Add windows aarch64 trampolines (#1190)

Lacking windows compatible aarch64 hardware, i cross compiled the
trampoline from x86_64 linux to aarch64-pc-windows-msvc; I added the
instructions to the puffin-trampoline readme. With some testing on an
aarch64 windows machine, this should be sufficient to build working
win_arm64 tagged wheels.

i686-pc-windows-msvc is failing with an error:

```
error: linking with `lld-link` failed: exit status: 1
  = note: lld-link: error: undefined symbol: __aulldiv
          >>> referenced by libcompiler_builtins-2fb09dee087e9f64.rlib(compiler_builtins-2fb09dee087e9f64.compiler_builtins.597f0152646f1b8-cgu.0.rcgu.o):(compiler_builtins::int::specialized_div_rem::u128_div_rem::h06aed1e23a3f8f5c)
          >>> referenced by libcompiler_builtins-2fb09dee087e9f64.rlib(compiler_builtins-2fb09dee087e9f64.compiler_builtins.597f0152646f1b8-cgu.0.rcgu.o):(compiler_builtins::int::specialized_div_rem::u128_div_rem::h06aed1e23a3f8f5c)
          >>> referenced by libcompiler_builtins-2fb09dee087e9f64.rlib(compiler_builtins-2fb09dee087e9f64.compiler_builtins.597f0152646f1b8-cgu.0.rcgu.o):(compiler_builtins::int::specialized_div_rem::u128_div_rem::h06aed1e23a3f8f5c)
          >>> referenced 4 more times

          lld-link: error: undefined symbol: __aullrem
          >>> referenced by libcompiler_builtins-2fb09dee087e9f64.rlib(compiler_builtins-2fb09dee087e9f64.compiler_builtins.597f0152646f1b8-cgu.0.rcgu.o):(compiler_builtins::int::specialized_div_rem::u128_div_rem::h06aed1e23a3f8f5c)
          >>> referenced by libcompiler_builtins-2fb09dee087e9f64.rlib(compiler_builtins-2fb09dee087e9f64.compiler_builtins.597f0152646f1b8-cgu.0.rcgu.o):(compiler_builtins::int::specialized_div_rem::u128_div_rem::h06aed1e23a3f8f5c)
          >>> referenced by libcompiler_builtins-2fb09dee087e9f64.rlib(compiler_builtins-2fb09dee087e9f64.compiler_builtins.597f0152646f1b8-cgu.0.rcgu.o):(compiler_builtins::int::specialized_div_rem::u128_div_rem::h06aed1e23a3f8f5c)
          >>> referenced 4 more times
```

crates/install-wheel-rs/src/wheel.rs

@@ -33,19 +33,21 @@ use crate::{find_dist_info, Error};
 /// `#!/usr/bin/env python`
 pub const SHEBANG_PYTHON: &str = "#!/usr/bin/env python";
 
-#[cfg(windows)]
+#[cfg(all(windows, target_arch = "x86_64"))]
 const LAUNCHER_X86_64_GUI: &[u8] =
-    include_bytes!("../../puffin-trampoline/trampolines/puffin-trampoline-gui.exe");
+    include_bytes!("../../puffin-trampoline/trampolines/puffin-trampoline-x86_64-gui.exe");
 
-#[cfg(windows)]
+#[cfg(all(windows, target_arch = "x86_64"))]
 const LAUNCHER_X86_64_CONSOLE: &[u8] =
-    include_bytes!("../../puffin-trampoline/trampolines/puffin-trampoline-console.exe");
+    include_bytes!("../../puffin-trampoline/trampolines/puffin-trampoline-x86_64-console.exe");
 
-#[cfg(not(windows))]
-const LAUNCHER_X86_64_GUI: &[u8] = &[];
+#[cfg(all(windows, target_arch = "aarch64"))]
+const LAUNCHER_AARCH64_GUI: &[u8] =
+    include_bytes!("../../puffin-trampoline/trampolines/puffin-trampoline-aarch64-gui.exe");
 
-#[cfg(not(windows))]
-const LAUNCHER_X86_64_CONSOLE: &[u8] = &[];
+#[cfg(all(windows, target_arch = "aarch64"))]
+const LAUNCHER_AARCH64_CONSOLE: &[u8] =
+    include_bytes!("../../puffin-trampoline/trampolines/puffin-trampoline-aarch64-console.exe");
 
 /// Wrapper script template function
 ///
@@ -293,6 +295,7 @@ fn get_shebang(location: &InstallLocation<impl AsRef<Path>>) -> String {
 /// to start the embedded script.
 ///
 /// <https://github.com/pypa/pip/blob/fd0ea6bc5e8cb95e518c23d901c26ca14db17f89/src/pip/_vendor/distlib/scripts.py#L248-L262>
+#[allow(unused_variables)]
 pub(crate) fn windows_script_launcher(
     launcher_python_script: &str,
     is_gui: bool,
@@ -303,7 +306,8 @@ pub(crate) fn windows_script_launcher(
         return Err(Error::NotWindows);
     }
 
-    let launcher_bin = match env::consts::ARCH {
+    let launcher_bin: &[u8] = match env::consts::ARCH {
+        #[cfg(all(windows, target_arch = "x86_64"))]
         "x86_64" => {
             if is_gui {
                 LAUNCHER_X86_64_GUI
@@ -311,9 +315,20 @@ pub(crate) fn windows_script_launcher(
                 LAUNCHER_X86_64_CONSOLE
             }
         }
+        #[cfg(all(windows, target_arch = "aarch64"))]
+        "aarch64" => {
+            if is_gui {
+                LAUNCHER_AARCH64_GUI
+            } else {
+                LAUNCHER_AARCH64_CONSOLE
+            }
+        }
+        #[cfg(windows)]
         arch => {
             return Err(Error::UnsupportedWindowsArch(arch));
         }
+        #[cfg(not(windows))]
+        arch => &[],
     };
 
     let mut payload: Vec<u8> = Vec::new();
@@ -1163,10 +1178,7 @@ mod test {
 
     use indoc::{formatdoc, indoc};
 
-    use super::{
-        parse_key_value_file, parse_wheel_version, read_record_file, relative_to, Script,
-        LAUNCHER_X86_64_CONSOLE, LAUNCHER_X86_64_GUI,
-    };
+    use super::{parse_key_value_file, parse_wheel_version, read_record_file, relative_to, Script};
 
     #[test]
     fn test_parse_key_value_file() {
@@ -1294,17 +1306,34 @@ mod test {
     }
 
     #[test]
+    #[cfg(all(windows, target_arch = "x86_64"))]
     fn test_launchers_are_small() {
         // At time of writing, they are 15872 bytes.
         assert!(
-            LAUNCHER_X86_64_GUI.len() < 20 * 1024,
+            super::LAUNCHER_X86_64_GUI.len() < 20 * 1024,
             "GUI launcher: {}",
-            LAUNCHER_X86_64_GUI.len()
+            super::LAUNCHER_X86_64_GUI.len()
         );
         assert!(
-            LAUNCHER_X86_64_CONSOLE.len() < 20 * 1024,
+            super::LAUNCHER_X86_64_CONSOLE.len() < 20 * 1024,
             "CLI launcher: {}",
-            LAUNCHER_X86_64_CONSOLE.len()
+            super::LAUNCHER_X86_64_CONSOLE.len()
+        );
+    }
+
+    #[test]
+    #[cfg(all(windows, target_arch = "aarch64"))]
+    fn test_launchers_are_small() {
+        // At time of writing, they are 14848 and 14336 bytes.
+        assert!(
+            super::LAUNCHER_AArch64_GUI.len() < 20 * 1024,
+            "GUI launcher: {}",
+            super::LAUNCHER_AArch64_GUI.len()
+        );
+        assert!(
+            super::LAUNCHER_AArch64_CONSOLE.len() < 20 * 1024,
+            "CLI launcher: {}",
+            super::LAUNCHER_AArch64_CONSOLE.len()
         );
     }
 }

crates/puffin-trampoline/README.md

@@ -112,3 +112,19 @@ Two approaches that are reasonably likely to work:
 Hopefully in the future as `#![no_std]` develops, this will get smoother.
 
 Also, sometimes it helps to fiddle with optimization levels.
+
+# Cross compiling from linux
+
+Install [cargo xwin](https://github.com/rust-cross/cargo-xwin). Use your
+package manager to install LLD and add the rustup targets:
+
+```shell
+sudo apt install llvm clang lld
+rustup target add x86_64-pc-windows-msvc
+rustup target add aarch64-pc-windows-msvc
+```
+
+```shell
+cargo +nightly xwin build --release -Z build-std=core,panic_abort,alloc -Z build-std-features=compiler-builtins-mem --target x86_64-pc-windows-msvc
+cargo +nightly xwin build --release -Z build-std=core,panic_abort,alloc -Z build-std-features=compiler-builtins-mem --target aarch64-pc-windows-msvc
+```