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fix: Fix zizmor handling of numbers in expressions - #1628
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| /// Parse a string into a number following GitHub Actions coercion rules. | ||
| /// | ||
| /// The string is trimmed and then parsed as: | ||
| /// - Empty/whitespace-only → 0.0 | ||
| /// - `0x` prefix → hexadecimal integer | ||
| /// - `0o` prefix → octal integer | ||
| /// - Otherwise → standard float parsing (decimal, scientific notation, | ||
| /// Infinity, -Infinity, NaN) |
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Hmm, are octals and hex numbers actually supported by GHA? The docs are naturally unclear:
(The docs for number say "any JSON number," which would need to be base 10. But then the example immediately below shows a hex number, naturally.)
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(If so, there's a possibility we need to update the Pest grammar as well.)
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Based on this, I think GitHub actually just uses JS's Number ctor:
...so naturally we have all of the JS coercion rules:
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I’m on my phone right now but the workflow here shows that it does support octal and hexadecimal : https://github.com/trail-of-forks/zizmor/actions/runs/22103104435/job/63877999605
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Gotcha. In that case I think we do (unfortunately) need to ensure our grammar handles those, plus implement the full JS coercion/number literal rules.
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Ugh, what the hell. I don't really understand where GitHub Actions number semantics come from, then. I think we need to fully understand how their own parser/evaluator works here before we can address this.
Would you mind going through that source tree and trying to understand what they're actually doing?
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Found it here: https://github.com/actions/runner/blob/main/src/Sdk/Expressions/Sdk/ExpressionUtility.cs#L223
I had an AI extract this function, create a binary, and reproduce the workflow result!
I'm working on aligning our parse_number_from_str on their function.
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I think this new implementation is aligned with the GH Action Runner one, and it matches the behavior of my test run here
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Thanks! I'll try and take a look today.
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Looks good to me, thanks @DarkaMaul! I think the pest grammar itself still needs to be updated too, right now it doesn't allow hex, octal, or exponent forms in the grammar itself.
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woodruffw
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Thanks @DarkaMaul, nice work!
Please add a release-notes entry and this'll be good to go 🙂
(Normally I'd push up on your branch but this is on trail-of-forks, so there's the GitHub org 3P PR bug blocking it.)
# Conflicts: # docs/release-notes.md
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Mandatory: This PR corresponds to an issue (if not, please create
one first) ( [BUG]: Incorrect evaluation of number in expressions #1625)
I hereby disclose the use of an LLM or other AI coding assistant in the
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Summary
The PR fixes
zizmorhandling of numbers in expression to align it with GitHub Action expression parser.Test Plan
This change is self contained with multiple tests. The only problem is that we have no easy way of tracking GitHub changes to their expression parser.