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Merged
tgross35 merged 2 commits into from
Sep 7, 2026
Merged

build: Restructure time64 config #5508

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ba3dc5c
build: Restructure time64 config
tgross35 Sep 5, 2026
3d2481e
build: Fix a comment about what `gnu_time_bits64` implies
tgross35 Sep 7, 2026
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128 changes: 64 additions & 64 deletions build.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -40,8 +40,9 @@ enum Cfg {
LinuxTimeBits64,
/// Corresponds to `_FILE_OFFSET_BITS=64` in glibc. Implies 32-bit GNU target.
GnuFileOffsetBits64,
/// Corresponds to `_TIME_BITS=64` in glibc. Also used in x86 Windows with GNU
/// to expose a 64-bit `time_t`. Implies 32-bit GNU target and 64-bit `off_t`.
/// Corresponds to `_TIME_BITS=64` in glibc. Also used in x86 Windows with GNU to expose a
/// 64-bit `time_t`. Implies 32-bit GNU target and, on platforms other than Windows, 64-bit
/// `off_t`.
GnuTimeBits64,
/// Musl 1.2+. Implies `target_env = "musl"`
MuslV1_2,
Expand Down Expand Up @@ -121,10 +122,6 @@ const CHECK_CFG_EXTRA: &[(&str, &[&str])] = &[
),
];

/// Musl architectures that define `_REDIR_TIME64` (i.e. those that transitioned
/// from 32-bit to 64-bit `time_t` and need `__*_time64` symbol redirects).
const MUSL_REDIR_TIME64_ARCHES: &[&str] = &["arm", "mips", "powerpc", "x86"];

/// Read from env, print more debug output via `cargo:warning` if set.
static VERBOSE_BUILD: AtomicBool = AtomicBool::new(false);

Expand Down Expand Up @@ -220,93 +217,96 @@ fn main() {
}
}

let mut musl_v1_2 = env_flag("CARGO_CFG_LIBC_UNSTABLE_MUSL_V1_2");
if let Ok(old_musl_v1_2_3) = env::var("CARGO_CFG_LIBC_UNSTABLE_MUSL_V1_2_3") {
let mut musl_v1_2_env = env_flag("CARGO_CFG_LIBC_UNSTABLE_MUSL_V1_2");
if let Ok(old_musl_v1_2_3_env) = env::var("CARGO_CFG_LIBC_UNSTABLE_MUSL_V1_2_3") {
println!(
"cargo:warning=`--cfg=libc_unstable_musl_v1_2_3` will be removed; \
set `--cfg=libc_unstable_musl_v1_2`instead"
);
musl_v1_2 |= old_musl_v1_2_3 != "0";
musl_v1_2_env |= old_musl_v1_2_3_env != "0";
}
if let Ok(old_musl_v1_2_3) = env::var("RUST_LIBC_UNSTABLE_MUSL_V1_2_3") {
if let Ok(old_musl_v1_2_3_env) = env::var("RUST_LIBC_UNSTABLE_MUSL_V1_2_3") {
println!(
"cargo:warning=RUST_LIBC_UNSTABLE_MUSL_V1_2_3 will be removed; \
set `--cfg=libc_unstable_musl_v1_2` via RUSTFLAGS instead"
);
musl_v1_2 |= old_musl_v1_2_3 != "0";
musl_v1_2_env |= old_musl_v1_2_3_env != "0";
}

// OpenHarmony uses a fork of the musl libc
let musl = target_env == "musl" || target_env == "ohos";

// loongarch64, hexagon, ohos and pauthtest only exist with recent musl
if target_arch == "loongarch64"
// Targets that only exist with recent musl. 32-bit targets not in this list need
// `_REDIR_TIME64` for 64-bit `time_t`.
let only_v1_2_on_musl = target_arch == "loongarch64"
|| target_arch == "hexagon"
|| target_arch == "riscv32"
|| target_env == "ohos"
|| target_abi == "pauthtest"
{
musl_v1_2 = true;
}
|| target_abi == "pauthtest";

// 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);

if musl && musl_v1_2 {
if musl_v1_2 {
cfgs.push(Cfg::MuslV1_2);
if target_ptr_width == "32" {
cfgs.push(Cfg::Musl32Time64);
cfgs.push(Cfg::LinuxTimeBits64);
}
if MUSL_REDIR_TIME64_ARCHES.contains(&target_arch.as_str()) {
cfgs.push(Cfg::MuslRedirTime64);
if !only_v1_2_on_musl {
// Older 32-bit arches need the redirects
cfgs.push(Cfg::MuslRedirTime64);
}
}
}

let uclibc_use_time64 = env_flag("CARGO_CFG_LIBC_UNSTABLE_UCLIBC_TIME64");
if target_env == "uclibc" && uclibc_use_time64 {
let uclibc_time64_env = env_flag("CARGO_CFG_LIBC_UNSTABLE_UCLIBC_TIME64");
let uclibc_time64 = target_env == "uclibc" && uclibc_time64_env;
if uclibc_time64 {
cfgs.push(Cfg::LinuxTimeBits64);
}

if target_env == "gnu"
&& matches!(target_os.as_str(), "linux" | "windows" | "hurd")
&& target_ptr_width == "32"
&& target_arch != "riscv32"
&& target_arch != "x86_64"
{
let defaultbits = "32";
let mut gnu_tb_env = env::var("CARGO_CFG_LIBC_UNSTABLE_GNU_TIME_BITS");

let mut tb_env = env::var("CARGO_CFG_LIBC_UNSTABLE_GNU_TIME_BITS");
// FIXME: remove these fallbacks in a few releases
if let Ok(old_gnu_tb_env) = env::var("RUST_LIBC_UNSTABLE_GNU_TIME_BITS") {
println!(
"cargo:warning=RUST_LIBC_UNSTABLE_GNU_TIME_BITS will be removed; \
set `--cfg=libc_unstable_gnu_time_bits=\"...\"` via RUSTFLAGS instead"
);
gnu_tb_env = gnu_tb_env.or(Ok(old_gnu_tb_env));
}
if env::var("RUST_LIBC_UNSTABLE_GNU_FILE_OFFSET_BITS").is_ok()
|| env::var("CARGO_CFG_LIBC_UNSTABLE_GNU_FILE_OFFSET_BITS").is_ok()
{
println!(
"cargo:warning=glibc file offset can no longer be set independently of \
`gnu_time_bits`"
);
}

// FIXME: remove these fallbacks in a few releases
if let Ok(old_tb_env) = env::var("RUST_LIBC_UNSTABLE_GNU_TIME_BITS") {
println!(
"cargo:warning=RUST_LIBC_UNSTABLE_GNU_TIME_BITS will be removed; \
set `--cfg=libc_unstable_gnu_time_bits=\"...\"` via RUSTFLAGS instead"
);
tb_env = tb_env.or(Ok(old_tb_env));
}
if env::var("RUST_LIBC_UNSTABLE_GNU_FILE_OFFSET_BITS").is_ok()
|| env::var("CARGO_CFG_LIBC_UNSTABLE_GNU_FILE_OFFSET_BITS").is_ok()
{
println!(
"cargo:warning=glibc file offset can no longer be set independently of \
`gnu_time_bits`"
);
let gnu32_timebits = match gnu_tb_env.as_deref() {
Err(_) => "32", // default to 32
Ok(tb) if tb == "64" => tb,
Ok(tb) if tb == "32" => tb,
Ok(_) => {
panic!("Invalid value for libc_unstable_gnu_time_bits. Must be 32, 64, or unset.")
}
};

let timebits = match tb_env.as_deref() {
Err(_) => defaultbits,
Ok(tb) if tb == "64" => tb,
Ok(tb) if tb == "32" => tb,
Ok(_) => {
panic!("Invalid value for libc_unstable_gnu_time_bits. Must be 32, 64, or unset.")
}
};

if timebits == "64" {
if target_os == "linux" {
cfgs.push(Cfg::LinuxTimeBits64);
}
cfgs.push(Cfg::GnuFileOffsetBits64);
cfgs.push(Cfg::GnuTimeBits64);
// 32-bit arches with 64-bit time_t by default. rv32 is 64-only, `x86_64` covers the x32 arch,
// `!(linux|windows|hurd)` covers vxworks and future platforms.
let gnu32_already_time64 = target_arch == "riscv32"
|| 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";

if gnu32_time64 && !gnu32_already_time64 {
// These configs all set up nonstandard options. They are not needed on platforms like
// riscv32, where 64-bit `time_t` is the default.
if target_os == "linux" {
cfgs.push(Cfg::LinuxTimeBits64);
}
cfgs.push(Cfg::GnuFileOffsetBits64);
cfgs.push(Cfg::GnuTimeBits64);
}

// On CI: deny all warnings
Expand Down
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