18 files changed, 187 insertions, 32 deletions
diff --git a/.gitmodules b/.gitmodules
index e79f2f089c1..0bbccb57130 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -25,7 +25,7 @@
 [submodule "src/llvm-project"]
 	path = src/llvm-project
 	url = https://github.com/rust-lang/llvm-project.git
-	branch = rustc/15.0-2022-12-07
+	branch = rustc/16.0-2023-03-06
 [submodule "src/doc/embedded-book"]
 	path = src/doc/embedded-book
 	url = https://github.com/rust-embedded/book.git
diff --git a/compiler/rustc_index/src/bit_set.rs b/compiler/rustc_index/src/bit_set.rs
index cbf169afb18..eba5b3ed882 100644
--- a/compiler/rustc_index/src/bit_set.rs
+++ b/compiler/rustc_index/src/bit_set.rs
@@ -1,5 +1,6 @@
 use crate::vec::{Idx, IndexVec};
 use arrayvec::ArrayVec;
+use smallvec::{smallvec, SmallVec};
 use std::fmt;
 use std::iter;
 use std::marker::PhantomData;
@@ -111,7 +112,7 @@ macro_rules! bit_relations_inherent_impls {
 #[derive(Eq, PartialEq, Hash, Decodable, Encodable)]
 pub struct BitSet<T> {
     domain_size: usize,
-    words: Vec<Word>,
+    words: SmallVec<[Word; 2]>,
     marker: PhantomData<T>,
 }
 
@@ -127,14 +128,15 @@ impl<T: Idx> BitSet<T> {
     #[inline]
     pub fn new_empty(domain_size: usize) -> BitSet<T> {
         let num_words = num_words(domain_size);
-        BitSet { domain_size, words: vec![0; num_words], marker: PhantomData }
+        BitSet { domain_size, words: smallvec![0; num_words], marker: PhantomData }
     }
 
     /// Creates a new, filled bitset with a given `domain_size`.
     #[inline]
     pub fn new_filled(domain_size: usize) -> BitSet<T> {
         let num_words = num_words(domain_size);
-        let mut result = BitSet { domain_size, words: vec![!0; num_words], marker: PhantomData };
+        let mut result =
+            BitSet { domain_size, words: smallvec![!0; num_words], marker: PhantomData };
         result.clear_excess_bits();
         result
     }
@@ -1571,7 +1573,7 @@ impl<T: Idx> From<BitSet<T>> for GrowableBitSet<T> {
 pub struct BitMatrix<R: Idx, C: Idx> {
     num_rows: usize,
     num_columns: usize,
-    words: Vec<Word>,
+    words: SmallVec<[Word; 2]>,
     marker: PhantomData<(R, C)>,
 }
 
@@ -1584,7 +1586,7 @@ impl<R: Idx, C: Idx> BitMatrix<R, C> {
         BitMatrix {
             num_rows,
             num_columns,
-            words: vec![0; num_rows * words_per_row],
+            words: smallvec![0; num_rows * words_per_row],
             marker: PhantomData,
         }
     }
diff --git a/compiler/rustc_middle/src/ty/mod.rs b/compiler/rustc_middle/src/ty/mod.rs
index e3cd5cca785..c6a56df5a5e 100644
--- a/compiler/rustc_middle/src/ty/mod.rs
+++ b/compiler/rustc_middle/src/ty/mod.rs
@@ -653,8 +653,8 @@ pub enum AliasRelationDirection {
 impl std::fmt::Display for AliasRelationDirection {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         match self {
-            AliasRelationDirection::Equate => write!(f, " == "),
-            AliasRelationDirection::Subtype => write!(f, " <: "),
+            AliasRelationDirection::Equate => write!(f, "=="),
+            AliasRelationDirection::Subtype => write!(f, "<:"),
         }
     }
 }
diff --git a/compiler/rustc_trait_selection/src/solve/project_goals.rs b/compiler/rustc_trait_selection/src/solve/project_goals.rs
index 525b3105538..14c5b83c6ca 100644
--- a/compiler/rustc_trait_selection/src/solve/project_goals.rs
+++ b/compiler/rustc_trait_selection/src/solve/project_goals.rs
@@ -174,7 +174,7 @@ impl<'tcx> assembly::GoalKind<'tcx> for ProjectionPredicate<'tcx> {
                 goal.predicate.def_id(),
                 impl_def_id
             )? else {
-                return ecx.evaluate_added_goals_and_make_canonical_response(Certainty::Yes);
+                return ecx.evaluate_added_goals_and_make_canonical_response(Certainty::AMBIGUOUS);
             };
 
             if !assoc_def.item.defaultness(tcx).has_value() {
diff --git a/library/core/src/alloc/mod.rs b/library/core/src/alloc/mod.rs
index a6082455fac..ff390322d55 100644
--- a/library/core/src/alloc/mod.rs
+++ b/library/core/src/alloc/mod.rs
@@ -95,10 +95,10 @@ impl fmt::Display for AllocError {
 /// # Safety
 ///
 /// * Memory blocks returned from an allocator must point to valid memory and retain their validity
-///   until the instance and all of its clones are dropped,
+///   until the instance and all of its copies and clones are dropped,
 ///
-/// * cloning or moving the allocator must not invalidate memory blocks returned from this
-///   allocator. A cloned allocator must behave like the same allocator, and
+/// * copying, cloning, or moving the allocator must not invalidate memory blocks returned from this
+///   allocator. A copied or cloned allocator must behave like the same allocator, and
 ///
 /// * any pointer to a memory block which is [*currently allocated*] may be passed to any other
 ///   method of the allocator.
diff --git a/library/core/src/hint.rs b/library/core/src/hint.rs
index ee13dae60b1..a205565773a 100644
--- a/library/core/src/hint.rs
+++ b/library/core/src/hint.rs
@@ -228,7 +228,7 @@ pub fn spin_loop() {
 /// This _immediately_ precludes any direct use of this function for cryptographic or security
 /// purposes.
 ///
-/// While not suitable in those mission-critical cases, `back_box`'s functionality can generally be
+/// While not suitable in those mission-critical cases, `black_box`'s functionality can generally be
 /// relied upon for benchmarking, and should be used there. It will try to ensure that the
 /// compiler doesn't optimize away part of the intended test code based on context. For
 /// example:
diff --git a/src/ci/docker/host-x86_64/dist-x86_64-linux/build-gcc.sh b/src/ci/docker/host-x86_64/dist-x86_64-linux/build-gcc.sh
index 9932b250566..41ca1385c75 100755
--- a/src/ci/docker/host-x86_64/dist-x86_64-linux/build-gcc.sh
+++ b/src/ci/docker/host-x86_64/dist-x86_64-linux/build-gcc.sh
@@ -3,7 +3,7 @@ set -ex
 
 source shared.sh
 
-GCC=7.5.0
+GCC=8.5.0
 
 curl https://ftp.gnu.org/gnu/gcc/gcc-$GCC/gcc-$GCC.tar.xz | xzcat | tar xf -
 cd gcc-$GCC
diff --git a/src/doc/rustdoc/src/write-documentation/what-to-include.md b/src/doc/rustdoc/src/write-documentation/what-to-include.md
index e1e09aa4a8a..cf1e6a8d3ca 100644
--- a/src/doc/rustdoc/src/write-documentation/what-to-include.md
+++ b/src/doc/rustdoc/src/write-documentation/what-to-include.md
@@ -39,7 +39,7 @@ warning: 1 warning emitted
 As a library author, adding the lint `#![deny(missing_docs)]` is a great way to
 ensure the project does not drift away from being documented well, and
 `#![warn(missing_docs)]` is a good way to move towards comprehensive
-documentation.  In addition to docs, `#![deny(missing_doc_code_examples)]`
+documentation.  In addition to docs, `#![deny(rustdoc::missing_doc_code_examples)]`
 ensures each function contains a usage example.  In our example above, the
 warning is resolved by adding crate level documentation.
 
diff --git a/src/librustdoc/html/render/print_item.rs b/src/librustdoc/html/render/print_item.rs
index 579b5a9c723..674cd0d62d4 100644
--- a/src/librustdoc/html/render/print_item.rs
+++ b/src/librustdoc/html/render/print_item.rs
@@ -1234,7 +1234,7 @@ fn item_enum(w: &mut Buffer, cx: &mut Context<'_>, it: &clean::Item, e: &clean::
                 w.write_str(",\n");
             }
 
-            if variants_stripped {
+            if variants_stripped && !it.is_non_exhaustive() {
                 w.write_str("    // some variants omitted\n");
             }
             if toggle {
diff --git a/src/llvm-project b/src/llvm-project
-Subproject fd949f3034f8a422ecfffa889c2823485dde4bd
+Subproject 2b9c52f66815bb8d6ea74a4b26df3410602be9b
diff --git a/tests/codegen/array-map.rs b/tests/codegen/array-map.rs
index 9298e89e397..7b8ab2c79a7 100644
--- a/tests/codegen/array-map.rs
+++ b/tests/codegen/array-map.rs
@@ -38,10 +38,10 @@ pub fn short_integer_zip_map(x: [u32; 8], y: [u32; 8]) -> [u32; 8] {
 //
 // CHECK-LABEL: @long_integer_map
 #[no_mangle]
-pub fn long_integer_map(x: [u32; 64]) -> [u32; 64] {
+pub fn long_integer_map(x: [u32; 512]) -> [u32; 512] {
     // CHECK: start:
-    // CHECK-NEXT: alloca [64 x i32]
-    // CHECK-NEXT: alloca %"core::mem::manually_drop::ManuallyDrop<[u32; 64]>"
+    // CHECK-NEXT: alloca [512 x i32]
+    // CHECK-NEXT: alloca %"core::mem::manually_drop::ManuallyDrop<[u32; 512]>"
     // CHECK-NOT: alloca
     // CHECK: mul <{{[0-9]+}} x i32>
     // CHECK: add <{{[0-9]+}} x i32>
diff --git a/tests/rustdoc-gui/auto-hide-trait-implementations.goml b/tests/rustdoc-gui/auto-hide-trait-implementations.goml
deleted file mode 100644
index 0a619c3524a..00000000000
--- a/tests/rustdoc-gui/auto-hide-trait-implementations.goml
+++ /dev/null
@@ -1,13 +0,0 @@
-// Checks that the setting "auto hide trait implementations" is working as expected.
-goto: "file://" + |DOC_PATH| + "/test_docs/struct.Foo.html"
-
-// By default, the trait implementations are not collapsed.
-assert-attribute: ("#trait-implementations-list > details", {"open": ""}, ALL)
-
-// We now set the setting to auto hide all trait implementations.
-local-storage: {"rustdoc-auto-hide-trait-implementations": "true" }
-// We reload to ensure the trait implementations are collapsed as expected.
-reload:
-
-// We now check that all matching elements don't have the open attributes.
-assert-attribute-false: ("#trait-implementations-list > details", {"open": ""}, ALL)
diff --git a/tests/rustdoc-gui/setting-auto-hide-trait-implementations.goml b/tests/rustdoc-gui/setting-auto-hide-trait-implementations.goml
new file mode 100644
index 00000000000..7355dddd39d
--- /dev/null
+++ b/tests/rustdoc-gui/setting-auto-hide-trait-implementations.goml
@@ -0,0 +1,47 @@
+// Checks that the setting "auto hide trait implementations" is working as expected.
+
+define-function: (
+    "check-setting",
+    (storage_value, setting_attribute_value, toggle_attribute_value),
+    block {
+        assert-local-storage: {"rustdoc-auto-hide-trait-implementations": |storage_value|}
+        click: "#settings-menu"
+        wait-for: "#settings"
+        assert-property: ("#auto-hide-trait-implementations", {"checked": |setting_attribute_value|})
+        assert-attribute: ("#trait-implementations-list > details", {"open": |toggle_attribute_value|}, ALL)
+    }
+)
+
+goto: "file://" + |DOC_PATH| + "/test_docs/struct.Foo.html"
+
+// By default, the trait implementations are not collapsed.
+call-function: ("check-setting", {
+    "storage_value": null,
+    "setting_attribute_value": "false",
+    "toggle_attribute_value": "",
+})
+
+// Now we change its value.
+click: "#auto-hide-trait-implementations"
+assert-local-storage: {"rustdoc-auto-hide-trait-implementations": "true"}
+
+// We check that the changes were applied as expected.
+reload:
+
+call-function: ("check-setting", {
+    "storage_value": "true",
+    "setting_attribute_value": "true",
+    "toggle_attribute_value": null,
+})
+
+// And now we re-disable the setting.
+click: "#auto-hide-trait-implementations"
+assert-local-storage: {"rustdoc-auto-hide-trait-implementations": "false"}
+
+// And we check everything is back the way it was before.
+reload:
+call-function: ("check-setting", {
+    "storage_value": "false",
+    "setting_attribute_value": "false",
+    "toggle_attribute_value": "",
+})
diff --git a/tests/rustdoc/issue-108925.rs b/tests/rustdoc/issue-108925.rs
new file mode 100644
index 00000000000..88aeb3c7f75
--- /dev/null
+++ b/tests/rustdoc/issue-108925.rs
@@ -0,0 +1,11 @@
+// @has issue_108925/enum.MyThing.html
+// @has - '//code' 'Shown'
+// @!has - '//code' 'NotShown'
+// @!has - '//code' '// some variants omitted'
+#[non_exhaustive]
+pub enum MyThing {
+    Shown,
+    #[doc(hidden)]
+    NotShown,
+}
+
diff --git a/tests/ui/traits/new-solver/specialization-transmute.rs b/tests/ui/traits/new-solver/specialization-transmute.rs
new file mode 100644
index 00000000000..a54701df4ef
--- /dev/null
+++ b/tests/ui/traits/new-solver/specialization-transmute.rs
@@ -0,0 +1,30 @@
+// compile-flags: -Ztrait-solver=next
+
+#![feature(specialization)]
+//~^ WARN the feature `specialization` is incomplete
+
+trait Default {
+   type Id;
+
+   fn intu(&self) -> &Self::Id;
+}
+
+impl<T> Default for T {
+   default type Id = T;
+
+   fn intu(&self) -> &Self::Id {
+        self
+        //~^ ERROR cannot satisfy `T <: <T as Default>::Id`
+   }
+}
+
+fn transmute<T: Default<Id = U>, U: Copy>(t: T) -> U {
+    *t.intu()
+}
+
+use std::num::NonZeroU8;
+fn main() {
+    let s = transmute::<u8, Option<NonZeroU8>>(0);
+    //~^ ERROR cannot satisfy `<u8 as Default>::Id == Option<NonZeroU8>
+    assert_eq!(s, None);
+}
diff --git a/tests/ui/traits/new-solver/specialization-transmute.stderr b/tests/ui/traits/new-solver/specialization-transmute.stderr
new file mode 100644
index 00000000000..e67c56afc0d
--- /dev/null
+++ b/tests/ui/traits/new-solver/specialization-transmute.stderr
@@ -0,0 +1,31 @@
+warning: the feature `specialization` is incomplete and may not be safe to use and/or cause compiler crashes
+  --> $DIR/specialization-transmute.rs:3:12
+   |
+LL | #![feature(specialization)]
+   |            ^^^^^^^^^^^^^^
+   |
+   = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
+   = help: consider using `min_specialization` instead, which is more stable and complete
+   = note: `#[warn(incomplete_features)]` on by default
+
+error[E0284]: type annotations needed: cannot satisfy `T <: <T as Default>::Id`
+  --> $DIR/specialization-transmute.rs:16:9
+   |
+LL |         self
+   |         ^^^^ cannot satisfy `T <: <T as Default>::Id`
+
+error[E0284]: type annotations needed: cannot satisfy `<u8 as Default>::Id == Option<NonZeroU8>`
+  --> $DIR/specialization-transmute.rs:27:13
+   |
+LL |     let s = transmute::<u8, Option<NonZeroU8>>(0);
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ cannot satisfy `<u8 as Default>::Id == Option<NonZeroU8>`
+   |
+note: required by a bound in `transmute`
+  --> $DIR/specialization-transmute.rs:21:25
+   |
+LL | fn transmute<T: Default<Id = U>, U: Copy>(t: T) -> U {
+   |                         ^^^^^^ required by this bound in `transmute`
+
+error: aborting due to 2 previous errors; 1 warning emitted
+
+For more information about this error, try `rustc --explain E0284`.
diff --git a/tests/ui/traits/new-solver/specialization-unconstrained.rs b/tests/ui/traits/new-solver/specialization-unconstrained.rs
new file mode 100644
index 00000000000..02150689ee5
--- /dev/null
+++ b/tests/ui/traits/new-solver/specialization-unconstrained.rs
@@ -0,0 +1,22 @@
+// compile-flags: -Ztrait-solver=next
+
+#![feature(specialization)]
+//~^ WARN the feature `specialization` is incomplete
+
+// Do not treat the RHS of a projection-goal as an unconstrained `Certainty::Yes` response
+// if the impl is still further specializable.
+
+trait Default {
+   type Id;
+}
+
+impl<T> Default for T {
+   default type Id = T;
+}
+
+fn test<T: Default<Id = U>, U>() {}
+
+fn main() {
+    test::<u32, ()>();
+    //~^ ERROR cannot satisfy `<u32 as Default>::Id == ()`
+}
diff --git a/tests/ui/traits/new-solver/specialization-unconstrained.stderr b/tests/ui/traits/new-solver/specialization-unconstrained.stderr
new file mode 100644
index 00000000000..910925cbaeb
--- /dev/null
+++ b/tests/ui/traits/new-solver/specialization-unconstrained.stderr
@@ -0,0 +1,25 @@
+warning: the feature `specialization` is incomplete and may not be safe to use and/or cause compiler crashes
+  --> $DIR/specialization-unconstrained.rs:3:12
+   |
+LL | #![feature(specialization)]
+   |            ^^^^^^^^^^^^^^
+   |
+   = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
+   = help: consider using `min_specialization` instead, which is more stable and complete
+   = note: `#[warn(incomplete_features)]` on by default
+
+error[E0284]: type annotations needed: cannot satisfy `<u32 as Default>::Id == ()`
+  --> $DIR/specialization-unconstrained.rs:20:5
+   |
+LL |     test::<u32, ()>();
+   |     ^^^^^^^^^^^^^^^ cannot satisfy `<u32 as Default>::Id == ()`
+   |
+note: required by a bound in `test`
+  --> $DIR/specialization-unconstrained.rs:17:20
+   |
+LL | fn test<T: Default<Id = U>, U>() {}
+   |                    ^^^^^^ required by this bound in `test`
+
+error: aborting due to previous error; 1 warning emitted
+
+For more information about this error, try `rustc --explain E0284`.