feat: deprecate windows time64_t

Functionality related to the Windows `time64_t` has been deprecated in
favor of a single, 64-bit wide `time_t`. This has also required some
work into getting rid of the conditional compilation uses of `time_t` on
GNU target environments, and tweaking the `max_align_t` type, as that
seemed to provide an incoherent interface in Windows with mingw32.

During this work, what seems like some incoherences in the CI pipeline
where found out, and have been addressed as well. This mostly consists
of a step where mingw32 was being installed and possible "fixed" but
that would never run because it relied on environment variables that
were only visible in the runner once the job coming after the one
setting up the Rust toolchain ran. This has now been removed in favor of
not performing any checks, as CI logs seem to have been running for some
time without this.

The FIXME comment on the tier 1 platform support for Windows with GNU
has also been removed as no segfaults were observed.

Author: dybucc

.github/workflows/ci.yaml

@@ -123,15 +123,13 @@ jobs:
             os: windows-11-arm
           - target: aarch64-unknown-linux-gnu
             os: ubuntu-24.04-arm
-          # FIXME: It currently causes segfaults.
-          #- target: i686-pc-windows-gnu
-          #  env: { ARCH_BITS: 32, ARCH: i686 }
+          - target: i686-pc-windows-gnu
+            os: windows-2025
           - target: i686-pc-windows-msvc
             os: windows-2025
           - target: i686-unknown-linux-gnu
           - target: x86_64-pc-windows-gnu
             os: windows-2025
-            env: { ARCH_BITS: 64, ARCH: x86_64 }
           - target: x86_64-pc-windows-msvc
             os: windows-2025
           - target: x86_64-unknown-linux-gnu

ci/install-rust.sh

@@ -38,23 +38,11 @@ if [ -n "${INSTALL_RUST_SRC:-}" ]; then
 fi
 
 if [ "$os" = "windows" ]; then
-    if [ "${ARCH_BITS:-}" = "i686" ]; then
-        echo "Install MinGW32"
-        choco install mingw --x86 --force
-    fi
-
     echo "Find GCC libraries"
     gcc -print-search-dirs
-    /usr/bin/find "C:\ProgramData\Chocolatey" -name "crt2*"
-    /usr/bin/find "C:\ProgramData\Chocolatey" -name "dllcrt2*"
-    /usr/bin/find "C:\ProgramData\Chocolatey" -name "libmsvcrt*"
-
-    if [ -n "${ARCH_BITS:-}" ]; then
-        echo "Fix MinGW"
-        for i in crt2.o dllcrt2.o libmingwex.a libmsvcrt.a; do
-            cp -f "/C/ProgramData/Chocolatey/lib/mingw/tools/install/mingw$ARCH_BITS/$ARCH-w64-mingw32/lib/$i" "$(rustc --print sysroot)/lib/rustlib/$TARGET/lib"
-        done
-    fi
+    /usr/bin/find "C:\ProgramData\chocolatey" -name "crt2*"
+    /usr/bin/find "C:\ProgramData\chocolatey" -name "dllcrt2*"
+    /usr/bin/find "C:\ProgramData\chocolatey" -name "libmsvcrt*"
 fi
 
 echo "Query rust and cargo versions"

libc-test/build.rs

@@ -753,7 +753,6 @@ fn test_cygwin(target: &str) {
 fn test_windows(target: &str) {
     assert!(target.contains("windows"));
     let gnu = target.contains("gnu");
-    let i686 = target.contains("i686");
 
     let mut cfg = ctest_cfg();
 
@@ -818,19 +817,9 @@ fn test_windows(target: &str) {
     cfg.skip_alias(move |alias| match alias.ident() {
         "SSIZE_T" if !gnu => true,
         "ssize_t" if !gnu => true,
-        // FIXME(windows): The size and alignment of this type are incorrect
-        "time_t" if gnu && i686 => true,
         _ => false,
     });
 
-    cfg.skip_struct(move |struct_| {
-        match struct_.ident() {
-            // FIXME(windows): The size and alignment of this struct are incorrect
-            "timespec" if gnu && i686 => true,
-            _ => false,
-        }
-    });
-
     cfg.skip_const(move |constant| {
         match constant.ident() {
             // FIXME(windows): API error:

src/windows/gnu/mod.rs

@@ -1,5 +1,7 @@
 use crate::prelude::*;
 
+// The below configuration for machines with 32-bit word size aligns with the
+// declaration in the `mingw-w64` headers.
 cfg_if! {
     if #[cfg(target_pointer_width = "64")] {
         s_no_extra_traits! {
@@ -10,9 +12,9 @@ cfg_if! {
         }
     } else if #[cfg(target_pointer_width = "32")] {
         s_no_extra_traits! {
-            #[repr(align(16))]
+            #[repr(align(8))]
             pub struct max_align_t {
-                priv_: [i64; 6],
+                priv_: [i64; 3],
             }
         }
     }

src/windows/mod.rs

@@ -18,13 +18,7 @@ pub type clock_t = i32;
 
 pub type errno_t = c_int;
 
-cfg_if! {
-    if #[cfg(all(target_arch = "x86", target_env = "gnu"))] {
-        pub type time_t = i32;
-    } else {
-        pub type time_t = i64;
-    }
-}
+pub type time_t = i64;
 
 pub type off_t = i32;
 pub type dev_t = u32;
@@ -34,6 +28,12 @@ extern_ty! {
     pub enum timezone {}
 }
 
+#[deprecated(
+    since = "1.0.0",
+    note = "This time-related value, among others, is part of the shift \
+            towards using a single, 64-bit-sized `time_t`. See #PENDING for \
+            discussion."
+)]
 pub type time64_t = i64;
 
 pub type SOCKET = crate::uintptr_t;