3aa14e3b2e
In its first step of computing transmutability, `rustc_transmutability` constructs a byte-level representation of type layout (`Tree`). Previously, this representation was computed for ADTs by inspecting the ADT definition and performing our own layout computations. This process was error-prone, verbose, and limited our ability to analyze many types (particularly default-repr types). In this PR, we instead construct `Tree`s from `rustc_target::abi::Layout`s. This helps ensure that layout optimizations are reflected our analyses, and increases the kinds of types we can now analyze, including: - default repr ADTs - transparent unions - `UnsafeCell`-containing types Overall, this PR expands the expressvity of `rustc_transmutability` to be much closer to the transmutability analysis performed by miri. Future PRs will work to close the remaining gaps (e.g., support for `Box`, raw pointers, `NonZero*`, coroutines, etc.).
34 lines
1.6 KiB
Plaintext
34 lines
1.6 KiB
Plaintext
error[E0277]: `&u8` cannot be safely transmuted into `&UnsafeCell<u8>`
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--> $DIR/unsafecell.rs:27:50
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LL | assert::is_maybe_transmutable::<&'static u8, &'static UnsafeCell<u8>>();
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| ^^^^^^^^^^^^^^^^^^^^^^^ the trait `Freeze` is not implemented for `&'static UnsafeCell<u8>`
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note: required by a bound in `is_maybe_transmutable`
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--> $DIR/unsafecell.rs:12:14
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LL | pub fn is_maybe_transmutable<Src, Dst>()
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| --------------------- required by a bound in this function
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LL | where
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LL | Dst: BikeshedIntrinsicFrom<Src, { Assume::SAFETY }>
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `is_maybe_transmutable`
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error[E0277]: `&UnsafeCell<u8>` cannot be safely transmuted into `&UnsafeCell<u8>`
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--> $DIR/unsafecell.rs:29:62
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LL | assert::is_maybe_transmutable::<&'static UnsafeCell<u8>, &'static UnsafeCell<u8>>();
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| ^^^^^^^^^^^^^^^^^^^^^^^ the trait `Freeze` is not implemented for `&'static UnsafeCell<u8>`
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note: required by a bound in `is_maybe_transmutable`
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--> $DIR/unsafecell.rs:12:14
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LL | pub fn is_maybe_transmutable<Src, Dst>()
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| --------------------- required by a bound in this function
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LL | where
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LL | Dst: BikeshedIntrinsicFrom<Src, { Assume::SAFETY }>
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `is_maybe_transmutable`
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error: aborting due to 2 previous errors
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For more information about this error, try `rustc --explain E0277`.
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