Release 0.9.0-alpha.1

Bump MSRV to 1.78.0.

gherrit-pr-id: Gswihhcmqo3istfrlivayevxcvnqhumln

Author: joshlf

.github/workflows/ci.yml

@@ -69,12 +69,7 @@ jobs:
           # which a particular feature is supported.
           "no-zerocopy-simd-x86-avx12-1-89-0",
           "no-zerocopy-core-error-1-81-0",
-          "no-zerocopy-diagnostic-on-unimplemented-1-78-0",
-          "no-zerocopy-generic-bounds-in-const-fn-1-61-0",
-          "no-zerocopy-target-has-atomics-1-60-0",
-          "no-zerocopy-aarch64-simd-1-59-0",
           "no-zerocopy-aarch64-simd-be-1-87-0",
-          "no-zerocopy-panic-in-const-and-vec-try-reserve-1-57-0"
         ]
         target: [
           "i686-unknown-linux-gnu",
@@ -108,18 +103,8 @@ jobs:
             features: "--all-features"
           - toolchain: "no-zerocopy-core-error-1-81-0"
             features: "--all-features"
-          - toolchain: "no-zerocopy-diagnostic-on-unimplemented-1-78-0"
-            features: "--all-features"
-          - toolchain: "no-zerocopy-generic-bounds-in-const-fn-1-61-0"
-            features: "--all-features"
-          - toolchain: "no-zerocopy-target-has-atomics-1-60-0"
-            features: "--all-features"
-          - toolchain: "no-zerocopy-aarch64-simd-1-59-0"
-            features: "--all-features"
           - toolchain: "no-zerocopy-aarch64-simd-be-1-87-0"
             features: "--all-features"
-          - toolchain: "no-zerocopy-panic-in-const-and-vec-try-reserve-1-57-0"
-            features: "--all-features"
           # Exclude any combination for the zerocopy-derive crate which
           # uses zerocopy features.
           - crate: "zerocopy-derive"
@@ -136,44 +121,12 @@ jobs:
             toolchain: "no-zerocopy-simd-x86-avx12-1-89-0"
           - crate: "zerocopy-derive"
             toolchain: "no-zerocopy-core-error-1-81-0"
-          - crate: "zerocopy-derive"
-            toolchain: "no-zerocopy-diagnostic-on-unimplemented-1-78-0"
-          - crate: "zerocopy-derive"
-            toolchain: "no-zerocopy-generic-bounds-in-const-fn-1-61-0"
-          - crate: "zerocopy-derive"
-            toolchain: "no-zerocopy-target-has-atomics-1-60-0"
-          - crate: "zerocopy-derive"
-            toolchain: "no-zerocopy-aarch64-simd-1-59-0"
           - crate: "zerocopy-derive"
             toolchain: "no-zerocopy-aarch64-simd-be-1-87-0"
-          - crate: "zerocopy-derive"
-            toolchain: "no-zerocopy-panic-in-const-and-vec-try-reserve-1-57-0"
           # Exclude stable/wasm since wasm is no longer provided via rustup on
           # stable.
           - toolchain: "stable"
             target: "wasm32-unknown-unknown"
-          # Exclude non-aarch64 targets from the `no-zerocopy-aarch64-simd-1-59-0`
-          # toolchain.
-          - toolchain: "no-zerocopy-aarch64-simd-1-59-0"
-            target: "i686-unknown-linux-gnu"
-          - toolchain: "no-zerocopy-aarch64-simd-1-59-0"
-            target: "x86_64-unknown-linux-gnu"
-          - toolchain: "no-zerocopy-aarch64-simd-1-59-0"
-            target: "arm-unknown-linux-gnueabi"
-          - toolchain: "no-zerocopy-aarch64-simd-1-59-0"
-            target: "powerpc-unknown-linux-gnu"
-          - toolchain: "no-zerocopy-aarch64-simd-1-59-0"
-            target: "powerpc64-unknown-linux-gnu"
-          - toolchain: "no-zerocopy-aarch64-simd-1-59-0"
-            target: "riscv64gc-unknown-linux-gnu"
-          - toolchain: "no-zerocopy-aarch64-simd-1-59-0"
-            target: "s390x-unknown-linux-gnu"
-          - toolchain: "no-zerocopy-aarch64-simd-1-59-0"
-            target: "x86_64-pc-windows-msvc"
-          - toolchain: "no-zerocopy-aarch64-simd-1-59-0"
-            target: "thumbv6m-none-eabi"
-          - toolchain: "no-zerocopy-aarch64-simd-1-59-0"
-            target: "wasm32-unknown-unknown"
           # Exclude non-aarch64 targets from the `no-zerocopy-aarch64-simd-be-1-87-0`
           # toolchain.
           - toolchain: "no-zerocopy-aarch64-simd-be-1-87-0"
@@ -217,50 +170,6 @@ jobs:
             target: "thumbv6m-none-eabi"
           - toolchain: "no-zerocopy-core-error-1-81-0"
             target: "wasm32-unknown-unknown"
-          # Exclude most targets from the
-          # `no-zerocopy-diagnostic-on-unimplemented-1-78-0` toolchain since the
-          # `no-zerocopy-diagnostic-on-unimplemented-1-78-0` feature is unrelated to
-          # compilation target. This only leaves i686 and x86_64 targets.
-          - toolchain: "no-zerocopy-diagnostic-on-unimplemented-1-78-0"
-            target: "arm-unknown-linux-gnueabi"
-          - toolchain: "no-zerocopy-diagnostic-on-unimplemented-1-78-0"
-            target: "aarch64-unknown-linux-gnu"
-          - toolchain: "no-zerocopy-diagnostic-on-unimplemented-1-78-0"
-            target: "powerpc-unknown-linux-gnu"
-          - toolchain: "no-zerocopy-diagnostic-on-unimplemented-1-78-0"
-            target: "powerpc64-unknown-linux-gnu"
-          - toolchain: "no-zerocopy-diagnostic-on-unimplemented-1-78-0"
-            target: "riscv64gc-unknown-linux-gnu"
-          - toolchain: "no-zerocopy-diagnostic-on-unimplemented-1-78-0"
-            target: "s390x-unknown-linux-gnu"
-          - toolchain: "no-zerocopy-diagnostic-on-unimplemented-1-78-0"
-            target: "x86_64-pc-windows-msvc"
-          - toolchain: "no-zerocopy-diagnostic-on-unimplemented-1-78-0"
-            target: "thumbv6m-none-eabi"
-          - toolchain: "no-zerocopy-diagnostic-on-unimplemented-1-78-0"
-            target: "wasm32-unknown-unknown"
-          # Exclude most targets from the
-          # `no-zerocopy-generic-bounds-in-const-fn-1-61-0` toolchain since the
-          # `no-zerocopy-generic-bounds-in-const-fn-1-61-0` feature is unrelated to
-          # compilation target. This only leaves i686 and x86_64 targets.
-          - toolchain: "no-zerocopy-generic-bounds-in-const-fn-1-61-0"
-            target: "arm-unknown-linux-gnueabi"
-          - toolchain: "no-zerocopy-generic-bounds-in-const-fn-1-61-0"
-            target: "aarch64-unknown-linux-gnu"
-          - toolchain: "no-zerocopy-generic-bounds-in-const-fn-1-61-0"
-            target: "powerpc-unknown-linux-gnu"
-          - toolchain: "no-zerocopy-generic-bounds-in-const-fn-1-61-0"
-            target: "powerpc64-unknown-linux-gnu"
-          - toolchain: "no-zerocopy-generic-bounds-in-const-fn-1-61-0"
-            target: "riscv64gc-unknown-linux-gnu"
-          - toolchain: "no-zerocopy-generic-bounds-in-const-fn-1-61-0"
-            target: "s390x-unknown-linux-gnu"
-          - toolchain: "no-zerocopy-generic-bounds-in-const-fn-1-61-0"
-            target: "x86_64-pc-windows-msvc"
-          - toolchain: "no-zerocopy-generic-bounds-in-const-fn-1-61-0"
-            target: "thumbv6m-none-eabi"
-          - toolchain: "no-zerocopy-generic-bounds-in-const-fn-1-61-0"
-            target: "wasm32-unknown-unknown"
           # Exclude `thumbv6m-none-eabi` combined with any feature that implies
           # the `std` feature since `thumbv6m-none-eabi` does not include a
           # pre-compiled std.

Cargo.lock

@@ -15,7 +15,7 @@
 [package]
 edition = "2021"
 name = "zerocopy"
-version = "0.8.48"
+version = "0.9.0-alpha.1"
 authors = [
     "Joshua Liebow-Feeser <[email protected]>",
     "Jack Wrenn <[email protected]>",
@@ -31,7 +31,8 @@ categories = [
 keywords = ["cast", "convert", "transmute", "transmutation", "type-punning"]
 license = "BSD-2-Clause OR Apache-2.0 OR MIT"
 repository = "https://github.com/google/zerocopy"
-rust-version = "1.56.0"
+# WARNING: Consult with the Rust for Linux project before increasing.
+rust-version = "1.78.0"
 
 exclude = [".*"]
 
@@ -64,43 +65,31 @@ no-zerocopy-simd-x86-avx12-1-89-0 = "1.89.0"
 # From 1.81.0, Rust supports the `core::error::Error` trait.
 no-zerocopy-core-error-1-81-0 = "1.81.0"
 
-# From 1.78.0, Rust supports the `#[diagnostic::on_unimplemented]` attribute.
-no-zerocopy-diagnostic-on-unimplemented-1-78-0 = "1.78.0"
-
-# From 1.61.0, Rust supports generic types with trait bounds in `const fn`.
-no-zerocopy-generic-bounds-in-const-fn-1-61-0 = "1.61.0"
-
-# From 1.60.0, Rust supports `cfg(target_has_atomics)`, which allows us to
-# detect whether a target supports particular sets of atomics.
-no-zerocopy-target-has-atomics-1-60-0 = "1.60.0"
-
-# When the "simd" feature is enabled, include SIMD types from the
-# `core::arch::aarch64` module, which was stabilized in 1.59.0. On earlier Rust
-# versions, these types require the "simd-nightly" feature.
-no-zerocopy-aarch64-simd-1-59-0 = "1.59.0"
-
 # Include SIMD types from `core::arch::aarch64` on big endian targets. Prior to
 # 1.87.0 (https://github.com/rust-lang/rust/pull/136831) the types were only
 # correct on little endian and backed off from stable in a breaking change.
 no-zerocopy-aarch64-simd-be-1-87-0 = "1.87.0"
 
-# Permit panicking in `const fn`s and calling `Vec::try_reserve`.
-no-zerocopy-panic-in-const-and-vec-try-reserve-1-57-0 = "1.57.0"
-
 [package.metadata.ci]
 # The versions of the stable and nightly compiler toolchains to use in CI.
 pinned-stable = "1.93.1"
 pinned-nightly = "nightly-2026-01-25"
 
 [package.metadata.docs.rs]
 all-features = true
-rustdoc-args = ["--cfg", "doc_cfg", "--generate-link-to-definition", "--extend-css", "rustdoc/style.css"]
+rustdoc-args = [
+    "--cfg",
+    "doc_cfg",
+    "--generate-link-to-definition",
+    "--extend-css",
+    "rustdoc/style.css",
+]
 targets = [
     "x86_64-unknown-linux-gnu",
     "x86_64-apple-darwin",
     "x86_64-pc-windows-msvc",
     "i686-unknown-linux-gnu",
-    "i686-pc-windows-msvc"
+    "i686-pc-windows-msvc",
 ]
 
 [package.metadata.playground]
@@ -124,13 +113,13 @@ __internal_use_only_features_that_work_on_stable = [
 ]
 
 [dependencies]
-zerocopy-derive = { version = "=0.8.48", path = "zerocopy-derive", optional = true }
+zerocopy-derive = { version = "=0.9.0-alpha.1", path = "zerocopy-derive", optional = true }
 
 # The "associated proc macro pattern" ensures that the versions of zerocopy and
 # zerocopy-derive remain equal, even if the 'derive' feature isn't used.
 # See: https://github.com/matklad/macro-dep-test
 [target.'cfg(any())'.dependencies]
-zerocopy-derive = { version = "=0.8.48", path = "zerocopy-derive" }
+zerocopy-derive = { version = "=0.9.0-alpha.1", path = "zerocopy-derive" }
 
 [dev-dependencies]
 # FIXME(#381) Remove this dependency once we have our own layout gadgets.
@@ -142,4 +131,4 @@ rustversion = "1.0"
 static_assertions = "1.1"
 testutil = { path = "testutil" }
 # In tests, unlike in production, zerocopy-derive is not optional
-zerocopy-derive = { version = "=0.8.48", path = "zerocopy-derive" }
+zerocopy-derive = { version = "=0.9.0-alpha.1", path = "zerocopy-derive" }

Cargo.toml

@@ -89,21 +89,36 @@ documented guarantees do not hold.
 
 ## MSRV
 
+TL;DR:
+- 0.8 is our long-term stability (LTS) release train. On 0.8, we consider MSRV bumps to be breaking changes.
+- On 0.9, we do *not* consider MSRV bumps to be breaking changes.
+
+### 0.8
+
 <!-- Our policy used to be simply that MSRV was a breaking change in all
 circumstances. This implicitly relied on syn having the same MSRV policy, which
 it does not. See #1085 and #1088. -->
 
+*This section only applies to the 0.8 version train.*
+
 Without the `derive` feature enabled, zerocopy's minimum supported Rust version
 (MSRV) is encoded the `package.rust-version` field in its `Cargo.toml` file. For
-zerocopy, we consider an increase in MSRV to be a semver-breaking change, and
-will only increase our MSRV during semver-breaking version changes (e.g., 0.1 ->
-0.2, 1.0 -> 2.0, etc).
+zerocopy, we consider an increase in MSRV to be a semver-breaking change. We
+will not bump our MSRV on the 0.8 version train.
 
 For zerocopy with the `derive` feature enabled, and for the zerocopy-derive
 crate, we inherit the maximum MSRV any of our dependencies. As of this writing
 (2024-10-03), at least one dependency (syn) does *not* consider MSRV increases
 to be semver-breaking changes. Thus, using the `derive` feature may result in
-the effective MSRV increasing within a semver version train.
+the effective MSRV increasing within 0.8.
+
+### 0.9
+
+*This section only applies to the 0.9 version train.*
+
+0.9 has no official MSRV policy. We do not consider MSRV bumps to be breaking
+changes. We may adopt *some* MSRV policy in the future, but we make no
+guarantees about what it will be.
 
 ## Yanking
 

POLICIES.md

@@ -33,7 +33,7 @@ This is equivalent to:
 `cargo +1.2.3 <command> [args]`
 
 ...where `1.2.3` is the toolchain version named by `<toolchain>` (e.g., `msrv` ->
-`1.56.0`).
+`1.78.0`).
 
 ### Toolchains
 
@@ -47,12 +47,12 @@ The `<toolchain>` argument is mandatory:
 
 ## MSRV (Minimum Supported Rust Version)
 
-The MSRV is **1.56.0**.
+The MSRV is **1.78.0**.
 
-- **Do NOT** use features stabilized after 1.56.0 unless version-gated.
+- **Do NOT** use features stabilized after 1.78.0 unless version-gated.
 - **Requirement:** Ask for user approval before introducing new version-gated
   behavior.
-- **Verify**: Ensure code compiles on 1.56.0 (`./cargo.sh +msrv ...`).
+- **Verify**: Ensure code compiles on 1.78.0 (`./cargo.sh +msrv ...`).
 
 ### Version Gating Convention
 

agent_docs/development.md

@@ -1059,8 +1059,8 @@ mod tests {
         /// themselves. This method is like `assert_eq!`, but it treats NaN
         /// values as equal.
         fn assert_eq_or_nan(self, other: Self) {
-            let slf = (!self.is_nan()).then(|| self);
-            let other = (!other.is_nan()).then(|| other);
+            let slf = (!self.is_nan()).then_some(self);
+            let other = (!other.is_nan()).then_some(other);
             assert_eq!(slf, other);
         }
     }
@@ -1090,8 +1090,8 @@ mod tests {
         /// themselves. This method is like `assert_eq!`, but it treats NaN
         /// values as equal.
         fn assert_eq_or_nan(self, other: Self) {
-            let slf = (!self.get().is_nan()).then(|| self);
-            let other = (!other.get().is_nan()).then(|| other);
+            let slf = (!self.get().is_nan()).then_some(self);
+            let other = (!other.get().is_nan()).then_some(other);
             assert_eq!(slf, other);
         }
     }
@@ -1401,7 +1401,7 @@ mod tests {
                 let t_t_res = val_or_none(t_t_res);
                 let t_n_res = val_or_none(t_n_res);
                 let n_t_res = val_or_none(n_t_res);
-                let n_n_res = (!T::Native::is_nan(n_n_res)).then(|| n_n_res);
+                let n_n_res = (!T::Native::is_nan(n_n_res)).then_some(n_n_res);
                 assert_eq!(t_t_res, n_n_res);
                 assert_eq!(t_n_res, n_n_res);
                 assert_eq!(n_t_res, n_n_res);
@@ -1419,7 +1419,7 @@ mod tests {
                     // NaN as `None` so they can still be compared.
                     let t_t_res = val_or_none(t_t_res);
                     let t_n_res = val_or_none(t_n_res);
-                    let n_t_res = (!T::Native::is_nan(n_t_res)).then(|| n_t_res);
+                    let n_t_res = (!T::Native::is_nan(n_t_res)).then_some(n_t_res);
                     assert_eq!(t_t_res, n_n_res);
                     assert_eq!(t_n_res, n_n_res);
                     assert_eq!(n_t_res, n_n_res);

src/byteorder.rs

@@ -383,15 +383,12 @@ const _: () = unsafe {
     unsafe_impl_for_power_set!(A, B, C, D, E, F, G, H, I, J, K, L -> M => Immutable for opt_unsafe_extern_c_fn!(...));
 };
 
-#[cfg(all(
-    not(no_zerocopy_target_has_atomics_1_60_0),
-    any(
-        target_has_atomic = "8",
-        target_has_atomic = "16",
-        target_has_atomic = "32",
-        target_has_atomic = "64",
-        target_has_atomic = "ptr"
-    )
+#[cfg(any(
+    target_has_atomic = "8",
+    target_has_atomic = "16",
+    target_has_atomic = "32",
+    target_has_atomic = "64",
+    target_has_atomic = "ptr"
 ))]
 #[cfg_attr(doc_cfg, doc(cfg(rust = "1.60.0")))]
 mod atomics {
@@ -1354,7 +1351,6 @@ mod simd {
         // Rust 1.87. (Context in https://github.com/rust-lang/stdarch/issues/1484). Support is
         // split in two different version ranges on top of the base configuration, requiring either
         // little endian or the more recent version to be detected as well.
-        #[cfg(not(no_zerocopy_aarch64_simd_1_59_0))]
         simd_arch_mod!(
             #[cfg(all(
                 target_arch = "aarch64", 
@@ -2371,7 +2367,7 @@ mod tests {
                 vector_signed_long,
                 vector_unsigned_long
             );
-            #[cfg(all(target_arch = "aarch64", not(no_zerocopy_aarch64_simd_1_59_0)))]
+            #[cfg(target_arch = "aarch64")]
             #[rustfmt::skip]
             test_simd_arch_mod!(
                 aarch64, float32x2_t, float32x4_t, float64x1_t, float64x2_t, int8x8_t, int8x8x2_t,

src/impls.rs

@@ -1390,7 +1390,7 @@ mod tests {
                             layout(size_info, align).validate_cast_and_convert_metadata(addr, bytes_len, cast_type)
                         }).map_err(|d| {
                             let msg = d.downcast::<&'static str>().ok().map(|s| *s.as_ref());
-                            assert!(msg.is_some() || cfg!(no_zerocopy_panic_in_const_and_vec_try_reserve_1_57_0), "non-string panic messages are not permitted when usage of panic in const fn is enabled");
+                            assert!(msg.is_some(), "non-string panic messages are not permitted when usage of panic in const fn is enabled");
                             msg
                         });
                         std::panic::set_hook(previous_hook);