Ensure that evaluating or validating a constant never reads from a static#67337
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Ensure that evaluating or validating a constant never reads from a static#67337bors merged 7 commits intorust-lang:masterfrom
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Oh I just realized this PR makes no sense. If the user points into the static, this PR won't detect that. We could poison |
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So if I recall correctly, in rust-lang/const-eval#17 (comment) and https://github.com/rust-lang/const-eval/blob/master/const.md#reading-statics, I also came to the conclusion that we want to guard accesses during execution, and not the final value. |
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That comment talks about not reading from (mutable) statics. I don't understand the connection to the final value not containing certain relocations.
Also, isn't code like this allowed? static FOO: i32 = 13;
const FOOPTR: &i32 = &FOO;So, I don't entirely understand how we even could backwards-compatibly forbid consts pointing to statics, and why we would want that? |
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No: |
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Hmm... I guess I went overboard when looking at it from the perspective of the comment, but just referencing a static is not allowed on stable, so this is what we want to forbid right now. |
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☔ The latest upstream changes (presumably #67485) made this pull request unmergeable. Please resolve the merge conflicts. |
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Dec 22, 2019
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Well, what this PR implement is not accessing a static. So the PR description is wrong, IMO. Except that, somehow, this also excludes referencing a static, and I am not sure why. |
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☔ The latest upstream changes (presumably #67540) made this pull request unmergeable. Please resolve the merge conflicts. |
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and some uses of it will be illegal forever (e.g. mutable or interior mutable statics)
Co-Authored-By: Ralf Jung <post@ralfj.de>
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The job Click to expand the log.I'm a bot! I can only do what humans tell me to, so if this was not helpful or you have suggestions for improvements, please ping or otherwise contact |
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Looking good! r=me with tests blessed. |
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@bors r=RalfJung |
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📌 Commit 87fea04 has been approved by |
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🌲 The tree is currently closed for pull requests below priority 100, this pull request will be tested once the tree is reopened |
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…t, r=RalfJung Ensure that evaluating or validating a constant never reads from a static r? @RalfJung as per rust-lang#66302 (comment) This does not yet address the fact that evaluation of a constant can read from a static (under unleash-miri)
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Rollup of 7 pull requests Successful merges: - #67337 (Ensure that evaluating or validating a constant never reads from a static) - #67543 (Add regression tests for fixed ICEs) - #67547 (Cleanup err codes) - #67551 (Add long error code explanation message for E0627) - #67561 (remove `description` from `Error` impls in docs) - #67569 (Clean up unsafety in char::encode_utf8) - #67572 (Use the chocolatey CDN directly to avoid the flaky API) Failed merges: r? @ghost
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r? @RalfJung
as per #66302 (comment)
This does not yet address the fact that evaluation of a constant can read from a static (under unleash-miri)