musl: add musl_time64 feature

This feature is enabled with independently from musl_v1_2_3 to support
time64.

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

(backport <rust-lang#4463>)
(cherry picked from commit 47960b4)

Author: xbjfk

build.rs

@@ -28,6 +28,8 @@ const ALLOWED_CFGS: &[&str] = &[
     // Corresponds to `__USE_TIME_BITS64` in UAPI
     "linux_time_bits64",
     "musl_v1_2_3",
+    // Corresponds to `_REDIR_TIME64` in musl
+    "musl32_time64",
     "vxworks_lt_25_09",
 ];
 
@@ -49,6 +51,9 @@ const CHECK_CFG_EXTRA: &[(&str, &[&str])] = &[
     ),
 ];
 
+/// Musl architectures that set `#define _REDIR_TIME64 1`.
+const MUSL_REDIR_TIME64_ARCHES: &[&str] = &["arm", "mips", "powerpc", "x86"];
+
 fn main() {
     // Avoid unnecessary re-building.
     println!("cargo:rerun-if-changed=build.rs");
@@ -99,12 +104,29 @@ fn main() {
         _ => (),
     }
 
-    let musl_v1_2_3 = env_flag("RUST_LIBC_UNSTABLE_MUSL_V1_2_3");
+    let mut musl_v1_2_3 = env_flag("RUST_LIBC_UNSTABLE_MUSL_V1_2_3");
     println!("cargo:rerun-if-env-changed=RUST_LIBC_UNSTABLE_MUSL_V1_2_3");
-    // loongarch64 and ohos have already updated
-    if musl_v1_2_3 || target_arch == "loongarch64" || target_env == "ohos" {
-        // FIXME(musl): enable time64 api as well
+
+    // OpenHarmony uses a fork of the musl libc
+    let musl = target_env == "musl" || target_env == "ohos";
+
+    // loongarch64 and ohos only exist with recent musl
+    if target_arch == "loongarch64" || target_env == "ohos" {
+        musl_v1_2_3 = true;
+    }
+
+    if musl && musl_v1_2_3 {
         set_cfg("musl_v1_2_3");
+        if MUSL_REDIR_TIME64_ARCHES.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");
+    if linux_time_bits64 {
+        set_cfg("linux_time_bits64");
     }
     println!("cargo:rerun-if-env-changed=RUST_LIBC_UNSTABLE_GNU_FILE_OFFSET_BITS");
     println!("cargo:rerun-if-env-changed=RUST_LIBC_UNSTABLE_GNU_TIME_BITS");

libc-test/build.rs

@@ -3836,6 +3836,7 @@ fn test_linux(target: &str) {
     let i686 = target.contains("i686");
     let ppc = target.contains("powerpc");
     let ppc64 = target.contains("powerpc64");
+    let ppc32 = ppc && !ppc64;
     let s390x = target.contains("s390x");
     let sparc64 = target.contains("sparc64");
     let x32 = target.contains("x32");
@@ -3848,6 +3849,8 @@ fn test_linux(target: &str) {
     let wasm32 = target.contains("wasm32");
     let uclibc = target.contains("uclibc");
     let mips = target.contains("mips");
+    let mips64 = target.contains("mips64");
+    let mips32 = mips && !mips64;
 
     let musl_v1_2_3 = env::var("RUST_LIBC_UNSTABLE_MUSL_V1_2_3").is_ok();
     if musl_v1_2_3 {
@@ -3856,8 +3859,12 @@ fn test_linux(target: &str) {
     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 arm || ppc32 || 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