teach clippy about IeeeFloat, and make all 'allow' into 'expect'

Author: RalfJung

clippy.toml

@@ -1 +1 @@
-arithmetic-side-effects-allowed = ["rustc_abi::Size"]
+arithmetic-side-effects-allowed = ["rustc_abi::Size", "rustc_apfloat::ieee::IeeeFloat"]

src/borrow_tracker/stacked_borrows/stack.rs

@@ -354,7 +354,7 @@ impl<'tcx> Stack {
         self.borrows.get(idx).cloned()
     }
 
-    #[allow(clippy::len_without_is_empty)] // Stacks are never empty
+    #[expect(clippy::len_without_is_empty)] // Stacks are never empty
     pub fn len(&self) -> usize {
         self.borrows.len()
     }

src/concurrency/weak_memory.rs

@@ -300,7 +300,6 @@ impl<'tcx> StoreBuffer {
         interp_ok(())
     }
 
-    #[allow(clippy::if_same_then_else, clippy::needless_bool)]
     /// Selects a valid store element in the buffer.
     fn fetch_store<R: rand::Rng + ?Sized>(
         &self,

src/eval.rs

@@ -423,7 +423,7 @@ pub fn create_ecx<'tcx>(
 /// Evaluates the entry function specified by `entry_id`.
 /// Returns `Some(return_code)` if program executed completed.
 /// Returns `None` if an evaluation error occurred.
-#[allow(clippy::needless_lifetimes)]
+#[expect(clippy::needless_lifetimes)]
 pub fn eval_entry<'tcx>(
     tcx: TyCtxt<'tcx>,
     entry_id: DefId,

src/helpers.rs

@@ -156,7 +156,7 @@ pub fn iter_exported_symbols<'tcx>(
     for cnum in dependency_format.1.iter().enumerate().filter_map(|(num, &linkage)| {
         // We add 1 to the number because that's what rustc also does everywhere it
         // calls `CrateNum::new`...
-        #[allow(clippy::arithmetic_side_effects)]
+        #[expect(clippy::arithmetic_side_effects)]
         (linkage != Linkage::NotLinked).then_some(CrateNum::new(num + 1))
     }) {
         // We can ignore `_export_info` here: we are a Rust crate, and everything is exported

src/intrinsics/mod.rs

@@ -292,7 +292,6 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
                 let b = this.read_scalar(b)?.to_f32()?;
                 let c = this.read_scalar(c)?.to_f32()?;
                 let fuse: bool = this.machine.rng.get_mut().gen();
-                #[allow(clippy::arithmetic_side_effects)] // float ops don't overflow
                 let res = if fuse {
                     // FIXME: Using host floats, to work around https://github.com/rust-lang/rustc_apfloat/issues/11
                     a.to_host().mul_add(b.to_host(), c.to_host()).to_soft()
@@ -308,7 +307,6 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
                 let b = this.read_scalar(b)?.to_f64()?;
                 let c = this.read_scalar(c)?.to_f64()?;
                 let fuse: bool = this.machine.rng.get_mut().gen();
-                #[allow(clippy::arithmetic_side_effects)] // float ops don't overflow
                 let res = if fuse {
                     // FIXME: Using host floats, to work around https://github.com/rust-lang/rustc_apfloat/issues/11
                     a.to_host().mul_add(b.to_host(), c.to_host()).to_soft()

src/intrinsics/simd.rs

@@ -750,7 +750,6 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
 
                     let val = if simd_element_to_bool(mask)? {
                         // Size * u64 is implemented as always checked
-                        #[allow(clippy::arithmetic_side_effects)]
                         let ptr = ptr.wrapping_offset(dest.layout.size * i, this);
                         let place = this.ptr_to_mplace(ptr, dest.layout);
                         this.read_immediate(&place)?
@@ -774,7 +773,6 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
 
                     if simd_element_to_bool(mask)? {
                         // Size * u64 is implemented as always checked
-                        #[allow(clippy::arithmetic_side_effects)]
                         let ptr = ptr.wrapping_offset(val.layout.size * i, this);
                         let place = this.ptr_to_mplace(ptr, val.layout);
                         this.write_immediate(*val, &place)?
@@ -831,7 +829,7 @@ fn simd_bitmask_index(idx: u32, vec_len: u32, endianness: Endian) -> u32 {
     assert!(idx < vec_len);
     match endianness {
         Endian::Little => idx,
-        #[allow(clippy::arithmetic_side_effects)] // idx < vec_len
+        #[expect(clippy::arithmetic_side_effects)] // idx < vec_len
         Endian::Big => vec_len - 1 - idx, // reverse order of bits
     }
 }

src/shims/foreign_items.rs

@@ -21,7 +21,7 @@ use crate::*;
 #[derive(Debug, Copy, Clone)]
 pub struct DynSym(Symbol);
 
-#[allow(clippy::should_implement_trait)]
+#[expect(clippy::should_implement_trait)]
 impl DynSym {
     pub fn from_str(name: &str) -> Self {
         DynSym(Symbol::intern(name))
@@ -648,7 +648,7 @@ trait EvalContextExtPriv<'tcx>: crate::MiriInterpCxExt<'tcx> {
                 let val = this.read_scalar(val)?.to_i32()?;
                 let num = this.read_target_usize(num)?;
                 // The docs say val is "interpreted as unsigned char".
-                #[allow(clippy::cast_sign_loss, clippy::cast_possible_truncation)]
+                #[expect(clippy::cast_sign_loss, clippy::cast_possible_truncation)]
                 let val = val as u8;
 
                 // C requires that this must always be a valid pointer (C18 §7.1.4).
@@ -661,7 +661,7 @@ trait EvalContextExtPriv<'tcx>: crate::MiriInterpCxExt<'tcx> {
                     .position(|&c| c == val)
                 {
                     let idx = u64::try_from(idx).unwrap();
-                    #[allow(clippy::arithmetic_side_effects)] // idx < num, so this never wraps
+                    #[expect(clippy::arithmetic_side_effects)] // idx < num, so this never wraps
                     let new_ptr = ptr.wrapping_offset(Size::from_bytes(num - idx - 1), this);
                     this.write_pointer(new_ptr, dest)?;
                 } else {
@@ -675,7 +675,7 @@ trait EvalContextExtPriv<'tcx>: crate::MiriInterpCxExt<'tcx> {
                 let val = this.read_scalar(val)?.to_i32()?;
                 let num = this.read_target_usize(num)?;
                 // The docs say val is "interpreted as unsigned char".
-                #[allow(clippy::cast_sign_loss, clippy::cast_possible_truncation)]
+                #[expect(clippy::cast_sign_loss, clippy::cast_possible_truncation)]
                 let val = val as u8;
 
                 // C requires that this must always be a valid pointer (C18 §7.1.4).

src/shims/io_error.rs

@@ -188,7 +188,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
     }
 
     /// The inverse of `io_error_to_errnum`.
-    #[allow(clippy::needless_return)]
+    #[expect(clippy::needless_return)]
     fn try_errnum_to_io_error(
         &self,
         errnum: Scalar,

src/shims/tls.rs

@@ -53,7 +53,7 @@ impl<'tcx> Default for TlsData<'tcx> {
 impl<'tcx> TlsData<'tcx> {
     /// Generate a new TLS key with the given destructor.
     /// `max_size` determines the integer size the key has to fit in.
-    #[allow(clippy::arithmetic_side_effects)]
+    #[expect(clippy::arithmetic_side_effects)]
     pub fn create_tls_key(
         &mut self,
         dtor: Option<ty::Instance<'tcx>>,

src/shims/unix/fs.rs

@@ -385,7 +385,7 @@ pub struct DirTable {
 }
 
 impl DirTable {
-    #[allow(clippy::arithmetic_side_effects)]
+    #[expect(clippy::arithmetic_side_effects)]
     fn insert_new(&mut self, read_dir: ReadDir) -> u64 {
         let id = self.next_id;
         self.next_id += 1;

src/shims/unix/linux/mem.rs

@@ -22,7 +22,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
         let flags = this.read_scalar(flags)?.to_i32()?;
 
         // old_address must be a multiple of the page size
-        #[allow(clippy::arithmetic_side_effects)] // PAGE_SIZE is nonzero
+        #[expect(clippy::arithmetic_side_effects)] // PAGE_SIZE is nonzero
         if old_address.addr().bytes() % this.machine.page_size != 0 || new_size == 0 {
             this.set_last_error(LibcError("EINVAL"))?;
             return interp_ok(this.eval_libc("MAP_FAILED"));

src/shims/unix/linux/sync.rs

@@ -182,7 +182,7 @@ pub fn futex<'tcx>(
             // before doing the syscall.
             this.atomic_fence(AtomicFenceOrd::SeqCst)?;
             let mut n = 0;
-            #[allow(clippy::arithmetic_side_effects)]
+            #[expect(clippy::arithmetic_side_effects)]
             for _ in 0..val {
                 if this.futex_wake(addr_usize, bitset)? {
                     n += 1;

src/shims/unix/mem.rs

@@ -132,7 +132,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
 
         // addr must be a multiple of the page size, but apart from that munmap is just implemented
         // as a dealloc.
-        #[allow(clippy::arithmetic_side_effects)] // PAGE_SIZE is nonzero
+        #[expect(clippy::arithmetic_side_effects)] // PAGE_SIZE is nonzero
         if addr.addr().bytes() % this.machine.page_size != 0 {
             return this.set_last_error_and_return_i32(LibcError("EINVAL"));
         }

src/shims/unix/sync.rs

@@ -685,7 +685,6 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
 
         let id = rwlock_get_data(this, rwlock_op)?.id;
 
-        #[allow(clippy::if_same_then_else)]
         if this.rwlock_reader_unlock(id)? || this.rwlock_writer_unlock(id)? {
             interp_ok(())
         } else {

src/shims/windows/foreign_items.rs

@@ -25,7 +25,7 @@ fn win_absolute<'tcx>(path: &Path) -> InterpResult<'tcx, io::Result<PathBuf>> {
 }
 
 #[cfg(unix)]
-#[allow(clippy::get_first, clippy::arithmetic_side_effects)]
+#[expect(clippy::get_first, clippy::arithmetic_side_effects)]
 fn win_absolute<'tcx>(path: &Path) -> InterpResult<'tcx, io::Result<PathBuf>> {
     // We are on Unix, so we need to implement parts of the logic ourselves.
     let bytes = path.as_os_str().as_encoded_bytes();

src/shims/windows/handle.rs

@@ -63,7 +63,7 @@ impl Handle {
         let floor_log2 = variant_count.ilog2();
 
         // we need to add one for non powers of two to compensate for the difference
-        #[allow(clippy::arithmetic_side_effects)] // cannot overflow
+        #[expect(clippy::arithmetic_side_effects)] // cannot overflow
         if variant_count.is_power_of_two() { floor_log2 } else { floor_log2 + 1 }
     }
 
@@ -88,8 +88,7 @@ impl Handle {
 
         // packs the data into the lower `data_size` bits
         // and packs the discriminant right above the data
-        #[allow(clippy::arithmetic_side_effects)] // cannot overflow
-        return discriminant << data_size | data;
+        discriminant << data_size | data
     }
 
     fn new(discriminant: u32, data: u32) -> Option<Self> {
@@ -107,11 +106,10 @@ impl Handle {
         let data_size = u32::BITS.strict_sub(disc_size);
 
         // the lower `data_size` bits of this mask are 1
-        #[allow(clippy::arithmetic_side_effects)] // cannot overflow
+        #[expect(clippy::arithmetic_side_effects)] // cannot overflow
         let data_mask = 2u32.pow(data_size) - 1;
 
         // the discriminant is stored right above the lower `data_size` bits
-        #[allow(clippy::arithmetic_side_effects)] // cannot overflow
         let discriminant = handle >> data_size;
 
         // the data is stored in the lower `data_size` bits
@@ -123,7 +121,7 @@ impl Handle {
     pub fn to_scalar(self, cx: &impl HasDataLayout) -> Scalar {
         // 64-bit handles are sign extended 32-bit handles
         // see https://docs.microsoft.com/en-us/windows/win32/winprog64/interprocess-communication
-        #[allow(clippy::cast_possible_wrap)] // we want it to wrap
+        #[expect(clippy::cast_possible_wrap)] // we want it to wrap
         let signed_handle = self.to_packed() as i32;
         Scalar::from_target_isize(signed_handle.into(), cx)
     }
@@ -134,7 +132,7 @@ impl Handle {
     ) -> InterpResult<'tcx, Option<Self>> {
         let sign_extended_handle = handle.to_target_isize(cx)?;
 
-        #[allow(clippy::cast_sign_loss)] // we want to lose the sign
+        #[expect(clippy::cast_sign_loss)] // we want to lose the sign
         let handle = if let Ok(signed_handle) = i32::try_from(sign_extended_handle) {
             signed_handle as u32
         } else {

src/shims/x86/gfni.rs

@@ -136,7 +136,7 @@ fn affine_transform<'tcx>(
 // This is a evaluated at compile time. Trait based conversion is not available.
 /// See <https://www.corsix.org/content/galois-field-instructions-2021-cpus> for the
 /// definition of `gf_inv` which was used for the creation of this table.
-#[allow(clippy::cast_possible_truncation)]
+#[expect(clippy::cast_possible_truncation)]
 static TABLE: [u8; 256] = {
     let mut array = [0; 256];
 
@@ -163,7 +163,7 @@ static TABLE: [u8; 256] = {
 /// polynomial representation with the reduction polynomial x^8 + x^4 + x^3 + x + 1.
 /// See <https://www.corsix.org/content/galois-field-instructions-2021-cpus> for details.
 // This is a const function. Trait based conversion is not available.
-#[allow(clippy::cast_possible_truncation)]
+#[expect(clippy::cast_possible_truncation)]
 const fn gf2p8_mul(left: u8, right: u8) -> u8 {
     // This implementation is based on the `gf2p8mul_byte` definition found inside the Intel intrinsics guide.
     // See https://www.intel.com/content/www/us/en/docs/intrinsics-guide/index.html#text=gf2p8mul

src/shims/x86/mod.rs

@@ -397,7 +397,6 @@ enum FloatUnaryOp {
 }
 
 /// Performs `which` scalar operation on `op` and returns the result.
-#[allow(clippy::arithmetic_side_effects)] // floating point operations without side effects
 fn unary_op_f32<'tcx>(
     this: &mut crate::MiriInterpCx<'tcx>,
     which: FloatUnaryOp,
@@ -426,7 +425,7 @@ fn unary_op_f32<'tcx>(
 }
 
 /// Disturbes a floating-point result by a relative error on the order of (-2^scale, 2^scale).
-#[allow(clippy::arithmetic_side_effects)] // floating point arithmetic cannot panic
+#[expect(clippy::arithmetic_side_effects)] // floating point arithmetic cannot panic
 fn apply_random_float_error<F: rustc_apfloat::Float>(
     this: &mut crate::MiriInterpCx<'_>,
     val: F,
@@ -1000,7 +999,6 @@ fn mask_load<'tcx>(
         let dest = this.project_index(&dest, i)?;
 
         if this.read_scalar(&mask)?.to_uint(mask_item_size)? >> high_bit_offset != 0 {
-            #[allow(clippy::arithmetic_side_effects)] // `Size` arithmetic is checked
             let ptr = ptr.wrapping_offset(dest.layout.size * i, &this.tcx);
             // Unaligned copy, which is what we want.
             this.mem_copy(ptr, dest.ptr(), dest.layout.size, /*nonoverlapping*/ true)?;
@@ -1036,7 +1034,6 @@ fn mask_store<'tcx>(
         if this.read_scalar(&mask)?.to_uint(mask_item_size)? >> high_bit_offset != 0 {
             // *Non-inbounds* pointer arithmetic to compute the destination.
             // (That's why we can't use a place projection.)
-            #[allow(clippy::arithmetic_side_effects)] // `Size` arithmetic is checked
             let ptr = ptr.wrapping_offset(value.layout.size * i, &this.tcx);
             // Deref the pointer *unaligned*, and do the copy.
             let dest = this.ptr_to_mplace_unaligned(ptr, value.layout);
@@ -1135,7 +1132,7 @@ fn pmulhrsw<'tcx>(
 
         // The result of this operation can overflow a signed 16-bit integer.
         // When `left` and `right` are -0x8000, the result is 0x8000.
-        #[allow(clippy::cast_possible_truncation)]
+        #[expect(clippy::cast_possible_truncation)]
         let res = res as i16;
 
         this.write_scalar(Scalar::from_i16(res), &dest)?;

src/shims/x86/sse42.rs

@@ -68,7 +68,7 @@ const USE_SIGNED: u8 = 2;
 /// The mask may be negated if negation flags inside the immediate byte are set.
 ///
 /// For more information, see the Intel Software Developer's Manual, Vol. 2b, Chapter 4.1.
-#[allow(clippy::arithmetic_side_effects)]
+#[expect(clippy::arithmetic_side_effects)]
 fn compare_strings<'tcx>(
     this: &mut MiriInterpCx<'tcx>,
     str1: &OpTy<'tcx>,
@@ -444,7 +444,7 @@ pub(super) trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
                 let crc = if bit_size == 64 {
                     // The 64-bit version will only consider the lower 32 bits,
                     // while the upper 32 bits get discarded.
-                    #[allow(clippy::cast_possible_truncation)]
+                    #[expect(clippy::cast_possible_truncation)]
                     u128::from((left.to_u64()? as u32).reverse_bits())
                 } else {
                     u128::from(left.to_u32()?.reverse_bits())

tests/pass/shims/x86/intrinsics-sha.rs

@@ -181,7 +181,7 @@ unsafe fn schedule(v0: __m128i, v1: __m128i, v2: __m128i, v3: __m128i) -> __m128
 }
 
 // we use unaligned loads with `__m128i` pointers
-#[allow(clippy::cast_ptr_alignment)]
+#[expect(clippy::cast_ptr_alignment)]
 #[target_feature(enable = "sha,sse2,ssse3,sse4.1")]
 unsafe fn digest_blocks(state: &mut [u32; 8], blocks: &[[u8; 64]]) {
     #[allow(non_snake_case)]