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crate: expose cfg for general 64-bit time_t functionality #5411

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7ab0b9d
crate: expose `cfg` for general time64
dybucc Aug 14, 2026
a7133fe
ci: make prevalent use of `time64` `cfg`
dybucc Aug 29, 2026
5028c86
ci: format yaml
dybucc Sep 1, 2026
c3b6f88
ci: use `TEST_MUSL_V1_2` in powerpc runs
dybucc Sep 10, 2026
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48 changes: 24 additions & 24 deletions .github/workflows/ci.yaml
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Original file line number Diff line number Diff line change
Expand Up @@ -71,7 +71,7 @@ jobs:
- toolchain: nightly
half: 2
- toolchain: beta
only: '(aarch64|x86_64)' # just a spot check for beta
only: "(aarch64|x86_64)" # just a spot check for beta
- toolchain: stable
- toolchain: 1.65.0 # msrv
runs-on: ubuntu-26.04
Expand Down Expand Up @@ -220,7 +220,7 @@ jobs:
- target: powerpc64-unknown-linux-gnu
- target: powerpc64-unknown-linux-musl
- target: powerpc64-unknown-linux-musl
env: { RUST_LIBC_UNSTABLE_MUSL_V1_2: 1 }
env: { TEST_MUSL_V1_2: 1 }
artifact-tag: new-musl
- target: powerpc64le-unknown-linux-gnu
- target: powerpc64le-unknown-linux-musl
Expand Down Expand Up @@ -392,34 +392,34 @@ jobs:
env:
RUSTFLAGS: "" # No need to check warnings on old MSRV, clear `-Dwarnings`
steps:
- uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
with:
persist-credentials: false
- run: |
msrv="$(
cargo metadata --format-version 1 |
jq -r --arg CRATE_NAME ctest '.packages | map(select((.name == $CRATE_NAME) and (.id | startswith("path+file")))) | first | .rust_version'
)"
echo "MSRV: $msrv"
echo "MSRV=$msrv" >> "$GITHUB_ENV"
- name: Install Rust
run: rustup update "$MSRV" --no-self-update && rustup default "$MSRV"
- uses: Swatinem/rust-cache@6323deb102c322ba6fcbdcafc7e3dddab59af2b6 # v2.9.2
- run: cargo build -p ctest
- uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
with:
persist-credentials: false
- run: |
msrv="$(
cargo metadata --format-version 1 |
jq -r --arg CRATE_NAME ctest '.packages | map(select((.name == $CRATE_NAME) and (.id | startswith("path+file")))) | first | .rust_version'
)"
echo "MSRV: $msrv"
echo "MSRV=$msrv" >> "$GITHUB_ENV"
- name: Install Rust
run: rustup update "$MSRV" --no-self-update && rustup default "$MSRV"
- uses: Swatinem/rust-cache@6323deb102c322ba6fcbdcafc7e3dddab59af2b6 # v2.9.2
- run: cargo build -p ctest
Comment thread
tgross35 marked this conversation as resolved.

docs:
name: Ensure docs build
runs-on: ubuntu-26.04
timeout-minutes: 10
steps:
- uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
with:
persist-credentials: false
- name: Install Rust
# FIXME(rust-lang/rust#160439): unpin once the issue is fixed
run: rustup update nightly-2026-08-02 --no-self-update && rustup default nightly-2026-08-02
- uses: Swatinem/rust-cache@6323deb102c322ba6fcbdcafc7e3dddab59af2b6 # v2.9.2
- run: cargo doc --workspace --no-deps
- uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
with:
persist-credentials: false
- name: Install Rust
# FIXME(rust-lang/rust#160439): unpin once the issue is fixed
run: rustup update nightly-2026-08-02 --no-self-update && rustup default nightly-2026-08-02
- uses: Swatinem/rust-cache@6323deb102c322ba6fcbdcafc7e3dddab59af2b6 # v2.9.2
- run: cargo doc --workspace --no-deps

zizmor:
name: Zizmor (Static analysis for GitHub Actions)
Expand Down
9 changes: 6 additions & 3 deletions build.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -246,9 +246,12 @@ fn main() {
|| target_env == "ohos"
|| target_abi == "pauthtest";

// Single entry-point to enable `time64` on supported platforms.
let time64 = env_flag("CARGO_CFG_LIBC_UNSTABLE_TIME64");

// OpenHarmony uses a fork of the musl libc
let musl = target_env == "musl" || target_env == "ohos";
let musl_v1_2 = musl && (musl_v1_2_env || only_v1_2_on_musl);
let musl_v1_2 = musl && (musl_v1_2_env || only_v1_2_on_musl || time64);

if musl_v1_2 {
cfgs.push(Cfg::MuslV1_2);
Expand All @@ -263,7 +266,7 @@ fn main() {
}

let uclibc_time64_env = env_flag("CARGO_CFG_LIBC_UNSTABLE_UCLIBC_TIME64");
let uclibc_time64 = target_env == "uclibc" && uclibc_time64_env;
let uclibc_time64 = target_env == "uclibc" && (uclibc_time64_env || time64);
if uclibc_time64 {
cfgs.push(Cfg::LinuxTimeBits64);
}
Expand Down Expand Up @@ -302,7 +305,7 @@ fn main() {
|| target_arch == "x86_64"
|| !matches!(target_os.as_str(), "linux" | "windows" | "hurd");
let gnu = target_env == "gnu";
let gnu32_time64 = gnu && target_ptr_width == "32" && gnu32_timebits == "64";
let gnu32_time64 = gnu && target_ptr_width == "32" && (gnu32_timebits == "64" || time64);

if gnu32_time64 && !gnu32_already_time64 {
// These configs all set up nonstandard options. They are not needed on platforms like
Expand Down
2 changes: 1 addition & 1 deletion ci/run-docker.sh
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Original file line number Diff line number Diff line change
Expand Up @@ -51,7 +51,7 @@ run() {

if [ -n "${TEST_UCLIBC_TIME64:-}" ]; then
build_args+=("--build-arg=TEST_UCLIBC_TIME64=1")
RUSTFLAGS="$RUSTFLAGS --cfg=libc_unstable_uclibc_time64"
RUSTFLAGS="$RUSTFLAGS --cfg=libc_unstable_time64"
fi
if [[ "$run_target" = *-linux-uclibc* ]]; then
if [ "${UCLIBC_TOOLCHAIN_URL:-}" ]; then
Expand Down
2 changes: 1 addition & 1 deletion ci/run.sh
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Expand Up @@ -60,5 +60,5 @@ $cmd --features extra_traits -- $test_flags

if [ "$env" = "gnu" ] && [ "$bits" = "32" ]; then
# shellcheck disable=SC2086
RUSTFLAGS="$RUSTFLAGS --cfg=libc_unstable_gnu_time_bits=\"64\"" $cmd -- $test_flags
RUSTFLAGS="$RUSTFLAGS --cfg=libc_unstable_time64" $cmd -- $test_flags
fi
15 changes: 8 additions & 7 deletions ci/verify-build.py
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Expand Up @@ -411,13 +411,14 @@ def test_target(cfg: Cfg, target: Target) -> TargetResult:
run(cmd, rustflags=rustflags)
run([*cmd, "--features=extra_traits"], rustflags=rustflags)

if "gnu" in target_env and target_bits == "32":
# Equivalent of _TIME_BITS=64
run(cmd, rustflags=f'{rustflags} --cfg=libc_unstable_gnu_time_bits="64"')

if "musl" in target_env:
# Check with breaking changes from musl, including 64-bit time_t on 32-bit
run(cmd, rustflags=f"{rustflags} --cfg=libc_unstable_musl_v1_2")
if (
("gnu" in target_env and target_bits == "32")
or "musl" in target_env
or "uclibc" in target_env
):
# Global toggle for `_TIME_BITS=64` on glibc, musl breaking changes and
# uClibc buil-time options concerning 64-bit `time_t`.
run(cmd, rustflags=f"{rustflags} --cfg=libc_unstable_time64")

# Test again without default features, i.e. without `std`
run([*cmd, "--no-default-features"], rustflags=rustflags)
Expand Down
15 changes: 10 additions & 5 deletions libc-test/build/main.rs
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@tgross35 tgross35 Sep 15, 2026

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"crate: expose cfg for general time64" please mention the cfg name in the commit message summary, it doesn't show up anywhere in this commit

@dybucc dybucc Sep 16, 2026

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It does, though (before this review, I mean.)

@tgross35 tgross35 Sep 16, 2026

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What am I missing? 3901563 has the text:

crate: expose cfg for general time64

Add cfg enabling time64 functionality across all supported targets.
This ensures users have a simple entry point to the crate functionality
gated behind one of linux_time_bits64, uclibc_time64 and
gnu_time_bits64. The new cfg goes by the name time64.

`libc_unstable_time64` is not in the summary, and I don't see it mentioned at all

@dybucc dybucc Sep 17, 2026

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It does; At the end. I mention time64 but not libc_unstable_time64
because all our public cfgs require libc_unstable_ to be prepended
to them. It seems to me like the commit history is something internal.

The PR summary also mentions it, though I get it is confusing to say
that the cfg itself is named time64.

The name of the cfg is time64.

@tgross35 tgross35 Sep 17, 2026

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It won't always be the case that they have a common prefix, this one is going to be stabilized as libc_time64. Just refer to them by the exact name to avoid confusion, when somebody greps in commit logs they're most likely going to be looking for the exact name rather than a substring of it.

Original file line number Diff line number Diff line change
Expand Up @@ -746,14 +746,16 @@ fn test_windows(t: &Target) {
}
cfg.define("_WIN32_WINNT", Some("0x8000"));

let win_gnu_x86_time64 = match env::var("CARGO_CFG_LIBC_UNSTABLE_GNU_TIME_BITS") {
let time64 = env_flag("CARGO_CFG_LIBC_UNSTABLE_TIME64");
let mut win_gnu_x86_time64 = match env::var("CARGO_CFG_LIBC_UNSTABLE_GNU_TIME_BITS") {
Ok(v) if v == "64" => true,
Ok(v) if v == "32" => false,
Ok(_) => {
panic!("Invalid value for `libc_unstable_gnu_time_bits`. Must be 32, 64 or unset.");
}
Err(_) => false,
};
win_gnu_x86_time64 |= time64;

// Needed for the Windows `time_t` test.
println!("cargo::rustc-check-cfg=cfg(gnu_time_bits64)");
Expand Down Expand Up @@ -3877,6 +3879,7 @@ fn config_gnu_bits(t: &Target, cfg: &mut ctest::TestGenerator) {
if t.gnu() && t.linux() && !t.x32() && !t.riscv32() && t.pointer_width == P32 {
let defaultbits = "32";
let mut tb_env = env::var("CARGO_CFG_LIBC_UNSTABLE_GNU_TIME_BITS");
let time64 = env_flag("CARGO_CFG_LIBC_UNSTABLE_TIME64");

// FIXME: remove these fallbacks in a few releases
if let Ok(old_tb_env) = env::var("RUST_LIBC_UNSTABLE_GNU_TIME_BITS") {
Expand Down Expand Up @@ -3905,7 +3908,7 @@ fn config_gnu_bits(t: &Target, cfg: &mut ctest::TestGenerator) {
}
};

if timebits == "64" {
if timebits == "64" || time64 {
cfg.define("_TIME_BITS", Some("64"));
cfg.define("_FILE_OFFSET_BITS", Some("64"));
cfg.cfg("linux_time_bits64", None);
Expand Down Expand Up @@ -3970,21 +3973,23 @@ fn test_linux(t: &Target) {
None => panic!("failed to detect kernel version for Linux target {t:?}",),
};

let time64 = env_flag("CARGO_CFG_LIBC_UNSTABLE_TIME64");

let mut musl_v1_2 = env_flag("CARGO_CFG_LIBC_UNSTABLE_MUSL_V1_2");
if musl_v1_2 {
assert!(musl);
}

// Some platforms only exist with recent musl. Keep in sync with libc's build.rs.
if musl && (loongarch64 || hexagon || pauthtest/* || ohos */) {
if musl && (loongarch64 || hexagon || pauthtest/* || ohos */ || time64) {
musl_v1_2 = true;
}

let old_musl = musl && !musl_v1_2;

let mut cfg = ctest_cfg();

if musl_v1_2 {
if musl && musl_v1_2 {
cfg.cfg("musl_v1_2", None);
if p32 {
cfg.cfg("musl32_time64", None);
Expand All @@ -3995,7 +4000,7 @@ fn test_linux(t: &Target) {
}
}

let uclibc_use_time64 = env_flag("CARGO_CFG_LIBC_UNSTABLE_UCLIBC_TIME64");
let uclibc_use_time64 = env_flag("CARGO_CFG_LIBC_UNSTABLE_UCLIBC_TIME64") || time64;
if uclibc && uclibc_use_time64 {
cfg.cfg("linux_time_bits64", None);
}
Expand Down
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