn fold<Acc, Fold>(self, init: Acc, fold: Fold) -> Acc
+    where
+        Fold: FnMut(Acc, Self::Item) -> Acc,
+    {
+        self.into_inner().fold(init, fold)
+    }
+
+    #[inline]
+    fn find<P>(&mut self, predicate: P) -> Option<Self::Item>
+    where
+        P: FnMut(&Self::Item) -> bool,
+    {
+        self.as_inner_mut().find(predicate)
+    }
+}
+
+#[stable(feature = "fused", since = "1.26.0")]
+impl<I> DoubleEndedIterator for Fuse<I>
+where
+    I: DoubleEndedIterator + FusedIterator,
+{
+    #[inline]
+    fn next_back(&mut self) -> Option<<I as Iterator>::Item> {
+        self.as_inner_mut().next_back()
+    }
+
+    #[inline]
+    fn nth_back(&mut self, n: usize) -> Option<<I as Iterator>::Item> {
+        self.as_inner_mut().nth_back(n)
+    }
+
+    #[inline]
+    fn try_rfold<Acc, Fold, R>(&mut self, init: Acc, fold: Fold) -> R
+    where
+        Self: Sized,
+        Fold: FnMut(Acc, Self::Item) -> R,
+        R: Try<Ok = Acc>,
+    {
+        self.as_inner_mut().try_rfold(init, fold)
+    }
+
+    #[inline]
+    fn rfold<Acc, Fold>(self, init: Acc, fold: Fold) -> Acc
+    where
+        Fold: FnMut(Acc, Self::Item) -> Acc,
+    {
+        self.into_inner().rfold(init, fold)
+    }
+
+    #[inline]
+    fn rfind<P>(&mut self, predicate: P) -> Option<Self::Item>
+    where
+        P: FnMut(&Self::Item) -> bool,
+    {
+        self.as_inner_mut().rfind(predicate)
+    }
+}
+
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<I> ExactSizeIterator for Fuse<I>
+where
+    I: ExactSizeIterator + FusedIterator,
+{
+    fn len(&self) -> usize {
+        self.as_inner().len()
+    }
+
+    fn is_empty(&self) -> bool {
+        self.as_inner().is_empty()
+    }
+}
+
+unsafe impl<I> TrustedRandomAccess for Fuse<I>
+where
+    I: TrustedRandomAccess,
+{
+    unsafe fn get_unchecked(&mut self, i: usize) -> I::Item {
+        match self.iter {
+            Some(ref mut iter) => iter.get_unchecked(i),
+            // SAFETY: the caller asserts there is an item at `i`, so we're not exhausted.
+            None => intrinsics::unreachable(),
+        }
+    }
+
+    fn may_have_side_effect() -> bool {
+        I::may_have_side_effect()
+    }
+}

src/libcore/iter/adapters/mod.rs

@@ -9,11 +9,13 @@ use super::{DoubleEndedIterator, ExactSizeIterator, FusedIterator, Iterator, Tru
 
 mod chain;
 mod flatten;
+mod fuse;
 mod zip;
 
 pub use self::chain::Chain;
 #[stable(feature = "rust1", since = "1.0.0")]
 pub use self::flatten::{FlatMap, Flatten};
+pub use self::fuse::Fuse;
 pub(crate) use self::zip::TrustedRandomAccess;
 pub use self::zip::Zip;
 
@@ -2238,261 +2240,6 @@ where
     }
 }
 
-/// An iterator that yields `None` forever after the underlying iterator
-/// yields `None` once.
-///
-/// This `struct` is created by the [`fuse`] method on [`Iterator`]. See its
-/// documentation for more.
-///
-/// [`fuse`]: trait.Iterator.html#method.fuse
-/// [`Iterator`]: trait.Iterator.html
-#[derive(Clone, Debug)]
-#[must_use = "iterators are lazy and do nothing unless consumed"]
-#[stable(feature = "rust1", since = "1.0.0")]
-pub struct Fuse<I> {
-    iter: I,
-    done: bool,
-}
-impl<I> Fuse<I> {
-    pub(super) fn new(iter: I) -> Fuse<I> {
-        Fuse { iter, done: false }
-    }
-}
-
-#[stable(feature = "fused", since = "1.26.0")]
-impl<I> FusedIterator for Fuse<I> where I: Iterator {}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<I> Iterator for Fuse<I>
-where
-    I: Iterator,
-{
-    type Item = <I as Iterator>::Item;
-
-    #[inline]
-    default fn next(&mut self) -> Option<<I as Iterator>::Item> {
-        if self.done {
-            None
-        } else {
-            let next = self.iter.next();
-            self.done = next.is_none();
-            next
-        }
-    }
-
-    #[inline]
-    default fn nth(&mut self, n: usize) -> Option<I::Item> {
-        if self.done {
-            None
-        } else {
-            let nth = self.iter.nth(n);
-            self.done = nth.is_none();
-            nth
-        }
-    }
-
-    #[inline]
-    default fn last(self) -> Option<I::Item> {
-        if self.done { None } else { self.iter.last() }
-    }
-
-    #[inline]
-    default fn count(self) -> usize {
-        if self.done { 0 } else { self.iter.count() }
-    }
-
-    #[inline]
-    default fn size_hint(&self) -> (usize, Option<usize>) {
-        if self.done { (0, Some(0)) } else { self.iter.size_hint() }
-    }
-
-    #[inline]
-    default fn try_fold<Acc, Fold, R>(&mut self, init: Acc, fold: Fold) -> R
-    where
-        Self: Sized,
-        Fold: FnMut(Acc, Self::Item) -> R,
-        R: Try<Ok = Acc>,
-    {
-        if self.done {
-            Try::from_ok(init)
-        } else {
-            let acc = self.iter.try_fold(init, fold)?;
-            self.done = true;
-            Try::from_ok(acc)
-        }
-    }
-
-    #[inline]
-    default fn fold<Acc, Fold>(self, init: Acc, fold: Fold) -> Acc
-    where
-        Fold: FnMut(Acc, Self::Item) -> Acc,
-    {
-        if self.done { init } else { self.iter.fold(init, fold) }
-    }
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<I> DoubleEndedIterator for Fuse<I>
-where
-    I: DoubleEndedIterator,
-{
-    #[inline]
-    default fn next_back(&mut self) -> Option<<I as Iterator>::Item> {
-        if self.done {
-            None
-        } else {
-            let next = self.iter.next_back();
-            self.done = next.is_none();
-            next
-        }
-    }
-
-    #[inline]
-    default fn nth_back(&mut self, n: usize) -> Option<<I as Iterator>::Item> {
-        if self.done {
-            None
-        } else {
-            let nth = self.iter.nth_back(n);
-            self.done = nth.is_none();
-            nth
-        }
-    }
-
-    #[inline]
-    default fn try_rfold<Acc, Fold, R>(&mut self, init: Acc, fold: Fold) -> R
-    where
-        Self: Sized,
-        Fold: FnMut(Acc, Self::Item) -> R,
-        R: Try<Ok = Acc>,
-    {
-        if self.done {
-            Try::from_ok(init)
-        } else {
-            let acc = self.iter.try_rfold(init, fold)?;
-            self.done = true;
-            Try::from_ok(acc)
-        }
-    }
-
-    #[inline]
-    default fn rfold<Acc, Fold>(self, init: Acc, fold: Fold) -> Acc
-    where
-        Fold: FnMut(Acc, Self::Item) -> Acc,
-    {
-        if self.done { init } else { self.iter.rfold(init, fold) }
-    }
-}
-
-unsafe impl<I> TrustedRandomAccess for Fuse<I>
-where
-    I: TrustedRandomAccess,
-{
-    unsafe fn get_unchecked(&mut self, i: usize) -> I::Item {
-        self.iter.get_unchecked(i)
-    }
-
-    fn may_have_side_effect() -> bool {
-        I::may_have_side_effect()
-    }
-}
-
-#[stable(feature = "fused", since = "1.26.0")]
-impl<I> Iterator for Fuse<I>
-where
-    I: FusedIterator,
-{
-    #[inline]
-    fn next(&mut self) -> Option<<I as Iterator>::Item> {
-        self.iter.next()
-    }
-
-    #[inline]
-    fn nth(&mut self, n: usize) -> Option<I::Item> {
-        self.iter.nth(n)
-    }
-
-    #[inline]
-    fn last(self) -> Option<I::Item> {
-        self.iter.last()
-    }
-
-    #[inline]
-    fn count(self) -> usize {
-        self.iter.count()
-    }
-
-    #[inline]
-    fn size_hint(&self) -> (usize, Option<usize>) {
-        self.iter.size_hint()
-    }
-
-    #[inline]
-    fn try_fold<Acc, Fold, R>(&mut self, init: Acc, fold: Fold) -> R
-    where
-        Self: Sized,
-        Fold: FnMut(Acc, Self::Item) -> R,
-        R: Try<Ok = Acc>,
-    {
-        self.iter.try_fold(init, fold)
-    }
-
-    #[inline]
-    fn fold<Acc, Fold>(self, init: Acc, fold: Fold) -> Acc
-    where
-        Fold: FnMut(Acc, Self::Item) -> Acc,
-    {
-        self.iter.fold(init, fold)
-    }
-}
-
-#[stable(feature = "fused", since = "1.26.0")]
-impl<I> DoubleEndedIterator for Fuse<I>
-where
-    I: DoubleEndedIterator + FusedIterator,
-{
-    #[inline]
-    fn next_back(&mut self) -> Option<<I as Iterator>::Item> {
-        self.iter.next_back()
-    }
-
-    #[inline]
-    fn nth_back(&mut self, n: usize) -> Option<<I as Iterator>::Item> {
-        self.iter.nth_back(n)
-    }
-
-    #[inline]
-    fn try_rfold<Acc, Fold, R>(&mut self, init: Acc, fold: Fold) -> R
-    where
-        Self: Sized,
-        Fold: FnMut(Acc, Self::Item) -> R,
-        R: Try<Ok = Acc>,
-    {
-        self.iter.try_rfold(init, fold)
-    }
-
-    #[inline]
-    fn rfold<Acc, Fold>(self, init: Acc, fold: Fold) -> Acc
-    where
-        Fold: FnMut(Acc, Self::Item) -> Acc,
-    {
-        self.iter.rfold(init, fold)
-    }
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<I> ExactSizeIterator for Fuse<I>
-where
-    I: ExactSizeIterator,
-{
-    fn len(&self) -> usize {
-        self.iter.len()
-    }
-
-    fn is_empty(&self) -> bool {
-        self.iter.is_empty()
-    }
-}
-
 /// An iterator that calls a function with a reference to each element before
 /// yielding it.
 ///

src/librustc/dep_graph/dep_node.rs

@@ -57,7 +57,7 @@ use crate::traits::query::{
     CanonicalTypeOpAscribeUserTypeGoal, CanonicalTypeOpEqGoal, CanonicalTypeOpNormalizeGoal,
     CanonicalTypeOpProvePredicateGoal, CanonicalTypeOpSubtypeGoal,
 };
-use crate::ty::subst::SubstsRef;
+use crate::ty::subst::{GenericArg, SubstsRef};
 use crate::ty::{self, ParamEnvAnd, Ty, TyCtxt};
 
 use rustc_data_structures::fingerprint::Fingerprint;

src/librustc/mir/interpret/allocation.rs

@@ -372,7 +372,7 @@ impl<'tcx, Tag: Copy, Extra: AllocationExtra<Tag>> Allocation<Tag, Extra> {
         let bytes = self.get_bytes_with_undef_and_ptr(cx, ptr, size)?;
         // Undef check happens *after* we established that the alignment is correct.
         // We must not return `Ok()` for unaligned pointers!
-        if self.check_defined(ptr, size).is_err() {
+        if self.is_defined(ptr, size).is_err() {
             // This inflates undefined bytes to the entire scalar, even if only a few
             // bytes are undefined.
             return Ok(ScalarMaybeUndef::Undef);
@@ -557,13 +557,19 @@ impl<'tcx, Tag: Copy, Extra> Allocation<Tag, Extra> {
 }
 
 /// Undefined bytes.
-impl<'tcx, Tag, Extra> Allocation<Tag, Extra> {
+impl<'tcx, Tag: Copy, Extra> Allocation<Tag, Extra> {
+    /// Checks whether the given range  is entirely defined.
+    ///
+    /// Returns `Ok(())` if it's defined. Otherwise returns the index of the byte
+    /// at which the first undefined access begins.
+    fn is_defined(&self, ptr: Pointer<Tag>, size: Size) -> Result<(), Size> {
+        self.undef_mask.is_range_defined(ptr.offset, ptr.offset + size)
+    }
+
     /// Checks that a range of bytes is defined. If not, returns the `ReadUndefBytes`
     /// error which will report the first byte which is undefined.
-    #[inline]
     fn check_defined(&self, ptr: Pointer<Tag>, size: Size) -> InterpResult<'tcx> {
-        self.undef_mask
-            .is_range_defined(ptr.offset, ptr.offset + size)
+        self.is_defined(ptr, size)
             .or_else(|idx| throw_ub!(InvalidUndefBytes(Some(Pointer::new(ptr.alloc_id, idx)))))
     }
 

src/librustc/query/mod.rs

@@ -9,7 +9,7 @@ use crate::traits::query::{
 };
 use crate::ty::query::queries;
 use crate::ty::query::QueryDescription;
-use crate::ty::subst::SubstsRef;
+use crate::ty::subst::{GenericArg, SubstsRef};
 use crate::ty::{self, ParamEnvAnd, Ty, TyCtxt};
 use rustc_hir::def_id::{CrateNum, DefId, LocalDefId};
 
@@ -1114,10 +1114,10 @@ rustc_queries! {
         }
 
         /// Do not call this query directly: invoke `normalize_erasing_regions` instead.
-        query normalize_ty_after_erasing_regions(
-            goal: ParamEnvAnd<'tcx, Ty<'tcx>>
-        ) -> Ty<'tcx> {
-            desc { "normalizing `{:?}`", goal }
+        query normalize_generic_arg_after_erasing_regions(
+            goal: ParamEnvAnd<'tcx, GenericArg<'tcx>>
+        ) -> GenericArg<'tcx> {
+            desc { "normalizing `{}`", goal.value }
         }
 
         query implied_outlives_bounds(

src/librustc/traits/structural_impls.rs

@@ -273,6 +273,20 @@ impl<'tcx> TypeVisitor<'tcx> for BoundNamesCollector {
         t.super_visit_with(self)
     }
 
+    fn visit_const(&mut self, c: &'tcx ty::Const<'tcx>) -> bool {
+        match c.val {
+            ty::ConstKind::Bound(debruijn, bound_var) if debruijn == self.binder_index => {
+                self.types.insert(
+                    bound_var.as_u32(),
+                    Symbol::intern(&format!("^{}", bound_var.as_u32())),
+                );
+            }
+            _ => (),
+        }
+
+        c.super_visit_with(self)
+    }
+
     fn visit_region(&mut self, r: ty::Region<'tcx>) -> bool {
         match r {
             ty::ReLateBound(index, br) if *index == self.binder_index => match br {

src/librustc/ty/fold.rs

@@ -978,17 +978,27 @@ impl<'tcx> TypeVisitor<'tcx> for LateBoundRegionsCollector {
         // ignore the inputs to a projection, as they may not appear
         // in the normalized form
         if self.just_constrained {
-            match t.kind {
-                ty::Projection(..) | ty::Opaque(..) => {
-                    return false;
-                }
-                _ => {}
+            if let ty::Projection(..) | ty::Opaque(..) = t.kind {
+                return false;
             }
         }
 
         t.super_visit_with(self)
     }
 
+    fn visit_const(&mut self, c: &'tcx ty::Const<'tcx>) -> bool {
+        // if we are only looking for "constrained" region, we have to
+        // ignore the inputs of an unevaluated const, as they may not appear
+        // in the normalized form
+        if self.just_constrained {
+            if let ty::ConstKind::Unevaluated(..) = c.val {
+                return false;
+            }
+        }
+
+        c.super_visit_with(self)
+    }
+
     fn visit_region(&mut self, r: ty::Region<'tcx>) -> bool {
         if let ty::ReLateBound(debruijn, br) = *r {
             if debruijn == self.current_index {

src/librustc/ty/normalize_erasing_regions.rs

@@ -4,8 +4,8 @@
 //!
 //! The methods in this file use a `TypeFolder` to recursively process
 //! contents, invoking the underlying
-//! `normalize_ty_after_erasing_regions` query for each type found
-//! within. (This underlying query is what is cached.)
+//! `normalize_generic_arg_after_erasing_regions` query for each type
+//! or constant found within. (This underlying query is what is cached.)
 
 use crate::ty::fold::{TypeFoldable, TypeFolder};
 use crate::ty::subst::{Subst, SubstsRef};
@@ -94,6 +94,12 @@ impl TypeFolder<'tcx> for NormalizeAfterErasingRegionsFolder<'tcx> {
     }
 
     fn fold_ty(&mut self, ty: Ty<'tcx>) -> Ty<'tcx> {
-        self.tcx.normalize_ty_after_erasing_regions(self.param_env.and(ty))
+        let arg = self.param_env.and(ty.into());
+        self.tcx.normalize_generic_arg_after_erasing_regions(arg).expect_ty()
+    }
+
+    fn fold_const(&mut self, c: &'tcx ty::Const<'tcx>) -> &'tcx ty::Const<'tcx> {
+        let arg = self.param_env.and(c.into());
+        self.tcx.normalize_generic_arg_after_erasing_regions(arg).expect_const()
     }
 }

src/librustc/ty/query/keys.rs

@@ -5,7 +5,7 @@ use crate::mir;
 use crate::traits;
 use crate::ty::fast_reject::SimplifiedType;
 use crate::ty::query::caches::DefaultCacheSelector;
-use crate::ty::subst::SubstsRef;
+use crate::ty::subst::{GenericArg, SubstsRef};
 use crate::ty::{self, Ty, TyCtxt};
 use rustc_hir::def_id::{CrateNum, DefId, LocalDefId, LOCAL_CRATE};
 use rustc_span::symbol::Symbol;
@@ -194,6 +194,17 @@ impl<'tcx> Key for ty::PolyTraitRef<'tcx> {
     }
 }
 
+impl<'tcx> Key for GenericArg<'tcx> {
+    type CacheSelector = DefaultCacheSelector;
+
+    fn query_crate(&self) -> CrateNum {
+        LOCAL_CRATE
+    }
+    fn default_span(&self, _: TyCtxt<'_>) -> Span {
+        DUMMY_SP
+    }
+}
+
 impl<'tcx> Key for &'tcx ty::Const<'tcx> {
     type CacheSelector = DefaultCacheSelector;
 

src/librustc/ty/query/mod.rs

@@ -31,7 +31,7 @@ use crate::traits::specialization_graph;
 use crate::traits::Clauses;
 use crate::traits::{self, Vtable};
 use crate::ty::steal::Steal;
-use crate::ty::subst::SubstsRef;
+use crate::ty::subst::{GenericArg, SubstsRef};
 use crate::ty::util::AlwaysRequiresDrop;
 use crate::ty::{self, AdtSizedConstraint, CrateInherentImpls, ParamEnvAnd, Ty, TyCtxt};
 use crate::util::common::ErrorReported;

src/librustc/ty/subst.rs

@@ -128,6 +128,14 @@ impl<'tcx> GenericArg<'tcx> {
             _ => bug!("expected a type, but found another kind"),
         }
     }
+
+    /// Unpack the `GenericArg` as a const when it is known certainly to be a const.
+    pub fn expect_const(self) -> &'tcx ty::Const<'tcx> {
+        match self.unpack() {
+            GenericArgKind::Const(c) => c,
+            _ => bug!("expected a const, but found another kind"),
+        }
+    }
 }
 
 impl<'a, 'tcx> Lift<'tcx> for GenericArg<'a> {

src/librustc_mir/interpret/memory.rs

@@ -473,7 +473,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> Memory<'mir, 'tcx, M> {
     }
 
     /// Gives raw access to the `Allocation`, without bounds or alignment checks.
-    /// Use the higher-level, `PlaceTy`- and `OpTy`-based APIs in `InterpCtx` instead!
+    /// Use the higher-level, `PlaceTy`- and `OpTy`-based APIs in `InterpCx` instead!
     pub fn get_raw(
         &self,
         id: AllocId,
@@ -510,7 +510,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> Memory<'mir, 'tcx, M> {
     }
 
     /// Gives raw mutable access to the `Allocation`, without bounds or alignment checks.
-    /// Use the higher-level, `PlaceTy`- and `OpTy`-based APIs in `InterpCtx` instead!
+    /// Use the higher-level, `PlaceTy`- and `OpTy`-based APIs in `InterpCx` instead!
     pub fn get_raw_mut(
         &mut self,
         id: AllocId,

src/librustc_session/session.rs

@@ -150,7 +150,7 @@ pub struct PerfStats {
     /// Total number of values canonicalized queries constructed.
     pub queries_canonicalized: AtomicUsize,
     /// Number of times this query is invoked.
-    pub normalize_ty_after_erasing_regions: AtomicUsize,
+    pub normalize_generic_arg_after_erasing_regions: AtomicUsize,
     /// Number of times this query is invoked.
     pub normalize_projection_ty: AtomicUsize,
 }
@@ -707,8 +707,8 @@ impl Session {
             self.perf_stats.queries_canonicalized.load(Ordering::Relaxed)
         );
         println!(
-            "normalize_ty_after_erasing_regions:            {}",
-            self.perf_stats.normalize_ty_after_erasing_regions.load(Ordering::Relaxed)
+            "normalize_generic_arg_after_erasing_regions:   {}",
+            self.perf_stats.normalize_generic_arg_after_erasing_regions.load(Ordering::Relaxed)
         );
         println!(
             "normalize_projection_ty:                       {}",
@@ -1080,7 +1080,7 @@ fn build_session_(
             symbol_hash_time: Lock::new(Duration::from_secs(0)),
             decode_def_path_tables_time: Lock::new(Duration::from_secs(0)),
             queries_canonicalized: AtomicUsize::new(0),
-            normalize_ty_after_erasing_regions: AtomicUsize::new(0),
+            normalize_generic_arg_after_erasing_regions: AtomicUsize::new(0),
             normalize_projection_ty: AtomicUsize::new(0),
         },
         code_stats: Default::default(),

src/librustc_trait_selection/traits/project.rs

@@ -387,6 +387,7 @@ impl<'a, 'b, 'tcx> TypeFolder<'tcx> for AssocTypeNormalizer<'a, 'b, 'tcx> {
     }
 
     fn fold_const(&mut self, constant: &'tcx ty::Const<'tcx>) -> &'tcx ty::Const<'tcx> {
+        let constant = constant.super_fold_with(self);
         constant.eval(self.selcx.tcx(), self.param_env)
     }
 }

src/librustc_trait_selection/traits/query/normalize.rs

@@ -191,6 +191,7 @@ impl<'cx, 'tcx> TypeFolder<'tcx> for QueryNormalizer<'cx, 'tcx> {
     }
 
     fn fold_const(&mut self, constant: &'tcx ty::Const<'tcx>) -> &'tcx ty::Const<'tcx> {
+        let constant = constant.super_fold_with(self);
         constant.eval(self.infcx.tcx, self.param_env)
     }
 }

src/librustc_traits/normalize_erasing_regions.rs

@@ -1,23 +1,24 @@
 use rustc::traits::query::NoSolution;
 use rustc::ty::query::Providers;
-use rustc::ty::{self, ParamEnvAnd, Ty, TyCtxt};
+use rustc::ty::subst::GenericArg;
+use rustc::ty::{self, ParamEnvAnd, TyCtxt};
 use rustc_infer::infer::TyCtxtInferExt;
 use rustc_trait_selection::traits::query::normalize::AtExt;
 use rustc_trait_selection::traits::{Normalized, ObligationCause};
 use std::sync::atomic::Ordering;
 
 crate fn provide(p: &mut Providers<'_>) {
-    *p = Providers { normalize_ty_after_erasing_regions, ..*p };
+    *p = Providers { normalize_generic_arg_after_erasing_regions, ..*p };
 }
 
-fn normalize_ty_after_erasing_regions<'tcx>(
+fn normalize_generic_arg_after_erasing_regions<'tcx>(
     tcx: TyCtxt<'tcx>,
-    goal: ParamEnvAnd<'tcx, Ty<'tcx>>,
-) -> Ty<'tcx> {
-    debug!("normalize_ty_after_erasing_regions(goal={:#?})", goal);
+    goal: ParamEnvAnd<'tcx, GenericArg<'tcx>>,
+) -> GenericArg<'tcx> {
+    debug!("normalize_generic_arg_after_erasing_regions(goal={:#?})", goal);
 
     let ParamEnvAnd { param_env, value } = goal;
-    tcx.sess.perf_stats.normalize_ty_after_erasing_regions.fetch_add(1, Ordering::Relaxed);
+    tcx.sess.perf_stats.normalize_generic_arg_after_erasing_regions.fetch_add(1, Ordering::Relaxed);
     tcx.infer_ctxt().enter(|infcx| {
         let cause = ObligationCause::dummy();
         match infcx.at(&cause, param_env).normalize(&value) {

src/test/mir-opt/inline/inline-into-box-place.rs

@@ -1,6 +1,7 @@
 // ignore-tidy-linelength
 // ignore-wasm32-bare compiled with panic=abort by default
 // compile-flags: -Z mir-opt-level=3
+// only-64bit FIXME: the mir representation of RawVec depends on ptr size
 #![feature(box_syntax)]
 
 fn main() {
@@ -55,7 +56,7 @@ fn main() {
 //   StorageLive(_2);
 //   _2 = Box(std::vec::Vec<u32>);
 //   _4 = &mut (*_2);
-//   ((*_4).0: alloc::raw_vec::RawVec<u32>) = const alloc::raw_vec::RawVec::<u32>::NEW;
+//   ((*_4).0: alloc::raw_vec::RawVec<u32>) = const ByRef { alloc: Allocation { bytes: [4, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0], relocations: Relocations(SortedMap { data: [] }), undef_mask: UndefMask { blocks: [65535], len: Size { raw: 16 } }, size: Size { raw: 16 }, align: Align { pow2: 3 }, mutability: Not, extra: () }, offset: Size { raw: 0 } }: alloc::raw_vec::RawVec::<u32>;
 //   ((*_4).1: usize) = const 0usize;
 //   _1 = move _2;
 //   StorageDead(_2);

src/test/ui/associated-const/defaults-cyclic-fail.rs

@@ -1,9 +1,9 @@
 // build-fail
+//~^ ERROR cycle detected when normalizing `<() as Tr>::A`
 
 // Cyclic assoc. const defaults don't error unless *used*
 trait Tr {
     const A: u8 = Self::B;
-    //~^ ERROR cycle detected when const-evaluating + checking `Tr::A`
 
     const B: u8 = Self::A;
 }

src/test/ui/associated-const/defaults-cyclic-fail.stderr

@@ -1,30 +1,42 @@
-error[E0391]: cycle detected when const-evaluating + checking `Tr::A`
-  --> $DIR/defaults-cyclic-fail.rs:5:5
+error[E0391]: cycle detected when normalizing `<() as Tr>::A`
+   |
+note: ...which requires const-evaluating + checking `Tr::A`...
+  --> $DIR/defaults-cyclic-fail.rs:6:5
    |
 LL |     const A: u8 = Self::B;
    |     ^^^^^^^^^^^^^^^^^^^^^^
+note: ...which requires const-evaluating + checking `Tr::A`...
+  --> $DIR/defaults-cyclic-fail.rs:6:5
    |
+LL |     const A: u8 = Self::B;
+   |     ^^^^^^^^^^^^^^^^^^^^^^
 note: ...which requires const-evaluating `Tr::A`...
-  --> $DIR/defaults-cyclic-fail.rs:5:19
+  --> $DIR/defaults-cyclic-fail.rs:6:5
    |
 LL |     const A: u8 = Self::B;
-   |                   ^^^^^^^
+   |     ^^^^^^^^^^^^^^^^^^^^^^
+   = note: ...which requires normalizing `<() as Tr>::B`...
+note: ...which requires const-evaluating + checking `Tr::B`...
+  --> $DIR/defaults-cyclic-fail.rs:8:5
+   |
+LL |     const B: u8 = Self::A;
+   |     ^^^^^^^^^^^^^^^^^^^^^^
 note: ...which requires const-evaluating + checking `Tr::B`...
   --> $DIR/defaults-cyclic-fail.rs:8:5
    |
 LL |     const B: u8 = Self::A;
    |     ^^^^^^^^^^^^^^^^^^^^^^
 note: ...which requires const-evaluating `Tr::B`...
-  --> $DIR/defaults-cyclic-fail.rs:8:19
+  --> $DIR/defaults-cyclic-fail.rs:8:5
    |
 LL |     const B: u8 = Self::A;
-   |                   ^^^^^^^
-   = note: ...which again requires const-evaluating + checking `Tr::A`, completing the cycle
+   |     ^^^^^^^^^^^^^^^^^^^^^^
+   = note: ...which again requires normalizing `<() as Tr>::A`, completing the cycle
 note: cycle used when const-evaluating `main`
-  --> $DIR/defaults-cyclic-fail.rs:16:16
+  --> $DIR/defaults-cyclic-fail.rs:14:1
    |
-LL |     assert_eq!(<() as Tr>::A, 0);
-   |                ^^^^^^^^^^^^^
+LL | fn main() {
+   | ^^^^^^^^^
 
 error: aborting due to previous error
 

src/test/ui/consts/const-size_of-cycle.stderr

@@ -25,7 +25,7 @@ note: ...which requires const-evaluating + checking `std::intrinsics::size_of`..
 LL |     pub fn size_of<T>() -> usize;
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    = note: ...which requires computing layout of `Foo`...
-   = note: ...which requires normalizing `ParamEnvAnd { param_env: ParamEnv { caller_bounds: [], reveal: All, def_id: None }, value: [u8; _] }`...
+   = note: ...which requires normalizing `[u8; _]`...
    = note: ...which again requires const-evaluating + checking `Foo::bytes::{{constant}}#0`, completing the cycle
 note: cycle used when processing `Foo`
   --> $DIR/const-size_of-cycle.rs:7:1