diff --git a/.github/ISSUE_TEMPLATE/library_tracking_issue.md b/.github/ISSUE_TEMPLATE/library_tracking_issue.md
index cbc4465fcfe..e879594b87a 100644
--- a/.github/ISSUE_TEMPLATE/library_tracking_issue.md
+++ b/.github/ISSUE_TEMPLATE/library_tracking_issue.md
@@ -2,7 +2,7 @@
 name: Library Tracking Issue
 about: A tracking issue for an unstable library feature.
 title: Tracking Issue for XXX
-labels: C-tracking-issue, T-libs
+labels: C-tracking-issue, T-libs-api
 ---
 <!--
 Thank you for creating a tracking issue!
@@ -60,7 +60,7 @@ unresolved questions left, the feature might be ready for stabilization.
 If this feature didn't go through the RFC process, a final commenting period
 (FCP) is always needed before stabilization. This works as follows:
 
-A library team member can kick off the stabilization process, at which point
+A library API team member can kick off the stabilization process, at which point
 the rfcbot will ask all the team members to verify they agree with
 stabilization. Once enough members agree and there are no concerns, the final
 commenting period begins: this issue will be marked as such and will be listed
diff --git a/Cargo.lock b/Cargo.lock
index 2f06506eaa4..bc8b79342b2 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -4609,9 +4609,9 @@ dependencies = [
 
 [[package]]
 name = "rustversion"
-version = "1.0.4"
+version = "1.0.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "cb5d2a036dc6d2d8fd16fde3498b04306e29bd193bf306a57427019b823d5acd"
+checksum = "61b3909d758bb75c79f23d4736fac9433868679d3ad2ea7a61e3c25cfda9a088"
 
 [[package]]
 name = "ryu"
diff --git a/compiler/rustc_middle/src/ty/layout.rs b/compiler/rustc_middle/src/ty/layout.rs
index 28a44b09de2..6b1ec1b0646 100644
--- a/compiler/rustc_middle/src/ty/layout.rs
+++ b/compiler/rustc_middle/src/ty/layout.rs
@@ -672,6 +672,15 @@ impl<'tcx> LayoutCx<'tcx, TyCtxt<'tcx>> {
 
             // SIMD vector types.
             ty::Adt(def, substs) if def.repr.simd() => {
+                if !def.is_struct() {
+                    // Should have yielded E0517 by now.
+                    tcx.sess.delay_span_bug(
+                        DUMMY_SP,
+                        "#[repr(simd)] was applied to an ADT that is not a struct",
+                    );
+                    return Err(LayoutError::Unknown(ty));
+                }
+
                 // Supported SIMD vectors are homogeneous ADTs with at least one field:
                 //
                 // * #[repr(simd)] struct S(T, T, T, T);
diff --git a/compiler/rustc_mir/src/transform/const_prop.rs b/compiler/rustc_mir/src/transform/const_prop.rs
index 73a0f5537c3..b56c247127c 100644
--- a/compiler/rustc_mir/src/transform/const_prop.rs
+++ b/compiler/rustc_mir/src/transform/const_prop.rs
@@ -1205,12 +1205,9 @@ impl<'mir, 'tcx> MutVisitor<'tcx> for ConstPropagator<'mir, 'tcx> {
                         let mut eval_to_int = |op| {
                             // This can be `None` if the lhs wasn't const propagated and we just
                             // triggered the assert on the value of the rhs.
-                            match self.eval_operand(op, source_info) {
-                                Some(op) => DbgVal::Val(
-                                    self.ecx.read_immediate(&op).unwrap().to_const_int(),
-                                ),
-                                None => DbgVal::Underscore,
-                            }
+                            self.eval_operand(op, source_info).map_or(DbgVal::Underscore, |op| {
+                                DbgVal::Val(self.ecx.read_immediate(&op).unwrap().to_const_int())
+                            })
                         };
                         let msg = match msg {
                             AssertKind::DivisionByZero(op) => {
diff --git a/library/core/src/cell.rs b/library/core/src/cell.rs
index f88a6e418c7..6af010e796d 100644
--- a/library/core/src/cell.rs
+++ b/library/core/src/cell.rs
@@ -488,6 +488,13 @@ impl<T: ?Sized> Cell<T> {
     /// This call borrows `Cell` mutably (at compile-time) which guarantees
     /// that we possess the only reference.
     ///
+    /// However be cautious: this method expects `self` to be mutable, which is
+    /// generally not the case when using a `Cell`. If you require interior
+    /// mutability by reference, consider using `RefCell` which provides
+    /// run-time checked mutable borrows through its [`borrow_mut`] method.
+    ///
+    /// [`borrow_mut`]: RefCell::borrow_mut()
+    ///
     /// # Examples
     ///
     /// ```
@@ -578,7 +585,7 @@ pub struct RefCell<T: ?Sized> {
     // Stores the location of the earliest currently active borrow.
     // This gets updated whenver we go from having zero borrows
     // to having a single borrow. When a borrow occurs, this gets included
-    // in the generated `BorroeError/`BorrowMutError`
+    // in the generated `BorrowError/`BorrowMutError`
     #[cfg(feature = "debug_refcell")]
     borrowed_at: Cell<Option<&'static crate::panic::Location<'static>>>,
     value: UnsafeCell<T>,
diff --git a/library/proc_macro/src/lib.rs b/library/proc_macro/src/lib.rs
index 26fbf50e2df..53f172717f0 100644
--- a/library/proc_macro/src/lib.rs
+++ b/library/proc_macro/src/lib.rs
@@ -708,7 +708,7 @@ impl Group {
     /// pub fn span_open(&self) -> Span {
     ///                 ^
     /// ```
-    #[unstable(feature = "proc_macro_span", issue = "54725")]
+    #[stable(feature = "proc_macro_group_span", since = "1.55.0")]
     pub fn span_open(&self) -> Span {
         Span(self.0.span_open())
     }
@@ -719,7 +719,7 @@ impl Group {
     /// pub fn span_close(&self) -> Span {
     ///                        ^
     /// ```
-    #[unstable(feature = "proc_macro_span", issue = "54725")]
+    #[stable(feature = "proc_macro_group_span", since = "1.55.0")]
     pub fn span_close(&self) -> Span {
         Span(self.0.span_close())
     }
diff --git a/library/test/src/formatters/junit.rs b/library/test/src/formatters/junit.rs
index ec66fc1219f..c4b0e1e5c23 100644
--- a/library/test/src/formatters/junit.rs
+++ b/library/test/src/formatters/junit.rs
@@ -79,7 +79,7 @@ impl<T: Write> OutputFormatter for JunitFormatter<T> {
                          name=\"{}\" time=\"{}\">",
                         class_name,
                         test_name,
-                        duration.as_secs()
+                        duration.as_secs_f64()
                     ))?;
                     self.write_message("<failure type=\"assert\"/>")?;
                     self.write_message("</testcase>")?;
@@ -91,7 +91,7 @@ impl<T: Write> OutputFormatter for JunitFormatter<T> {
                          name=\"{}\" time=\"{}\">",
                         class_name,
                         test_name,
-                        duration.as_secs()
+                        duration.as_secs_f64()
                     ))?;
                     self.write_message(&*format!("<failure message=\"{}\" type=\"assert\"/>", m))?;
                     self.write_message("</testcase>")?;
@@ -103,7 +103,7 @@ impl<T: Write> OutputFormatter for JunitFormatter<T> {
                          name=\"{}\" time=\"{}\">",
                         class_name,
                         test_name,
-                        duration.as_secs()
+                        duration.as_secs_f64()
                     ))?;
                     self.write_message("<failure type=\"timeout\"/>")?;
                     self.write_message("</testcase>")?;
@@ -123,7 +123,7 @@ impl<T: Write> OutputFormatter for JunitFormatter<T> {
                          name=\"{}\" time=\"{}\"/>",
                         class_name,
                         test_name,
-                        duration.as_secs()
+                        duration.as_secs_f64()
                     ))?;
                 }
             }
diff --git a/src/librustdoc/html/render/print_item.rs b/src/librustdoc/html/render/print_item.rs
index 8fd53538912..48cbd94ccab 100644
--- a/src/librustdoc/html/render/print_item.rs
+++ b/src/librustdoc/html/render/print_item.rs
@@ -981,7 +981,9 @@ fn item_enum(w: &mut Buffer, cx: &Context<'_>, it: &clean::Item, e: &clean::Enum
                 }
                 w.write_str(")");
             }
-            w.write_str("</code></div>");
+            w.write_str("</code>");
+            render_stability_since(w, variant, it, cx.tcx());
+            w.write_str("</div>");
             document(w, cx, variant, Some(it));
             document_non_exhaustive(w, variant);
 
@@ -1023,7 +1025,6 @@ fn item_enum(w: &mut Buffer, cx: &Context<'_>, it: &clean::Item, e: &clean::Enum
                 w.write_str("</div></div>");
                 toggle_close(w);
             }
-            render_stability_since(w, variant, it, cx.tcx());
         }
     }
     let def_id = it.def_id.expect_real();
diff --git a/src/librustdoc/html/static/rustdoc.css b/src/librustdoc/html/static/rustdoc.css
index 9a59ee528a0..89f5d592241 100644
--- a/src/librustdoc/html/static/rustdoc.css
+++ b/src/librustdoc/html/static/rustdoc.css
@@ -653,6 +653,12 @@ a {
 	background: transparent;
 }
 
+.small-section-header {
+	display: flex;
+	justify-content: space-between;
+	position: relative;
+}
+
 .small-section-header:hover > .anchor {
 	display: initial;
 }
diff --git a/src/test/ui/repr/issue-83505-repr-simd.rs b/src/test/ui/repr/issue-83505-repr-simd.rs
new file mode 100644
index 00000000000..280b771d015
--- /dev/null
+++ b/src/test/ui/repr/issue-83505-repr-simd.rs
@@ -0,0 +1,10 @@
+// Regression test for the ICE described in #83505.
+
+#![crate_type="lib"]
+
+#[repr(simd)]
+//~^ ERROR: attribute should be applied to a struct [E0517]
+//~| ERROR: unsupported representation for zero-variant enum [E0084]
+enum Es {}
+static CLs: Es;
+//~^ ERROR: free static item without body
diff --git a/src/test/ui/repr/issue-83505-repr-simd.stderr b/src/test/ui/repr/issue-83505-repr-simd.stderr
new file mode 100644
index 00000000000..f1390a65201
--- /dev/null
+++ b/src/test/ui/repr/issue-83505-repr-simd.stderr
@@ -0,0 +1,30 @@
+error: free static item without body
+  --> $DIR/issue-83505-repr-simd.rs:9:1
+   |
+LL | static CLs: Es;
+   | ^^^^^^^^^^^^^^-
+   |               |
+   |               help: provide a definition for the static: `= <expr>;`
+
+error[E0517]: attribute should be applied to a struct
+  --> $DIR/issue-83505-repr-simd.rs:5:8
+   |
+LL | #[repr(simd)]
+   |        ^^^^
+...
+LL | enum Es {}
+   | ---------- not a struct
+
+error[E0084]: unsupported representation for zero-variant enum
+  --> $DIR/issue-83505-repr-simd.rs:5:1
+   |
+LL | #[repr(simd)]
+   | ^^^^^^^^^^^^^
+...
+LL | enum Es {}
+   | ---------- zero-variant enum
+
+error: aborting due to 3 previous errors
+
+Some errors have detailed explanations: E0084, E0517.
+For more information about an error, try `rustc --explain E0084`.