musl: add musl_time64 feature

This feature is enabled with independently from musl_v1_2_3 to support
time64. This also sets a musl_not_time64 feature to make `cfg`
statements easier to read.

Defining linux_time_bits64 makes this roughly equivalent to upstream
commit bminor/musl@f12bd8e.

Author: xbjfk

build.rs

@@ -24,6 +24,7 @@ const ALLOWED_CFGS: &[&str] = &[
     // Corresponds to `__USE_TIME_BITS64` in UAPI
     "linux_time_bits64",
     "musl_v1_2_3",
+    "musl32_time64",
 ];
 
 // Extra values to allow for check-cfg.
@@ -44,6 +45,8 @@ const CHECK_CFG_EXTRA: &[(&str, &[&str])] = &[
     ),
 ];
 
+const MUSL_TIME64_ARCHS: &[&str] = &["arm", "mips", "powerpc", "x86"];
+
 fn main() {
     // Avoid unnecessary re-building.
     println!("cargo:rerun-if-changed=build.rs");
@@ -90,10 +93,16 @@ fn main() {
 
     let musl_v1_2_3 = env::var("RUST_LIBC_UNSTABLE_MUSL_V1_2_3").is_ok();
     println!("cargo:rerun-if-env-changed=RUST_LIBC_UNSTABLE_MUSL_V1_2_3");
+    let musl32_time64 = env::var("RUST_LIBC_UNSTABLE_MUSL_TIME64").is_ok();
+    println!("cargo:rerun-if-env-changed=RUST_LIBC_UNSTABLE_MUSL_TIME64");
     // loongarch64 and ohos have already updated
-    if musl_v1_2_3 || target_os == "loongarch64" || target_env == "ohos" {
-        // FIXME(musl): enable time64 api as well
+    if ((musl_v1_2_3 || target_os == "loongarch64") && target_env == "musl") || target_env == "ohos"
+    {
         set_cfg("musl_v1_2_3");
+        if musl32_time64 && MUSL_TIME64_ARCHS.contains(&target_arch.as_str()) {
+            set_cfg("musl32_time64");
+            set_cfg("linux_time_bits64");
+        }
     }
     let linux_time_bits64 = env::var("RUST_LIBC_UNSTABLE_LINUX_TIME_BITS64").is_ok();
     println!("cargo:rerun-if-env-changed=RUST_LIBC_UNSTABLE_LINUX_TIME_BITS64");

libc-test/build.rs

@@ -3683,14 +3683,22 @@ fn test_linux(target: &str) {
     let loongarch64 = target.contains("loongarch64");
     let wasm32 = target.contains("wasm32");
     let uclibc = target.contains("uclibc");
+    let mips64 = target.contains("mips64");
+    let mips32 = target.contains("mips") && !mips64;
 
     let musl_v1_2_3 = env::var("RUST_LIBC_UNSTABLE_MUSL_V1_2_3").is_ok();
+    let musl32_time64 = env::var("RUST_LIBC_UNSTABLE_MUSL_TIME64").is_ok();
     let old_musl = musl && !musl_v1_2_3;
 
     let mut cfg = ctest_cfg();
-    if musl_v1_2_3 {
+    if (musl_v1_2_3 || loongarch64) && musl {
         cfg.cfg("musl_v1_2_3", None);
+        if musl32_time64 && (arm || ppc || x86_32 || mips32) {
+            cfg.cfg("musl32_time64", None);
+            cfg.cfg("linux_time_bits64", None);
+        }
     }
+
     cfg.define("_GNU_SOURCE", None);
     // This macro re-defines fscanf,scanf,sscanf to link to the symbols that are
     // deprecated since glibc >= 2.29. This allows Rust binaries to link against