Fix ICE on offsetted ZST pointer #147576
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Fix ICE on offsetted ZST pointer #147576
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Some changes occurred in compiler/rustc_codegen_gcc Some changes occurred in compiler/rustc_codegen_cranelift cc @bjorn3 |
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| const A: *const () = (&() as *const ()).wrapping_byte_add(2); | ||
| const B: *const () = (&Foo as *const _ as *const ()).wrapping_byte_add(2); | ||
| const C: *const () = (&Foo as *const _ as *const ()).wrapping_byte_add(usize::MAX); | ||
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I don't understand this at all. Can you explain a little? Perhaps this test needs an explanatory comment at the top?
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I extended with a longer comment, but without a bit more detail on what you're confused by it's hard to know whether it helps. Let me know.
A grep for `const_usize.*align` found the same code copied to rustc_codegen_gcc but I don't see other cases where we get this wrong.
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I'm not sure this is the right fix, but it's simple enough and does roughly what I'd expect. Like with the previous optimization to codegen usize rather than a zero-sized static, there's no guarantee that we continue returning a particular value from the offsetting.
A grep for
const_usize.*alignfound the same code copied to rustc_codegen_gcc and cranelift but a quick skim didn't find other cases of similar 'optimization'. That said, I'm not convinced I caught everything, it's not trivial to search for this.Closes #147516