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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-17 12:02:58 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-17 12:02:58 +0000 |
commit | 698f8c2f01ea549d77d7dc3338a12e04c11057b9 (patch) | |
tree | 173a775858bd501c378080a10dca74132f05bc50 /src/tools/clippy/tests/ui/transmutes_expressible_as_ptr_casts.rs | |
parent | Initial commit. (diff) | |
download | rustc-698f8c2f01ea549d77d7dc3338a12e04c11057b9.tar.xz rustc-698f8c2f01ea549d77d7dc3338a12e04c11057b9.zip |
Adding upstream version 1.64.0+dfsg1.upstream/1.64.0+dfsg1
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to '')
-rw-r--r-- | src/tools/clippy/tests/ui/transmutes_expressible_as_ptr_casts.rs | 77 |
1 files changed, 77 insertions, 0 deletions
diff --git a/src/tools/clippy/tests/ui/transmutes_expressible_as_ptr_casts.rs b/src/tools/clippy/tests/ui/transmutes_expressible_as_ptr_casts.rs new file mode 100644 index 000000000..b9e446dc8 --- /dev/null +++ b/src/tools/clippy/tests/ui/transmutes_expressible_as_ptr_casts.rs @@ -0,0 +1,77 @@ +// run-rustfix +#![warn(clippy::transmutes_expressible_as_ptr_casts)] +// These two warnings currently cover the cases transmutes_expressible_as_ptr_casts +// would otherwise be responsible for +#![warn(clippy::useless_transmute)] +#![warn(clippy::transmute_ptr_to_ptr)] +#![allow(dead_code, unused_unsafe, clippy::borrow_as_ptr)] + +use std::mem::{size_of, transmute}; + +// rustc_typeck::check::cast contains documentation about when a cast `e as U` is +// valid, which we quote from below. +fn main() { + // We should see an error message for each transmute, and no error messages for + // the casts, since the casts are the recommended fixes. + + // e is an integer and U is *U_0, while U_0: Sized; addr-ptr-cast + let _ptr_i32_transmute = unsafe { transmute::<usize, *const i32>(usize::MAX) }; + let ptr_i32 = usize::MAX as *const i32; + + // e has type *T, U is *U_0, and either U_0: Sized ... + let _ptr_i8_transmute = unsafe { transmute::<*const i32, *const i8>(ptr_i32) }; + let _ptr_i8 = ptr_i32 as *const i8; + + let slice_ptr = &[0, 1, 2, 3] as *const [i32]; + + // ... or pointer_kind(T) = pointer_kind(U_0); ptr-ptr-cast + let _ptr_to_unsized_transmute = unsafe { transmute::<*const [i32], *const [u32]>(slice_ptr) }; + let _ptr_to_unsized = slice_ptr as *const [u32]; + // TODO: We could try testing vtable casts here too, but maybe + // we should wait until std::raw::TraitObject is stabilized? + + // e has type *T and U is a numeric type, while T: Sized; ptr-addr-cast + let _usize_from_int_ptr_transmute = unsafe { transmute::<*const i32, usize>(ptr_i32) }; + let _usize_from_int_ptr = ptr_i32 as usize; + + let array_ref: &[i32; 4] = &[1, 2, 3, 4]; + + // e has type &[T; n] and U is *const T; array-ptr-cast + let _array_ptr_transmute = unsafe { transmute::<&[i32; 4], *const [i32; 4]>(array_ref) }; + let _array_ptr = array_ref as *const [i32; 4]; + + fn foo(_: usize) -> u8 { + 42 + } + + // e is a function pointer type and U has type *T, while T: Sized; fptr-ptr-cast + let _usize_ptr_transmute = unsafe { transmute::<fn(usize) -> u8, *const usize>(foo) }; + let _usize_ptr_transmute = foo as *const usize; + + // e is a function pointer type and U is an integer; fptr-addr-cast + let _usize_from_fn_ptr_transmute = unsafe { transmute::<fn(usize) -> u8, usize>(foo) }; + let _usize_from_fn_ptr = foo as *const usize; +} + +// If a ref-to-ptr cast of this form where the pointer type points to a type other +// than the referenced type, calling `CastCheck::do_check` has been observed to +// cause an ICE error message. `do_check` is currently called inside the +// `transmutes_expressible_as_ptr_casts` check, but other, more specific lints +// currently prevent it from being called in these cases. This test is meant to +// fail if the ordering of the checks ever changes enough to cause these cases to +// fall through into `do_check`. +fn trigger_do_check_to_emit_error(in_param: &[i32; 1]) -> *const u8 { + unsafe { transmute::<&[i32; 1], *const u8>(in_param) } +} + +#[repr(C)] +struct Single(u64); + +#[repr(C)] +struct Pair(u32, u32); + +fn cannot_be_expressed_as_pointer_cast(in_param: Single) -> Pair { + assert_eq!(size_of::<Single>(), size_of::<Pair>()); + + unsafe { transmute::<Single, Pair>(in_param) } +} |