diff --git a/compiler/rustc_const_eval/src/util/caller_location.rs b/compiler/rustc_const_eval/src/util/caller_location.rs index 671214002a0d8..a51a5751dc47c 100644 --- a/compiler/rustc_const_eval/src/util/caller_location.rs +++ b/compiler/rustc_const_eval/src/util/caller_location.rs @@ -22,13 +22,14 @@ fn alloc_caller_location<'tcx>( assert!(!filename.as_str().as_bytes().contains(&0)); let loc_details = ecx.tcx.sess.opts.unstable_opts.location_detail; - let file_wide_ptr = { + let filename = { let filename = if loc_details.file { filename.as_str() } else { "" }; let filename_with_nul = filename.to_owned() + "\0"; // This can fail if rustc runs out of memory right here. Trying to emit an error would be // pointless, since that would require allocating more memory than these short strings. let file_ptr = ecx.allocate_bytes_dedup(filename_with_nul.as_bytes()).unwrap(); - Immediate::new_slice(file_ptr.into(), filename_with_nul.len().try_into().unwrap(), ecx) + let file_len = u64::try_from(filename.len()).unwrap(); + Immediate::new_slice(file_ptr.into(), file_len, ecx) }; let line = if loc_details.line { Scalar::from_u32(line) } else { Scalar::from_u32(0) }; let col = if loc_details.column { Scalar::from_u32(col) } else { Scalar::from_u32(0) }; @@ -42,11 +43,8 @@ fn alloc_caller_location<'tcx>( let location = ecx.allocate(loc_layout, MemoryKind::CallerLocation).unwrap(); // Initialize fields. - ecx.write_immediate( - file_wide_ptr, - &ecx.project_field(&location, FieldIdx::from_u32(0)).unwrap(), - ) - .expect("writing to memory we just allocated cannot fail"); + ecx.write_immediate(filename, &ecx.project_field(&location, FieldIdx::from_u32(0)).unwrap()) + .expect("writing to memory we just allocated cannot fail"); ecx.write_scalar(line, &ecx.project_field(&location, FieldIdx::from_u32(1)).unwrap()) .expect("writing to memory we just allocated cannot fail"); ecx.write_scalar(col, &ecx.project_field(&location, FieldIdx::from_u32(2)).unwrap()) diff --git a/library/core/src/panic/location.rs b/library/core/src/panic/location.rs index f1eedede8aab9..1e950d6e4988b 100644 --- a/library/core/src/panic/location.rs +++ b/library/core/src/panic/location.rs @@ -1,5 +1,6 @@ use crate::ffi::CStr; use crate::fmt; +use crate::marker::PhantomData; /// A struct containing information about the location of a panic. /// @@ -33,14 +34,13 @@ use crate::fmt; #[derive(Copy, Clone, Eq, Hash, Ord, PartialEq, PartialOrd)] #[stable(feature = "panic_hooks", since = "1.10.0")] pub struct Location<'a> { - // Note: this filename will have exactly one nul byte at its end, but otherwise - // it must never contain interior nul bytes. This is relied on for the conversion - // to `CStr` below. - // - // The prefix of the string without the trailing nul byte will be a regular UTF8 `str`. - file_bytes_with_nul: &'a [u8], + // A raw pointer is used rather than a reference because the pointer is valid for one more byte + // than the length stored in this pointer; the additional byte is the NUL-terminator used by + // `Location::file_with_nul`. + filename: *const str, line: u32, col: u32, + _filename: PhantomData<&'a str>, } #[stable(feature = "panic_hooks", since = "1.10.0")] @@ -143,10 +143,8 @@ impl<'a> Location<'a> { #[stable(feature = "panic_hooks", since = "1.10.0")] #[rustc_const_stable(feature = "const_location_fields", since = "1.79.0")] pub const fn file(&self) -> &str { - let str_len = self.file_bytes_with_nul.len() - 1; - // SAFETY: `file_bytes_with_nul` without the trailing nul byte is guaranteed to be - // valid UTF8. - unsafe { crate::str::from_raw_parts(self.file_bytes_with_nul.as_ptr(), str_len) } + // SAFETY: The filename is valid. + unsafe { &*self.filename } } /// Returns the name of the source file as a nul-terminated `CStr`. @@ -157,9 +155,15 @@ impl<'a> Location<'a> { #[unstable(feature = "file_with_nul", issue = "141727")] #[inline] pub const fn file_with_nul(&self) -> &CStr { - // SAFETY: `file_bytes_with_nul` is guaranteed to have a trailing nul byte and no - // interior nul bytes. - unsafe { CStr::from_bytes_with_nul_unchecked(self.file_bytes_with_nul) } + // SAFETY: The filename is valid for `filename_len+1` bytes, so this addition can't + // overflow. + let cstr_len = unsafe { crate::mem::size_of_val_raw(self.filename).unchecked_add(1) }; + + // SAFETY: The filename is valid for `filename_len+1` bytes. + let slice = unsafe { crate::slice::from_raw_parts(self.filename as *const _, cstr_len) }; + + // SAFETY: The filename is guaranteed to have a trailing nul byte and no interior nul bytes. + unsafe { CStr::from_bytes_with_nul_unchecked(slice) } } /// Returns the line number from which the panic originated. @@ -220,3 +224,8 @@ impl fmt::Display for Location<'_> { write!(formatter, "{}:{}:{}", self.file(), self.line, self.col) } } + +#[stable(feature = "panic_hooks", since = "1.10.0")] +unsafe impl Send for Location<'_> {} +#[stable(feature = "panic_hooks", since = "1.10.0")] +unsafe impl Sync for Location<'_> {}