From 6357d4166475d64bc98f34ed895ee03f2a0ba3b1 Mon Sep 17 00:00:00 2001
From: Matthew Maurer <mmaurer@google.com>
Date: Tue, 30 Jul 2024 22:52:51 +0000
Subject: [PATCH] android: Remove libstd hacks for unsupported Android APIs

Our minimum supported API version is 21, remove hacks to support older
Android APIs.
---
 library/std/src/sys/pal/mod.rs          | 21 +++----
 library/std/src/sys/pal/unix/android.rs | 81 -------------------------
 library/std/src/sys/pal/unix/mod.rs     |  5 --
 3 files changed, 7 insertions(+), 100 deletions(-)
 delete mode 100644 library/std/src/sys/pal/unix/android.rs

diff --git a/library/std/src/sys/pal/mod.rs b/library/std/src/sys/pal/mod.rs
index df0176244489a..652ac28e5ccee 100644
--- a/library/std/src/sys/pal/mod.rs
+++ b/library/std/src/sys/pal/mod.rs
@@ -77,21 +77,14 @@ cfg_if::cfg_if! {
 }
 
 #[cfg(not(test))]
-cfg_if::cfg_if! {
-    if #[cfg(target_os = "android")] {
-        pub use self::android::log2f32;
-        pub use self::android::log2f64;
-    } else {
-        #[inline]
-        pub fn log2f32(n: f32) -> f32 {
-            unsafe { crate::intrinsics::log2f32(n) }
-        }
+#[inline]
+pub fn log2f32(n: f32) -> f32 {
+    unsafe { crate::intrinsics::log2f32(n) }
+}
 
-        #[inline]
-        pub fn log2f64(n: f64) -> f64 {
-            unsafe { crate::intrinsics::log2f64(n) }
-        }
-    }
+#[inline]
+pub fn log2f64(n: f64) -> f64 {
+    unsafe { crate::intrinsics::log2f64(n) }
 }
 
 #[cfg(not(target_os = "uefi"))]
diff --git a/library/std/src/sys/pal/unix/android.rs b/library/std/src/sys/pal/unix/android.rs
deleted file mode 100644
index 0f704994f550a..0000000000000
--- a/library/std/src/sys/pal/unix/android.rs
+++ /dev/null
@@ -1,81 +0,0 @@
-//! Android ABI-compatibility module
-//!
-//! The ABI of Android has changed quite a bit over time, and std attempts to be
-//! both forwards and backwards compatible as much as possible. We want to
-//! always work with the most recent version of Android, but we also want to
-//! work with older versions of Android for whenever projects need to.
-//!
-//! Our current minimum supported Android version is `android-9`, e.g., Android
-//! with API level 9. We then in theory want to work on that and all future
-//! versions of Android!
-//!
-//! Some of the detection here is done at runtime via `dlopen` and
-//! introspection. Other times no detection is performed at all and we just
-//! provide a fallback implementation as some versions of Android we support
-//! don't have the function.
-//!
-//! You'll find more details below about why each compatibility shim is needed.
-
-#![cfg(target_os = "android")]
-
-use libc::{c_int, sighandler_t};
-
-use super::weak::weak;
-
-// The `log2` and `log2f` functions apparently appeared in android-18, or at
-// least you can see they're not present in the android-17 header [1] and they
-// are present in android-18 [2].
-//
-// [1]: https://chromium.googlesource.com/android_tools/+/20ee6d20/ndk/platforms
-//                                       /android-17/arch-arm/usr/include/math.h
-// [2]: https://chromium.googlesource.com/android_tools/+/20ee6d20/ndk/platforms
-//                                       /android-18/arch-arm/usr/include/math.h
-//
-// Note that these shims are likely less precise than directly calling `log2`,
-// but hopefully that should be enough for now...
-//
-// Note that mathematically, for any arbitrary `y`:
-//
-//      log_2(x) = log_y(x) / log_y(2)
-//               = log_y(x) / (1 / log_2(y))
-//               = log_y(x) * log_2(y)
-//
-// Hence because `ln` (log_e) is available on all Android we just choose `y = e`
-// and get:
-//
-//      log_2(x) = ln(x) * log_2(e)
-
-#[cfg(not(test))]
-pub fn log2f32(f: f32) -> f32 {
-    f.ln() * crate::f32::consts::LOG2_E
-}
-
-#[cfg(not(test))]
-pub fn log2f64(f: f64) -> f64 {
-    f.ln() * crate::f64::consts::LOG2_E
-}
-
-// Back in the day [1] the `signal` function was just an inline wrapper
-// around `bsd_signal`, but starting in API level android-20 the `signal`
-// symbols was introduced [2]. Finally, in android-21 the API `bsd_signal` was
-// removed [3].
-//
-// Basically this means that if we want to be binary compatible with multiple
-// Android releases (oldest being 9 and newest being 21) then we need to check
-// for both symbols and not actually link against either.
-//
-// [1]: https://chromium.googlesource.com/android_tools/+/20ee6d20/ndk/platforms
-//                                       /android-18/arch-arm/usr/include/signal.h
-// [2]: https://chromium.googlesource.com/android_tools/+/fbd420/ndk_experimental
-//                                       /platforms/android-20/arch-arm
-//                                       /usr/include/signal.h
-// [3]: https://chromium.googlesource.com/android_tools/+/20ee6d/ndk/platforms
-//                                       /android-21/arch-arm/usr/include/signal.h
-pub unsafe fn signal(signum: c_int, handler: sighandler_t) -> sighandler_t {
-    weak!(fn signal(c_int, sighandler_t) -> sighandler_t);
-    weak!(fn bsd_signal(c_int, sighandler_t) -> sighandler_t);
-
-    let f = signal.get().or_else(|| bsd_signal.get());
-    let f = f.expect("neither `signal` nor `bsd_signal` symbols found");
-    f(signum, handler)
-}
diff --git a/library/std/src/sys/pal/unix/mod.rs b/library/std/src/sys/pal/unix/mod.rs
index 3fc51ff59a936..b62129f4cdd26 100644
--- a/library/std/src/sys/pal/unix/mod.rs
+++ b/library/std/src/sys/pal/unix/mod.rs
@@ -8,7 +8,6 @@ use crate::io::ErrorKind;
 pub mod weak;
 
 pub mod alloc;
-pub mod android;
 pub mod args;
 pub mod env;
 pub mod fd;
@@ -237,12 +236,8 @@ pub unsafe fn cleanup() {
 }
 
 #[allow(unused_imports)]
-#[cfg(not(target_os = "android"))]
 pub use libc::signal;
 
-#[cfg(target_os = "android")]
-pub use crate::sys::android::signal;
-
 #[inline]
 pub(crate) fn is_interrupted(errno: i32) -> bool {
     errno == libc::EINTR