Fix vtable size check for never #422
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danielsn
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Aug 12, 2021
| let check = Expr::eq(Expr::object_size(temp_var.address_of()), vt_size.clone()); | ||
| let assert_msg = format!("Correct CBMC vtable size for {:?}", operand_type.kind()); | ||
| let cbmc_size = if ty.clone().is_empty() { | ||
| // CBMC errors on passing a pointer to void to __CPROVER_OBJECT_SIZE, so just pass 0 |
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Are we guaranteed this is correct? Or is this a temporary hack?
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Added an assert for the Never case and a link showing that we do know the size is 0. This way, will get a more detailed error if this fails again for a different type.
danielsn
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Description of changes:
With some combinations of traits and the Never type, the CBMC-time sanity check assert fails because you cannot take an object size of void.
Breaking this into its own PR to land since it's coming up outside of drop work.
Resolved issues:
Resolves #421
Call-outs:
Working on getting a small example now, but a little difficulty since this happens in external crate code.
Testing:
Existing tests, working on minimal example.
No.
Checklist
By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 and MIT licenses.