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Empowering everyone to build reliable and efficient software.
9a48bd2f21
typestate now drops constraints correctly in the post-state of a move expression or a declaration whose op is a move. It doesn't yet drop constraints mentioning variables that get updated. To do this, I had to change typestate to use trit-vectors instead of bit-vectors, because for every constraint, there are three possible values: known-to-be-false (e.g. after x <- y, init(y) is known-to-be-false), known-to-be-true, and unknown. Before, we conflated known-to-be-false with unknown. But move requires them to be treated differently. Consider: (program a) (a1) x = 1; (a2) y <- x; (a3) log x; (program b) (b1) x = 1; (b2) y <- z; (b3) log x; With only two values, the postcondition of statement a2 for constraint init(x) is the same as that of b2: 0. But in (a2)'s postcondition, init(x) *must* be false, but in (b2)'s condition, it's just whatever it was in the postcondition of the preceding statement. |
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| .gitignore | ||
| AUTHORS.txt | ||
| configure | ||
| LICENSE.txt | ||
| Makefile.in | ||
| README | ||
This is a compiler and suite of associated libraries and documentation for the Rust programming language. See LICENSE.txt for terms of copyright and redistribution. See http://github.com/graydon/rust for current development page.