Merge pull request #4329 from RalfJung/no-casts

enable clippy::as_conversions to fully rule out as-casts

Author: RalfJung

src/tools/miri/src/alloc_addresses/mod.rs

@@ -168,7 +168,7 @@ trait EvalContextExtPriv<'tcx>: crate::MiriInterpCxExt<'tcx> {
                 AllocKind::Dead => unreachable!(),
             };
             // We don't have to expose this pointer yet, we do that in `prepare_for_native_call`.
-            return interp_ok(base_ptr.addr().try_into().unwrap());
+            return interp_ok(base_ptr.addr().to_u64());
         }
         // We are not in native lib mode, so we control the addresses ourselves.
         if let Some((reuse_addr, clock)) = global_state.reuse.take_addr(

src/tools/miri/src/alloc_addresses/reuse_pool.rs

@@ -4,6 +4,7 @@ use rand::Rng;
 use rustc_abi::{Align, Size};
 
 use crate::concurrency::VClock;
+use crate::helpers::ToUsize as _;
 use crate::{MemoryKind, MiriConfig, ThreadId};
 
 const MAX_POOL_SIZE: usize = 64;
@@ -46,7 +47,7 @@ impl ReusePool {
     }
 
     fn subpool(&mut self, align: Align) -> &mut Vec<(u64, Size, ThreadId, VClock)> {
-        let pool_idx: usize = align.bytes().trailing_zeros().try_into().unwrap();
+        let pool_idx: usize = align.bytes().trailing_zeros().to_usize();
         if self.pool.len() <= pool_idx {
             self.pool.resize(pool_idx + 1, Vec::new());
         }

src/tools/miri/src/alloc_bytes.rs

@@ -5,6 +5,8 @@ use std::{alloc, slice};
 use rustc_abi::{Align, Size};
 use rustc_middle::mir::interpret::AllocBytes;
 
+use crate::helpers::ToU64 as _;
+
 /// Allocation bytes that explicitly handle the layout of the data they're storing.
 /// This is necessary to interface with native code that accesses the program store in Miri.
 #[derive(Debug)]
@@ -21,7 +23,7 @@ pub struct MiriAllocBytes {
 impl Clone for MiriAllocBytes {
     fn clone(&self) -> Self {
         let bytes: Cow<'_, [u8]> = Cow::Borrowed(self);
-        let align = Align::from_bytes(self.layout.align().try_into().unwrap()).unwrap();
+        let align = Align::from_bytes(self.layout.align().to_u64()).unwrap();
         MiriAllocBytes::from_bytes(bytes, align)
     }
 }
@@ -90,7 +92,7 @@ impl AllocBytes for MiriAllocBytes {
         let align = align.bytes();
         // SAFETY: `alloc_fn` will only be used with `size != 0`.
         let alloc_fn = |layout| unsafe { alloc::alloc(layout) };
-        let alloc_bytes = MiriAllocBytes::alloc_with(size.try_into().unwrap(), align, alloc_fn)
+        let alloc_bytes = MiriAllocBytes::alloc_with(size.to_u64(), align, alloc_fn)
             .unwrap_or_else(|()| {
                 panic!("Miri ran out of memory: cannot create allocation of {size} bytes")
             });

src/tools/miri/src/borrow_tracker/tree_borrows/unimap.rs

@@ -17,6 +17,8 @@ use std::mem;
 
 use rustc_data_structures::fx::FxHashMap;
 
+use crate::helpers::ToUsize;
+
 /// Intermediate key between a UniKeyMap and a UniValMap.
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
 pub struct UniIndex {
@@ -158,7 +160,7 @@ where
 impl<V> UniValMap<V> {
     /// Whether this index has an associated value.
     pub fn contains_idx(&self, idx: UniIndex) -> bool {
-        self.data.get(idx.idx as usize).and_then(Option::as_ref).is_some()
+        self.data.get(idx.idx.to_usize()).and_then(Option::as_ref).is_some()
     }
 
     /// Reserve enough space to insert the value at the right index.
@@ -174,29 +176,29 @@ impl<V> UniValMap<V> {
 
     /// Assign a value to the index. Permanently overwrites any previous value.
     pub fn insert(&mut self, idx: UniIndex, val: V) {
-        self.extend_to_length(idx.idx as usize + 1);
-        self.data[idx.idx as usize] = Some(val)
+        self.extend_to_length(idx.idx.to_usize() + 1);
+        self.data[idx.idx.to_usize()] = Some(val)
     }
 
     /// Get the value at this index, if it exists.
     pub fn get(&self, idx: UniIndex) -> Option<&V> {
-        self.data.get(idx.idx as usize).and_then(Option::as_ref)
+        self.data.get(idx.idx.to_usize()).and_then(Option::as_ref)
     }
 
     /// Get the value at this index mutably, if it exists.
     pub fn get_mut(&mut self, idx: UniIndex) -> Option<&mut V> {
-        self.data.get_mut(idx.idx as usize).and_then(Option::as_mut)
+        self.data.get_mut(idx.idx.to_usize()).and_then(Option::as_mut)
     }
 
     /// Delete any value associated with this index.
     /// Returns None if the value was not present, otherwise
     /// returns the previously stored value.
     pub fn remove(&mut self, idx: UniIndex) -> Option<V> {
-        if idx.idx as usize >= self.data.len() {
+        if idx.idx.to_usize() >= self.data.len() {
             return None;
         }
         let mut res = None;
-        mem::swap(&mut res, &mut self.data[idx.idx as usize]);
+        mem::swap(&mut res, &mut self.data[idx.idx.to_usize()]);
         res
     }
 }
@@ -209,8 +211,8 @@ pub struct UniEntry<'a, V> {
 impl<'a, V> UniValMap<V> {
     /// Get a wrapper around a mutable access to the value corresponding to `idx`.
     pub fn entry(&'a mut self, idx: UniIndex) -> UniEntry<'a, V> {
-        self.extend_to_length(idx.idx as usize + 1);
-        UniEntry { inner: &mut self.data[idx.idx as usize] }
+        self.extend_to_length(idx.idx.to_usize() + 1);
+        UniEntry { inner: &mut self.data[idx.idx.to_usize()] }
     }
 }
 

src/tools/miri/src/concurrency/cpu_affinity.rs

@@ -25,7 +25,7 @@ impl CpuAffinityMask {
         let mut this = Self([0; Self::CPU_MASK_BYTES]);
 
         // the default affinity mask includes only the available CPUs
-        for i in 0..cpu_count as usize {
+        for i in 0..cpu_count.to_usize() {
             this.set(cx, i);
         }
 

src/tools/miri/src/concurrency/vector_clock.rs

@@ -7,6 +7,7 @@ use rustc_span::{DUMMY_SP, Span, SpanData};
 use smallvec::SmallVec;
 
 use super::data_race::NaReadType;
+use crate::helpers::ToUsize;
 
 /// A vector clock index, this is associated with a thread id
 /// but in some cases one vector index may be shared with
@@ -157,7 +158,7 @@ impl VClock {
 
     #[inline]
     pub(super) fn index_mut(&mut self, index: VectorIdx) -> &mut VTimestamp {
-        self.0.as_mut_slice().get_mut(index.to_u32() as usize).unwrap()
+        self.0.as_mut_slice().get_mut(index.to_u32().to_usize()).unwrap()
     }
 
     /// Get a mutable slice to the internal vector with minimum `min_len`
@@ -420,7 +421,7 @@ impl Index<VectorIdx> for VClock {
 
     #[inline]
     fn index(&self, index: VectorIdx) -> &VTimestamp {
-        self.as_slice().get(index.to_u32() as usize).unwrap_or(&VTimestamp::ZERO)
+        self.as_slice().get(index.to_u32().to_usize()).unwrap_or(&VTimestamp::ZERO)
     }
 }
 

src/tools/miri/src/helpers.rs

@@ -1412,3 +1412,26 @@ pub(crate) fn windows_check_buffer_size((success, len): (bool, u64)) -> u32 {
         u32::try_from(len).unwrap()
     }
 }
+
+/// We don't support 16-bit systems, so let's have ergonomic conversion from `u32` to `usize`.
+pub trait ToUsize {
+    fn to_usize(self) -> usize;
+}
+
+impl ToUsize for u32 {
+    fn to_usize(self) -> usize {
+        self.try_into().unwrap()
+    }
+}
+
+/// Similarly, a maximum address size of `u64` is assumed widely here, so let's have ergonomic
+/// converion from `usize` to `u64`.
+pub trait ToU64 {
+    fn to_u64(self) -> u64;
+}
+
+impl ToU64 for usize {
+    fn to_u64(self) -> u64 {
+        self.try_into().unwrap()
+    }
+}

src/tools/miri/src/intrinsics/simd.rs

@@ -634,7 +634,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
                 let index_len = index.len();
 
                 assert_eq!(left_len, right_len);
-                assert_eq!(index_len as u64, dest_len);
+                assert_eq!(u64::try_from(index_len).unwrap(), dest_len);
 
                 for i in 0..dest_len {
                     let src_index: u64 =

src/tools/miri/src/lib.rs

@@ -41,14 +41,7 @@
     rustc::potential_query_instability,
     rustc::untranslatable_diagnostic,
 )]
-#![warn(
-    rust_2018_idioms,
-    unqualified_local_imports,
-    clippy::cast_possible_wrap, // unsigned -> signed
-    clippy::cast_sign_loss, // signed -> unsigned
-    clippy::cast_lossless,
-    clippy::cast_possible_truncation,
-)]
+#![warn(rust_2018_idioms, unqualified_local_imports, clippy::as_conversions)]
 // Needed for rustdoc from bootstrap (with `-Znormalize-docs`).
 #![recursion_limit = "256"]
 
@@ -140,7 +133,7 @@ pub use crate::eval::{
     AlignmentCheck, BacktraceStyle, IsolatedOp, MiriConfig, MiriEntryFnType, RejectOpWith,
     ValidationMode, create_ecx, eval_entry,
 };
-pub use crate::helpers::{AccessKind, EvalContextExt as _};
+pub use crate::helpers::{AccessKind, EvalContextExt as _, ToU64 as _, ToUsize as _};
 pub use crate::intrinsics::EvalContextExt as _;
 pub use crate::machine::{
     AllocExtra, DynMachineCallback, FrameExtra, MachineCallback, MemoryKind, MiriInterpCx,

src/tools/miri/src/shims/backtrace.rs

@@ -25,7 +25,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
 
         let frame_count = this.active_thread_stack().len();
 
-        this.write_scalar(Scalar::from_target_usize(frame_count.try_into().unwrap(), this), dest)
+        this.write_scalar(Scalar::from_target_usize(frame_count.to_u64(), this), dest)
     }
 
     fn handle_miri_get_backtrace(
@@ -70,7 +70,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
             }
             1 =>
                 for (i, ptr) in ptrs.into_iter().enumerate() {
-                    let offset = ptr_layout.size.checked_mul(i.try_into().unwrap(), this).unwrap();
+                    let offset = ptr_layout.size.checked_mul(i.to_u64(), this).unwrap();
 
                     let op_place = buf_place.offset(offset, ptr_layout, this)?;
 
@@ -158,11 +158,11 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
             }
             1 => {
                 this.write_scalar(
-                    Scalar::from_target_usize(name.len().try_into().unwrap(), this),
+                    Scalar::from_target_usize(name.len().to_u64(), this),
                     &this.project_field(dest, 0)?,
                 )?;
                 this.write_scalar(
-                    Scalar::from_target_usize(filename.len().try_into().unwrap(), this),
+                    Scalar::from_target_usize(filename.len().to_u64(), this),
                     &this.project_field(dest, 1)?,
                 )?;
             }