diff --git a/compiler/rustc_typeck/src/check/callee.rs b/compiler/rustc_typeck/src/check/callee.rs
index e67ee1cab3df2..eea8f40635d74 100644
--- a/compiler/rustc_typeck/src/check/callee.rs
+++ b/compiler/rustc_typeck/src/check/callee.rs
@@ -496,7 +496,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             call_expr.span,
             call_expr,
             fn_sig.inputs(),
-            &expected_arg_tys,
+            expected_arg_tys,
             arg_exprs,
             fn_sig.c_variadic,
             TupleArgumentsFlag::DontTupleArguments,
@@ -529,7 +529,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             call_expr.span,
             call_expr,
             fn_sig.inputs(),
-            &expected_arg_tys,
+            expected_arg_tys,
             arg_exprs,
             fn_sig.c_variadic,
             TupleArgumentsFlag::TupleArguments,
diff --git a/compiler/rustc_typeck/src/check/fn_ctxt/checks.rs b/compiler/rustc_typeck/src/check/fn_ctxt/checks.rs
index 11b63a99043b7..e796fe58170d2 100644
--- a/compiler/rustc_typeck/src/check/fn_ctxt/checks.rs
+++ b/compiler/rustc_typeck/src/check/fn_ctxt/checks.rs
@@ -62,7 +62,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 sp,
                 expr,
                 &err_inputs,
-                &[],
+                vec![],
                 args_no_rcvr,
                 false,
                 tuple_arguments,
@@ -73,7 +73,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
 
         let method = method.unwrap();
         // HACK(eddyb) ignore self in the definition (see above).
-        let expected_arg_tys = self.expected_inputs_for_expected_output(
+        let expected_input_tys = self.expected_inputs_for_expected_output(
             sp,
             expected,
             method.sig.output(),
@@ -83,7 +83,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             sp,
             expr,
             &method.sig.inputs()[1..],
-            &expected_arg_tys[..],
+            expected_input_tys,
             args_no_rcvr,
             method.sig.c_variadic,
             tuple_arguments,
@@ -96,34 +96,43 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
     /// method calls and overloaded operators.
     pub(in super::super) fn check_argument_types(
         &self,
-        sp: Span,
-        expr: &'tcx hir::Expr<'tcx>,
-        fn_inputs: &[Ty<'tcx>],
-        expected_arg_tys: &[Ty<'tcx>],
-        args: &'tcx [hir::Expr<'tcx>],
+        // Span enclosing the call site
+        call_span: Span,
+        // Expression of the call site
+        call_expr: &'tcx hir::Expr<'tcx>,
+        // Types (as defined in the *signature* of the target function)
+        formal_input_tys: &[Ty<'tcx>],
+        // More specific expected types, after unifying with caller output types
+        expected_input_tys: Vec<Ty<'tcx>>,
+        // The expressions for each provided argument
+        provided_args: &'tcx [hir::Expr<'tcx>],
+        // Whether the function is variadic, for example when imported from C
         c_variadic: bool,
+        // Whether the arguments have been bundled in a tuple (ex: closures)
         tuple_arguments: TupleArgumentsFlag,
-        def_id: Option<DefId>,
+        // The DefId for the function being called, for better error messages
+        fn_def_id: Option<DefId>,
     ) {
         let tcx = self.tcx;
         // Grab the argument types, supplying fresh type variables
         // if the wrong number of arguments were supplied
-        let supplied_arg_count = if tuple_arguments == DontTupleArguments { args.len() } else { 1 };
+        let supplied_arg_count =
+            if tuple_arguments == DontTupleArguments { provided_args.len() } else { 1 };
 
         // All the input types from the fn signature must outlive the call
         // so as to validate implied bounds.
-        for (&fn_input_ty, arg_expr) in iter::zip(fn_inputs, args) {
+        for (&fn_input_ty, arg_expr) in iter::zip(formal_input_tys, provided_args) {
             self.register_wf_obligation(fn_input_ty.into(), arg_expr.span, traits::MiscObligation);
         }
 
-        let expected_arg_count = fn_inputs.len();
+        let expected_arg_count = formal_input_tys.len();
 
         let param_count_error = |expected_count: usize,
                                  arg_count: usize,
                                  error_code: &str,
                                  c_variadic: bool,
                                  sugg_unit: bool| {
-            let (span, start_span, args, ctor_of) = match &expr.kind {
+            let (span, start_span, args, ctor_of) = match &call_expr.kind {
                 hir::ExprKind::Call(
                     hir::Expr {
                         span,
@@ -156,14 +165,14 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                     &args[1..], // Skip the receiver.
                     None,       // methods are never ctors
                 ),
-                k => span_bug!(sp, "checking argument types on a non-call: `{:?}`", k),
+                k => span_bug!(call_span, "checking argument types on a non-call: `{:?}`", k),
             };
-            let arg_spans = if args.is_empty() {
+            let arg_spans = if provided_args.is_empty() {
                 // foo()
                 // ^^^-- supplied 0 arguments
                 // |
                 // expected 2 arguments
-                vec![tcx.sess.source_map().next_point(start_span).with_hi(sp.hi())]
+                vec![tcx.sess.source_map().next_point(start_span).with_hi(call_span.hi())]
             } else {
                 // foo(1, 2, 3)
                 // ^^^ -  -  - supplied 3 arguments
@@ -196,7 +205,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 );
             }
 
-            if let Some(def_id) = def_id {
+            if let Some(def_id) = fn_def_id {
                 if let Some(def_span) = tcx.def_ident_span(def_id) {
                     let mut spans: MultiSpan = def_span.into();
 
@@ -218,7 +227,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             }
 
             if sugg_unit {
-                let sugg_span = tcx.sess.source_map().end_point(expr.span);
+                let sugg_span = tcx.sess.source_map().end_point(call_expr.span);
                 // remove closing `)` from the span
                 let sugg_span = sugg_span.shrink_to_lo();
                 err.span_suggestion(
@@ -240,110 +249,148 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             err.emit();
         };
 
-        let mut expected_arg_tys = expected_arg_tys.to_vec();
-
-        let formal_tys = if tuple_arguments == TupleArguments {
-            let tuple_type = self.structurally_resolved_type(sp, fn_inputs[0]);
+        let (formal_input_tys, expected_input_tys) = if tuple_arguments == TupleArguments {
+            let tuple_type = self.structurally_resolved_type(call_span, formal_input_tys[0]);
             match tuple_type.kind() {
-                ty::Tuple(arg_types) if arg_types.len() != args.len() => {
-                    param_count_error(arg_types.len(), args.len(), "E0057", false, false);
-                    expected_arg_tys = vec![];
-                    self.err_args(args.len())
+                ty::Tuple(arg_types) if arg_types.len() != provided_args.len() => {
+                    param_count_error(arg_types.len(), provided_args.len(), "E0057", false, false);
+                    (self.err_args(provided_args.len()), vec![])
                 }
                 ty::Tuple(arg_types) => {
-                    expected_arg_tys = match expected_arg_tys.get(0) {
+                    let expected_input_tys = match expected_input_tys.get(0) {
                         Some(&ty) => match ty.kind() {
                             ty::Tuple(ref tys) => tys.iter().map(|k| k.expect_ty()).collect(),
                             _ => vec![],
                         },
                         None => vec![],
                     };
-                    arg_types.iter().map(|k| k.expect_ty()).collect()
+                    (arg_types.iter().map(|k| k.expect_ty()).collect(), expected_input_tys)
                 }
                 _ => {
                     struct_span_err!(
                         tcx.sess,
-                        sp,
+                        call_span,
                         E0059,
                         "cannot use call notation; the first type parameter \
                          for the function trait is neither a tuple nor unit"
                     )
                     .emit();
-                    expected_arg_tys = vec![];
-                    self.err_args(args.len())
+                    (self.err_args(provided_args.len()), vec![])
                 }
             }
         } else if expected_arg_count == supplied_arg_count {
-            fn_inputs.to_vec()
+            (formal_input_tys.to_vec(), expected_input_tys)
         } else if c_variadic {
             if supplied_arg_count >= expected_arg_count {
-                fn_inputs.to_vec()
+                (formal_input_tys.to_vec(), expected_input_tys)
             } else {
                 param_count_error(expected_arg_count, supplied_arg_count, "E0060", true, false);
-                expected_arg_tys = vec![];
-                self.err_args(supplied_arg_count)
+                (self.err_args(supplied_arg_count), vec![])
             }
         } else {
             // is the missing argument of type `()`?
-            let sugg_unit = if expected_arg_tys.len() == 1 && supplied_arg_count == 0 {
-                self.resolve_vars_if_possible(expected_arg_tys[0]).is_unit()
-            } else if fn_inputs.len() == 1 && supplied_arg_count == 0 {
-                self.resolve_vars_if_possible(fn_inputs[0]).is_unit()
+            let sugg_unit = if expected_input_tys.len() == 1 && supplied_arg_count == 0 {
+                self.resolve_vars_if_possible(expected_input_tys[0]).is_unit()
+            } else if formal_input_tys.len() == 1 && supplied_arg_count == 0 {
+                self.resolve_vars_if_possible(formal_input_tys[0]).is_unit()
             } else {
                 false
             };
             param_count_error(expected_arg_count, supplied_arg_count, "E0061", false, sugg_unit);
 
-            expected_arg_tys = vec![];
-            self.err_args(supplied_arg_count)
+            (self.err_args(supplied_arg_count), vec![])
         };
 
         debug!(
-            "check_argument_types: formal_tys={:?}",
-            formal_tys.iter().map(|t| self.ty_to_string(*t)).collect::<Vec<String>>()
+            "check_argument_types: formal_input_tys={:?}",
+            formal_input_tys.iter().map(|t| self.ty_to_string(*t)).collect::<Vec<String>>()
         );
 
-        // If there is no expectation, expect formal_tys.
-        let expected_arg_tys =
-            if !expected_arg_tys.is_empty() { expected_arg_tys } else { formal_tys.clone() };
+        // If there is no expectation, expect formal_input_tys.
+        let expected_input_tys = if !expected_input_tys.is_empty() {
+            expected_input_tys
+        } else {
+            formal_input_tys.clone()
+        };
+
+        assert_eq!(expected_input_tys.len(), formal_input_tys.len());
 
+        // Keep track of the fully coerced argument types
         let mut final_arg_types: Vec<(usize, Ty<'_>, Ty<'_>)> = vec![];
 
+        // We introduce a helper function to demand that a given argument satisfy a given input
+        // This is more complicated than just checking type equality, as arguments could be coerced
+        // This version writes those types back so further type checking uses the narrowed types
+        let demand_compatible = |idx, final_arg_types: &mut Vec<(usize, Ty<'tcx>, Ty<'tcx>)>| {
+            let formal_input_ty: Ty<'tcx> = formal_input_tys[idx];
+            let expected_input_ty: Ty<'tcx> = expected_input_tys[idx];
+            let provided_arg = &provided_args[idx];
+
+            debug!("checking argument {}: {:?} = {:?}", idx, provided_arg, formal_input_ty);
+
+            // The special-cased logic below has three functions:
+            // 1. Provide as good of an expected type as possible.
+            let expectation = Expectation::rvalue_hint(self, expected_input_ty);
+
+            let checked_ty = self.check_expr_with_expectation(provided_arg, expectation);
+
+            // 2. Coerce to the most detailed type that could be coerced
+            //    to, which is `expected_ty` if `rvalue_hint` returns an
+            //    `ExpectHasType(expected_ty)`, or the `formal_ty` otherwise.
+            let coerced_ty = expectation.only_has_type(self).unwrap_or(formal_input_ty);
+
+            // Keep track of these for below
+            final_arg_types.push((idx, checked_ty, coerced_ty));
+
+            // Cause selection errors caused by resolving a single argument to point at the
+            // argument and not the call. This is otherwise redundant with the `demand_coerce`
+            // call immediately after, but it lets us customize the span pointed to in the
+            // fulfillment error to be more accurate.
+            let _ =
+                self.resolve_vars_with_obligations_and_mutate_fulfillment(coerced_ty, |errors| {
+                    self.point_at_type_arg_instead_of_call_if_possible(errors, call_expr);
+                    self.point_at_arg_instead_of_call_if_possible(
+                        errors,
+                        &final_arg_types,
+                        call_expr,
+                        call_span,
+                        provided_args,
+                    );
+                });
+
+            // We're processing function arguments so we definitely want to use
+            // two-phase borrows.
+            self.demand_coerce(&provided_arg, checked_ty, coerced_ty, None, AllowTwoPhase::Yes);
+
+            // 3. Relate the expected type and the formal one,
+            //    if the expected type was used for the coercion.
+            self.demand_suptype(provided_arg.span, formal_input_ty, coerced_ty);
+        };
+
         // Check the arguments.
         // We do this in a pretty awful way: first we type-check any arguments
         // that are not closures, then we type-check the closures. This is so
         // that we have more information about the types of arguments when we
         // type-check the functions. This isn't really the right way to do this.
         for check_closures in [false, true] {
-            debug!("check_closures={}", check_closures);
-
             // More awful hacks: before we check argument types, try to do
             // an "opportunistic" trait resolution of any trait bounds on
             // the call. This helps coercions.
             if check_closures {
                 self.select_obligations_where_possible(false, |errors| {
-                    self.point_at_type_arg_instead_of_call_if_possible(errors, expr);
+                    self.point_at_type_arg_instead_of_call_if_possible(errors, call_expr);
                     self.point_at_arg_instead_of_call_if_possible(
                         errors,
                         &final_arg_types,
-                        expr,
-                        sp,
-                        &args,
+                        call_expr,
+                        call_span,
+                        &provided_args,
                     );
                 })
             }
 
-            // For C-variadic functions, we don't have a declared type for all of
-            // the arguments hence we only do our usual type checking with
-            // the arguments who's types we do know.
-            let t = if c_variadic {
-                expected_arg_count
-            } else if tuple_arguments == TupleArguments {
-                args.len()
-            } else {
-                supplied_arg_count
-            };
-            for (i, arg) in args.iter().take(t).enumerate() {
+            let minimum_input_count = formal_input_tys.len();
+            for (idx, arg) in provided_args.iter().enumerate() {
                 // Warn only for the first loop (the "no closures" one).
                 // Closure arguments themselves can't be diverging, but
                 // a previous argument can, e.g., `foo(panic!(), || {})`.
@@ -351,53 +398,21 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                     self.warn_if_unreachable(arg.hir_id, arg.span, "expression");
                 }
 
-                let is_closure = matches!(arg.kind, ExprKind::Closure(..));
+                // For C-variadic functions, we don't have a declared type for all of
+                // the arguments hence we only do our usual type checking with
+                // the arguments who's types we do know. However, we *can* check
+                // for unreachable expressions (see above).
+                // FIXME: unreachable warning current isn't emitted
+                if idx >= minimum_input_count {
+                    continue;
+                }
 
+                let is_closure = matches!(arg.kind, ExprKind::Closure(..));
                 if is_closure != check_closures {
                     continue;
                 }
 
-                let formal_ty = formal_tys[i];
-                debug!("checking argument {}: {:?} = {:?}", i, arg, formal_ty);
-
-                // The special-cased logic below has three functions:
-                // 1. Provide as good of an expected type as possible.
-                let expected = Expectation::rvalue_hint(self, expected_arg_tys[i]);
-
-                let checked_ty = self.check_expr_with_expectation(&arg, expected);
-
-                // 2. Coerce to the most detailed type that could be coerced
-                //    to, which is `expected_ty` if `rvalue_hint` returns an
-                //    `ExpectHasType(expected_ty)`, or the `formal_ty` otherwise.
-                let coerce_ty = expected.only_has_type(self).unwrap_or(formal_ty);
-
-                final_arg_types.push((i, checked_ty, coerce_ty));
-
-                // Cause selection errors caused by resolving a single argument to point at the
-                // argument and not the call. This is otherwise redundant with the `demand_coerce`
-                // call immediately after, but it lets us customize the span pointed to in the
-                // fulfillment error to be more accurate.
-                let _ = self.resolve_vars_with_obligations_and_mutate_fulfillment(
-                    coerce_ty,
-                    |errors| {
-                        self.point_at_type_arg_instead_of_call_if_possible(errors, expr);
-                        self.point_at_arg_instead_of_call_if_possible(
-                            errors,
-                            &final_arg_types,
-                            expr,
-                            sp,
-                            args,
-                        );
-                    },
-                );
-
-                // We're processing function arguments so we definitely want to use
-                // two-phase borrows.
-                self.demand_coerce(&arg, checked_ty, coerce_ty, None, AllowTwoPhase::Yes);
-
-                // 3. Relate the expected type and the formal one,
-                //    if the expected type was used for the coercion.
-                self.demand_suptype(arg.span, formal_ty, coerce_ty);
+                demand_compatible(idx, &mut final_arg_types);
             }
         }
 
@@ -410,7 +425,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 MissingCastForVariadicArg { sess, span, ty, cast_ty }.diagnostic().emit()
             }
 
-            for arg in args.iter().skip(expected_arg_count) {
+            for arg in provided_args.iter().skip(expected_arg_count) {
                 let arg_ty = self.check_expr(&arg);
 
                 // There are a few types which get autopromoted when passed via varargs
diff --git a/library/std/src/net/ip/tests.rs b/library/std/src/net/ip/tests.rs
index 632d4683b4159..7956c6a25e495 100644
--- a/library/std/src/net/ip/tests.rs
+++ b/library/std/src/net/ip/tests.rs
@@ -77,10 +77,10 @@ fn test_from_str_ipv4_in_ipv6() {
     let none: Option<Ipv4Addr> = "::127.0.0.1:".parse().ok();
     assert_eq!(None, none);
     // not enough groups
-    let none: Option<Ipv6Addr> = "1.2.3.4.5:127.0.0.1".parse().ok();
+    let none: Option<Ipv6Addr> = "1:2:3:4:5:127.0.0.1".parse().ok();
     assert_eq!(None, none);
     // too many groups
-    let none: Option<Ipv6Addr> = "1.2.3.4.5:6:7:127.0.0.1".parse().ok();
+    let none: Option<Ipv6Addr> = "1:2:3:4:5:6:7:127.0.0.1".parse().ok();
     assert_eq!(None, none);
 }
 
diff --git a/src/librustdoc/html/static/css/rustdoc.css b/src/librustdoc/html/static/css/rustdoc.css
index d82c65398b835..28cb8ae48e210 100644
--- a/src/librustdoc/html/static/css/rustdoc.css
+++ b/src/librustdoc/html/static/css/rustdoc.css
@@ -1080,8 +1080,11 @@ body.blur > :not(#help) {
 
 .impl-items .srclink, .impl .srclink, .methods .srclink {
 	/* Override header settings otherwise it's too bold */
-	font-size: 1.0625rem;
 	font-weight: normal;
+	font-size: 1rem;
+}
+.impl .srclink {
+	font-size: 1.0625rem;
 }
 
 .rightside {
@@ -1117,6 +1120,7 @@ pre.rust .question-mark {
 
 a.test-arrow {
 	display: inline-block;
+	visibility: hidden;
 	position: absolute;
 	padding: 5px 10px 5px 10px;
 	border-radius: 5px;
@@ -1125,10 +1129,12 @@ a.test-arrow {
 	right: 5px;
 	z-index: 1;
 }
+.example-wrap:hover .test-arrow {
+	visibility: visible;
+}
 a.test-arrow:hover{
 	text-decoration: none;
 }
-
 .section-header:hover a:before {
 	position: absolute;
 	left: -25px;
diff --git a/src/librustdoc/html/static/css/themes/ayu.css b/src/librustdoc/html/static/css/themes/ayu.css
index 38040eeca52d4..6ed7845e83a35 100644
--- a/src/librustdoc/html/static/css/themes/ayu.css
+++ b/src/librustdoc/html/static/css/themes/ayu.css
@@ -351,11 +351,8 @@ a.test-arrow:hover {
 	color: #999;
 }
 
-:target, :target > * {
-	background: rgba(255, 236, 164, 0.06);
-}
-
 :target {
+	background: rgba(255, 236, 164, 0.06);
 	border-right: 3px solid rgba(255, 180, 76, 0.85);
 }
 
diff --git a/src/librustdoc/html/static/css/themes/dark.css b/src/librustdoc/html/static/css/themes/dark.css
index f4181e431c896..64b6eb6696b83 100644
--- a/src/librustdoc/html/static/css/themes/dark.css
+++ b/src/librustdoc/html/static/css/themes/dark.css
@@ -295,11 +295,8 @@ a.test-arrow:hover{
 	color: #999;
 }
 
-:target, :target > * {
-	background-color: #494a3d;
-}
-
 :target {
+	background-color: #494a3d;
 	border-right: 3px solid #bb7410;
 }
 
diff --git a/src/librustdoc/html/static/css/themes/light.css b/src/librustdoc/html/static/css/themes/light.css
index 176f63098a49f..dbacc9f30735b 100644
--- a/src/librustdoc/html/static/css/themes/light.css
+++ b/src/librustdoc/html/static/css/themes/light.css
@@ -284,11 +284,8 @@ a.test-arrow:hover{
 	color: #999;
 }
 
-:target, :target > * {
-	background: #FDFFD3;
-}
-
 :target {
+	background: #FDFFD3;
 	border-right: 3px solid #AD7C37;
 }
 
diff --git a/src/librustdoc/passes/check_doc_test_visibility.rs b/src/librustdoc/passes/check_doc_test_visibility.rs
index b86ec8abefaae..e8f8ff988c1f0 100644
--- a/src/librustdoc/passes/check_doc_test_visibility.rs
+++ b/src/librustdoc/passes/check_doc_test_visibility.rs
@@ -131,7 +131,7 @@ crate fn look_for_tests<'tcx>(cx: &DocContext<'tcx>, dox: &str, item: &Item) {
             );
         }
     } else if tests.found_tests > 0
-        && !cx.cache.access_levels.is_public(item.def_id.expect_def_id())
+        && !cx.cache.access_levels.is_exported(item.def_id.expect_def_id())
     {
         cx.tcx.struct_span_lint_hir(
             crate::lint::PRIVATE_DOC_TESTS,
diff --git a/src/librustdoc/passes/collect_intra_doc_links.rs b/src/librustdoc/passes/collect_intra_doc_links.rs
index 26ccdb1c87ecc..7953008628204 100644
--- a/src/librustdoc/passes/collect_intra_doc_links.rs
+++ b/src/librustdoc/passes/collect_intra_doc_links.rs
@@ -13,7 +13,7 @@ use rustc_hir::def::{
     PerNS,
 };
 use rustc_hir::def_id::{CrateNum, DefId};
-use rustc_middle::ty::TyCtxt;
+use rustc_middle::ty::{Ty, TyCtxt};
 use rustc_middle::{bug, span_bug, ty};
 use rustc_resolve::ParentScope;
 use rustc_session::lint::Lint;
@@ -618,6 +618,39 @@ impl<'a, 'tcx> LinkCollector<'a, 'tcx> {
         })
     }
 
+    /// Convert a PrimitiveType to a Ty, where possible.
+    ///
+    /// This is used for resolving trait impls for primitives
+    fn primitive_type_to_ty(&mut self, prim: PrimitiveType) -> Option<Ty<'tcx>> {
+        use PrimitiveType::*;
+        let tcx = self.cx.tcx;
+
+        // FIXME: Only simple types are supported here, see if we can support
+        // other types such as Tuple, Array, Slice, etc.
+        // See https://github.com/rust-lang/rust/issues/90703#issuecomment-1004263455
+        Some(tcx.mk_ty(match prim {
+            Bool => ty::Bool,
+            Str => ty::Str,
+            Char => ty::Char,
+            Never => ty::Never,
+            I8 => ty::Int(ty::IntTy::I8),
+            I16 => ty::Int(ty::IntTy::I16),
+            I32 => ty::Int(ty::IntTy::I32),
+            I64 => ty::Int(ty::IntTy::I64),
+            I128 => ty::Int(ty::IntTy::I128),
+            Isize => ty::Int(ty::IntTy::Isize),
+            F32 => ty::Float(ty::FloatTy::F32),
+            F64 => ty::Float(ty::FloatTy::F64),
+            U8 => ty::Uint(ty::UintTy::U8),
+            U16 => ty::Uint(ty::UintTy::U16),
+            U32 => ty::Uint(ty::UintTy::U32),
+            U64 => ty::Uint(ty::UintTy::U64),
+            U128 => ty::Uint(ty::UintTy::U128),
+            Usize => ty::Uint(ty::UintTy::Usize),
+            _ => return None,
+        }))
+    }
+
     /// Returns:
     /// - None if no associated item was found
     /// - Some((_, _, Some(_))) if an item was found and should go through a side channel
@@ -632,7 +665,25 @@ impl<'a, 'tcx> LinkCollector<'a, 'tcx> {
         let tcx = self.cx.tcx;
 
         match root_res {
-            Res::Primitive(prim) => self.resolve_primitive_associated_item(prim, ns, item_name),
+            Res::Primitive(prim) => {
+                self.resolve_primitive_associated_item(prim, ns, item_name).or_else(|| {
+                    let assoc_item = self
+                        .primitive_type_to_ty(prim)
+                        .map(|ty| {
+                            resolve_associated_trait_item(ty, module_id, item_name, ns, self.cx)
+                        })
+                        .flatten();
+
+                    assoc_item.map(|item| {
+                        let kind = item.kind;
+                        let fragment = UrlFragment::from_assoc_item(item_name, kind, false);
+                        // HACK(jynelson): `clean` expects the type, not the associated item
+                        // but the disambiguator logic expects the associated item.
+                        // Store the kind in a side channel so that only the disambiguator logic looks at it.
+                        (root_res, fragment, Some((kind.as_def_kind(), item.def_id)))
+                    })
+                })
+            }
             Res::Def(DefKind::TyAlias, did) => {
                 // Resolve the link on the type the alias points to.
                 // FIXME: if the associated item is defined directly on the type alias,
@@ -666,8 +717,13 @@ impl<'a, 'tcx> LinkCollector<'a, 'tcx> {
                     // To handle that properly resolve() would have to support
                     // something like [`ambi_fn`](<SomeStruct as SomeTrait>::ambi_fn)
                     .or_else(|| {
-                        let item =
-                            resolve_associated_trait_item(did, module_id, item_name, ns, self.cx);
+                        let item = resolve_associated_trait_item(
+                            tcx.type_of(did),
+                            module_id,
+                            item_name,
+                            ns,
+                            self.cx,
+                        );
                         debug!("got associated item {:?}", item);
                         item
                     });
@@ -767,12 +823,12 @@ impl<'a, 'tcx> LinkCollector<'a, 'tcx> {
 /// Given `[std::io::Error::source]`, where `source` is unresolved, this would
 /// find `std::error::Error::source` and return
 /// `<io::Error as error::Error>::source`.
-fn resolve_associated_trait_item(
-    did: DefId,
+fn resolve_associated_trait_item<'a>(
+    ty: Ty<'a>,
     module: DefId,
     item_name: Symbol,
     ns: Namespace,
-    cx: &mut DocContext<'_>,
+    cx: &mut DocContext<'a>,
 ) -> Option<ty::AssocItem> {
     // FIXME: this should also consider blanket impls (`impl<T> X for T`). Unfortunately
     // `get_auto_trait_and_blanket_impls` is broken because the caching behavior is wrong. In the
@@ -780,7 +836,7 @@ fn resolve_associated_trait_item(
 
     // Next consider explicit impls: `impl MyTrait for MyType`
     // Give precedence to inherent impls.
-    let traits = traits_implemented_by(cx, did, module);
+    let traits = traits_implemented_by(cx, ty, module);
     debug!("considering traits {:?}", traits);
     let mut candidates = traits.iter().filter_map(|&trait_| {
         cx.tcx.associated_items(trait_).find_by_name_and_namespace(
@@ -799,7 +855,11 @@ fn resolve_associated_trait_item(
 ///
 /// NOTE: this cannot be a query because more traits could be available when more crates are compiled!
 /// So it is not stable to serialize cross-crate.
-fn traits_implemented_by(cx: &mut DocContext<'_>, type_: DefId, module: DefId) -> FxHashSet<DefId> {
+fn traits_implemented_by<'a>(
+    cx: &mut DocContext<'a>,
+    ty: Ty<'a>,
+    module: DefId,
+) -> FxHashSet<DefId> {
     let mut resolver = cx.resolver.borrow_mut();
     let in_scope_traits = cx.module_trait_cache.entry(module).or_insert_with(|| {
         resolver.access(|resolver| {
@@ -813,7 +873,6 @@ fn traits_implemented_by(cx: &mut DocContext<'_>, type_: DefId, module: DefId) -
     });
 
     let tcx = cx.tcx;
-    let ty = tcx.type_of(type_);
     let iter = in_scope_traits.iter().flat_map(|&trait_| {
         trace!("considering explicit impl for trait {:?}", trait_);
 
@@ -826,19 +885,10 @@ fn traits_implemented_by(cx: &mut DocContext<'_>, type_: DefId, module: DefId) -
                 "comparing type {} with kind {:?} against type {:?}",
                 impl_type,
                 impl_type.kind(),
-                type_
+                ty
             );
             // Fast path: if this is a primitive simple `==` will work
-            let saw_impl = impl_type == ty
-                || match impl_type.kind() {
-                    // Check if these are the same def_id
-                    ty::Adt(def, _) => {
-                        debug!("adt def_id: {:?}", def.did);
-                        def.did == type_
-                    }
-                    ty::Foreign(def_id) => *def_id == type_,
-                    _ => false,
-                };
+            let saw_impl = impl_type == ty;
 
             if saw_impl { Some(trait_) } else { None }
         })
diff --git a/src/test/rustdoc-gui/run-on-hover.goml b/src/test/rustdoc-gui/run-on-hover.goml
new file mode 100644
index 0000000000000..b8efa8e302f71
--- /dev/null
+++ b/src/test/rustdoc-gui/run-on-hover.goml
@@ -0,0 +1,7 @@
+// Example code blocks sometimes have a "Run" button to run them on the
+// Playground. That button is hidden until the user hovers over the code block.
+// This test checks that it is hidden, and that it shows on hover.
+goto: file://|DOC_PATH|/test_docs/fn.foo.html
+assert-css: (".test-arrow", {"visibility": "hidden"})
+move-cursor-to: ".example-wrap"
+assert-css: (".test-arrow", {"visibility": "visible"})
diff --git a/src/test/rustdoc-gui/src-font-size.goml b/src/test/rustdoc-gui/src-font-size.goml
new file mode 100644
index 0000000000000..b0b2f122afdb9
--- /dev/null
+++ b/src/test/rustdoc-gui/src-font-size.goml
@@ -0,0 +1,12 @@
+// This test ensures that the "[src]" have the same font size as their headers
+// to avoid having some weird height difference in the background when the element
+// is selected.
+goto: file://|DOC_PATH|/test_docs/struct.Foo.html
+show-text: true
+// Check the impl headers.
+assert-css: (".impl.has-srclink .srclink", {"font-size": "17px"}, ALL)
+// The ".6" part is because the font-size is actually "1.1em".
+assert-css: (".impl.has-srclink .code-header.in-band", {"font-size": "17.6px"}, ALL)
+// Check the impl items.
+assert-css: (".impl-items .has-srclink .srclink", {"font-size": "16px"}, ALL)
+assert-css: (".impl-items .has-srclink .code-header", {"font-size": "16px"}, ALL)
diff --git a/src/test/rustdoc-gui/src/test_docs/lib.rs b/src/test/rustdoc-gui/src/test_docs/lib.rs
index 9b37703dded4b..f75de949292a1 100644
--- a/src/test/rustdoc-gui/src/test_docs/lib.rs
+++ b/src/test/rustdoc-gui/src/test_docs/lib.rs
@@ -1,5 +1,6 @@
 //! The point of this crate is to be able to have enough different "kinds" of
 //! documentation generated so we can test each different features.
+#![doc(html_playground_url="https://play.rust-lang.org/")]
 
 #![crate_name = "test_docs"]
 #![feature(rustdoc_internals)]
diff --git a/src/test/rustdoc-ui/intra-doc/non-path-primitives.rs b/src/test/rustdoc-ui/intra-doc/non-path-primitives.rs
index 75159979e8890..587cbad684864 100644
--- a/src/test/rustdoc-ui/intra-doc/non-path-primitives.rs
+++ b/src/test/rustdoc-ui/intra-doc/non-path-primitives.rs
@@ -28,7 +28,6 @@
 //! [unit::eq] //~ ERROR unresolved
 //! [tuple::eq] //~ ERROR unresolved
 //! [fn::eq] //~ ERROR unresolved
-//! [never::eq] //~ ERROR unresolved
 
 // FIXME(#78800): This breaks because it's a blanket impl
 // (I think? Might break for other reasons too.)
diff --git a/src/test/rustdoc-ui/intra-doc/non-path-primitives.stderr b/src/test/rustdoc-ui/intra-doc/non-path-primitives.stderr
index 610c830560527..4828a30446355 100644
--- a/src/test/rustdoc-ui/intra-doc/non-path-primitives.stderr
+++ b/src/test/rustdoc-ui/intra-doc/non-path-primitives.stderr
@@ -53,17 +53,11 @@ error: unresolved link to `fn::eq`
 LL | //! [fn::eq]
    |      ^^^^^^ the builtin type `fn` has no associated item named `eq`
 
-error: unresolved link to `never::eq`
-  --> $DIR/non-path-primitives.rs:31:6
-   |
-LL | //! [never::eq]
-   |      ^^^^^^^^^ the builtin type `never` has no associated item named `eq`
-
 error: unresolved link to `reference::deref`
-  --> $DIR/non-path-primitives.rs:35:6
+  --> $DIR/non-path-primitives.rs:34:6
    |
 LL | //! [reference::deref]
    |      ^^^^^^^^^^^^^^^^ the builtin type `reference` has no associated item named `deref`
 
-error: aborting due to 9 previous errors
+error: aborting due to 8 previous errors
 
diff --git a/src/test/rustdoc-ui/private-public-item-doc-test.rs b/src/test/rustdoc-ui/private-public-item-doc-test.rs
new file mode 100644
index 0000000000000..7cc62b38cc260
--- /dev/null
+++ b/src/test/rustdoc-ui/private-public-item-doc-test.rs
@@ -0,0 +1,11 @@
+#![deny(rustdoc::private_doc_tests)]
+
+mod foo {
+    /// private doc test
+    ///
+    /// ```
+    /// assert!(false);
+    /// ```
+    //~^^^^^ ERROR documentation test in private item
+    pub fn bar() {}
+}
diff --git a/src/test/rustdoc-ui/private-public-item-doc-test.stderr b/src/test/rustdoc-ui/private-public-item-doc-test.stderr
new file mode 100644
index 0000000000000..f50dbd1844e7a
--- /dev/null
+++ b/src/test/rustdoc-ui/private-public-item-doc-test.stderr
@@ -0,0 +1,18 @@
+error: documentation test in private item
+  --> $DIR/private-public-item-doc-test.rs:4:5
+   |
+LL | /     /// private doc test
+LL | |     ///
+LL | |     /// ```
+LL | |     /// assert!(false);
+LL | |     /// ```
+   | |___________^
+   |
+note: the lint level is defined here
+  --> $DIR/private-public-item-doc-test.rs:1:9
+   |
+LL | #![deny(rustdoc::private_doc_tests)]
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to previous error
+
diff --git a/src/test/rustdoc-ui/public-reexported-item-doc-test.rs b/src/test/rustdoc-ui/public-reexported-item-doc-test.rs
new file mode 100644
index 0000000000000..b86a53305a175
--- /dev/null
+++ b/src/test/rustdoc-ui/public-reexported-item-doc-test.rs
@@ -0,0 +1,16 @@
+// check-pass
+
+#![deny(rustdoc::private_doc_tests)]
+
+pub fn foo() {}
+
+mod private {
+    /// re-exported doc test
+    ///
+    /// ```
+    /// assert!(true);
+    /// ```
+    pub fn bar() {}
+}
+
+pub use private::bar;
diff --git a/src/test/rustdoc/intra-doc/prim-associated-traits.rs b/src/test/rustdoc/intra-doc/prim-associated-traits.rs
new file mode 100644
index 0000000000000..8639a24f7f386
--- /dev/null
+++ b/src/test/rustdoc/intra-doc/prim-associated-traits.rs
@@ -0,0 +1,46 @@
+#![feature(never_type)]
+use std::str::FromStr;
+
+// @has 'prim_associated_traits/struct.Number.html' '//a[@href="{{channel}}/std/primitive.f64.html#method.from_str"]' 'f64::from_str()'
+// @has 'prim_associated_traits/struct.Number.html' '//a[@href="{{channel}}/std/primitive.f32.html#method.from_str"]' 'f32::from_str()'
+// @has 'prim_associated_traits/struct.Number.html' '//a[@href="{{channel}}/std/primitive.isize.html#method.from_str"]' 'isize::from_str()'
+// @has 'prim_associated_traits/struct.Number.html' '//a[@href="{{channel}}/std/primitive.i8.html#method.from_str"]' 'i8::from_str()'
+// @has 'prim_associated_traits/struct.Number.html' '//a[@href="{{channel}}/std/primitive.i16.html#method.from_str"]' 'i16::from_str()'
+// @has 'prim_associated_traits/struct.Number.html' '//a[@href="{{channel}}/std/primitive.i32.html#method.from_str"]' 'i32::from_str()'
+// @has 'prim_associated_traits/struct.Number.html' '//a[@href="{{channel}}/std/primitive.i64.html#method.from_str"]' 'i64::from_str()'
+// @has 'prim_associated_traits/struct.Number.html' '//a[@href="{{channel}}/std/primitive.i128.html#method.from_str"]' 'i128::from_str()'
+// @has 'prim_associated_traits/struct.Number.html' '//a[@href="{{channel}}/std/primitive.usize.html#method.from_str"]' 'usize::from_str()'
+// @has 'prim_associated_traits/struct.Number.html' '//a[@href="{{channel}}/std/primitive.u8.html#method.from_str"]' 'u8::from_str()'
+// @has 'prim_associated_traits/struct.Number.html' '//a[@href="{{channel}}/std/primitive.u16.html#method.from_str"]' 'u16::from_str()'
+// @has 'prim_associated_traits/struct.Number.html' '//a[@href="{{channel}}/std/primitive.u32.html#method.from_str"]' 'u32::from_str()'
+// @has 'prim_associated_traits/struct.Number.html' '//a[@href="{{channel}}/std/primitive.u64.html#method.from_str"]' 'u64::from_str()'
+// @has 'prim_associated_traits/struct.Number.html' '//a[@href="{{channel}}/std/primitive.u128.html#method.from_str"]' 'u128::from_str()'
+// @has 'prim_associated_traits/struct.Number.html' '//a[@href="{{channel}}/std/primitive.char.html#method.from_str"]' 'char::from_str()'
+// @has 'prim_associated_traits/struct.Number.html' '//a[@href="{{channel}}/std/primitive.bool.html#method.from_str"]' 'bool::from_str()'
+// @has 'prim_associated_traits/struct.Number.html' '//a[@href="{{channel}}/std/primitive.str.html#method.eq"]' 'str::eq()'
+// @has 'prim_associated_traits/struct.Number.html' '//a[@href="{{channel}}/std/primitive.never.html#method.eq"]' 'never::eq()'
+/// [`f64::from_str()`] [`f32::from_str()`] [`isize::from_str()`] [`i8::from_str()`]
+/// [`i16::from_str()`] [`i32::from_str()`] [`i64::from_str()`] [`i128::from_str()`]
+/// [`u16::from_str()`] [`u32::from_str()`] [`u64::from_str()`] [`u128::from_str()`]
+/// [`usize::from_str()`] [`u8::from_str()`] [`char::from_str()`] [`bool::from_str()`]
+/// [`str::eq()`] [`never::eq()`]
+pub struct Number {
+    pub f_64: f64,
+    pub f_32: f32,
+    pub i_size: isize,
+    pub i_8: i8,
+    pub i_16: i16,
+    pub i_32: i32,
+    pub i_64: i64,
+    pub i_128: i128,
+    pub u_size: usize,
+    pub u_8: u8,
+    pub u_16: u16,
+    pub u_32: u32,
+    pub u_64: u64,
+    pub u_128: u128,
+    pub ch: char,
+    pub boolean: bool,
+    pub string: str,
+    pub n: !,
+}
diff --git a/src/test/ui/borrowck/issue-92015.rs b/src/test/ui/borrowck/issue-92015.rs
new file mode 100644
index 0000000000000..16d651717ff2c
--- /dev/null
+++ b/src/test/ui/borrowck/issue-92015.rs
@@ -0,0 +1,7 @@
+// Regression test for #92105.
+// ICE when mutating immutable reference from last statement of a block.
+
+fn main() {
+    let foo = Some(&0).unwrap();
+    *foo = 1; //~ ERROR cannot assign
+}
diff --git a/src/test/ui/borrowck/issue-92015.stderr b/src/test/ui/borrowck/issue-92015.stderr
new file mode 100644
index 0000000000000..32a65d3b5bb0f
--- /dev/null
+++ b/src/test/ui/borrowck/issue-92015.stderr
@@ -0,0 +1,11 @@
+error[E0594]: cannot assign to `*foo`, which is behind a `&` reference
+  --> $DIR/issue-92015.rs:6:5
+   |
+LL |     let foo = Some(&0).unwrap();
+   |         --- help: consider changing this to be a mutable reference: `&mut i32`
+LL |     *foo = 1;
+   |     ^^^^^^^^ `foo` is a `&` reference, so the data it refers to cannot be written
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0594`.
diff --git a/src/test/ui/c-variadic/variadic-unreachable-arg-error.rs b/src/test/ui/c-variadic/variadic-unreachable-arg-error.rs
new file mode 100644
index 0000000000000..f60f6f3e80872
--- /dev/null
+++ b/src/test/ui/c-variadic/variadic-unreachable-arg-error.rs
@@ -0,0 +1,14 @@
+// check-pass
+
+#![feature(c_variadic)]
+
+extern "C" {
+    fn foo(f: isize, x: u8, ...);
+}
+
+fn main() {
+    unsafe {
+        // FIXME: Ideally we could give an unreachable warning
+        foo(1, loop {}, 1usize);
+    }
+}