Non-deterministic behavior with `auto_detect_solc`

[fubhy]

Component

Forge

Have you ensured that all of these are up to date?

• [X] Foundry
• [X] Foundryup

What version of Foundry are you on?

forge 0.2.0 (33f3fee 2023-05-26T00:03:48.457406188Z)

What command(s) is the bug in?

forge build

Operating System

Linux

Describe the bug

NOTE: I also opened a feature request related to this: https://github.com/foundry-rs/foundry/issues/5049

I'm currently debugging an issue where auto_detect_solc behaves somewhat non-deterministically and chooses different solc versions between CI and local runs. Locally, it uses 0.8.17 and in CI it uses 0.8.20 for some files.

The underlying issue seems to be that if it finds a file that has a version range that is supported by any installed solc version it will use that pre-installed solc version instead of downloading the highest available version. So depending on the environment it is run in, if there's already solc 0.8.17 available (which is the case locally), it will use that. But if that's not available (e.g. in CI where it installs those on every run), it will download the highest match (0.8.20) and then use that.

EDIT: This also seems to be affected by caches.

Given the non-deterministic / environment-dependent behavior of this I'd categorize that as a bug.

[mattsse]

somewhat non-deterministically and chooses different solc versions between CI and local runs.

since this happens in CI I assume you have already compatible versions installed locally

ref: https://github.com/gakonst/ethers-rs/blob/master/ethers-solc/src/resolver/mod.rs#L17

[fubhy]

somewhat non-deterministically and chooses different solc versions between CI and local runs.

since this happens in CI I assume you have already compatible versions installed locally

ref: https://github.com/gakonst/ethers-rs/blob/master/ethers-solc/src/resolver/mod.rs#L17

Ah, yes. That's where this feature requests would then come in imho: https://github.com/foundry-rs/foundry/issues/5049

That wouldn't solve all edge cases but probably most of them (e.g. if there are still multiple possible versions within the configured range it wouldn't solve it but that's probably less likely).

[mattsse]

I guess this is a reasonable request and could be solved by changed it to a set of solc versions.

supportive

[fubhy]

I guess this is a reasonable request and could be solved by changed it to a set of solc versions.

supportive

Would you implement it by

a) turning solc_version into a set (optionally) and changing it's behavior to work "together" with auto_detect_solc. Such that: if it's a set, auto_detect_solc is enabled, if it's a single value it's disabled and that single version is enforced

or b) add a new option auto_detect_solc_versions?

Happy to work on this and submit a PR. My preference would be a) if that can be implemented without causing any breaking changes.

[mattsse]

turning solc_version into a set (optionally)

there's a distinction between a pinned version and a range, pinning a version makes finding a compatible version obsolete. whereas a range would limit the possible options.

I'm not entirely sure how to implement this, the relevant code is here:

https://github.com/gakonst/ethers-rs/blob/6708c1fc0c43eb81ec6ade10cbb0a980e67ecdf6/ethers-solc/src/compile/project.rs#L156-L157

[fubhy]

Gotcha. So I guess we'd want a third with_sources_and_solc_range path in ethers-solc first?

[mattsse]

yeah, which provides a HashSet of allowed versions, I think that should work