[beta] Revert c unwind abi PR #84672
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Some changes occured to rustc_codegen_cranelift cc @bjorn3 |
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@bors r+ rollup=never |
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⌛ Testing commit 6033cca with merge 56912a4aca04886881e70a24dc9ba1035bcd417a... |
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160 errors, I think all from Miri, that look like this: |
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closing in favor of PR #84722. (See description of that PR for why; in short, fixing the Miri fallout would have been too painful.) |
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…t-of-84158, r=Mark-Simulacrum backport: move new c abi abort behavior behind feature gate This is a backport of PR rust-lang#84158 to the beta branch. The original T-compiler plan was to revert PR rust-lang#76570 in its entirety, as was attempted in PR rust-lang#84672. But the revert did not go smoothly (details below). Therefore, we are backporting PR rust-lang#84158 instead, which was our established backup plan if a revert did not go smoothly. I have manually confirmed that this backport fixes the luajit issue described on issue rust-lang#83541 <details> <summary>Click for details as to why revert of PR rust-lang#76570 did not go smoothly.</summary> It turns out that Miri had been subsequently updated to reflect changes to `rustc_target` that landed in PR rust-lang#76570. This meant that the attempt to land PR rust-lang#84672 broke Miri builds. Normally we allow tools to break when landing PR's (and just expect follow-up PR's to fix the tools), but we don't allow it for tools in the run-up to a release. (We shouldn't be using that uniform policy for all tools. Miri should be allow to break during the week before a release; but currently we cannot express that, due to issue rust-lang#74709.) Therefore, its a lot of pain to try to revert PR rust-lang#76570. And we're going with the backup plan. </details> Original commit message follows: ---- *Background* In rust-lang#76570, new ABI strings including `C-unwind` were introduced. Their behavior is specified in RFC 2945 <sup>[1]</sup>. However, it was reported in the #ffi-unwind stream of the Rust community Zulip that this had altered the way that `extern "C"` functions behaved even when the `c_unwind` feature gate was not active. <sup>[2]</sup> *Overview* This makes a small patch to `rustc_mir_build::build::should_abort_on_panic`, so that the same behavior from before is in place when the `c_unwind` gate is not active. `rustc_middle::ty::layout::fn_can_unwind` is not touched, as the visible behavior should not differ before/after rust-lang#76570. <sup>[3]</sup> ### Footnotes 1.: https://github.com/rust-lang/rfcs/blob/master/text/2945-c-unwind-abi.md 2.: https://rust-lang.zulipchat.com/#narrow/stream/210922-project-ffi-unwind/topic/Is.20unwinding.20through.20extern.20C.20UB.3F/near/230112325 3.: https://github.com/rust-lang/rust/pull/76570/files#diff-b0320c2b8868f325d83c027fc5d71732636e9763551e35895488f30fe057c6e9L2599-R2617 [1]: https://github.com/rust-lang/rfcs/blob/master/text/2945-c-unwind-abi.md [2]: https://rust-lang.zulipchat.com/#narrow/stream/210922-project-ffi-unwind/topic/Is.20unwinding.20through.20extern.20C.20UB.3F/near/230112325 [3]: https://github.com/rust-lang/rust/pull/76570/files#diff-b0320c2b8868f325d83c027fc5d71732636e9763551e35895488f30fe057c6e9L2599-R2617
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As discussed in #84158 (comment), the compiler team decided we would first try to revert PR #76570 on beta in order to ensure that things like issue #83541 do not hit stable.
This PR is the aforementioned reversion of PR #76570.