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make NOP dyn casts not require anything about the vtable #100208

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merged 1 commit into from
Aug 19, 2022

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RalfJung
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@RalfJung RalfJung commented Aug 6, 2022

As suggested on Zulip. This matches what the codegen backends already do, and what Miri did do until #99420 when I made it super extra paranoid.

@rustbot rustbot added the T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. label Aug 6, 2022
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rustbot commented Aug 6, 2022

Some changes occurred in compiler/rustc_codegen_cranelift

cc @bjorn3

Some changes occurred to the CTFE / Miri engine

cc @rust-lang/miri

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r? @petrochenkov

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@rust-highfive rust-highfive added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Aug 6, 2022
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I'm not familiar with this part of the compiler, but the change seems simple enough.
r=me unless there are some open questions about semantics of this operation.
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@rustbot rustbot added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Aug 7, 2022
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RalfJung commented Aug 7, 2022

This undoes a thing we recently changed, so I think it is fairly harmless. It's also a rather small low-priority PR though so we can wait for @bjorn3 or @oli-obk to take a look.

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No reply, so I guess let's just land this -- we can always adjust later.

@bors r=petrochenkov

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bors commented Aug 18, 2022

📌 Commit 3c8563a has been approved by petrochenkov

It is now in the queue for this repository.

@bors bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Aug 18, 2022
bors added a commit to rust-lang-ci/rust that referenced this pull request Aug 19, 2022
Rollup of 9 pull requests

Successful merges:

 - rust-lang#99576 (Do not allow `Drop` impl on foreign fundamental types)
 - rust-lang#100081 (never consider unsafe blocks unused if they would be required with deny(unsafe_op_in_unsafe_fn))
 - rust-lang#100208 (make NOP dyn casts not require anything about the vtable)
 - rust-lang#100494 (Cleanup rustdoc themes)
 - rust-lang#100522 (Only check the `DefId` for the recursion check in MIR inliner.)
 - rust-lang#100592 (Manually implement Debug for ImportKind.)
 - rust-lang#100598 (Don't fix builtin index when Where clause is found)
 - rust-lang#100721 (Add diagnostics lints to `rustc_type_ir` module)
 - rust-lang#100731 (rustdoc: count deref and non-deref as same set of used methods)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup
@bors bors merged commit c4707ff into rust-lang:master Aug 19, 2022
@rustbot rustbot added this to the 1.65.0 milestone Aug 19, 2022
bors added a commit to rust-lang/miri that referenced this pull request Aug 20, 2022
allow NOP-casts with mismatching vtables

The Miri side of rust-lang/rust#100208.
@RalfJung RalfJung deleted the dyn-upcast-nop branch August 21, 2022 12:52
bjorn3 pushed a commit to bjorn3/rust that referenced this pull request Aug 24, 2022
…enkov

make NOP dyn casts not require anything about the vtable

As suggested [on Zulip](https://rust-lang.zulipchat.com/#narrow/stream/144729-t-types/topic/dyn-upcasting.20stabilization/near/292151439). This matches what the codegen backends already do, and what Miri did do until rust-lang#99420 when I made it super extra paranoid.
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