Removed the last dependencies breaking no-std build. #669
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Removed to_binary, which was used only in a debug display. Replaced once_cell with lazy_static. The no-std build of once_cell did not support the Sync version of OnceCell, that was needed when creating static variables. On the other hand, lazy_static is the complete solution for lazyly initialized (Sync) static variables, and is no-std. With this changes, revm builds on a no-std platform.
crates/precompile/Cargo.toml
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| sha2 = { version = "0.10.5", default-features = false } | ||
| sha3 = { version = "0.10.7", default-features = false } | ||
| lazy_static = "1.4" |
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lazy_static is unmaintained. Please just use once_cell with default-features = false.
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That was my first try, doesn't work with once_cell::unsync::OnceCell, which is not Sync, thus it can't be used to initialize a static variable. It seems lazy_static manages to do it by using a spin-lock, what once_cell doesn't have.
Anyway, the other crate I removed, to-binary, is also unmaintained and is older, so I don't see the issue of using lazy_static.
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See the once_cell FAQ:
- Does this crate support
no_std - Should I use
std::cell::OnceCell,once_cell, orlazy_static?
I say we enable the critical-section feature. cc @rakita
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Just found once_cell::race. I'll use it instead of lazy_static.
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OnceCell was stabilised inside rust, I would check if it works
https://doc.rust-lang.org/nightly/core/cell/struct.OnceCell.html#:~:text=Struct%20core%3A%3Acell%3A%3AOnceCell&text=A%20cell%20which%20can%20be,borrow%20checks%20(unlike%20RefCell%20).
to-binary is not relevant at all as it had very simpler usecase,
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Sorry, it seems once_cell::race doesn't provide a generic OnceCell, instead it is specialized for some types that can be handled by atomic instructions. I'll change this PR to use critical-section.
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Sorry, it seems
once_cell::racedoesn't provide a genericOnceCell, instead it is specialized for some types that can be handled by atomic instructions. I'll change this PR to use critical-section.
Just came here to write this. We can use once_cell::race::OnlyBox, it does not require std and it fits nicely with the code
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Well, I just pushed a version using critical-section, had to add a new feature and all. Should I change?
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Well, I just pushed a version using
critical-section, had to add a new feature and all. Should I change?
It would be better to change it, fewer features to maintain and it would work out of the box ( pun intended :))
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@lvella what is the best build command to add to CL for |
I don't know the best, but what I have been using is this target that has no std available, so a dependency can't inadvertedly rely on it. |
* Removed the last dependencies breaking no-std build. Removed to_binary, which was used only in a debug display. Replaced once_cell with lazy_static. The no-std build of once_cell did not support the Sync version of OnceCell, that was needed when creating static variables. On the other hand, lazy_static is the complete solution for lazyly initialized (Sync) static variables, and is no-std. With this changes, revm builds on a no-std platform. * Reverting back to OnceCell. * Hex encoding debug print. * Using race::OnceBox instead of critical-section. * Lint error.
* Removed the last dependencies breaking no-std build. Removed to_binary, which was used only in a debug display. Replaced once_cell with lazy_static. The no-std build of once_cell did not support the Sync version of OnceCell, that was needed when creating static variables. On the other hand, lazy_static is the complete solution for lazyly initialized (Sync) static variables, and is no-std. With this changes, revm builds on a no-std platform. * Reverting back to OnceCell. * Hex encoding debug print. * Using race::OnceBox instead of critical-section. * Lint error.
Removed to_binary, which was used only in a debug display.
Replaced once_cell with lazy_static. The no-std build of once_cell did not support the Sync version of OnceCell, that was needed when creating static variables. On the other hand, lazy_static is the complete solution for lazyly initialized (Sync) static variables, and is no-std.
With this changes, revm builds on a no-std platform.