miri: layout should not affect CTFE checks (outside of validation) #55142
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RalfJung
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oli-obk
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Oct 17, 2018
| @@ -688,9 +688,6 @@ impl<'a, 'mir, 'tcx, M: Machine<'a, 'mir, 'tcx>> EvalContext<'a, 'mir, 'tcx, M> | |||
| rval: OpTy<'tcx, M::PointerTag>, | |||
| ) -> EvalResult<'tcx, (u128, usize)> { | |||
| trace!("read_discriminant_value {:#?}", rval.layout); | |||
| if rval.layout.abi.is_uninhabited() { | |||
| return err!(Unreachable); | |||
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Since this is unreachable (pun intended), can you change this into an assert?
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I am not sure if it is unreachable. But I am sure that the behavior we want is to treat such enums like all the others.
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gist: the code is unreachable right now, but probably not in the future. Also empty enums aren't special and we'll fail on attempting to read their discriminant, so everything is good.
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@bors r+ rollup |
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📌 Commit c31819b has been approved by |
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…li-obk miri: layout should not affect CTFE checks (outside of validation) Either the enum has no valid discriminant, then the code later will catch that; or it does, then we shouldn't error out so early (absent enforcing validity). Interestingly, the miri test suite still passes; my guess is we don't even get here for uninhabited types? r? @oli-obk
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Rollup of 18 pull requests Successful merges: - #54646 (improve documentation on std::thread::sleep) - #54933 (Cleanup the rest of codegen_llvm) - #54964 (Run both lldb and gdb tests) - #55016 (Deduplicate some code and compile-time values around vtables) - #55031 (Improve verify_llvm_ir config option) - #55050 (doc std::fmt: the Python inspiration is already mentioned in precedin…) - #55077 (rustdoc: Use dyn keyword when rendering dynamic traits) - #55080 (Detect if access to localStorage is forbidden by the user's browser) - #55090 (regression test for move out of borrow via pattern) - #55102 (resolve: Do not skip extern prelude during speculative resolution) - #55104 (Add test for #34229) - #55111 ([Rustc Book] Explain --cfg's arguments) - #55122 (Cleanup mir/borrowck) - #55127 (Remove HybridBitSet::dummy) - #55128 (Fix LLVMRustInlineAsmVerify return type mismatch) - #55142 (miri: layout should not affect CTFE checks (outside of validation)) - #55151 (Cleanup nll) - #55161 ([librustdoc] Disable spellcheck for search field)
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Either the enum has no valid discriminant, then the code later will catch that; or it does, then we shouldn't error out so early (absent enforcing validity).
Interestingly, the miri test suite still passes; my guess is we don't even get here for uninhabited types?
r? @oli-obk