Auto merge of rust-lang#3694 - southball:fix/use_strict_ops_instead_of_checked_ops, r=RalfJung

Use strict ops instead of checked ops

## What

Replace `checked_add(...).unwrap()` with `strict_add(...)`, etc.

Resolves rust-lang#3668.

Author: bors

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

@@ -97,7 +97,7 @@ impl GlobalStateInner {
 fn align_addr(addr: u64, align: u64) -> u64 {
     match addr % align {
         0 => addr,
-        rem => addr.checked_add(align).unwrap() - rem,
+        rem => addr.strict_add(align) - rem,
     }
 }
 

src/tools/miri/src/eval.rs

@@ -303,7 +303,7 @@ pub fn create_ecx<'tcx>(
         let mut argvs = Vec::<Immediate<Provenance>>::with_capacity(config.args.len());
         for arg in config.args.iter() {
             // Make space for `0` terminator.
-            let size = u64::try_from(arg.len()).unwrap().checked_add(1).unwrap();
+            let size = u64::try_from(arg.len()).unwrap().strict_add(1);
             let arg_type = Ty::new_array(tcx, tcx.types.u8, size);
             let arg_place =
                 ecx.allocate(ecx.layout_of(arg_type)?, MiriMemoryKind::Machine.into())?;

src/tools/miri/src/helpers.rs

@@ -973,7 +973,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
         // If `size` is smaller or equal than `bytes.len()`, writing `bytes` plus the required null
         // terminator to memory using the `ptr` pointer would cause an out-of-bounds access.
         let string_length = u64::try_from(c_str.len()).unwrap();
-        let string_length = string_length.checked_add(1).unwrap();
+        let string_length = string_length.strict_add(1);
         if size < string_length {
             return Ok((false, string_length));
         }
@@ -1037,7 +1037,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
         // If `size` is smaller or equal than `bytes.len()`, writing `bytes` plus the required
         // 0x0000 terminator to memory would cause an out-of-bounds access.
         let string_length = u64::try_from(wide_str.len()).unwrap();
-        let string_length = string_length.checked_add(1).unwrap();
+        let string_length = string_length.strict_add(1);
         if size < string_length {
             return Ok((false, string_length));
         }
@@ -1406,7 +1406,7 @@ pub(crate) fn windows_check_buffer_size((success, len): (bool, u64)) -> u32 {
     if success {
         // If the function succeeds, the return value is the number of characters stored in the target buffer,
         // not including the terminating null character.
-        u32::try_from(len.checked_sub(1).unwrap()).unwrap()
+        u32::try_from(len.strict_sub(1)).unwrap()
     } else {
         // If the target buffer was not large enough to hold the data, the return value is the buffer size, in characters,
         // required to hold the string and its terminating null character.

src/tools/miri/src/shims/foreign_items.rs

@@ -402,7 +402,7 @@ trait EvalContextExtPriv<'tcx>: crate::MiriInterpCxExt<'tcx> {
                 });
                 let (_, addr) = ptr.into_parts(); // we know the offset is absolute
                 // Cannot panic since `align` is a power of 2 and hence non-zero.
-                if addr.bytes().checked_rem(align.bytes()).unwrap() != 0 {
+                if addr.bytes().strict_rem(align.bytes()) != 0 {
                     throw_unsup_format!(
                         "`miri_promise_symbolic_alignment`: pointer is not actually aligned"
                     );
@@ -714,7 +714,7 @@ trait EvalContextExtPriv<'tcx>: crate::MiriInterpCxExt<'tcx> {
                 // That is probably overly cautious, but there also is no fundamental
                 // reason to have `strcpy` destroy pointer provenance.
                 // This reads at least 1 byte, so we are already enforcing that this is a valid pointer.
-                let n = this.read_c_str(ptr_src)?.len().checked_add(1).unwrap();
+                let n = this.read_c_str(ptr_src)?.len().strict_add(1);
                 this.mem_copy(ptr_src, ptr_dest, Size::from_bytes(n), true)?;
                 this.write_pointer(ptr_dest, dest)?;
             }

src/tools/miri/src/shims/time.rs

@@ -165,7 +165,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
                 ("tm_hour", dt.hour().into()),
                 ("tm_mday", dt.day().into()),
                 ("tm_mon", dt.month0().into()),
-                ("tm_year", dt.year().checked_sub(1900).unwrap().into()),
+                ("tm_year", dt.year().strict_sub(1900).into()),
                 ("tm_wday", dt.weekday().num_days_from_sunday().into()),
                 ("tm_yday", dt.ordinal0().into()),
                 ("tm_isdst", tm_isdst),

src/tools/miri/src/shims/unix/env.rs

@@ -81,10 +81,8 @@ impl<'tcx> UnixEnvVars<'tcx> {
             return Ok(None);
         };
         // The offset is used to strip the "{name}=" part of the string.
-        let var_ptr = var_ptr.offset(
-            Size::from_bytes(u64::try_from(name.len()).unwrap().checked_add(1).unwrap()),
-            ecx,
-        )?;
+        let var_ptr = var_ptr
+            .offset(Size::from_bytes(u64::try_from(name.len()).unwrap().strict_add(1)), ecx)?;
         Ok(Some(var_ptr))
     }
 

src/tools/miri/src/shims/unix/fd.rs

@@ -240,7 +240,7 @@ impl FdTable {
         let new_fd = candidate_new_fd.unwrap_or_else(|| {
             // find_map ran out of BTreeMap entries before finding a free fd, use one plus the
             // maximum fd in the map
-            self.fds.last_key_value().map(|(fd, _)| fd.checked_add(1).unwrap()).unwrap_or(min_fd)
+            self.fds.last_key_value().map(|(fd, _)| fd.strict_add(1)).unwrap_or(min_fd)
         });
 
         self.fds.try_insert(new_fd, file_handle).unwrap();

src/tools/miri/src/shims/unix/socket.rs

@@ -116,7 +116,7 @@ impl FileDescription for SocketPair {
         };
         let mut writebuf = writebuf.borrow_mut();
         let data_size = writebuf.buf.len();
-        let available_space = MAX_SOCKETPAIR_BUFFER_CAPACITY.checked_sub(data_size).unwrap();
+        let available_space = MAX_SOCKETPAIR_BUFFER_CAPACITY.strict_sub(data_size);
         if available_space == 0 {
             if self.is_nonblock {
                 // Non-blocking socketpair with a full buffer.

src/tools/miri/src/shims/windows/foreign_items.rs

@@ -647,7 +647,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
                     // If the function succeeds, the return value is the length of the string that
                     // is copied to the buffer, in characters, not including the terminating null
                     // character.
-                    this.write_int(size_needed.checked_sub(1).unwrap(), dest)?;
+                    this.write_int(size_needed.strict_sub(1), dest)?;
                 } else {
                     // If the buffer is too small to hold the module name, the string is truncated
                     // to nSize characters including the terminating null character, the function
@@ -689,7 +689,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
                     throw_unsup_format!("FormatMessageW: buffer not big enough");
                 }
                 // The return value is the number of characters stored *excluding* the null terminator.
-                this.write_int(length.checked_sub(1).unwrap(), dest)?;
+                this.write_int(length.strict_sub(1), dest)?;
             }
 
             // Incomplete shims that we "stub out" just to get pre-main initialization code to work.

src/tools/miri/src/shims/windows/handle.rs

@@ -74,7 +74,7 @@ impl Handle {
     /// None of this layout is guaranteed to applications by Windows or Miri.
     fn to_packed(self) -> u32 {
         let disc_size = Self::packed_disc_size();
-        let data_size = u32::BITS.checked_sub(disc_size).unwrap();
+        let data_size = u32::BITS.strict_sub(disc_size);
 
         let discriminant = self.discriminant();
         let data = self.data();
@@ -103,7 +103,7 @@ impl Handle {
     /// see docs for `to_packed`
     fn from_packed(handle: u32) -> Option<Self> {
         let disc_size = Self::packed_disc_size();
-        let data_size = u32::BITS.checked_sub(disc_size).unwrap();
+        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