Lower MSRV to 1.56 #574
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Lower MSRV to 1.56 #574
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In order to do this, we make a few changes:
- In 1.56, panicking is not supported in `const fn`s. In order to
support 1.56 while still panicking in `const fn`s in later versions,
we make a few changes:
- We introduce a `build.rs` script which detects the Rust toolchain
version and emits the cfg `zerocopy_panic_in_const_fn` if the Rust
version is at least 1.57.
- In some `const fn`s, we put debug assertions behind
`#[cfg(zerocopy_panic_in_const_fn)]`.
- In some `const fn`s, we replace `unreachable!()` with non-panicking
code when `#[cfg(not(zerocopy_panic_in_const_fn))]`.
- In one case, we compile a method as either a `const fn` or a
non-`const fn` depending on `zerocopy_panic_in_const_fn`.
- We replace `&*dst` with `transmute(dst)`.
- We make sure that, in `impl` blocks, `const` parameters always come
last.
- We make the `byteorder` feature/crate dependency off by default. This
is a breaking change, and so we bump the version number to
0.8.0-alpha.
Release 0.8.0-alpha.
Makes progress on #554
joshlf
commented
Nov 2, 2023
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| .ok_or("failed to find msrv: no `rust-version` key present")? | ||
| .to_string(); |
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We'll need to find a way to work around oli-obk/cargo_metadata#253.
joshlf
commented
Nov 3, 2023
| authors = ["Joshua Liebow-Feeser <[email protected]>"] | ||
| description = "Utilities for zero-copy parsing and serialization" | ||
| license = "BSD-2-Clause OR Apache-2.0 OR MIT" | ||
| repository = "https://github.com/google/zerocopy" | ||
| rust-version = "1.60.0" | ||
| rust-version = "1.56.0" |
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We may need to update our testing infrastructure to support testing on more stable toolchains other than one MSRV and one stable. In particular, we'll want to test on every toolchain that enables some functionality in build.rs. If our MSRV is A, our build.rs emits a particular cfg for versions B and above (B > A), and our pinned stable is C (C > B), then if we only test on A and C in CI, it's possible for behavior which is gated behind the cfg to be broken on any version in the range [B, C). Thus, we should test on B as well. In the general case, we need the ability to test on the full list of toolchain versions that invoke distinct build.rs behavior.
This was referenced Dec 4, 2023
joshlf
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Dec 28, 2023
Remove the `byteorder` feature and the dependency on the `byteorder` crate. Replace the `ByteOrder` trait and types which implement it from the `byteorder` crate with our own native implementations. This prepares us for a future commit in which we will make some of our functions and methods `const`. This commit doesn't implement this yet because it doesn't play nicely with our current MSRV; in order to support this, we'll need to introduce machinery that allows us to compile functions as conditionally `const` depending on what Rust toolchain version is used. See #574 for a prototype of this machinery. Add `Usize` and `Isize` byte order-aware types. Closes #438
joshlf
added a commit
that referenced
this pull request
Dec 28, 2023
Remove the `byteorder` feature and the dependency on the `byteorder` crate. Replace the `ByteOrder` trait and types which implement it from the `byteorder` crate with our own native implementations. This prepares us for a future commit in which we will make some of our functions and methods `const`. This commit doesn't implement this yet because it doesn't play nicely with our current MSRV; in order to support this, we'll need to introduce machinery that allows us to compile functions as conditionally `const` depending on what Rust toolchain version is used. See #574 for a prototype of this machinery. Add `Usize` and `Isize` byte order-aware types. Closes #438
joshlf
added a commit
that referenced
this pull request
Dec 28, 2023
Remove the `byteorder` feature and the dependency on the `byteorder` crate. Replace the `ByteOrder` trait and types which implement it from the `byteorder` crate with our own native implementations. This prepares us for a future commit in which we will make some of our functions and methods `const`. This commit doesn't implement this yet because it doesn't play nicely with our current MSRV; in order to support this, we'll need to introduce machinery that allows us to compile functions as conditionally `const` depending on what Rust toolchain version is used. See #574 for a prototype of this machinery. Add `Usize` and `Isize` byte order-aware types. Closes #438
joshlf
added a commit
that referenced
this pull request
Jan 18, 2024
Remove the `byteorder` feature and the dependency on the `byteorder` crate. Replace the `ByteOrder` trait and types which implement it from the `byteorder` crate with our own native implementations. This prepares us for a future commit in which we will make some of our functions and methods `const`. This commit doesn't implement this yet because it doesn't play nicely with our current MSRV; in order to support this, we'll need to introduce machinery that allows us to compile functions as conditionally `const` depending on what Rust toolchain version is used. See #574 for a prototype of this machinery. Add `Usize` and `Isize` byte order-aware types. Closes #438
github-merge-queue bot
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Jan 18, 2024
Remove the `byteorder` feature and the dependency on the `byteorder` crate. Replace the `ByteOrder` trait and types which implement it from the `byteorder` crate with our own native implementations. This prepares us for a future commit in which we will make some of our functions and methods `const`. This commit doesn't implement this yet because it doesn't play nicely with our current MSRV; in order to support this, we'll need to introduce machinery that allows us to compile functions as conditionally `const` depending on what Rust toolchain version is used. See #574 for a prototype of this machinery. Add `Usize` and `Isize` byte order-aware types. Closes #438
|
Superseded by #855. |
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In order to do this, we make a few changes:
const fns. In order tosupport 1.56 while still panicking in
const fns in later versions,we make a few changes:
build.rsscript which detects the Rust toolchainversion and emits the cfg
zerocopy_panic_in_const_fnif the Rustversion is at least 1.57.
const fns, we put debug assertions behind#[cfg(zerocopy_panic_in_const_fn)].const fns, we replaceunreachable!()with non-panickingcode when
#[cfg(not(zerocopy_panic_in_const_fn))].const fnor anon-
const fndepending onzerocopy_panic_in_const_fn.&*dstwithtransmute(dst).implblocks,constparameters always comelast.
byteorderfeature/crate dependency off by default. Thisis a breaking change, and so we bump the version number to
0.8.0-alpha.
Release 0.8.0-alpha.
Makes progress on #554