Auto merge of #131690 - matthiaskrgr:rollup-mcau4ol, r=matthiaskrgr

Rollup of 8 pull requests

Successful merges:

 - #129424 (Stabilize `Pin::as_deref_mut()`)
 - #131332 (Fix clobber_abi and disallow SVE-related registers in Arm64EC inline assembly)
 - #131384 (Update precondition tests (especially for zero-size access to null))
 - #131430 (Special treatment empty tuple when suggest adding a string literal in format macro.)
 - #131550 (Make some tweaks to extern block diagnostics)
 - #131667 (Fix AArch64InlineAsmReg::emit)
 - #131679 (compiletest: Document various parts of compiletest's `lib.rs`)
 - #131682 (Tag PRs affecting compiletest with `A-compiletest`)

Failed merges:

 - #131496 (Stabilise `const_make_ascii`.)

r? `@ghost`
`@rustbot` modify labels: rollup

compiler/rustc_ast_passes/messages.ftl

@@ -62,12 +62,12 @@ ast_passes_equality_in_where = equality constraints are not yet supported in `wh
 
 ast_passes_extern_block_suggestion = if you meant to declare an externally defined function, use an `extern` block
 
-ast_passes_extern_fn_qualifiers = functions in `extern` blocks cannot have qualifiers
+ast_passes_extern_fn_qualifiers = functions in `extern` blocks cannot have `{$kw}` qualifier
     .label = in this `extern` block
-    .suggestion = remove this qualifier
+    .suggestion = remove the `{$kw}` qualifier
 
-ast_passes_extern_invalid_safety = items in unadorned `extern` blocks cannot have safety qualifiers
+ast_passes_extern_invalid_safety = items in `extern` blocks without an `unsafe` qualifier cannot have safety qualifiers
-    .suggestion = add unsafe to this `extern` block
+    .suggestion = add `unsafe` to this `extern` block
 
 ast_passes_extern_item_ascii = items in `extern` blocks cannot use non-ascii identifiers
     .label = in this `extern` block

compiler/rustc_ast_passes/src/ast_validation.rs

@@ -524,21 +524,24 @@ impl<'a> AstValidator<'a> {
         // Deconstruct to ensure exhaustiveness
         FnHeader { safety: _, coroutine_kind, constness, ext }: FnHeader,
     ) {
-        let report_err = |span| {
+        let report_err = |span, kw| {
-            self.dcx()
+            self.dcx().emit_err(errors::FnQualifierInExtern {
-                .emit_err(errors::FnQualifierInExtern { span, block: self.current_extern_span() });
+                span,
+                kw,
+                block: self.current_extern_span(),
+            });
         };
         match coroutine_kind {
-            Some(knd) => report_err(knd.span()),
+            Some(kind) => report_err(kind.span(), kind.as_str()),
             None => (),
         }
         match constness {
-            Const::Yes(span) => report_err(span),
+            Const::Yes(span) => report_err(span, "const"),
             Const::No => (),
         }
         match ext {
             Extern::None => (),
-            Extern::Implicit(span) | Extern::Explicit(_, span) => report_err(span),
+            Extern::Implicit(span) | Extern::Explicit(_, span) => report_err(span, "extern"),
         }
     }
 

compiler/rustc_ast_passes/src/errors.rs

@@ -295,6 +295,7 @@ pub(crate) struct FnQualifierInExtern {
     pub span: Span,
     #[label]
     pub block: Span,
+    pub kw: &'static str,
 }
 
 #[derive(Diagnostic)]

compiler/rustc_builtin_macros/src/format.rs

@@ -195,12 +195,26 @@ fn make_format_args(
                                     Applicability::MaybeIncorrect,
                                 );
                             } else {
-                                let sugg_fmt = match args.explicit_args().len() {
+                                // `{}` or `()`
-                                    0 => "{}".to_string(),
+                                let should_suggest = |kind: &ExprKind| -> bool {
-                                    count => {
+                                    match kind {
-                                        format!("{}{{}}", "{} ".repeat(count))
+                                        ExprKind::Block(b, None) if b.stmts.is_empty() => true,
+                                        ExprKind::Tup(v) if v.is_empty() => true,
+                                        _ => false,
                                     }
                                 };
+
+                                let mut sugg_fmt = String::new();
+                                for kind in std::iter::once(&efmt.kind)
+                                    .chain(args.explicit_args().into_iter().map(|a| &a.expr.kind))
+                                {
+                                    sugg_fmt.push_str(if should_suggest(kind) {
+                                        "{:?} "
+                                    } else {
+                                        "{} "
+                                    });
+                                }
+                                sugg_fmt = sugg_fmt.trim_end().to_string();
                                 err.span_suggestion(
                                     unexpanded_fmt_span.shrink_to_lo(),
                                     "you might be missing a string literal to format with",

compiler/rustc_codegen_llvm/src/asm.rs

@@ -542,57 +542,16 @@ fn xmm_reg_index(reg: InlineAsmReg) -> Option<u32> {
 
 /// If the register is an AArch64 integer register then return its index.
 fn a64_reg_index(reg: InlineAsmReg) -> Option<u32> {
-    use AArch64InlineAsmReg::*;
+    match reg {
-    // Unlike `a64_vreg_index`, we can't subtract `x0` to get the u32 because
+        InlineAsmReg::AArch64(r) => r.reg_index(),
-    // `x19` and `x29` are missing and the integer constants for the
+        _ => None,
-    // `x0`..`x30` enum variants don't all match the register number. E.g. the
+    }
-    // integer constant for `x18` is 18, but the constant for `x20` is 19.
-    Some(match reg {
-        InlineAsmReg::AArch64(r) => match r {
-            x0 => 0,
-            x1 => 1,
-            x2 => 2,
-            x3 => 3,
-            x4 => 4,
-            x5 => 5,
-            x6 => 6,
-            x7 => 7,
-            x8 => 8,
-            x9 => 9,
-            x10 => 10,
-            x11 => 11,
-            x12 => 12,
-            x13 => 13,
-            x14 => 14,
-            x15 => 15,
-            x16 => 16,
-            x17 => 17,
-            x18 => 18,
-            // x19 is reserved
-            x20 => 20,
-            x21 => 21,
-            x22 => 22,
-            x23 => 23,
-            x24 => 24,
-            x25 => 25,
-            x26 => 26,
-            x27 => 27,
-            x28 => 28,
-            // x29 is reserved
-            x30 => 30,
-            _ => return None,
-        },
-        _ => return None,
-    })
 }
 
 /// If the register is an AArch64 vector register then return its index.
 fn a64_vreg_index(reg: InlineAsmReg) -> Option<u32> {
-    use AArch64InlineAsmReg::*;
     match reg {
-        InlineAsmReg::AArch64(reg) if reg as u32 >= v0 as u32 && reg as u32 <= v31 as u32 => {
+        InlineAsmReg::AArch64(reg) => reg.vreg_index(),
-            Some(reg as u32 - v0 as u32)
-        }
         _ => None,
     }
 }

compiler/rustc_target/src/asm/aarch64.rs

@@ -64,6 +64,7 @@ impl AArch64InlineAsmRegClass {
                 neon: I8, I16, I32, I64, F16, F32, F64, F128,
                     VecI8(8), VecI16(4), VecI32(2), VecI64(1), VecF16(4), VecF32(2), VecF64(1),
                     VecI8(16), VecI16(8), VecI32(4), VecI64(2), VecF16(8), VecF32(4), VecF64(2);
+                // Note: When adding support for SVE vector types, they must be rejected for Arm64EC.
             },
             Self::preg => &[],
         }
@@ -96,7 +97,7 @@ fn restricted_for_arm64ec(
     _is_clobber: bool,
 ) -> Result<(), &'static str> {
     if arch == InlineAsmArch::Arm64EC {
-        Err("x13, x14, x23, x24, x28, v16-v31 cannot be used for Arm64EC")
+        Err("x13, x14, x23, x24, x28, v16-v31, p*, ffr cannot be used for Arm64EC")
     } else {
         Ok(())
     }
@@ -165,23 +166,23 @@ def_regs! {
         v29: vreg = ["v29", "b29", "h29", "s29", "d29", "q29", "z29"] % restricted_for_arm64ec,
         v30: vreg = ["v30", "b30", "h30", "s30", "d30", "q30", "z30"] % restricted_for_arm64ec,
         v31: vreg = ["v31", "b31", "h31", "s31", "d31", "q31", "z31"] % restricted_for_arm64ec,
-        p0: preg = ["p0"],
+        p0: preg = ["p0"] % restricted_for_arm64ec,
-        p1: preg = ["p1"],
+        p1: preg = ["p1"] % restricted_for_arm64ec,
-        p2: preg = ["p2"],
+        p2: preg = ["p2"] % restricted_for_arm64ec,
-        p3: preg = ["p3"],
+        p3: preg = ["p3"] % restricted_for_arm64ec,
-        p4: preg = ["p4"],
+        p4: preg = ["p4"] % restricted_for_arm64ec,
-        p5: preg = ["p5"],
+        p5: preg = ["p5"] % restricted_for_arm64ec,
-        p6: preg = ["p6"],
+        p6: preg = ["p6"] % restricted_for_arm64ec,
-        p7: preg = ["p7"],
+        p7: preg = ["p7"] % restricted_for_arm64ec,
-        p8: preg = ["p8"],
+        p8: preg = ["p8"] % restricted_for_arm64ec,
-        p9: preg = ["p9"],
+        p9: preg = ["p9"] % restricted_for_arm64ec,
-        p10: preg = ["p10"],
+        p10: preg = ["p10"] % restricted_for_arm64ec,
-        p11: preg = ["p11"],
+        p11: preg = ["p11"] % restricted_for_arm64ec,
-        p12: preg = ["p12"],
+        p12: preg = ["p12"] % restricted_for_arm64ec,
-        p13: preg = ["p13"],
+        p13: preg = ["p13"] % restricted_for_arm64ec,
-        p14: preg = ["p14"],
+        p14: preg = ["p14"] % restricted_for_arm64ec,
-        p15: preg = ["p15"],
+        p15: preg = ["p15"] % restricted_for_arm64ec,
-        ffr: preg = ["ffr"],
+        ffr: preg = ["ffr"] % restricted_for_arm64ec,
         #error = ["x19", "w19"] =>
             "x19 is used internally by LLVM and cannot be used as an operand for inline asm",
         #error = ["x29", "w29", "fp", "wfp"] =>
@@ -200,12 +201,66 @@ impl AArch64InlineAsmReg {
         _arch: InlineAsmArch,
         modifier: Option<char>,
     ) -> fmt::Result {
-        let (prefix, index) = if (self as u32) < Self::v0 as u32 {
+        let (prefix, index) = if let Some(index) = self.reg_index() {
-            (modifier.unwrap_or('x'), self as u32 - Self::x0 as u32)
+            (modifier.unwrap_or('x'), index)
+        } else if let Some(index) = self.vreg_index() {
+            (modifier.unwrap_or('v'), index)
         } else {
-            (modifier.unwrap_or('v'), self as u32 - Self::v0 as u32)
+            return out.write_str(self.name());
         };
         assert!(index < 32);
         write!(out, "{prefix}{index}")
     }
+
+    /// If the register is an integer register then return its index.
+    pub fn reg_index(self) -> Option<u32> {
+        // Unlike `vreg_index`, we can't subtract `x0` to get the u32 because
+        // `x19` and `x29` are missing and the integer constants for the
+        // `x0`..`x30` enum variants don't all match the register number. E.g. the
+        // integer constant for `x18` is 18, but the constant for `x20` is 19.
+        use AArch64InlineAsmReg::*;
+        Some(match self {
+            x0 => 0,
+            x1 => 1,
+            x2 => 2,
+            x3 => 3,
+            x4 => 4,
+            x5 => 5,
+            x6 => 6,
+            x7 => 7,
+            x8 => 8,
+            x9 => 9,
+            x10 => 10,
+            x11 => 11,
+            x12 => 12,
+            x13 => 13,
+            x14 => 14,
+            x15 => 15,
+            x16 => 16,
+            x17 => 17,
+            x18 => 18,
+            // x19 is reserved
+            x20 => 20,
+            x21 => 21,
+            x22 => 22,
+            x23 => 23,
+            x24 => 24,
+            x25 => 25,
+            x26 => 26,
+            x27 => 27,
+            x28 => 28,
+            // x29 is reserved
+            x30 => 30,
+            _ => return None,
+        })
+    }
+
+    /// If the register is a vector register then return its index.
+    pub fn vreg_index(self) -> Option<u32> {
+        use AArch64InlineAsmReg::*;
+        if self as u32 >= v0 as u32 && self as u32 <= v31 as u32 {
+            return Some(self as u32 - v0 as u32);
+        }
+        None
+    }
 }

compiler/rustc_target/src/asm/mod.rs

@@ -890,6 +890,7 @@ pub enum InlineAsmClobberAbi {
     Arm,
     AArch64,
     AArch64NoX18,
+    Arm64EC,
     RiscV,
     LoongArch,
     S390x,
@@ -932,7 +933,7 @@ impl InlineAsmClobberAbi {
                 _ => Err(&["C", "system", "efiapi"]),
             },
             InlineAsmArch::Arm64EC => match name {
-                "C" | "system" => Ok(InlineAsmClobberAbi::AArch64NoX18),
+                "C" | "system" => Ok(InlineAsmClobberAbi::Arm64EC),
                 _ => Err(&["C", "system"]),
             },
             InlineAsmArch::RiscV32 | InlineAsmArch::RiscV64 => match name {
@@ -1033,7 +1034,6 @@ impl InlineAsmClobberAbi {
                     p0, p1, p2, p3, p4, p5, p6, p7,
                     p8, p9, p10, p11, p12, p13, p14, p15,
                     ffr,
-
                 }
             },
             InlineAsmClobberAbi::AArch64NoX18 => clobbered_regs! {
@@ -1052,7 +1052,20 @@ impl InlineAsmClobberAbi {
                     p0, p1, p2, p3, p4, p5, p6, p7,
                     p8, p9, p10, p11, p12, p13, p14, p15,
                     ffr,
+                }
+            },
+            InlineAsmClobberAbi::Arm64EC => clobbered_regs! {
+                AArch64 AArch64InlineAsmReg {
+                    // x13 and x14 cannot be used in Arm64EC.
+                    x0, x1, x2, x3, x4, x5, x6, x7,
+                    x8, x9, x10, x11, x12, x15,
+                    x16, x17, x30,
 
+                    // Technically the low 64 bits of v8-v15 are preserved, but
+                    // we have no way of expressing this using clobbers.
+                    v0, v1, v2, v3, v4, v5, v6, v7,
+                    v8, v9, v10, v11, v12, v13, v14, v15,
+                    // v16-v31, p*, and ffr cannot be used in Arm64EC.
                 }
             },
             InlineAsmClobberAbi::Arm => clobbered_regs! {

library/core/src/ascii/ascii_char.rs

@@ -506,7 +506,7 @@ impl AsciiChar {
     pub const unsafe fn digit_unchecked(d: u8) -> Self {
         assert_unsafe_precondition!(
             check_language_ub,
-            "`AsciiChar::digit_unchecked` input cannot exceed 9.",
+            "`ascii::Char::digit_unchecked` input cannot exceed 9.",
             (d: u8 = d) => d < 10
         );
 

library/core/src/intrinsics.rs

@@ -64,6 +64,7 @@
 #![allow(missing_docs)]
 
 use crate::marker::{DiscriminantKind, Tuple};
+use crate::mem::SizedTypeProperties;
 use crate::{ptr, ub_checks};
 
 pub mod mir;
@@ -3364,10 +3365,12 @@ pub const unsafe fn copy_nonoverlapping<T>(src: *const T, dst: *mut T, count: us
             size: usize = size_of::<T>(),
             align: usize = align_of::<T>(),
             count: usize = count,
-        ) =>
+        ) => {
-        ub_checks::is_aligned_and_not_null(src, align)
+            let zero_size = count == 0 || size == 0;
-            && ub_checks::is_aligned_and_not_null(dst, align)
+            ub_checks::is_aligned_and_not_null(src, align, zero_size)
+                && ub_checks::is_aligned_and_not_null(dst, align, zero_size)
                 && ub_checks::is_nonoverlapping(src, dst, size, count)
+        }
     );
 
     // SAFETY: the safety contract for `copy_nonoverlapping` must be
@@ -3465,9 +3468,10 @@ pub const unsafe fn copy<T>(src: *const T, dst: *mut T, count: usize) {
                 src: *const () = src as *const (),
                 dst: *mut () = dst as *mut (),
                 align: usize = align_of::<T>(),
+                zero_size: bool = T::IS_ZST || count == 0,
             ) =>
-            ub_checks::is_aligned_and_not_null(src, align)
+            ub_checks::is_aligned_and_not_null(src, align, zero_size)
-                && ub_checks::is_aligned_and_not_null(dst, align)
+                && ub_checks::is_aligned_and_not_null(dst, align, zero_size)
         );
         copy(src, dst, count)
     }
@@ -3544,7 +3548,8 @@ pub const unsafe fn write_bytes<T>(dst: *mut T, val: u8, count: usize) {
             (
                 addr: *const () = dst as *const (),
                 align: usize = align_of::<T>(),
-            ) => ub_checks::is_aligned_and_not_null(addr, align)
+                zero_size: bool = T::IS_ZST || count == 0,
+            ) => ub_checks::is_aligned_and_not_null(addr, align, zero_size)
         );
         write_bytes(dst, val, count)
     }

library/core/src/pin.rs

@@ -1422,7 +1422,7 @@ impl<Ptr: DerefMut> Pin<Ptr> {
     /// move in the future, and this method does not enable the pointee to move. "Malicious"
     /// implementations of `Ptr::DerefMut` are likewise ruled out by the contract of
     /// `Pin::new_unchecked`.
-    #[unstable(feature = "pin_deref_mut", issue = "86918")]
+    #[stable(feature = "pin_deref_mut", since = "CURRENT_RUSTC_VERSION")]
     #[must_use = "`self` will be dropped if the result is not used"]
     #[inline(always)]
     pub fn as_deref_mut(self: Pin<&mut Pin<Ptr>>) -> Pin<&mut Ptr::Target> {

library/core/src/ptr/mod.rs

@@ -448,7 +448,7 @@
 
 use crate::cmp::Ordering;
 use crate::marker::FnPtr;
-use crate::mem::{self, MaybeUninit};
+use crate::mem::{self, MaybeUninit, SizedTypeProperties};
 use crate::{fmt, hash, intrinsics, ub_checks};
 
 mod alignment;
@@ -1165,10 +1165,12 @@ pub const unsafe fn swap_nonoverlapping<T>(x: *mut T, y: *mut T, count: usize) {
             size: usize = size_of::<T>(),
             align: usize = align_of::<T>(),
             count: usize = count,
-        ) =>
+        ) => {
-        ub_checks::is_aligned_and_not_null(x, align)
+            let zero_size = size == 0 || count == 0;
-            && ub_checks::is_aligned_and_not_null(y, align)
+            ub_checks::is_aligned_and_not_null(x, align, zero_size)
+                && ub_checks::is_aligned_and_not_null(y, align, zero_size)
                 && ub_checks::is_nonoverlapping(x, y, size, count)
+        }
     );
 
     // Split up the slice into small power-of-two-sized chunks that LLVM is able
@@ -1278,7 +1280,8 @@ pub const unsafe fn replace<T>(dst: *mut T, src: T) -> T {
             (
                 addr: *const () = dst as *const (),
                 align: usize = align_of::<T>(),
-            ) => ub_checks::is_aligned_and_not_null(addr, align)
+                is_zst: bool = T::IS_ZST,
+            ) => ub_checks::is_aligned_and_not_null(addr, align, is_zst)
         );
         mem::replace(&mut *dst, src)
     }
@@ -1430,7 +1433,8 @@ pub const unsafe fn read<T>(src: *const T) -> T {
             (
                 addr: *const () = src as *const (),
                 align: usize = align_of::<T>(),
-            ) => ub_checks::is_aligned_and_not_null(addr, align)
+                is_zst: bool = T::IS_ZST,
+            ) => ub_checks::is_aligned_and_not_null(addr, align, is_zst)
         );
         crate::intrinsics::read_via_copy(src)
     }
@@ -1635,7 +1639,8 @@ pub const unsafe fn write<T>(dst: *mut T, src: T) {
             (
                 addr: *mut () = dst as *mut (),
                 align: usize = align_of::<T>(),
-            ) => ub_checks::is_aligned_and_not_null(addr, align)
+                is_zst: bool = T::IS_ZST,
+            ) => ub_checks::is_aligned_and_not_null(addr, align, is_zst)
         );
         intrinsics::write_via_move(dst, src)
     }
@@ -1808,7 +1813,8 @@ pub unsafe fn read_volatile<T>(src: *const T) -> T {
             (
                 addr: *const () = src as *const (),
                 align: usize = align_of::<T>(),
-            ) => ub_checks::is_aligned_and_not_null(addr, align)
+                is_zst: bool = T::IS_ZST,
+            ) => ub_checks::is_aligned_and_not_null(addr, align, is_zst)
         );
         intrinsics::volatile_load(src)
     }
@@ -1887,7 +1893,8 @@ pub unsafe fn write_volatile<T>(dst: *mut T, src: T) {
             (
                 addr: *mut () = dst as *mut (),
                 align: usize = align_of::<T>(),
-            ) => ub_checks::is_aligned_and_not_null(addr, align)
+                is_zst: bool = T::IS_ZST,
+            ) => ub_checks::is_aligned_and_not_null(addr, align, is_zst)
         );
         intrinsics::volatile_store(dst, src);
     }

library/core/src/slice/raw.rs

@@ -132,7 +132,7 @@ pub const unsafe fn from_raw_parts<'a, T>(data: *const T, len: usize) -> &'a [T]
                 align: usize = align_of::<T>(),
                 len: usize = len,
             ) =>
-            ub_checks::is_aligned_and_not_null(data, align)
+            ub_checks::is_aligned_and_not_null(data, align, false)
                 && ub_checks::is_valid_allocation_size(size, len)
         );
         &*ptr::slice_from_raw_parts(data, len)
@@ -187,7 +187,7 @@ pub const unsafe fn from_raw_parts_mut<'a, T>(data: *mut T, len: usize) -> &'a m
                 align: usize = align_of::<T>(),
                 len: usize = len,
             ) =>
-            ub_checks::is_aligned_and_not_null(data, align)
+            ub_checks::is_aligned_and_not_null(data, align, false)
                 && ub_checks::is_valid_allocation_size(size, len)
         );
         &mut *ptr::slice_from_raw_parts_mut(data, len)

library/core/src/ub_checks.rs

@@ -109,15 +109,15 @@ pub(crate) const fn check_language_ub() -> bool {
     intrinsics::ub_checks() && const_eval_select((), comptime, runtime)
 }
 
-/// Checks whether `ptr` is properly aligned with respect to
+/// Checks whether `ptr` is properly aligned with respect to the given alignment, and
-/// `align_of::<T>()`.
+/// if `is_zst == false`, that `ptr` is not null.
 ///
 /// In `const` this is approximate and can fail spuriously. It is primarily intended
 /// for `assert_unsafe_precondition!` with `check_language_ub`, in which case the
 /// check is anyway not executed in `const`.
 #[inline]
-pub(crate) const fn is_aligned_and_not_null(ptr: *const (), align: usize) -> bool {
+pub(crate) const fn is_aligned_and_not_null(ptr: *const (), align: usize, is_zst: bool) -> bool {
-    !ptr.is_null() && ptr.is_aligned_to(align)
+    ptr.is_aligned_to(align) && (is_zst || !ptr.is_null())
 }
 
 #[inline]

src/tools/compiletest/src/lib.rs

@@ -43,6 +43,11 @@ use crate::common::{
 use crate::header::HeadersCache;
 use crate::util::logv;
 
+/// Creates the `Config` instance for this invocation of compiletest.
+///
+/// The config mostly reflects command-line arguments, but there might also be
+/// some code here that inspects environment variables or even runs executables
+/// (e.g. when discovering debugger versions).
 pub fn parse_config(args: Vec<String>) -> Config {
     let mut opts = Options::new();
     opts.reqopt("", "compile-lib-path", "path to host shared libraries", "PATH")
@@ -413,6 +418,7 @@ pub fn opt_str2(maybestr: Option<String>) -> String {
     }
 }
 
+/// Called by `main` after the config has been parsed.
 pub fn run_tests(config: Arc<Config>) {
     // If we want to collect rustfix coverage information,
     // we first make sure that the coverage file does not exist.
@@ -454,6 +460,8 @@ pub fn run_tests(config: Arc<Config>) {
         configs.push(config.clone());
     };
 
+    // Discover all of the tests in the test suite directory, and build a libtest
+    // structure for each test (or each revision of a multi-revision test).
     let mut tests = Vec::new();
     for c in configs {
         let mut found_paths = HashSet::new();
@@ -463,7 +471,12 @@ pub fn run_tests(config: Arc<Config>) {
 
     tests.sort_by(|a, b| a.desc.name.as_slice().cmp(&b.desc.name.as_slice()));
 
+    // Delegate to libtest to filter and run the big list of structures created
+    // during test discovery. When libtest decides to run a test, it will invoke
+    // the corresponding closure created by `make_test_closure`.
     let res = test::run_tests_console(&opts, tests);
+
+    // Check the outcome reported by libtest.
     match res {
         Ok(true) => {}
         Ok(false) => {
@@ -532,6 +545,11 @@ pub fn test_opts(config: &Config) -> test::TestOpts {
     }
 }
 
+/// Creates libtest structures for every test/revision in the test suite directory.
+///
+/// This always inspects _all_ test files in the suite (e.g. all 17k+ ui tests),
+/// regardless of whether any filters/tests were specified on the command-line,
+/// because filtering is handled later by libtest.
 pub fn make_tests(
     config: Arc<Config>,
     tests: &mut Vec<test::TestDescAndFn>,
@@ -610,10 +628,17 @@ fn common_inputs_stamp(config: &Config) -> Stamp {
     stamp
 }
 
+/// Returns a list of modified/untracked test files that should be run when
+/// the `--only-modified` flag is in use.
+///
+/// (Might be inaccurate in some cases.)
 fn modified_tests(config: &Config, dir: &Path) -> Result<Vec<PathBuf>, String> {
+    // If `--only-modified` wasn't passed, the list of modified tests won't be
+    // used for anything, so avoid some work and just return an empty list.
     if !config.only_modified {
         return Ok(vec![]);
     }
+
     let files =
         get_git_modified_files(&config.git_config(), Some(dir), &vec!["rs", "stderr", "fixed"])?
             .unwrap_or(vec![]);
@@ -634,6 +659,8 @@ fn modified_tests(config: &Config, dir: &Path) -> Result<Vec<PathBuf>, String> {
     Ok(full_paths)
 }
 
+/// Recursively scans a directory to find test files and create test structures
+/// that will be handed over to libtest.
 fn collect_tests_from_dir(
     config: Arc<Config>,
     cache: &HeadersCache,
@@ -650,6 +677,8 @@ fn collect_tests_from_dir(
         return Ok(());
     }
 
+    // For run-make tests, a "test file" is actually a directory that contains
+    // an `rmake.rs` or `Makefile`"
     if config.mode == Mode::RunMake {
         if dir.join("Makefile").exists() && dir.join("rmake.rs").exists() {
             return Err(io::Error::other(
@@ -663,6 +692,7 @@ fn collect_tests_from_dir(
                 relative_dir: relative_dir_path.parent().unwrap().to_path_buf(),
             };
             tests.extend(make_test(config, cache, &paths, inputs, poisoned));
+            // This directory is a test, so don't try to find other tests inside it.
             return Ok(());
         }
     }
@@ -677,22 +707,27 @@ fn collect_tests_from_dir(
     fs::create_dir_all(&build_dir).unwrap();
 
     // Add each `.rs` file as a test, and recurse further on any
-    // subdirectories we find, except for `aux` directories.
+    // subdirectories we find, except for `auxiliary` directories.
     // FIXME: this walks full tests tree, even if we have something to ignore
     // use walkdir/ignore like in tidy?
     for file in fs::read_dir(dir)? {
         let file = file?;
         let file_path = file.path();
         let file_name = file.file_name();
+
         if is_test(&file_name) && (!config.only_modified || modified_tests.contains(&file_path)) {
+            // We found a test file, so create the corresponding libtest structures.
             debug!("found test file: {:?}", file_path.display());
+
+            // Record the stem of the test file, to check for overlaps later.
             let rel_test_path = relative_dir_path.join(file_path.file_stem().unwrap());
             found_paths.insert(rel_test_path);
+
             let paths =
                 TestPaths { file: file_path, relative_dir: relative_dir_path.to_path_buf() };
-
             tests.extend(make_test(config.clone(), cache, &paths, inputs, poisoned))
         } else if file_path.is_dir() {
+            // Recurse to find more tests in a subdirectory.
             let relative_file_path = relative_dir_path.join(file.file_name());
             if &file_name != "auxiliary" {
                 debug!("found directory: {:?}", file_path.display());
@@ -728,6 +763,8 @@ pub fn is_test(file_name: &OsString) -> bool {
     !invalid_prefixes.iter().any(|p| file_name.starts_with(p))
 }
 
+/// For a single test file, creates one or more test structures (one per revision)
+/// that can be handed over to libtest to run, possibly in parallel.
 fn make_test(
     config: Arc<Config>,
     cache: &HeadersCache,
@@ -735,6 +772,9 @@ fn make_test(
     inputs: &Stamp,
     poisoned: &mut bool,
 ) -> Vec<test::TestDescAndFn> {
+    // For run-make tests, each "test file" is actually a _directory_ containing
+    // an `rmake.rs` or `Makefile`. But for the purposes of directive parsing,
+    // we want to look at that recipe file, not the directory itself.
     let test_path = if config.mode == Mode::RunMake {
         if testpaths.file.join("rmake.rs").exists() && testpaths.file.join("Makefile").exists() {
             panic!("run-make tests cannot have both `rmake.rs` and `Makefile`");
@@ -750,26 +790,40 @@ fn make_test(
     } else {
         PathBuf::from(&testpaths.file)
     };
+
+    // Scan the test file to discover its revisions, if any.
     let early_props = EarlyProps::from_file(&config, &test_path);
 
-    // Incremental tests are special, they inherently cannot be run in parallel.
+    // Normally we create one libtest structure per revision, with two exceptions:
-    // `runtest::run` will be responsible for iterating over revisions.
+    // - If a test doesn't use revisions, create a dummy revision (None) so that
+    //   the test can still run.
+    // - Incremental tests inherently can't run their revisions in parallel, so
+    //   we treat them like non-revisioned tests here. Incremental revisions are
+    //   handled internally by `runtest::run` instead.
     let revisions = if early_props.revisions.is_empty() || config.mode == Mode::Incremental {
         vec![None]
     } else {
         early_props.revisions.iter().map(|r| Some(r.as_str())).collect()
     };
 
+    // For each revision (or the sole dummy revision), create and return a
+    // `test::TestDescAndFn` that can be handed over to libtest.
     revisions
         .into_iter()
         .map(|revision| {
+            // Create a test name and description to hand over to libtest.
             let src_file =
                 std::fs::File::open(&test_path).expect("open test file to parse ignores");
             let test_name = crate::make_test_name(&config, testpaths, revision);
+            // Create a libtest description for the test/revision.
+            // This is where `ignore-*`/`only-*`/`needs-*` directives are handled,
+            // because they need to set the libtest ignored flag.
             let mut desc = make_test_description(
                 &config, cache, test_name, &test_path, src_file, revision, poisoned,
             );
-            // Ignore tests that already run and are up to date with respect to inputs.
+
+            // If a test's inputs haven't changed since the last time it ran,
+            // mark it as ignored so that libtest will skip it.
             if !config.force_rerun
                 && is_up_to_date(&config, testpaths, &early_props, revision, inputs)
             {
@@ -777,18 +831,25 @@ fn make_test(
                 // Keep this in sync with the "up-to-date" message detected by bootstrap.
                 desc.ignore_message = Some("up-to-date");
             }
-            test::TestDescAndFn {
+
-                desc,
+            // Create the callback that will run this test/revision when libtest calls it.
-                testfn: make_test_closure(config.clone(), testpaths, revision),
+            let testfn = make_test_closure(config.clone(), testpaths, revision);
-            }
+
+            test::TestDescAndFn { desc, testfn }
         })
         .collect()
 }
 
+/// The path of the `stamp` file that gets created or updated whenever a
+/// particular test completes successfully.
 fn stamp(config: &Config, testpaths: &TestPaths, revision: Option<&str>) -> PathBuf {
     output_base_dir(config, testpaths, revision).join("stamp")
 }
 
+/// Returns a list of files that, if modified, would cause this test to no
+/// longer be up-to-date.
+///
+/// (Might be inaccurate in some cases.)
 fn files_related_to_test(
     config: &Config,
     testpaths: &TestPaths,
@@ -824,46 +885,61 @@ fn files_related_to_test(
     related
 }
 
+/// Checks whether a particular test/revision is "up-to-date", meaning that no
+/// relevant files/settings have changed since the last time the test succeeded.
+///
+/// (This is not very reliable in some circumstances, so the `--force-rerun`
+/// flag can be used to ignore up-to-date checking and always re-run tests.)
 fn is_up_to_date(
     config: &Config,
     testpaths: &TestPaths,
     props: &EarlyProps,
     revision: Option<&str>,
-    inputs: &Stamp,
+    inputs: &Stamp, // Last-modified timestamp of the compiler, compiletest etc
 ) -> bool {
     let stamp_name = stamp(config, testpaths, revision);
-    // Check hash.
+    // Check the config hash inside the stamp file.
     let contents = match fs::read_to_string(&stamp_name) {
         Ok(f) => f,
         Err(ref e) if e.kind() == ErrorKind::InvalidData => panic!("Can't read stamp contents"),
+        // The test hasn't succeeded yet, so it is not up-to-date.
         Err(_) => return false,
     };
     let expected_hash = runtest::compute_stamp_hash(config);
     if contents != expected_hash {
+        // Some part of compiletest configuration has changed since the test
+        // last succeeded, so it is not up-to-date.
         return false;
     }
 
-    // Check timestamps.
+    // Check the timestamp of the stamp file against the last modified time
+    // of all files known to be relevant to the test.
     let mut inputs = inputs.clone();
     for path in files_related_to_test(config, testpaths, props, revision) {
         inputs.add_path(&path);
     }
 
+    // If no relevant files have been modified since the stamp file was last
+    // written, the test is up-to-date.
     inputs < Stamp::from_path(&stamp_name)
 }
 
+/// The maximum of a set of file-modified timestamps.
 #[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord)]
 struct Stamp {
     time: SystemTime,
 }
 
 impl Stamp {
+    /// Creates a timestamp holding the last-modified time of the specified file.
     fn from_path(path: &Path) -> Self {
         let mut stamp = Stamp { time: SystemTime::UNIX_EPOCH };
         stamp.add_path(path);
         stamp
     }
 
+    /// Updates this timestamp to the last-modified time of the specified file,
+    /// if it is later than the currently-stored timestamp.
     fn add_path(&mut self, path: &Path) {
         let modified = fs::metadata(path)
             .and_then(|metadata| metadata.modified())
@@ -871,6 +947,9 @@ impl Stamp {
         self.time = self.time.max(modified);
     }
 
+    /// Updates this timestamp to the most recent last-modified time of all files
+    /// recursively contained in the given directory, if it is later than the
+    /// currently-stored timestamp.
     fn add_dir(&mut self, path: &Path) {
         for entry in WalkDir::new(path) {
             let entry = entry.unwrap();
@@ -886,6 +965,7 @@ impl Stamp {
     }
 }
 
+/// Creates a name for this test/revision that can be handed over to libtest.
 fn make_test_name(
     config: &Config,
     testpaths: &TestPaths,
@@ -914,20 +994,41 @@ fn make_test_name(
     ))
 }
 
+/// Creates a callback for this test/revision that libtest will call when it
+/// decides to actually run the underlying test.
 fn make_test_closure(
     config: Arc<Config>,
     testpaths: &TestPaths,
     revision: Option<&str>,
 ) -> test::TestFn {
-    let config = config.clone();
     let testpaths = testpaths.clone();
     let revision = revision.map(str::to_owned);
+
+    // This callback is the link between compiletest's test discovery code,
+    // and the parts of compiletest that know how to run an individual test.
     test::DynTestFn(Box::new(move || {
         runtest::run(config, &testpaths, revision.as_deref());
         Ok(())
     }))
 }
 
+/// Checks that test discovery didn't find any tests whose name stem is a prefix
+/// of some other tests's name.
+///
+/// For example, suppose the test suite contains these two test files:
+/// - `tests/rustdoc/primitive.rs`
+/// - `tests/rustdoc/primitive/no_std.rs`
+///
+/// The test runner might put the output from those tests in these directories:
+/// - `$build/test/rustdoc/primitive/`
+/// - `$build/test/rustdoc/primitive/no_std/`
+///
+/// Because one output path is a subdirectory of the other, the two tests might
+/// interfere with each other in unwanted ways, especially if the test runner
+/// decides to delete test output directories to clean them between runs.
+/// To avoid problems, we forbid test names from overlapping in this way.
+///
+/// See <https://github.com/rust-lang/rust/pull/109509> for more context.
 fn check_overlapping_tests(found_paths: &HashSet<PathBuf>) {
     let mut collisions = Vec::new();
     for path in found_paths {

tests/codegen/asm-arm64ec-clobbers.rs

@@ -0,0 +1,36 @@
+//@ assembly-output: emit-asm
+//@ compile-flags: --target arm64ec-pc-windows-msvc
+//@ needs-llvm-components: aarch64
+
+#![crate_type = "rlib"]
+#![feature(no_core, rustc_attrs, lang_items, asm_experimental_arch)]
+#![no_core]
+
+#[lang = "sized"]
+trait Sized {}
+
+#[rustc_builtin_macro]
+macro_rules! asm {
+    () => {};
+}
+
+// CHECK-LABEL: @cc_clobber
+// CHECK: call void asm sideeffect "", "~{cc}"()
+#[no_mangle]
+pub unsafe fn cc_clobber() {
+    asm!("", options(nostack, nomem));
+}
+
+// CHECK-LABEL: @no_clobber
+// CHECK: call void asm sideeffect "", ""()
+#[no_mangle]
+pub unsafe fn no_clobber() {
+    asm!("", options(nostack, nomem, preserves_flags));
+}
+
+// CHECK-LABEL: @clobber_abi
+// CHECK: asm sideeffect "", "={w0},={w1},={w2},={w3},={w4},={w5},={w6},={w7},={w8},={w9},={w10},={w11},={w12},={w15},={w16},={w17},={w30},={q0},={q1},={q2},={q3},={q4},={q5},={q6},={q7},={q8},={q9},={q10},={q11},={q12},={q13},={q14},={q15}"()
+#[no_mangle]
+pub unsafe fn clobber_abi() {
+    asm!("", clobber_abi("C"), options(nostack, nomem, preserves_flags));
+}

tests/rustdoc-json/fns/extern_safe.rs

@@ -2,7 +2,7 @@ extern "C" {
     //@ is "$.index[*][?(@.name=='f1')].inner.function.header.is_unsafe" true
     pub fn f1();
 
-    // items in unadorned `extern` blocks cannot have safety qualifiers
+    // items in `extern` blocks without an `unsafe` qualifier cannot have safety qualifiers
 }
 
 unsafe extern "C" {

tests/ui/asm/aarch64/aarch64-sve.rs

@@ -0,0 +1,28 @@
+//@ only-aarch64
+//@ build-pass
+//@ needs-asm-support
+
+#![crate_type = "rlib"]
+#![feature(no_core, rustc_attrs, lang_items)]
+#![no_core]
+
+// AArch64 test corresponding to arm64ec-sve.rs.
+
+#[lang = "sized"]
+trait Sized {}
+#[lang = "copy"]
+trait Copy {}
+
+impl Copy for f64 {}
+
+#[rustc_builtin_macro]
+macro_rules! asm {
+    () => {};
+}
+
+fn f(x: f64) {
+    unsafe {
+        asm!("", out("p0") _);
+        asm!("", out("ffr") _);
+    }
+}

tests/ui/asm/aarch64/arm64ec-sve.rs

@@ -0,0 +1,31 @@
+//@ compile-flags: --target arm64ec-pc-windows-msvc
+//@ needs-asm-support
+//@ needs-llvm-components: aarch64
+
+#![crate_type = "rlib"]
+#![feature(no_core, rustc_attrs, lang_items, asm_experimental_arch)]
+#![no_core]
+
+// SVE cannot be used for Arm64EC
+// https://github.com/rust-lang/rust/pull/131332#issuecomment-2401189142
+
+#[lang = "sized"]
+trait Sized {}
+#[lang = "copy"]
+trait Copy {}
+
+impl Copy for f64 {}
+
+#[rustc_builtin_macro]
+macro_rules! asm {
+    () => {};
+}
+
+fn f(x: f64) {
+    unsafe {
+        asm!("", out("p0") _);
+        //~^ ERROR cannot use register `p0`
+        asm!("", out("ffr") _);
+        //~^ ERROR cannot use register `ffr`
+    }
+}

tests/ui/asm/aarch64/arm64ec-sve.stderr

@@ -0,0 +1,14 @@
+error: cannot use register `p0`: x13, x14, x23, x24, x28, v16-v31, p*, ffr cannot be used for Arm64EC
+  --> $DIR/arm64ec-sve.rs:26:18
+   |
+LL |         asm!("", out("p0") _);
+   |                  ^^^^^^^^^^^
+
+error: cannot use register `ffr`: x13, x14, x23, x24, x28, v16-v31, p*, ffr cannot be used for Arm64EC
+  --> $DIR/arm64ec-sve.rs:28:18
+   |
+LL |         asm!("", out("ffr") _);
+   |                  ^^^^^^^^^^^^
+
+error: aborting due to 2 previous errors
+

tests/ui/extern/issue-95829.rs

@@ -2,7 +2,7 @@
 
 extern {
     async fn L() { //~ ERROR: incorrect function inside `extern` block
-        //~^ ERROR: functions in `extern` blocks cannot have qualifiers
+        //~^ ERROR: functions in `extern` blocks cannot have `async` qualifier
         async fn M() {}
     }
 }

tests/ui/extern/issue-95829.stderr

@@ -15,13 +15,13 @@ LL | |     }
    = help: you might have meant to write a function accessible through FFI, which can be done by writing `extern fn` outside of the `extern` block
    = note: for more information, visit https://doc.rust-lang.org/std/keyword.extern.html
 
-error: functions in `extern` blocks cannot have qualifiers
+error: functions in `extern` blocks cannot have `async` qualifier
   --> $DIR/issue-95829.rs:4:5
    |
 LL | extern {
    | ------ in this `extern` block
 LL |     async fn L() {
-   |     ^^^^^ help: remove this qualifier
+   |     ^^^^^ help: remove the `async` qualifier
 
 error: aborting due to 2 previous errors
 

tests/ui/macros/format-empty-block-unit-tuple-suggestion-130170.fixed

@@ -0,0 +1,13 @@
+//@ run-rustfix
+
+fn main() {
+    let s = "123";
+    println!("{:?} {} {}", {}, "sss", s);
+    //~^ ERROR format argument must be a string literal
+    println!("{:?}", {});
+    //~^ ERROR format argument must be a string literal
+    println!("{} {} {} {:?}", s, "sss", s, {});
+    //~^ ERROR format argument must be a string literal
+    println!("{:?} {} {:?}", (), s, {});
+    //~^ ERROR format argument must be a string literal
+}

tests/ui/macros/format-empty-block-unit-tuple-suggestion-130170.rs

@@ -0,0 +1,13 @@
+//@ run-rustfix
+
+fn main() {
+    let s = "123";
+    println!({}, "sss", s);
+    //~^ ERROR format argument must be a string literal
+    println!({});
+    //~^ ERROR format argument must be a string literal
+    println!(s, "sss", s, {});
+    //~^ ERROR format argument must be a string literal
+    println!((), s, {});
+    //~^ ERROR format argument must be a string literal
+}

tests/ui/macros/format-empty-block-unit-tuple-suggestion-130170.stderr

@@ -0,0 +1,46 @@
+error: format argument must be a string literal
+  --> $DIR/format-empty-block-unit-tuple-suggestion-130170.rs:5:14
+   |
+LL |     println!({}, "sss", s);
+   |              ^^
+   |
+help: you might be missing a string literal to format with
+   |
+LL |     println!("{:?} {} {}", {}, "sss", s);
+   |              +++++++++++++
+
+error: format argument must be a string literal
+  --> $DIR/format-empty-block-unit-tuple-suggestion-130170.rs:7:14
+   |
+LL |     println!({});
+   |              ^^
+   |
+help: you might be missing a string literal to format with
+   |
+LL |     println!("{:?}", {});
+   |              +++++++
+
+error: format argument must be a string literal
+  --> $DIR/format-empty-block-unit-tuple-suggestion-130170.rs:9:14
+   |
+LL |     println!(s, "sss", s, {});
+   |              ^
+   |
+help: you might be missing a string literal to format with
+   |
+LL |     println!("{} {} {} {:?}", s, "sss", s, {});
+   |              ++++++++++++++++
+
+error: format argument must be a string literal
+  --> $DIR/format-empty-block-unit-tuple-suggestion-130170.rs:11:14
+   |
+LL |     println!((), s, {});
+   |              ^^
+   |
+help: you might be missing a string literal to format with
+   |
+LL |     println!("{:?} {} {:?}", (), s, {});
+   |              +++++++++++++++
+
+error: aborting due to 4 previous errors
+

tests/ui/parser/fn-header-semantic-fail.rs

@@ -41,15 +41,15 @@ fn main() {
     }
 
     extern "C" {
-        async fn fe1(); //~ ERROR functions in `extern` blocks cannot have qualifiers
+        async fn fe1(); //~ ERROR functions in `extern` blocks cannot
-        unsafe fn fe2(); //~ ERROR items in unadorned `extern` blocks cannot have safety qualifiers
+        unsafe fn fe2(); //~ ERROR items in `extern` blocks without an `unsafe` qualifier cannot
-        const fn fe3(); //~ ERROR functions in `extern` blocks cannot have qualifiers
+        const fn fe3(); //~ ERROR functions in `extern` blocks cannot
-        extern "C" fn fe4(); //~ ERROR functions in `extern` blocks cannot have qualifiers
+        extern "C" fn fe4(); //~ ERROR functions in `extern` blocks cannot
         const async unsafe extern "C" fn fe5();
         //~^ ERROR functions in `extern` blocks
         //~| ERROR functions in `extern` blocks
         //~| ERROR functions in `extern` blocks
         //~| ERROR functions cannot be both `const` and `async`
-        //~| ERROR items in unadorned `extern` blocks cannot have safety qualifiers
+        //~| ERROR items in `extern` blocks without an `unsafe` qualifier cannot have
     }
 }

tests/ui/parser/fn-header-semantic-fail.stderr

@@ -70,77 +70,77 @@ LL |         const async unsafe extern "C" fn fi5() {}
    |         |     `async` because of this
    |         `const` because of this
 
-error: functions in `extern` blocks cannot have qualifiers
+error: functions in `extern` blocks cannot have `async` qualifier
   --> $DIR/fn-header-semantic-fail.rs:44:9
    |
 LL |     extern "C" {
    |     ---------- in this `extern` block
 LL |         async fn fe1();
-   |         ^^^^^ help: remove this qualifier
+   |         ^^^^^ help: remove the `async` qualifier
 
-error: items in unadorned `extern` blocks cannot have safety qualifiers
+error: items in `extern` blocks without an `unsafe` qualifier cannot have safety qualifiers
   --> $DIR/fn-header-semantic-fail.rs:45:9
    |
 LL |         unsafe fn fe2();
    |         ^^^^^^^^^^^^^^^^
    |
-help: add unsafe to this `extern` block
+help: add `unsafe` to this `extern` block
    |
 LL |     unsafe extern "C" {
    |     ++++++
 
-error: functions in `extern` blocks cannot have qualifiers
+error: functions in `extern` blocks cannot have `const` qualifier
   --> $DIR/fn-header-semantic-fail.rs:46:9
    |
 LL |     extern "C" {
    |     ---------- in this `extern` block
 ...
 LL |         const fn fe3();
-   |         ^^^^^ help: remove this qualifier
+   |         ^^^^^ help: remove the `const` qualifier
 
-error: functions in `extern` blocks cannot have qualifiers
+error: functions in `extern` blocks cannot have `extern` qualifier
   --> $DIR/fn-header-semantic-fail.rs:47:9
    |
 LL |     extern "C" {
    |     ---------- in this `extern` block
 ...
 LL |         extern "C" fn fe4();
-   |         ^^^^^^^^^^ help: remove this qualifier
+   |         ^^^^^^^^^^ help: remove the `extern` qualifier
 
-error: functions in `extern` blocks cannot have qualifiers
+error: functions in `extern` blocks cannot have `async` qualifier
   --> $DIR/fn-header-semantic-fail.rs:48:15
    |
 LL |     extern "C" {
    |     ---------- in this `extern` block
 ...
 LL |         const async unsafe extern "C" fn fe5();
-   |               ^^^^^ help: remove this qualifier
+   |               ^^^^^ help: remove the `async` qualifier
 
-error: functions in `extern` blocks cannot have qualifiers
+error: functions in `extern` blocks cannot have `const` qualifier
   --> $DIR/fn-header-semantic-fail.rs:48:9
    |
 LL |     extern "C" {
    |     ---------- in this `extern` block
 ...
 LL |         const async unsafe extern "C" fn fe5();
-   |         ^^^^^ help: remove this qualifier
+   |         ^^^^^ help: remove the `const` qualifier
 
-error: functions in `extern` blocks cannot have qualifiers
+error: functions in `extern` blocks cannot have `extern` qualifier
   --> $DIR/fn-header-semantic-fail.rs:48:28
    |
 LL |     extern "C" {
    |     ---------- in this `extern` block
 ...
 LL |         const async unsafe extern "C" fn fe5();
-   |                            ^^^^^^^^^^ help: remove this qualifier
+   |                            ^^^^^^^^^^ help: remove the `extern` qualifier
 
-error: items in unadorned `extern` blocks cannot have safety qualifiers
+error: items in `extern` blocks without an `unsafe` qualifier cannot have safety qualifiers
   --> $DIR/fn-header-semantic-fail.rs:48:9
    |
 LL |         const async unsafe extern "C" fn fe5();
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
-help: add unsafe to this `extern` block
+help: add `unsafe` to this `extern` block
    |
 LL |     unsafe extern "C" {
    |     ++++++

tests/ui/parser/no-const-fn-in-extern-block.rs

@@ -1,9 +1,9 @@
 extern "C" {
     const fn foo();
-    //~^ ERROR functions in `extern` blocks cannot have qualifiers
+    //~^ ERROR functions in `extern` blocks cannot
     const unsafe fn bar();
-    //~^ ERROR functions in `extern` blocks cannot have qualifiers
+    //~^ ERROR functions in `extern` blocks cannot
-    //~| ERROR items in unadorned `extern` blocks cannot have safety qualifiers
+    //~| ERROR items in `extern` blocks without an `unsafe` qualifier cannot
 }
 
 fn main() {}

tests/ui/parser/no-const-fn-in-extern-block.stderr

@@ -1,27 +1,27 @@
-error: functions in `extern` blocks cannot have qualifiers
+error: functions in `extern` blocks cannot have `const` qualifier
   --> $DIR/no-const-fn-in-extern-block.rs:2:5
    |
 LL | extern "C" {
    | ---------- in this `extern` block
 LL |     const fn foo();
-   |     ^^^^^ help: remove this qualifier
+   |     ^^^^^ help: remove the `const` qualifier
 
-error: functions in `extern` blocks cannot have qualifiers
+error: functions in `extern` blocks cannot have `const` qualifier
   --> $DIR/no-const-fn-in-extern-block.rs:4:5
    |
 LL | extern "C" {
    | ---------- in this `extern` block
 ...
 LL |     const unsafe fn bar();
-   |     ^^^^^ help: remove this qualifier
+   |     ^^^^^ help: remove the `const` qualifier
 
-error: items in unadorned `extern` blocks cannot have safety qualifiers
+error: items in `extern` blocks without an `unsafe` qualifier cannot have safety qualifiers
   --> $DIR/no-const-fn-in-extern-block.rs:4:5
    |
 LL |     const unsafe fn bar();
    |     ^^^^^^^^^^^^^^^^^^^^^^
    |
-help: add unsafe to this `extern` block
+help: add `unsafe` to this `extern` block
    |
 LL | unsafe extern "C" {
    | ++++++

tests/ui/precondition-checks/alignment.rs

@@ -0,0 +1,11 @@
+//@ run-fail
+//@ compile-flags: -Copt-level=3 -Cdebug-assertions=no -Zub-checks=yes
+//@ error-pattern: unsafe precondition(s) violated: Alignment::new_unchecked requires
+
+#![feature(ptr_alignment_type)]
+
+fn main() {
+    unsafe {
+        std::ptr::Alignment::new_unchecked(0);
+    }
+}

tests/ui/precondition-checks/ascii-char-digit_unchecked.rs

@@ -0,0 +1,11 @@
+//@ run-fail
+//@ compile-flags: -Copt-level=3 -Cdebug-assertions=no -Zub-checks=yes
+//@ error-pattern: unsafe precondition(s) violated: `ascii::Char::digit_unchecked` input cannot exceed 9
+
+#![feature(ascii_char)]
+
+fn main() {
+    unsafe {
+        std::ascii::Char::digit_unchecked(b'a');
+    }
+}

tests/ui/precondition-checks/assert_unchecked.rs

@@ -0,0 +1,9 @@
+//@ run-fail
+//@ compile-flags: -Copt-level=3 -Cdebug-assertions=no -Zub-checks=yes
+//@ error-pattern: unsafe precondition(s) violated: hint::assert_unchecked must never be called when the condition is false
+
+fn main() {
+    unsafe {
+        std::hint::assert_unchecked(false);
+    }
+}

tests/ui/precondition-checks/char-from_u32_unchecked.rs

@@ -0,0 +1,9 @@
+//@ run-fail
+//@ compile-flags: -Copt-level=3 -Cdebug-assertions=no -Zub-checks=yes
+//@ error-pattern: unsafe precondition(s) violated: invalid value for `char`
+
+fn main() {
+    unsafe {
+        char::from_u32_unchecked(0xD801);
+    }
+}

tests/ui/precondition-checks/copy-nonoverlapping.rs

@@ -0,0 +1,25 @@
+//@ run-fail
+//@ compile-flags: -Copt-level=3 -Cdebug-assertions=no -Zub-checks=yes
+//@ error-pattern: unsafe precondition(s) violated: ptr::copy_nonoverlapping requires
+//@ revisions: null_src null_dst misaligned_src misaligned_dst overlapping
+
+use std::ptr;
+
+fn main() {
+    let src = [0u16; 3];
+    let mut dst = [0u16; 3];
+    let src = src.as_ptr();
+    let dst = dst.as_mut_ptr();
+    unsafe {
+        #[cfg(null_src)]
+        ptr::copy_nonoverlapping(ptr::null(), dst, 1);
+        #[cfg(null_dst)]
+        ptr::copy_nonoverlapping(src, ptr::null_mut(), 1);
+        #[cfg(misaligned_src)]
+        ptr::copy_nonoverlapping(src.byte_add(1), dst, 1);
+        #[cfg(misaligned_dst)]
+        ptr::copy_nonoverlapping(src, dst.byte_add(1), 1);
+        #[cfg(overlapping)]
+        ptr::copy_nonoverlapping(dst, dst.add(1), 2);
+    }
+}

tests/ui/precondition-checks/copy.rs

@@ -0,0 +1,23 @@
+//@ run-fail
+//@ compile-flags: -Copt-level=3 -Cdebug-assertions=no -Zub-checks=yes
+//@ error-pattern: unsafe precondition(s) violated: ptr::copy requires
+//@ revisions: null_src null_dst misaligned_src misaligned_dst
+
+use std::ptr;
+
+fn main() {
+    let src = [0u16; 3];
+    let mut dst = [0u16; 3];
+    let src = src.as_ptr();
+    let dst = dst.as_mut_ptr();
+    unsafe {
+        #[cfg(null_src)]
+        ptr::copy(ptr::null(), dst, 1);
+        #[cfg(null_dst)]
+        ptr::copy(src, ptr::null_mut(), 1);
+        #[cfg(misaligned_src)]
+        ptr::copy(src.byte_add(1), dst, 1);
+        #[cfg(misaligned_dst)]
+        ptr::copy(src, dst.byte_add(1), 1);
+    }
+}

tests/ui/precondition-checks/layout.rs

@@ -0,0 +1,15 @@
+//@ run-fail
+//@ compile-flags: -Copt-level=3 -Cdebug-assertions=no -Zub-checks=yes
+//@ error-pattern: unsafe precondition(s) violated: Layout::from_size_align_unchecked requires
+//@ revisions: toolarge badalign
+//@[toolarge] compile-flags: --cfg toolarge
+//@[badalign] compile-flags: --cfg badalign
+
+fn main() {
+    unsafe {
+        #[cfg(toolarge)]
+        std::alloc::Layout::from_size_align_unchecked(isize::MAX as usize, 2);
+        #[cfg(badalign)]
+        std::alloc::Layout::from_size_align_unchecked(1, 3);
+    }
+}

tests/ui/precondition-checks/misaligned-slice.rs

@@ -1,10 +0,0 @@
-//@ run-fail
-//@ compile-flags: -Copt-level=3 -Cdebug-assertions=no -Zub-checks=yes
-//@ error-pattern: unsafe precondition(s) violated: slice::from_raw_parts
-//@ ignore-debug
-
-fn main() {
-    unsafe {
-        let _s: &[u64] = std::slice::from_raw_parts(1usize as *const u64, 0);
-    }
-}

tests/ui/precondition-checks/nonnull.rs

@@ -0,0 +1,9 @@
+//@ run-fail
+//@ compile-flags: -Copt-level=3 -Cdebug-assertions=no -Zub-checks=yes
+//@ error-pattern: unsafe precondition(s) violated: NonNull::new_unchecked requires
+
+fn main() {
+    unsafe {
+        std::ptr::NonNull::new_unchecked(std::ptr::null_mut::<u8>());
+    }
+}

tests/ui/precondition-checks/nonzero-from_mut_unchecked.rs

@@ -0,0 +1,12 @@
+//@ run-fail
+//@ compile-flags: -Copt-level=3 -Cdebug-assertions=no -Zub-checks=yes
+//@ error-pattern: unsafe precondition(s) violated: NonZero::from_mut_unchecked requires
+
+#![feature(nonzero_from_mut)]
+
+fn main() {
+    unsafe {
+        let mut num = 0u8;
+        std::num::NonZeroU8::from_mut_unchecked(&mut num);
+    }
+}

tests/ui/precondition-checks/nonzero-new_unchecked.rs

@@ -0,0 +1,9 @@
+//@ run-fail
+//@ compile-flags: -Copt-level=3 -Cdebug-assertions=no -Zub-checks=yes
+//@ error-pattern: unsafe precondition(s) violated: NonZero::new_unchecked requires
+
+fn main() {
+    unsafe {
+        std::num::NonZeroU8::new_unchecked(0);
+    }
+}

tests/ui/precondition-checks/null-slice.rs

@@ -1,10 +0,0 @@
-//@ run-fail
-//@ compile-flags: -Copt-level=3 -Cdebug-assertions=no -Zub-checks=yes
-//@ error-pattern: unsafe precondition(s) violated: slice::from_raw_parts
-//@ ignore-debug
-
-fn main() {
-    unsafe {
-        let _s: &[u8] = std::slice::from_raw_parts(std::ptr::null(), 0);
-    }
-}

tests/ui/precondition-checks/out-of-bounds-get-unchecked.rs

@@ -1,11 +0,0 @@
-//@ run-fail
-//@ compile-flags: -Copt-level=3 -Cdebug-assertions=no -Zub-checks=yes
-//@ error-pattern: slice::get_unchecked requires
-//@ ignore-debug
-
-fn main() {
-    unsafe {
-        let sli: &[u8] = &[0];
-        sli.get_unchecked(1);
-    }
-}

tests/ui/precondition-checks/read.rs

@@ -0,0 +1,18 @@
+//@ run-fail
+//@ compile-flags: -Copt-level=3 -Cdebug-assertions=no -Zub-checks=yes
+//@ error-pattern: unsafe precondition(s) violated: ptr::read requires
+//@ revisions: null misaligned
+//@ ignore-test
+
+use std::ptr;
+
+fn main() {
+    let src = [0u16; 2];
+    let src = src.as_ptr();
+    unsafe {
+        #[cfg(null)]
+        ptr::read(ptr::null::<u8>());
+        #[cfg(misaligned)]
+        ptr::read(src.byte_add(1));
+    }
+}

tests/ui/precondition-checks/read_volatile.rs

@@ -0,0 +1,17 @@
+//@ run-fail
+//@ compile-flags: -Copt-level=3 -Cdebug-assertions=no -Zub-checks=yes
+//@ error-pattern: unsafe precondition(s) violated: ptr::read_volatile requires
+//@ revisions: null misaligned
+
+use std::ptr;
+
+fn main() {
+    let src = [0u16; 2];
+    let src = src.as_ptr();
+    unsafe {
+        #[cfg(null)]
+        ptr::read_volatile(ptr::null::<u8>());
+        #[cfg(misaligned)]
+        ptr::read_volatile(src.byte_add(1));
+    }
+}

tests/ui/precondition-checks/replace.rs

@@ -0,0 +1,17 @@
+//@ run-fail
+//@ compile-flags: -Copt-level=3 -Cdebug-assertions=no -Zub-checks=yes
+//@ error-pattern: unsafe precondition(s) violated: ptr::replace requires
+//@ revisions: null misaligned
+
+use std::ptr;
+
+fn main() {
+    let mut dst = [0u16; 2];
+    let dst = dst.as_mut_ptr();
+    unsafe {
+        #[cfg(null)]
+        ptr::replace(ptr::null_mut::<u8>(), 1);
+        #[cfg(misaligned)]
+        ptr::replace(dst.byte_add(1), 1u16);
+    }
+}

tests/ui/precondition-checks/slice-from-raw-parts-mut.rs

@@ -0,0 +1,16 @@
+//@ run-fail
+//@ compile-flags: -Copt-level=3 -Cdebug-assertions=no -Zub-checks=yes
+//@ error-pattern: unsafe precondition(s) violated: slice::from_raw_parts_mut requires
+//@ revisions: null misaligned toolarge
+
+fn main() {
+    unsafe {
+        #[cfg(null)]
+        let _s: &mut [u8] = std::slice::from_raw_parts_mut(std::ptr::null_mut(), 0);
+        #[cfg(misaligned)]
+        let _s: &mut [u16] = std::slice::from_raw_parts_mut(1usize as *mut u16, 0);
+        #[cfg(toolarge)]
+        let _s: &mut [u16] =
+            std::slice::from_raw_parts_mut(2usize as *mut u16, isize::MAX as usize);
+    }
+}

tests/ui/precondition-checks/slice-from-raw-parts.rs

@@ -0,0 +1,15 @@
+//@ run-fail
+//@ compile-flags: -Copt-level=3 -Cdebug-assertions=no -Zub-checks=yes
+//@ error-pattern: unsafe precondition(s) violated: slice::from_raw_parts requires
+//@ revisions: null misaligned toolarge
+
+fn main() {
+    unsafe {
+        #[cfg(null)]
+        let _s: &[u8] = std::slice::from_raw_parts(std::ptr::null(), 0);
+        #[cfg(misaligned)]
+        let _s: &[u16] = std::slice::from_raw_parts(1usize as *const u16, 0);
+        #[cfg(toolarge)]
+        let _s: &[u16] = std::slice::from_raw_parts(2usize as *const u16, isize::MAX as usize);
+    }
+}

tests/ui/precondition-checks/slice-get_unchecked.rs

@@ -0,0 +1,20 @@
+//@ run-fail
+//@ compile-flags: -Copt-level=3 -Cdebug-assertions=no -Zub-checks=yes
+//@ error-pattern: unsafe precondition(s) violated: slice::get_unchecked requires
+//@ revisions: usize range range_to range_from backwards_range
+
+fn main() {
+    unsafe {
+        let s = &[0];
+        #[cfg(usize)]
+        s.get_unchecked(1);
+        #[cfg(range)]
+        s.get_unchecked(1..2);
+        #[cfg(range_to)]
+        s.get_unchecked(..2);
+        #[cfg(range_from)]
+        s.get_unchecked(2..);
+        #[cfg(backwards_range)]
+        s.get_unchecked(1..0);
+     }
+}

tests/ui/precondition-checks/slice-get_unchecked_mut.rs

@@ -0,0 +1,20 @@
+//@ run-fail
+//@ compile-flags: -Copt-level=3 -Cdebug-assertions=no -Zub-checks=yes
+//@ error-pattern: unsafe precondition(s) violated: slice::get_unchecked_mut requires
+//@ revisions: usize range range_to range_from backwards_range
+
+fn main() {
+    unsafe {
+        let mut s = &mut [0];
+        #[cfg(usize)]
+        s.get_unchecked_mut(1);
+        #[cfg(range)]
+        s.get_unchecked_mut(1..2);
+        #[cfg(range_to)]
+        s.get_unchecked_mut(..2);
+        #[cfg(range_from)]
+        s.get_unchecked_mut(2..);
+        #[cfg(backwards_range)]
+        s.get_unchecked_mut(1..0);
+     }
+}

tests/ui/precondition-checks/slice-swap_unchecked.rs

@@ -0,0 +1,14 @@
+//@ run-fail
+//@ compile-flags: -Copt-level=3 -Cdebug-assertions=no -Zub-checks=yes
+//@ error-pattern: index out of bounds: the len is 2 but the index is 2
+//@ revisions: oob_a oob_b
+
+fn main() {
+    let mut pair = [0u8; 2];
+    unsafe {
+        #[cfg(oob_a)]
+        pair.swap(0, 2);
+        #[cfg(oob_b)]
+        pair.swap(2, 0);
+    }
+}

tests/ui/precondition-checks/str-get_unchecked.rs

@@ -0,0 +1,18 @@
+//@ run-fail
+//@ compile-flags: -Copt-level=3 -Cdebug-assertions=no -Zub-checks=yes
+//@ error-pattern: unsafe precondition(s) violated: str::get_unchecked requires
+//@ revisions: range range_to range_from backwards_range
+
+fn main() {
+    unsafe {
+        let s = "💅";
+        #[cfg(range)]
+        s.get_unchecked(4..5);
+        #[cfg(range_to)]
+        s.get_unchecked(..5);
+        #[cfg(range_from)]
+        s.get_unchecked(5..);
+        #[cfg(backwards_range)]
+        s.get_unchecked(1..0);
+    }
+}

tests/ui/precondition-checks/str-get_unchecked_mut.rs

@@ -0,0 +1,19 @@
+//@ run-fail
+//@ compile-flags: -Copt-level=3 -Cdebug-assertions=no -Zub-checks=yes
+//@ error-pattern: unsafe precondition(s) violated: str::get_unchecked_mut requires
+//@ revisions: range range_to range_from backwards_range
+
+fn main() {
+    unsafe {
+        let mut s: String = "💅".chars().collect();
+        let mut s: &mut str = &mut s;
+        #[cfg(range)]
+        s.get_unchecked_mut(4..5);
+        #[cfg(range_to)]
+        s.get_unchecked_mut(..5);
+        #[cfg(range_from)]
+        s.get_unchecked_mut(5..);
+        #[cfg(backwards_range)]
+        s.get_unchecked_mut(1..0);
+    }
+}

tests/ui/precondition-checks/swap-nonoverlapping.rs

@@ -0,0 +1,25 @@
+//@ run-fail
+//@ compile-flags: -Copt-level=3 -Cdebug-assertions=no -Zub-checks=yes
+//@ error-pattern: unsafe precondition(s) violated: ptr::swap_nonoverlapping requires
+//@ revisions: null_src null_dst misaligned_src misaligned_dst overlapping
+
+use std::ptr;
+
+fn main() {
+    let mut src = [0u16; 3];
+    let mut dst = [0u16; 3];
+    let src = src.as_mut_ptr();
+    let dst = dst.as_mut_ptr();
+    unsafe {
+        #[cfg(null_src)]
+        ptr::swap_nonoverlapping(ptr::null_mut(), dst, 1);
+        #[cfg(null_dst)]
+        ptr::swap_nonoverlapping(src, ptr::null_mut(), 1);
+        #[cfg(misaligned_src)]
+        ptr::swap_nonoverlapping(src.byte_add(1), dst, 1);
+        #[cfg(misaligned_dst)]
+        ptr::swap_nonoverlapping(src, dst.byte_add(1), 1);
+        #[cfg(overlapping)]
+        ptr::swap_nonoverlapping(dst, dst.add(1), 2);
+    }
+}

tests/ui/precondition-checks/unchecked_add.rs

@@ -0,0 +1,9 @@
+//@ run-fail
+//@ compile-flags: -Copt-level=3 -Cdebug-assertions=no -Zub-checks=yes
+//@ error-pattern: unsafe precondition(s) violated: u8::unchecked_add cannot overflow
+
+fn main() {
+    unsafe {
+        1u8.unchecked_add(u8::MAX);
+    }
+}

tests/ui/precondition-checks/unchecked_mul.rs

@@ -0,0 +1,9 @@
+//@ run-fail
+//@ compile-flags: -Copt-level=3 -Cdebug-assertions=no -Zub-checks=yes
+//@ error-pattern: unsafe precondition(s) violated: u8::unchecked_add cannot overflow
+
+fn main() {
+    unsafe {
+        2u8.unchecked_add(u8::MAX);
+    }
+}

tests/ui/precondition-checks/unchecked_shl.rs

@@ -0,0 +1,11 @@
+//@ run-fail
+//@ compile-flags: -Copt-level=3 -Cdebug-assertions=no -Zub-checks=yes
+//@ error-pattern: unsafe precondition(s) violated: u8::unchecked_shl cannot overflow
+
+#![feature(unchecked_shifts)]
+
+fn main() {
+    unsafe {
+        0u8.unchecked_shl(u8::BITS);
+    }
+}

tests/ui/precondition-checks/unchecked_shr.rs

@@ -0,0 +1,11 @@
+//@ run-fail
+//@ compile-flags: -Copt-level=3 -Cdebug-assertions=no -Zub-checks=yes
+//@ error-pattern: unsafe precondition(s) violated: u8::unchecked_shr cannot overflow
+
+#![feature(unchecked_shifts)]
+
+fn main() {
+    unsafe {
+        0u8.unchecked_shr(u8::BITS);
+    }
+}

tests/ui/precondition-checks/unchecked_sub.rs

@@ -0,0 +1,9 @@
+//@ run-fail
+//@ compile-flags: -Copt-level=3 -Cdebug-assertions=no -Zub-checks=yes
+//@ error-pattern: unsafe precondition(s) violated: u8::unchecked_sub cannot overflow
+
+fn main() {
+    unsafe {
+        0u8.unchecked_sub(1u8);
+    }
+}

tests/ui/precondition-checks/unreachable_unchecked.rs

@@ -0,0 +1,9 @@
+//@ run-fail
+//@ compile-flags: -Copt-level=3 -Cdebug-assertions=no -Zub-checks=yes
+//@ error-pattern: unsafe precondition(s) violated: hint::unreachable_unchecked must never be reached
+
+fn main() {
+    unsafe {
+        std::hint::unreachable_unchecked();
+    }
+}

tests/ui/precondition-checks/write.rs

@@ -0,0 +1,18 @@
+//@ run-fail
+//@ compile-flags: -Copt-level=3 -Cdebug-assertions=no -Zub-checks=yes
+//@ error-pattern: unsafe precondition(s) violated: ptr::write requires
+//@ revisions: null misaligned
+//@ ignore-test
+
+use std::ptr;
+
+fn main() {
+    let mut dst = [0u16; 2];
+    let mut dst = dst.as_mut_ptr();
+    unsafe {
+        #[cfg(null)]
+        ptr::write(ptr::null_mut::<u8>(), 1u8);
+        #[cfg(misaligned)]
+        ptr::write(dst.byte_add(1), 1u16);
+    }
+}

tests/ui/precondition-checks/write_bytes.rs

@@ -0,0 +1,18 @@
+//@ run-fail
+//@ compile-flags: -Copt-level=3 -Cdebug-assertions=no -Zub-checks=yes
+//@ error-pattern: unsafe precondition(s) violated: ptr::write requires
+//@ revisions: null misaligned
+//@ ignore-test
+
+use std::ptr;
+
+fn main() {
+    let mut dst = [0u16; 2];
+    let mut dst = dst.as_mut_ptr();
+    unsafe {
+        #[cfg(null)]
+        ptr::write_bytes(ptr::null_mut::<u8>(), 1u8, 2);
+        #[cfg(misaligned)]
+        ptr::write_bytes(dst.byte_add(1), 1u8, 2);
+    }
+}

tests/ui/precondition-checks/write_volatile.rs

@@ -0,0 +1,17 @@
+//@ run-fail
+//@ compile-flags: -Copt-level=3 -Cdebug-assertions=no -Zub-checks=yes
+//@ error-pattern: unsafe precondition(s) violated: ptr::write_volatile requires
+//@ revisions: null misaligned
+
+use std::ptr;
+
+fn main() {
+    let mut dst = [0u16; 2];
+    let mut dst = dst.as_mut_ptr();
+    unsafe {
+        #[cfg(null)]
+        ptr::write_volatile(ptr::null_mut::<u8>(), 1u8);
+        #[cfg(misaligned)]
+        ptr::write_volatile(dst.byte_add(1), 1u16);
+    }
+}

tests/ui/precondition-checks/zero-size-null.rs

@@ -0,0 +1,21 @@
+// Test that none of the precondition checks panic on zero-sized reads or writes through null.
+
+//@ run-pass
+//@ compile-flags: -Zmir-opt-level=0 -Copt-level=0 -Cdebug-assertions=yes
+
+use std::ptr;
+
+fn main() {
+    unsafe {
+        ptr::copy_nonoverlapping::<u8>(ptr::null(), ptr::null_mut(), 0);
+        ptr::copy_nonoverlapping::<()>(ptr::null(), ptr::null_mut(), 123);
+        ptr::copy::<u8>(ptr::null(), ptr::null_mut(), 0);
+        ptr::copy::<()>(ptr::null(), ptr::null_mut(), 123);
+        ptr::swap::<()>(ptr::null_mut(), ptr::null_mut());
+        ptr::replace::<()>(ptr::null_mut(), ());
+        ptr::read::<()>(ptr::null());
+        ptr::write::<()>(ptr::null_mut(), ());
+        ptr::read_volatile::<()>(ptr::null());
+        ptr::write_volatile::<()>(ptr::null_mut(), ());
+    }
+}

tests/ui/rust-2024/unsafe-extern-blocks/safe-unsafe-on-unadorned-extern-block.edition2021.stderr

@@ -1,21 +1,21 @@
-error: items in unadorned `extern` blocks cannot have safety qualifiers
+error: items in `extern` blocks without an `unsafe` qualifier cannot have safety qualifiers
   --> $DIR/safe-unsafe-on-unadorned-extern-block.rs:8:5
    |
 LL |     safe static TEST1: i32;
    |     ^^^^^^^^^^^^^^^^^^^^^^^
    |
-help: add unsafe to this `extern` block
+help: add `unsafe` to this `extern` block
    |
 LL | unsafe extern "C" {
    | ++++++
 
-error: items in unadorned `extern` blocks cannot have safety qualifiers
+error: items in `extern` blocks without an `unsafe` qualifier cannot have safety qualifiers
   --> $DIR/safe-unsafe-on-unadorned-extern-block.rs:10:5
    |
 LL |     safe fn test1(i: i32);
    |     ^^^^^^^^^^^^^^^^^^^^^^
    |
-help: add unsafe to this `extern` block
+help: add `unsafe` to this `extern` block
    |
 LL | unsafe extern "C" {
    | ++++++

tests/ui/rust-2024/unsafe-extern-blocks/safe-unsafe-on-unadorned-extern-block.edition2024.stderr

@@ -10,24 +10,24 @@ LL | |
 LL | | }
    | |_^
 
-error: items in unadorned `extern` blocks cannot have safety qualifiers
+error: items in `extern` blocks without an `unsafe` qualifier cannot have safety qualifiers
   --> $DIR/safe-unsafe-on-unadorned-extern-block.rs:8:5
    |
 LL |     safe static TEST1: i32;
    |     ^^^^^^^^^^^^^^^^^^^^^^^
    |
-help: add unsafe to this `extern` block
+help: add `unsafe` to this `extern` block
    |
 LL | unsafe extern "C" {
    | ++++++
 
-error: items in unadorned `extern` blocks cannot have safety qualifiers
+error: items in `extern` blocks without an `unsafe` qualifier cannot have safety qualifiers
   --> $DIR/safe-unsafe-on-unadorned-extern-block.rs:10:5
    |
 LL |     safe fn test1(i: i32);
    |     ^^^^^^^^^^^^^^^^^^^^^^
    |
-help: add unsafe to this `extern` block
+help: add `unsafe` to this `extern` block
    |
 LL | unsafe extern "C" {
    | ++++++

tests/ui/rust-2024/unsafe-extern-blocks/safe-unsafe-on-unadorned-extern-block.rs

@@ -6,9 +6,9 @@
 extern "C" {
     //[edition2024]~^ ERROR extern blocks must be unsafe
     safe static TEST1: i32;
-    //~^ ERROR items in unadorned `extern` blocks cannot have safety qualifiers
+    //~^ ERROR items in `extern` blocks without an `unsafe` qualifier cannot have safety qualifiers
     safe fn test1(i: i32);
-    //~^ ERROR items in unadorned `extern` blocks cannot have safety qualifiers
+    //~^ ERROR items in `extern` blocks without an `unsafe` qualifier cannot have safety qualifiers
 }
 
 fn test2() {

tests/ui/rust-2024/unsafe-extern-blocks/unsafe-on-extern-block-issue-126756.fixed

@@ -3,7 +3,7 @@
 #![allow(dead_code)]
 
 unsafe extern "C" {
-    unsafe fn foo(); //~ ERROR items in unadorned `extern` blocks cannot have safety qualifiers
+    unsafe fn foo(); //~ ERROR items in `extern` blocks without an `unsafe` qualifier cannot have safety qualifiers
 }
 
 fn main() {}

tests/ui/rust-2024/unsafe-extern-blocks/unsafe-on-extern-block-issue-126756.rs

@@ -3,7 +3,7 @@
 #![allow(dead_code)]
 
 extern "C" {
-    unsafe fn foo(); //~ ERROR items in unadorned `extern` blocks cannot have safety qualifiers
+    unsafe fn foo(); //~ ERROR items in `extern` blocks without an `unsafe` qualifier cannot have safety qualifiers
 }
 
 fn main() {}

tests/ui/rust-2024/unsafe-extern-blocks/unsafe-on-extern-block-issue-126756.stderr

@@ -1,10 +1,10 @@
-error: items in unadorned `extern` blocks cannot have safety qualifiers
+error: items in `extern` blocks without an `unsafe` qualifier cannot have safety qualifiers
   --> $DIR/unsafe-on-extern-block-issue-126756.rs:6:5
    |
 LL |     unsafe fn foo();
    |     ^^^^^^^^^^^^^^^^
    |
-help: add unsafe to this `extern` block
+help: add `unsafe` to this `extern` block
    |
 LL | unsafe extern "C" {
    | ++++++

triagebot.toml

@@ -431,6 +431,11 @@ trigger_files = [
     "src/tools/run-make-support"
 ]
 
+[autolabel."A-compiletest"]
+trigger_files = [
+    "src/tools/compiletest"
+]
+
 [notify-zulip."I-prioritize"]
 zulip_stream = 245100 # #t-compiler/wg-prioritization/alerts
 topic = "#{number} {title}"