some fixes for clashing_extern_declarations lint #130301
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| b_layout, | ||
| a_layout == b_layout | ||
| ); | ||
| Ok(a_layout == b_layout) |
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I ended up removing this logic entirely. It is never sound to do this, and none of the tests relied on this, so the motivation is unclear.
If this warns for too many real-world cases, people will tell us. :)
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| @@ -311,9 +311,9 @@ fn structurally_same_type_impl<'tcx>( | |||
| }, | |||
| ) | |||
| } | |||
| (Array(a_ty, a_const), Array(b_ty, b_const)) => { | |||
| // For arrays, we also check the constness of the type. | |||
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Thanks for fixing this and I agree with the changes, even if they cause the lint to fire more aggressively it's like... objectively more correct. @bors r+ |
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…iaskrgr Rollup of 6 pull requests Successful merges: - rust-lang#129320 (Fix crash when labeling arguments for call_once and friends) - rust-lang#130266 (target: default to the medium code model on LoongArch targets) - rust-lang#130297 (Dataflow cleanups) - rust-lang#130299 (Add set_dcx to ParseSess) - rust-lang#130301 (some fixes for clashing_extern_declarations lint) - rust-lang#130305 (Clippy: consider msrv for const context for const_float_bits_conv) r? `@ghost` `@rustbot` modify labels: rollup
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…iaskrgr Rollup of 6 pull requests Successful merges: - rust-lang#129320 (Fix crash when labeling arguments for call_once and friends) - rust-lang#130266 (target: default to the medium code model on LoongArch targets) - rust-lang#130297 (Dataflow cleanups) - rust-lang#130299 (Add set_dcx to ParseSess) - rust-lang#130301 (some fixes for clashing_extern_declarations lint) - rust-lang#130305 (Clippy: consider msrv for const context for const_float_bits_conv) r? `@ghost` `@rustbot` modify labels: rollup
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Rollup merge of rust-lang#130301 - RalfJung:clashing_extern_declarations, r=compiler-errors some fixes for clashing_extern_declarations lint There were two issues with the clashing_extern_declarations lint: - It would accept non-`repr(C)` structs as compatible with each other by comparing their fields in declaration order, but the fields could have different memory order (and with `-Zrandomize-layout`, this can really happen). - It would accept two types as compatible if `compare_layouts` returns `true`, but that function actually just compared the *ABI*, not the fully layout -- and all sized structs with more than 2 fields have the same ABI (`Abi::Aggregate`), so this missed a *lot* of cases. We don't currently have a clear spec for what we *want* to consider "clashing" and what is fine, so I otherwise kept the original logic. I hope to have a t-lang discussion about this at some point. But meanwhile, these changes seem like clear bugfixes.
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There were two issues with the clashing_extern_declarations lint:
repr(C)structs as compatible with each other by comparing their fields in declaration order, but the fields could have different memory order (and with-Zrandomize-layout, this can really happen).compare_layoutsreturnstrue, but that function actually just compared the ABI, not the fully layout -- and all sized structs with more than 2 fields have the same ABI (Abi::Aggregate), so this missed a lot of cases.We don't currently have a clear spec for what we want to consider "clashing" and what is fine, so I otherwise kept the original logic. I hope to have a t-lang discussion about this at some point. But meanwhile, these changes seem like clear bugfixes.