feat: disallow non-deterministic iteration order#3
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kevaundray wants to merge 4 commits intoparadigmxyz:mainfrom
Open
feat: disallow non-deterministic iteration order#3kevaundray wants to merge 4 commits intoparadigmxyz:mainfrom
kevaundray wants to merge 4 commits intoparadigmxyz:mainfrom
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kevaundray
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Feb 14, 2026
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| // TODO: `reveal_witness` from reth uses B256Map. We would need to change it from | ||
| // there first. | ||
| #[allow(clippy::disallowed_types)] | ||
| use alloy_primitives::map::B256Map; |
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This would need to be fixed in reth
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This can be somewhat tricky because the change would need to also happen in dependencies (mainly reth and alloy) -- HashMap is technically okay to use, but one would just need to ensure that the iteration order is deterministic. This is already done in some places with |
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Problem
Some zkVMs run/execute the program multiple times while proving. For example, this can be done once with the emulator and then another time with an assembly generated version of the emulator. These two runs for correctness reasons should match, however since
HashMap::iteris non-deterministic, this is not the case.Moreover, deterministic runs make it a lot easier to debug programs.
For why HashMap is non-deterministic, one can see here
Suggested solution
Replace all usages of HashMap with IndexMap or BTreeMap. These implementations have stable iteration orders. Also added a clippy lint to ensure that those types cannot be used in this crate.
Notes
This is somewhat a fairly common issue in code that requires/desire deterministic builds like compilers, see here and here
This PR would only partially solve the issue since some crates in reth also use HashMap