diff --git a/compiler/rustc_error_messages/locales/en-US/passes.ftl b/compiler/rustc_error_messages/locales/en-US/passes.ftl
index 91857dd227ddd..0c2ab3d08f9de 100644
--- a/compiler/rustc_error_messages/locales/en-US/passes.ftl
+++ b/compiler/rustc_error_messages/locales/en-US/passes.ftl
@@ -710,3 +710,24 @@ passes_ignored_derived_impls =
       [one] trait {$trait_list}, but this is
      *[other] traits {$trait_list}, but these are
     } intentionally ignored during dead code analysis
+
+passes_proc_macro_typeerror = mismatched {$kind} signature
+    .label = found {$found}, expected type `proc_macro::TokenStream`
+    .note = {$kind}s must have a signature of `{$expected_signature}`
+
+passes_proc_macro_diff_arg_count = mismatched {$kind} signature
+    .label = found unexpected {$count ->
+      [one] argument
+     *[other] arguments
+    }
+    .note = {$kind}s must have a signature of `{$expected_signature}`
+
+passes_proc_macro_missing_args = mismatched {$kind} signature
+    .label = {$kind} must have {$expected_input_count ->
+      [one] one argument
+     *[other] two arguments
+    } of type `proc_macro::TokenStream`
+
+passes_proc_macro_invalid_abi = proc macro functions may not be `extern "{$abi}"`
+
+passes_proc_macro_unsafe = proc macro functions may not be `unsafe`
diff --git a/compiler/rustc_passes/src/check_attr.rs b/compiler/rustc_passes/src/check_attr.rs
index f9f9799d3e4f2..4232985325945 100644
--- a/compiler/rustc_passes/src/check_attr.rs
+++ b/compiler/rustc_passes/src/check_attr.rs
@@ -6,11 +6,12 @@
 
 use crate::errors::{
     self, AttrApplication, DebugVisualizerUnreadable, InvalidAttrAtCrateLevel, ObjectLifetimeErr,
-    OnlyHasEffectOn, TransparentIncompatible, UnrecognizedReprHint,
+    OnlyHasEffectOn, ProcMacroDiffArguments, ProcMacroInvalidAbi, ProcMacroMissingArguments,
+    ProcMacroTypeError, ProcMacroUnsafe, TransparentIncompatible, UnrecognizedReprHint,
 };
 use rustc_ast::{ast, AttrStyle, Attribute, LitKind, MetaItemKind, MetaItemLit, NestedMetaItem};
 use rustc_data_structures::fx::FxHashMap;
-use rustc_errors::{fluent, Applicability, MultiSpan};
+use rustc_errors::{fluent, Applicability, IntoDiagnosticArg, MultiSpan};
 use rustc_expand::base::resolve_path;
 use rustc_feature::{AttributeDuplicates, AttributeType, BuiltinAttribute, BUILTIN_ATTRIBUTE_MAP};
 use rustc_hir as hir;
@@ -19,11 +20,12 @@ use rustc_hir::intravisit::{self, Visitor};
 use rustc_hir::{
     self, FnSig, ForeignItem, HirId, Item, ItemKind, TraitItem, CRATE_HIR_ID, CRATE_OWNER_ID,
 };
-use rustc_hir::{MethodKind, Target};
+use rustc_hir::{MethodKind, Target, Unsafety};
 use rustc_middle::hir::nested_filter;
 use rustc_middle::middle::resolve_lifetime::ObjectLifetimeDefault;
+use rustc_middle::ty::fast_reject::{DeepRejectCtxt, TreatParams};
 use rustc_middle::ty::query::Providers;
-use rustc_middle::ty::TyCtxt;
+use rustc_middle::ty::{ParamEnv, TyCtxt};
 use rustc_session::lint::builtin::{
     CONFLICTING_REPR_HINTS, INVALID_DOC_ATTRIBUTES, UNUSED_ATTRIBUTES,
 };
@@ -31,6 +33,7 @@ use rustc_session::parse::feature_err;
 use rustc_span::symbol::{kw, sym, Symbol};
 use rustc_span::{Span, DUMMY_SP};
 use rustc_target::spec::abi::Abi;
+use std::cell::Cell;
 use std::collections::hash_map::Entry;
 
 pub(crate) fn target_from_impl_item<'tcx>(
@@ -62,8 +65,29 @@ enum ItemLike<'tcx> {
     ForeignItem,
 }
 
+#[derive(Copy, Clone)]
+pub(crate) enum ProcMacroKind {
+    FunctionLike,
+    Derive,
+    Attribute,
+}
+
+impl IntoDiagnosticArg for ProcMacroKind {
+    fn into_diagnostic_arg(self) -> rustc_errors::DiagnosticArgValue<'static> {
+        match self {
+            ProcMacroKind::Attribute => "attribute proc macro",
+            ProcMacroKind::Derive => "derive proc macro",
+            ProcMacroKind::FunctionLike => "function-like proc macro",
+        }
+        .into_diagnostic_arg()
+    }
+}
+
 struct CheckAttrVisitor<'tcx> {
     tcx: TyCtxt<'tcx>,
+
+    // Whether or not this visitor should abort after finding errors
+    abort: Cell<bool>,
 }
 
 impl CheckAttrVisitor<'_> {
@@ -173,7 +197,7 @@ impl CheckAttrVisitor<'_> {
                 sym::path => self.check_generic_attr(hir_id, attr, target, Target::Mod),
                 sym::plugin_registrar => self.check_plugin_registrar(hir_id, attr, target),
                 sym::macro_export => self.check_macro_export(hir_id, attr, target),
-                sym::ignore | sym::should_panic | sym::proc_macro_derive => {
+                sym::ignore | sym::should_panic => {
                     self.check_generic_attr(hir_id, attr, target, Target::Fn)
                 }
                 sym::automatically_derived => {
@@ -183,6 +207,16 @@ impl CheckAttrVisitor<'_> {
                     self.check_generic_attr(hir_id, attr, target, Target::Mod)
                 }
                 sym::rustc_object_lifetime_default => self.check_object_lifetime_default(hir_id),
+                sym::proc_macro => {
+                    self.check_proc_macro(hir_id, target, ProcMacroKind::FunctionLike)
+                }
+                sym::proc_macro_attribute => {
+                    self.check_proc_macro(hir_id, target, ProcMacroKind::Attribute);
+                }
+                sym::proc_macro_derive => {
+                    self.check_generic_attr(hir_id, attr, target, Target::Fn);
+                    self.check_proc_macro(hir_id, target, ProcMacroKind::Derive)
+                }
                 _ => {}
             }
 
@@ -2063,6 +2097,103 @@ impl CheckAttrVisitor<'_> {
             errors::Unused { attr_span: attr.span, note },
         );
     }
+
+    /// A best effort attempt to create an error for a mismatching proc macro signature.
+    ///
+    /// If this best effort goes wrong, it will just emit a worse error later (see #102923)
+    fn check_proc_macro(&self, hir_id: HirId, target: Target, kind: ProcMacroKind) {
+        let expected_input_count = match kind {
+            ProcMacroKind::Attribute => 2,
+            ProcMacroKind::Derive | ProcMacroKind::FunctionLike => 1,
+        };
+
+        let expected_signature = match kind {
+            ProcMacroKind::Attribute => "fn(TokenStream, TokenStream) -> TokenStream",
+            ProcMacroKind::Derive | ProcMacroKind::FunctionLike => "fn(TokenStream) -> TokenStream",
+        };
+
+        let tcx = self.tcx;
+        if target == Target::Fn {
+            let Some(tokenstream) = tcx.get_diagnostic_item(sym::TokenStream) else {return};
+            let tokenstream = tcx.type_of(tokenstream);
+
+            let id = hir_id.expect_owner();
+            let hir_sig = tcx.hir().fn_sig_by_hir_id(hir_id).unwrap();
+
+            let sig = tcx.liberate_late_bound_regions(id.to_def_id(), tcx.fn_sig(id));
+            let sig = tcx.normalize_erasing_regions(ParamEnv::empty(), sig);
+
+            // We don't currently require that the function signature is equal to
+            // `fn(TokenStream) -> TokenStream`, but instead monomorphizes to
+            // `fn(TokenStream) -> TokenStream` after some substitution of generic arguments.
+            //
+            // Properly checking this means pulling in additional `rustc` crates, so we don't.
+            let drcx = DeepRejectCtxt { treat_obligation_params: TreatParams::AsInfer };
+
+            if sig.abi != Abi::Rust {
+                tcx.sess.emit_err(ProcMacroInvalidAbi { span: hir_sig.span, abi: sig.abi.name() });
+                self.abort.set(true);
+            }
+
+            if sig.unsafety == Unsafety::Unsafe {
+                tcx.sess.emit_err(ProcMacroUnsafe { span: hir_sig.span });
+                self.abort.set(true);
+            }
+
+            let output = sig.output();
+
+            // Typecheck the output
+            if !drcx.types_may_unify(output, tokenstream) {
+                tcx.sess.emit_err(ProcMacroTypeError {
+                    span: hir_sig.decl.output.span(),
+                    found: output,
+                    kind,
+                    expected_signature,
+                });
+                self.abort.set(true);
+            }
+
+            if sig.inputs().len() < expected_input_count {
+                tcx.sess.emit_err(ProcMacroMissingArguments {
+                    expected_input_count,
+                    span: hir_sig.span,
+                    kind,
+                    expected_signature,
+                });
+                self.abort.set(true);
+            }
+
+            // Check that the inputs are correct, if there are enough.
+            if sig.inputs().len() >= expected_input_count {
+                for (arg, input) in
+                    sig.inputs().iter().zip(hir_sig.decl.inputs).take(expected_input_count)
+                {
+                    if !drcx.types_may_unify(*arg, tokenstream) {
+                        tcx.sess.emit_err(ProcMacroTypeError {
+                            span: input.span,
+                            found: *arg,
+                            kind,
+                            expected_signature,
+                        });
+                        self.abort.set(true);
+                    }
+                }
+            }
+
+            // Check that there are not too many arguments
+            let body_id = tcx.hir().body_owned_by(id.def_id);
+            let excess = tcx.hir().body(body_id).params.get(expected_input_count..);
+            if let Some(excess @ [begin @ end] | excess @ [begin, .., end]) = excess {
+                tcx.sess.emit_err(ProcMacroDiffArguments {
+                    span: begin.span.to(end.span),
+                    count: excess.len(),
+                    kind,
+                    expected_signature,
+                });
+                self.abort.set(true);
+            }
+        }
+    }
 }
 
 impl<'tcx> Visitor<'tcx> for CheckAttrVisitor<'tcx> {
@@ -2225,12 +2356,15 @@ fn check_non_exported_macro_for_invalid_attrs(tcx: TyCtxt<'_>, item: &Item<'_>)
 }
 
 fn check_mod_attrs(tcx: TyCtxt<'_>, module_def_id: LocalDefId) {
-    let check_attr_visitor = &mut CheckAttrVisitor { tcx };
+    let check_attr_visitor = &mut CheckAttrVisitor { tcx, abort: Cell::new(false) };
     tcx.hir().visit_item_likes_in_module(module_def_id, check_attr_visitor);
     if module_def_id.is_top_level_module() {
         check_attr_visitor.check_attributes(CRATE_HIR_ID, DUMMY_SP, Target::Mod, None);
         check_invalid_crate_level_attr(tcx, tcx.hir().krate_attrs());
     }
+    if check_attr_visitor.abort.get() {
+        tcx.sess.abort_if_errors()
+    }
 }
 
 pub(crate) fn provide(providers: &mut Providers) {
diff --git a/compiler/rustc_passes/src/errors.rs b/compiler/rustc_passes/src/errors.rs
index 9c6519ea4bb24..9e05ad22e6241 100644
--- a/compiler/rustc_passes/src/errors.rs
+++ b/compiler/rustc_passes/src/errors.rs
@@ -12,6 +12,7 @@ use rustc_macros::{Diagnostic, LintDiagnostic, Subdiagnostic};
 use rustc_middle::ty::{MainDefinition, Ty};
 use rustc_span::{Span, Symbol, DUMMY_SP};
 
+use crate::check_attr::ProcMacroKind;
 use crate::lang_items::Duplicate;
 
 #[derive(Diagnostic)]
@@ -1515,3 +1516,52 @@ pub struct ChangeFieldsToBeOfUnitType {
     #[suggestion_part(code = "()")]
     pub spans: Vec<Span>,
 }
+
+#[derive(Diagnostic)]
+#[diag(passes_proc_macro_typeerror)]
+#[note]
+pub(crate) struct ProcMacroTypeError<'tcx> {
+    #[primary_span]
+    #[label]
+    pub span: Span,
+    pub found: Ty<'tcx>,
+    pub kind: ProcMacroKind,
+    pub expected_signature: &'static str,
+}
+
+#[derive(Diagnostic)]
+#[diag(passes_proc_macro_diff_arg_count)]
+pub(crate) struct ProcMacroDiffArguments {
+    #[primary_span]
+    #[label]
+    pub span: Span,
+    pub count: usize,
+    pub kind: ProcMacroKind,
+    pub expected_signature: &'static str,
+}
+
+#[derive(Diagnostic)]
+#[diag(passes_proc_macro_missing_args)]
+pub(crate) struct ProcMacroMissingArguments {
+    #[primary_span]
+    #[label]
+    pub span: Span,
+    pub expected_input_count: usize,
+    pub kind: ProcMacroKind,
+    pub expected_signature: &'static str,
+}
+
+#[derive(Diagnostic)]
+#[diag(passes_proc_macro_invalid_abi)]
+pub(crate) struct ProcMacroInvalidAbi {
+    #[primary_span]
+    pub span: Span,
+    pub abi: &'static str,
+}
+
+#[derive(Diagnostic)]
+#[diag(passes_proc_macro_unsafe)]
+pub(crate) struct ProcMacroUnsafe {
+    #[primary_span]
+    pub span: Span,
+}
diff --git a/compiler/rustc_span/src/symbol.rs b/compiler/rustc_span/src/symbol.rs
index 706002f79b1fb..7ac4cf648a0df 100644
--- a/compiler/rustc_span/src/symbol.rs
+++ b/compiler/rustc_span/src/symbol.rs
@@ -287,6 +287,7 @@ symbols! {
         Target,
         ToOwned,
         ToString,
+        TokenStream,
         Try,
         TryCaptureGeneric,
         TryCapturePrintable,
diff --git a/library/alloc/src/vec/drain.rs b/library/alloc/src/vec/drain.rs
index 541f99bcfaba4..2b1a787cc5499 100644
--- a/library/alloc/src/vec/drain.rs
+++ b/library/alloc/src/vec/drain.rs
@@ -223,9 +223,9 @@ impl<T, A: Allocator> Drop for Drain<'_, T, A> {
         }
 
         // as_slice() must only be called when iter.len() is > 0 because
-        // vec::Splice modifies vec::Drain fields and may grow the vec which would invalidate
-        // the iterator's internal pointers. Creating a reference to deallocated memory
-        // is invalid even when it is zero-length
+        // it also gets touched by vec::Splice which may turn it into a dangling pointer
+        // which would make it and the vec pointer point to different allocations which would
+        // lead to invalid pointer arithmetic below.
         let drop_ptr = iter.as_slice().as_ptr();
 
         unsafe {
diff --git a/library/alloc/src/vec/splice.rs b/library/alloc/src/vec/splice.rs
index bad765c7f51fa..1861147fe72fb 100644
--- a/library/alloc/src/vec/splice.rs
+++ b/library/alloc/src/vec/splice.rs
@@ -54,6 +54,12 @@ impl<I: Iterator, A: Allocator> ExactSizeIterator for Splice<'_, I, A> {}
 impl<I: Iterator, A: Allocator> Drop for Splice<'_, I, A> {
     fn drop(&mut self) {
         self.drain.by_ref().for_each(drop);
+        // At this point draining is done and the only remaining tasks are splicing
+        // and moving things into the final place.
+        // Which means we can replace the slice::Iter with pointers that won't point to deallocated
+        // memory, so that Drain::drop is still allowed to call iter.len(), otherwise it would break
+        // the ptr.sub_ptr contract.
+        self.drain.iter = (&[]).iter();
 
         unsafe {
             if self.drain.tail_len == 0 {
diff --git a/library/core/src/ptr/const_ptr.rs b/library/core/src/ptr/const_ptr.rs
index 0a74c03d70f3a..7b1cb5488bcac 100644
--- a/library/core/src/ptr/const_ptr.rs
+++ b/library/core/src/ptr/const_ptr.rs
@@ -202,14 +202,11 @@ impl<T: ?Sized> *const T {
     #[must_use]
     #[inline(always)]
     #[unstable(feature = "strict_provenance", issue = "95228")]
-    pub fn addr(self) -> usize
-    where
-        T: Sized,
-    {
+    pub fn addr(self) -> usize {
         // FIXME(strict_provenance_magic): I am magic and should be a compiler intrinsic.
         // SAFETY: Pointer-to-integer transmutes are valid (if you are okay with losing the
         // provenance).
-        unsafe { mem::transmute(self) }
+        unsafe { mem::transmute(self.cast::<()>()) }
     }
 
     /// Gets the "address" portion of the pointer, and 'exposes' the "provenance" part for future
@@ -239,12 +236,9 @@ impl<T: ?Sized> *const T {
     #[must_use]
     #[inline(always)]
     #[unstable(feature = "strict_provenance", issue = "95228")]
-    pub fn expose_addr(self) -> usize
-    where
-        T: Sized,
-    {
+    pub fn expose_addr(self) -> usize {
         // FIXME(strict_provenance_magic): I am magic and should be a compiler intrinsic.
-        self as usize
+        self.cast::<()>() as usize
     }
 
     /// Creates a new pointer with the given address.
@@ -262,10 +256,7 @@ impl<T: ?Sized> *const T {
     #[must_use]
     #[inline]
     #[unstable(feature = "strict_provenance", issue = "95228")]
-    pub fn with_addr(self, addr: usize) -> Self
-    where
-        T: Sized,
-    {
+    pub fn with_addr(self, addr: usize) -> Self {
         // FIXME(strict_provenance_magic): I am magic and should be a compiler intrinsic.
         //
         // In the mean-time, this operation is defined to be "as if" it was
@@ -288,10 +279,7 @@ impl<T: ?Sized> *const T {
     #[must_use]
     #[inline]
     #[unstable(feature = "strict_provenance", issue = "95228")]
-    pub fn map_addr(self, f: impl FnOnce(usize) -> usize) -> Self
-    where
-        T: Sized,
-    {
+    pub fn map_addr(self, f: impl FnOnce(usize) -> usize) -> Self {
         self.with_addr(f(self.addr()))
     }
 
diff --git a/library/core/src/ptr/mut_ptr.rs b/library/core/src/ptr/mut_ptr.rs
index d70fb70c79fa4..ed1e3bd481227 100644
--- a/library/core/src/ptr/mut_ptr.rs
+++ b/library/core/src/ptr/mut_ptr.rs
@@ -208,14 +208,11 @@ impl<T: ?Sized> *mut T {
     #[must_use]
     #[inline(always)]
     #[unstable(feature = "strict_provenance", issue = "95228")]
-    pub fn addr(self) -> usize
-    where
-        T: Sized,
-    {
+    pub fn addr(self) -> usize {
         // FIXME(strict_provenance_magic): I am magic and should be a compiler intrinsic.
         // SAFETY: Pointer-to-integer transmutes are valid (if you are okay with losing the
         // provenance).
-        unsafe { mem::transmute(self) }
+        unsafe { mem::transmute(self.cast::<()>()) }
     }
 
     /// Gets the "address" portion of the pointer, and 'exposes' the "provenance" part for future
@@ -245,12 +242,9 @@ impl<T: ?Sized> *mut T {
     #[must_use]
     #[inline(always)]
     #[unstable(feature = "strict_provenance", issue = "95228")]
-    pub fn expose_addr(self) -> usize
-    where
-        T: Sized,
-    {
+    pub fn expose_addr(self) -> usize {
         // FIXME(strict_provenance_magic): I am magic and should be a compiler intrinsic.
-        self as usize
+        self.cast::<()>() as usize
     }
 
     /// Creates a new pointer with the given address.
@@ -268,10 +262,7 @@ impl<T: ?Sized> *mut T {
     #[must_use]
     #[inline]
     #[unstable(feature = "strict_provenance", issue = "95228")]
-    pub fn with_addr(self, addr: usize) -> Self
-    where
-        T: Sized,
-    {
+    pub fn with_addr(self, addr: usize) -> Self {
         // FIXME(strict_provenance_magic): I am magic and should be a compiler intrinsic.
         //
         // In the mean-time, this operation is defined to be "as if" it was
@@ -294,10 +285,7 @@ impl<T: ?Sized> *mut T {
     #[must_use]
     #[inline]
     #[unstable(feature = "strict_provenance", issue = "95228")]
-    pub fn map_addr(self, f: impl FnOnce(usize) -> usize) -> Self
-    where
-        T: Sized,
-    {
+    pub fn map_addr(self, f: impl FnOnce(usize) -> usize) -> Self {
         self.with_addr(f(self.addr()))
     }
 
diff --git a/library/core/src/ptr/non_null.rs b/library/core/src/ptr/non_null.rs
index af79d4bbd836c..8c1a648860555 100644
--- a/library/core/src/ptr/non_null.rs
+++ b/library/core/src/ptr/non_null.rs
@@ -268,10 +268,7 @@ impl<T: ?Sized> NonNull<T> {
     #[must_use]
     #[inline]
     #[unstable(feature = "strict_provenance", issue = "95228")]
-    pub fn addr(self) -> NonZeroUsize
-    where
-        T: Sized,
-    {
+    pub fn addr(self) -> NonZeroUsize {
         // SAFETY: The pointer is guaranteed by the type to be non-null,
         // meaning that the address will be non-zero.
         unsafe { NonZeroUsize::new_unchecked(self.pointer.addr()) }
@@ -286,10 +283,7 @@ impl<T: ?Sized> NonNull<T> {
     #[must_use]
     #[inline]
     #[unstable(feature = "strict_provenance", issue = "95228")]
-    pub fn with_addr(self, addr: NonZeroUsize) -> Self
-    where
-        T: Sized,
-    {
+    pub fn with_addr(self, addr: NonZeroUsize) -> Self {
         // SAFETY: The result of `ptr::from::with_addr` is non-null because `addr` is guaranteed to be non-zero.
         unsafe { NonNull::new_unchecked(self.pointer.with_addr(addr.get()) as *mut _) }
     }
@@ -303,10 +297,7 @@ impl<T: ?Sized> NonNull<T> {
     #[must_use]
     #[inline]
     #[unstable(feature = "strict_provenance", issue = "95228")]
-    pub fn map_addr(self, f: impl FnOnce(NonZeroUsize) -> NonZeroUsize) -> Self
-    where
-        T: Sized,
-    {
+    pub fn map_addr(self, f: impl FnOnce(NonZeroUsize) -> NonZeroUsize) -> Self {
         self.with_addr(f(self.addr()))
     }
 
diff --git a/library/proc_macro/src/lib.rs b/library/proc_macro/src/lib.rs
index f0e4f5d8a8013..8bff40c279aaa 100644
--- a/library/proc_macro/src/lib.rs
+++ b/library/proc_macro/src/lib.rs
@@ -74,6 +74,7 @@ pub fn is_available() -> bool {
 ///
 /// This is both the input and output of `#[proc_macro]`, `#[proc_macro_attribute]`
 /// and `#[proc_macro_derive]` definitions.
+#[rustc_diagnostic_item = "TokenStream"]
 #[stable(feature = "proc_macro_lib", since = "1.15.0")]
 #[derive(Clone)]
 pub struct TokenStream(Option<bridge::client::TokenStream>);
diff --git a/library/std/src/os/net/linux_ext/addr.rs b/library/std/src/os/net/linux_ext/addr.rs
index df3fc8e6a3b66..85065984fbbb1 100644
--- a/library/std/src/os/net/linux_ext/addr.rs
+++ b/library/std/src/os/net/linux_ext/addr.rs
@@ -38,7 +38,7 @@ pub trait SocketAddrExt: Sealed {
     ///     Ok(())
     /// }
     /// ```
-    fn from_abstract_name<N>(name: &N) -> crate::io::Result<SocketAddr>
+    fn from_abstract_name<N>(name: N) -> crate::io::Result<SocketAddr>
     where
         N: AsRef<[u8]>;
 
diff --git a/library/std/src/os/unix/net/addr.rs b/library/std/src/os/unix/net/addr.rs
index 81ac829d21bc8..ece2b33bddf36 100644
--- a/library/std/src/os/unix/net/addr.rs
+++ b/library/std/src/os/unix/net/addr.rs
@@ -256,7 +256,7 @@ impl linux_ext::addr::SocketAddrExt for SocketAddr {
         if let AddressKind::Abstract(name) = self.address() { Some(name) } else { None }
     }
 
-    fn from_abstract_name<N>(name: &N) -> crate::io::Result<Self>
+    fn from_abstract_name<N>(name: N) -> crate::io::Result<Self>
     where
         N: AsRef<[u8]>,
     {
diff --git a/src/librustdoc/html/static/css/settings.css b/src/librustdoc/html/static/css/settings.css
index 91419093147d7..3fa478751737f 100644
--- a/src/librustdoc/html/static/css/settings.css
+++ b/src/librustdoc/html/static/css/settings.css
@@ -33,10 +33,6 @@
 	padding-bottom: 1px;
 }
 
-.radio-line .setting-name {
-	width: 100%;
-}
-
 .radio-line .choice {
 	margin-top: 0.1em;
 	margin-bottom: 0.1em;
diff --git a/src/librustdoc/html/static/js/settings.js b/src/librustdoc/html/static/js/settings.js
index 9ed8f63610ff6..84df1b7d3911a 100644
--- a/src/librustdoc/html/static/js/settings.js
+++ b/src/librustdoc/html/static/js/settings.js
@@ -135,7 +135,7 @@
                 // This is a select setting.
                 output += `\
 <div class="radio-line" id="${js_data_name}">
-    <span class="setting-name">${setting_name}</span>
+    <div class="setting-name">${setting_name}</div>
 <div class="choices">`;
                 onEach(setting["options"], option => {
                     const checked = option === setting["default"] ? " checked" : "";
diff --git a/src/tools/miri/tests/pass/vec.rs b/src/tools/miri/tests/pass/vec.rs
index 3a6655e2ba69f..30a28bc5803dd 100644
--- a/src/tools/miri/tests/pass/vec.rs
+++ b/src/tools/miri/tests/pass/vec.rs
@@ -162,6 +162,11 @@ fn reverse() {
     assert!(v[0].0 == 49);
 }
 
+fn miri_issue_2759() {
+    let mut input = "1".to_string();
+    input.replace_range(0..0, "0");
+}
+
 fn main() {
     assert_eq!(vec_reallocate().len(), 5);
 
@@ -191,4 +196,5 @@ fn main() {
     swap();
     swap_remove();
     reverse();
+    miri_issue_2759();
 }
diff --git a/tests/assembly/is_aligned.rs b/tests/assembly/is_aligned.rs
index 04b5de8342370..620a3da94636e 100644
--- a/tests/assembly/is_aligned.rs
+++ b/tests/assembly/is_aligned.rs
@@ -1,5 +1,5 @@
 // assembly-output: emit-asm
-// min-llvm-version: 14.0
+// min-llvm-version: 15.0
 // only-x86_64
 // revisions: opt-speed opt-size
 // [opt-speed] compile-flags: -Copt-level=1
diff --git a/tests/codegen/issue-96497-slice-size-nowrap.rs b/tests/codegen/issue-96497-slice-size-nowrap.rs
index a5dbef9346027..0413ed6b26f36 100644
--- a/tests/codegen/issue-96497-slice-size-nowrap.rs
+++ b/tests/codegen/issue-96497-slice-size-nowrap.rs
@@ -3,7 +3,7 @@
 // in some situations, see https://github.com/rust-lang/rust/issues/96497#issuecomment-1112865218
 
 // compile-flags: -O
-// min-llvm-version: 14.0
+// min-llvm-version: 15.0
 
 #![crate_type="lib"]
 
diff --git a/tests/rustdoc-gui/settings.goml b/tests/rustdoc-gui/settings.goml
index f236dc3e0fe76..72de41e41bae1 100644
--- a/tests/rustdoc-gui/settings.goml
+++ b/tests/rustdoc-gui/settings.goml
@@ -105,6 +105,33 @@ assert-css: (
         "box-shadow": "rgb(33, 150, 243) 0px 0px 1px 1px",
     },
 )
+// Now we check the setting-name for radio buttons is on a different line than the label.
+compare-elements-position-near: (
+    "#theme .setting-name",
+    "#theme .choices",
+    {"x": 1}
+)
+compare-elements-position-near-false: (
+    "#theme .setting-name",
+    "#theme .choices",
+    {"y": 1}
+)
+// Now we check that the label positions are all on the same line.
+compare-elements-position-near: (
+    "#theme .choices #theme-light",
+    "#theme .choices #theme-dark",
+    {"y": 1}
+)
+compare-elements-position-near: (
+    "#theme .choices #theme-dark",
+    "#theme .choices #theme-ayu",
+    {"y": 1}
+)
+compare-elements-position-near: (
+    "#theme .choices #theme-ayu",
+    "#theme .choices #theme-system-preference",
+    {"y": 1}
+)
 
 // First we check the "default" display for toggles.
 assert-css: (
diff --git a/tests/ui/proc-macro/allowed-signatures.rs b/tests/ui/proc-macro/allowed-signatures.rs
new file mode 100644
index 0000000000000..03c6ef86632df
--- /dev/null
+++ b/tests/ui/proc-macro/allowed-signatures.rs
@@ -0,0 +1,24 @@
+// check-pass
+
+#![crate_type = "proc-macro"]
+#![allow(private_in_public)]
+extern crate proc_macro;
+use proc_macro::TokenStream;
+
+#[proc_macro]
+pub fn foo<T>(t: T) -> TokenStream {
+  TokenStream::new()
+}
+
+trait Project {
+    type Assoc;
+}
+
+impl Project for () {
+    type Assoc = TokenStream;
+}
+
+#[proc_macro]
+pub fn uwu(_input: <() as Project>::Assoc) -> <() as Project>::Assoc {
+    TokenStream::new()
+}
diff --git a/tests/ui/proc-macro/proc-macro-abi.rs b/tests/ui/proc-macro/proc-macro-abi.rs
new file mode 100644
index 0000000000000..8e9d50d7832d5
--- /dev/null
+++ b/tests/ui/proc-macro/proc-macro-abi.rs
@@ -0,0 +1,28 @@
+#![crate_type = "proc-macro"]
+#![allow(warnings)]
+
+extern crate proc_macro;
+use proc_macro::TokenStream;
+
+#[proc_macro]
+pub extern "C" fn abi(a: TokenStream) -> TokenStream {
+    //~^ ERROR proc macro functions may not be `extern "C"`
+    a
+}
+
+#[proc_macro]
+pub extern "system" fn abi2(a: TokenStream) -> TokenStream {
+    //~^ ERROR proc macro functions may not be `extern "system"`
+    a
+}
+
+#[proc_macro]
+pub extern fn abi3(a: TokenStream) -> TokenStream {
+    //~^ ERROR proc macro functions may not be `extern "C"`
+    a
+}
+
+#[proc_macro]
+pub extern "Rust" fn abi4(a: TokenStream) -> TokenStream {
+    a
+}
diff --git a/tests/ui/proc-macro/proc-macro-abi.stderr b/tests/ui/proc-macro/proc-macro-abi.stderr
new file mode 100644
index 0000000000000..fa5f5dc098998
--- /dev/null
+++ b/tests/ui/proc-macro/proc-macro-abi.stderr
@@ -0,0 +1,20 @@
+error: proc macro functions may not be `extern "C"`
+  --> $DIR/proc-macro-abi.rs:8:1
+   |
+LL | pub extern "C" fn abi(a: TokenStream) -> TokenStream {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: proc macro functions may not be `extern "system"`
+  --> $DIR/proc-macro-abi.rs:14:1
+   |
+LL | pub extern "system" fn abi2(a: TokenStream) -> TokenStream {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: proc macro functions may not be `extern "C"`
+  --> $DIR/proc-macro-abi.rs:20:1
+   |
+LL | pub extern fn abi3(a: TokenStream) -> TokenStream {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to 3 previous errors
+
diff --git a/tests/ui/proc-macro/signature-proc-macro-attribute.rs b/tests/ui/proc-macro/signature-proc-macro-attribute.rs
new file mode 100644
index 0000000000000..fb17710950106
--- /dev/null
+++ b/tests/ui/proc-macro/signature-proc-macro-attribute.rs
@@ -0,0 +1,29 @@
+#![crate_type = "proc-macro"]
+
+extern crate proc_macro;
+use proc_macro::TokenStream;
+
+#[proc_macro_attribute]
+pub fn bad_input(input: String) -> TokenStream {
+    //~^ ERROR mismatched attribute proc macro signature
+    ::proc_macro::TokenStream::new()
+}
+
+#[proc_macro_attribute]
+pub fn bad_output(input: TokenStream) -> String {
+    //~^ ERROR mismatched attribute proc macro signature
+    //~| ERROR mismatched attribute proc macro signature
+    String::from("blah")
+}
+
+#[proc_macro_attribute]
+pub fn bad_everything(input: String) -> String {
+    //~^ ERROR mismatched attribute proc macro signature
+    //~| ERROR mismatched attribute proc macro signature
+    input
+}
+
+#[proc_macro_attribute]
+pub fn too_many(a: TokenStream, b: TokenStream, c: String) -> TokenStream {
+    //~^ ERROR mismatched attribute proc macro signature
+}
diff --git a/tests/ui/proc-macro/signature-proc-macro-attribute.stderr b/tests/ui/proc-macro/signature-proc-macro-attribute.stderr
new file mode 100644
index 0000000000000..ecfd2b06e109c
--- /dev/null
+++ b/tests/ui/proc-macro/signature-proc-macro-attribute.stderr
@@ -0,0 +1,42 @@
+error: mismatched attribute proc macro signature
+  --> $DIR/signature-proc-macro-attribute.rs:7:1
+   |
+LL | pub fn bad_input(input: String) -> TokenStream {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ attribute proc macro must have two arguments of type `proc_macro::TokenStream`
+
+error: mismatched attribute proc macro signature
+  --> $DIR/signature-proc-macro-attribute.rs:13:42
+   |
+LL | pub fn bad_output(input: TokenStream) -> String {
+   |                                          ^^^^^^ found std::string::String, expected type `proc_macro::TokenStream`
+   |
+   = note: attribute proc macros must have a signature of `fn(TokenStream, TokenStream) -> TokenStream`
+
+error: mismatched attribute proc macro signature
+  --> $DIR/signature-proc-macro-attribute.rs:13:1
+   |
+LL | pub fn bad_output(input: TokenStream) -> String {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ attribute proc macro must have two arguments of type `proc_macro::TokenStream`
+
+error: mismatched attribute proc macro signature
+  --> $DIR/signature-proc-macro-attribute.rs:20:41
+   |
+LL | pub fn bad_everything(input: String) -> String {
+   |                                         ^^^^^^ found std::string::String, expected type `proc_macro::TokenStream`
+   |
+   = note: attribute proc macros must have a signature of `fn(TokenStream, TokenStream) -> TokenStream`
+
+error: mismatched attribute proc macro signature
+  --> $DIR/signature-proc-macro-attribute.rs:20:1
+   |
+LL | pub fn bad_everything(input: String) -> String {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ attribute proc macro must have two arguments of type `proc_macro::TokenStream`
+
+error: mismatched attribute proc macro signature
+  --> $DIR/signature-proc-macro-attribute.rs:27:49
+   |
+LL | pub fn too_many(a: TokenStream, b: TokenStream, c: String) -> TokenStream {
+   |                                                 ^^^^^^^^^ found unexpected argument
+
+error: aborting due to 6 previous errors
+
diff --git a/tests/ui/proc-macro/signature-proc-macro-derive.rs b/tests/ui/proc-macro/signature-proc-macro-derive.rs
new file mode 100644
index 0000000000000..a079157538fb6
--- /dev/null
+++ b/tests/ui/proc-macro/signature-proc-macro-derive.rs
@@ -0,0 +1,28 @@
+#![crate_type = "proc-macro"]
+
+extern crate proc_macro;
+use proc_macro::TokenStream;
+
+#[proc_macro_derive(Blah)]
+pub fn bad_input(input: String) -> TokenStream {
+    //~^ ERROR mismatched derive proc macro signature
+    TokenStream::new()
+}
+
+#[proc_macro_derive(Bleh)]
+pub fn bad_output(input: TokenStream) -> String {
+    //~^ ERROR mismatched derive proc macro signature
+    String::from("blah")
+}
+
+#[proc_macro_derive(Bluh)]
+pub fn bad_everything(input: String) -> String {
+    //~^ ERROR mismatched derive proc macro signature
+    //~| ERROR mismatched derive proc macro signature
+    input
+}
+
+#[proc_macro_derive(Blih)]
+pub fn too_many(a: TokenStream, b: TokenStream, c: String) -> TokenStream {
+    //~^ ERROR mismatched derive proc macro signature
+}
diff --git a/tests/ui/proc-macro/signature-proc-macro-derive.stderr b/tests/ui/proc-macro/signature-proc-macro-derive.stderr
new file mode 100644
index 0000000000000..bb2bd9a93d24b
--- /dev/null
+++ b/tests/ui/proc-macro/signature-proc-macro-derive.stderr
@@ -0,0 +1,40 @@
+error: mismatched derive proc macro signature
+  --> $DIR/signature-proc-macro-derive.rs:7:25
+   |
+LL | pub fn bad_input(input: String) -> TokenStream {
+   |                         ^^^^^^ found std::string::String, expected type `proc_macro::TokenStream`
+   |
+   = note: derive proc macros must have a signature of `fn(TokenStream) -> TokenStream`
+
+error: mismatched derive proc macro signature
+  --> $DIR/signature-proc-macro-derive.rs:13:42
+   |
+LL | pub fn bad_output(input: TokenStream) -> String {
+   |                                          ^^^^^^ found std::string::String, expected type `proc_macro::TokenStream`
+   |
+   = note: derive proc macros must have a signature of `fn(TokenStream) -> TokenStream`
+
+error: mismatched derive proc macro signature
+  --> $DIR/signature-proc-macro-derive.rs:19:41
+   |
+LL | pub fn bad_everything(input: String) -> String {
+   |                                         ^^^^^^ found std::string::String, expected type `proc_macro::TokenStream`
+   |
+   = note: derive proc macros must have a signature of `fn(TokenStream) -> TokenStream`
+
+error: mismatched derive proc macro signature
+  --> $DIR/signature-proc-macro-derive.rs:19:30
+   |
+LL | pub fn bad_everything(input: String) -> String {
+   |                              ^^^^^^ found std::string::String, expected type `proc_macro::TokenStream`
+   |
+   = note: derive proc macros must have a signature of `fn(TokenStream) -> TokenStream`
+
+error: mismatched derive proc macro signature
+  --> $DIR/signature-proc-macro-derive.rs:26:33
+   |
+LL | pub fn too_many(a: TokenStream, b: TokenStream, c: String) -> TokenStream {
+   |                                 ^^^^^^^^^^^^^^^^^^^^^^^^^ found unexpected arguments
+
+error: aborting due to 5 previous errors
+
diff --git a/tests/ui/proc-macro/signature-proc-macro.rs b/tests/ui/proc-macro/signature-proc-macro.rs
new file mode 100644
index 0000000000000..35d5be2171283
--- /dev/null
+++ b/tests/ui/proc-macro/signature-proc-macro.rs
@@ -0,0 +1,28 @@
+#![crate_type = "proc-macro"]
+
+extern crate proc_macro;
+use proc_macro::TokenStream;
+
+#[proc_macro]
+pub fn bad_input(input: String) -> TokenStream {
+    //~^ ERROR mismatched function-like proc macro signature
+    ::proc_macro::TokenStream::new()
+}
+
+#[proc_macro]
+pub fn bad_output(input: TokenStream) -> String {
+    //~^ ERROR mismatched function-like proc macro signature
+    String::from("blah")
+}
+
+#[proc_macro]
+pub fn bad_everything(input: String) -> String {
+    //~^ ERROR mismatched function-like proc macro signature
+    //~| ERROR mismatched function-like proc macro signature
+    input
+}
+
+#[proc_macro]
+pub fn too_many(a: TokenStream, b: TokenStream, c: String) -> TokenStream {
+    //~^ ERROR mismatched function-like proc macro signature
+}
diff --git a/tests/ui/proc-macro/signature-proc-macro.stderr b/tests/ui/proc-macro/signature-proc-macro.stderr
new file mode 100644
index 0000000000000..32241e1b9e00a
--- /dev/null
+++ b/tests/ui/proc-macro/signature-proc-macro.stderr
@@ -0,0 +1,40 @@
+error: mismatched function-like proc macro signature
+  --> $DIR/signature-proc-macro.rs:7:25
+   |
+LL | pub fn bad_input(input: String) -> TokenStream {
+   |                         ^^^^^^ found std::string::String, expected type `proc_macro::TokenStream`
+   |
+   = note: function-like proc macros must have a signature of `fn(TokenStream) -> TokenStream`
+
+error: mismatched function-like proc macro signature
+  --> $DIR/signature-proc-macro.rs:13:42
+   |
+LL | pub fn bad_output(input: TokenStream) -> String {
+   |                                          ^^^^^^ found std::string::String, expected type `proc_macro::TokenStream`
+   |
+   = note: function-like proc macros must have a signature of `fn(TokenStream) -> TokenStream`
+
+error: mismatched function-like proc macro signature
+  --> $DIR/signature-proc-macro.rs:19:41
+   |
+LL | pub fn bad_everything(input: String) -> String {
+   |                                         ^^^^^^ found std::string::String, expected type `proc_macro::TokenStream`
+   |
+   = note: function-like proc macros must have a signature of `fn(TokenStream) -> TokenStream`
+
+error: mismatched function-like proc macro signature
+  --> $DIR/signature-proc-macro.rs:19:30
+   |
+LL | pub fn bad_everything(input: String) -> String {
+   |                              ^^^^^^ found std::string::String, expected type `proc_macro::TokenStream`
+   |
+   = note: function-like proc macros must have a signature of `fn(TokenStream) -> TokenStream`
+
+error: mismatched function-like proc macro signature
+  --> $DIR/signature-proc-macro.rs:26:33
+   |
+LL | pub fn too_many(a: TokenStream, b: TokenStream, c: String) -> TokenStream {
+   |                                 ^^^^^^^^^^^^^^^^^^^^^^^^^ found unexpected arguments
+
+error: aborting due to 5 previous errors
+
diff --git a/tests/ui/proc-macro/signature.rs b/tests/ui/proc-macro/signature.rs
index 2302238253e82..11187aa31bd80 100644
--- a/tests/ui/proc-macro/signature.rs
+++ b/tests/ui/proc-macro/signature.rs
@@ -8,6 +8,10 @@ extern crate proc_macro;
 
 #[proc_macro_derive(A)]
 pub unsafe extern "C" fn foo(a: i32, b: u32) -> u32 {
-    //~^ ERROR: expected a `Fn<(proc_macro::TokenStream,)>` closure, found `unsafe extern "C" fn
+    //~^ ERROR: mismatched derive proc macro signature
+    //~| mismatched derive proc macro signature
+    //~| mismatched derive proc macro signature
+    //~| proc macro functions may not be `extern
+    //~| proc macro functions may not be `unsafe
     loop {}
 }
diff --git a/tests/ui/proc-macro/signature.stderr b/tests/ui/proc-macro/signature.stderr
index 79f2001da0055..3dbe3f22a0df8 100644
--- a/tests/ui/proc-macro/signature.stderr
+++ b/tests/ui/proc-macro/signature.stderr
@@ -1,20 +1,36 @@
-error[E0277]: expected a `Fn<(proc_macro::TokenStream,)>` closure, found `unsafe extern "C" fn(i32, u32) -> u32 {foo}`
+error: proc macro functions may not be `extern "C"`
   --> $DIR/signature.rs:10:1
    |
-LL | / pub unsafe extern "C" fn foo(a: i32, b: u32) -> u32 {
-LL | |
-LL | |     loop {}
-LL | | }
-   | | ^
-   | | |
-   | |_call the function in a closure: `|| unsafe { /* code */ }`
-   |   required by a bound introduced by this call
+LL | pub unsafe extern "C" fn foo(a: i32, b: u32) -> u32 {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: proc macro functions may not be `unsafe`
+  --> $DIR/signature.rs:10:1
+   |
+LL | pub unsafe extern "C" fn foo(a: i32, b: u32) -> u32 {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: mismatched derive proc macro signature
+  --> $DIR/signature.rs:10:49
+   |
+LL | pub unsafe extern "C" fn foo(a: i32, b: u32) -> u32 {
+   |                                                 ^^^ found u32, expected type `proc_macro::TokenStream`
+   |
+   = note: derive proc macros must have a signature of `fn(TokenStream) -> TokenStream`
+
+error: mismatched derive proc macro signature
+  --> $DIR/signature.rs:10:33
+   |
+LL | pub unsafe extern "C" fn foo(a: i32, b: u32) -> u32 {
+   |                                 ^^^ found i32, expected type `proc_macro::TokenStream`
+   |
+   = note: derive proc macros must have a signature of `fn(TokenStream) -> TokenStream`
+
+error: mismatched derive proc macro signature
+  --> $DIR/signature.rs:10:38
    |
-   = help: the trait `Fn<(proc_macro::TokenStream,)>` is not implemented for fn item `unsafe extern "C" fn(i32, u32) -> u32 {foo}`
-   = note: unsafe function cannot be called generically without an unsafe block
-note: required by a bound in `ProcMacro::custom_derive`
-  --> $SRC_DIR/proc_macro/src/bridge/client.rs:LL:COL
+LL | pub unsafe extern "C" fn foo(a: i32, b: u32) -> u32 {
+   |                                      ^^^^^^ found unexpected argument
 
-error: aborting due to previous error
+error: aborting due to 5 previous errors
 
-For more information about this error, try `rustc --explain E0277`.