Currently we pick "weird" numbers like `1114112` for `None::<char>`. While that's not *wrong*, it's kinda *unnatural* -- a human wouldn't make that choice.
This PR instead picks `-1` for thinge like `None::<char>` -- like clang's `WEOF` -- and `None::<bool>` and such.
Any enums with more than one niched value (so not `Result` nor `Option`) remain as they were before.
Moreover, dereference `ty_layout.align` for `#[rustc_dump_layout(align)]`
to render `align: Align($N bytes)` instead of `align: AbiAlign { abi: Align($N bytes) }`
which contains the same amount of information but it more concise and legible.
All usages of `memory_index` start by calling `invert_bijective_mapping`, so
storing the inverted mapping directly saves some work and simplifies the code.
`panic!` does not print any identifying information for threads that are
unnamed. However, in many cases, the thread ID can be determined.
This changes the panic message from something like this:
thread '<unnamed>' panicked at src/main.rs:3:5:
explicit panic
To something like this:
thread '<unnamed>' (0xff9bf) panicked at src/main.rs:3:5:
explicit panic
Stack overflow messages are updated as well.
This change applies to both named and unnamed threads. The ID printed is
the OS integer thread ID rather than the Rust thread ID, which should
also be what debuggers print.
As a temporary measure while a proper fix for
`tests/ui/sized-hierarchy/incomplete-inference-issue-143992.rs`
is implemented, make `MetaSized` obligations always hold. In effect,
temporarily reverting the `sized_hierarchy` feature. This is a small
change that can be backported.
`tests/ui`: A New Order [21/N]
> [!NOTE]
>
> Intermediate commits are intended to help review, but will be squashed prior to merge.
Some `tests/ui/` housekeeping, to trim down number of tests directly under `tests/ui/`. Part of rust-lang/rust#133895.
r? `@tgross35`
In PR 90877 T-lang decided not to remove `intrinsics::pref_align_of`.
However, the intrinsic and its supporting code
1. is a nightly feature, so can be removed at compiler/libs discretion
2. requires considerable effort in the compiler to support, as it
necessarily complicates every single site reasoning about alignment
3. has been justified based on relevance to codegen, but it is only a
requirement for C++ (not C, not Rust) stack frame layout for AIX,
in ways Rust would not consider even with increased C++ interop
4. is only used by rustc to overalign some globals, not correctness
5. can be adequately replaced by other rules for globals, as it mostly
affects alignments for a few types under 16 bytes of alignment
6. has only one clear benefactor: automating C -> Rust translation
for GNU extensions like `__alignof`
7. such code was likely intended to be `alignof` or `_Alignof`,
because the GNU extension is a "false friend" of the C keyword,
which makes the choice to support such a mapping very questionable
8. makes it easy to do incorrect codegen in the compiler by its mere
presence as usual Rust rules of alignment (e.g. `size == align * N`)
do not hold with preferred alignment
The implementation is clearly damaging the code quality of the compiler.
Thus it is within the compiler team's purview to simply rip it out.
If T-lang wishes to have this intrinsic restored for c2rust's benefit,
it would have to use a radically different implementation that somehow
does not cause internal incorrectness.
Until then, remove the intrinsic and its supporting code, as one tool
and an ill-considered GCC extension cannot justify risking correctness.
Because we touch a fair amount of the compiler to change this at all,
and unfortunately the duplication of AbiAndPrefAlign is deep-rooted,
we keep an "AbiAlign" type which we can wean code off later.
Scott McMurray