Support native ARM64 MSVC toolchain, and fallback to x64 if emulation is available

dev-tools/gen-windows-sys-binding/Cargo.toml

@@ -5,4 +5,5 @@ edition = "2018"
 publish = false
 
 [dependencies]
-windows-bindgen = "0.49"
+windows-bindgen = "0.53"
+tempfile = "3"

dev-tools/gen-windows-sys-binding/src/main.rs

@@ -3,7 +3,7 @@
 
 use std::{
     fs,
-    io::{self, Write},
+    io::{self, Read, Write},
 };
 
 /// This is printed to the file before the rest of the contents.
@@ -17,49 +17,48 @@ const PRELUDE: &str = r#"// This file is autogenerated.
 // ```
 "#;
 
-const POSTLUDE: &str = r#"
-/// Adapted from
-/// [`core::ptr::invalid_mut()`](https://doc.rust-lang.org/src/core/ptr/mod.rs.html#600-607).
-///
-/// This function should actually use `core::mem::transmute` but due to msrv
-/// we use `as` casting instead.
-///
-/// Once msrv is bumped to 1.56, replace this with `core::mem::transmute` since
-/// it is const stablised in 1.56
-///
-/// NOTE that once supports `strict_provenance` we would also have to update
-/// this.
-const fn invalid_mut<T>(addr: usize) -> *mut T {
-    addr as *mut T
-}
-"#;
-
 fn main() -> io::Result<()> {
     let manifest_dir = env!("CARGO_MANIFEST_DIR");
-    // Load the list of APIs
+    let temp_file = tempfile::Builder::new()
+        .suffix(".rs")
+        .tempfile()
+        .expect("failed to create temp file");
+
+    // Common args to windows_bindgen.
+    let mut args = vec![
+        "--config",
+        "std",
+        "flatten",
+        "--out",
+        temp_file.path().to_str().unwrap(),
+        "--filter",
+    ];
+
+    // Append the list of APIs
     let buffer = fs::read_to_string(format!("{manifest_dir}/windows_sys.list"))
-        .expect("failed to read windows_sys.list");
-    let names: Vec<&str> = buffer
-        .lines()
-        .filter_map(|line| {
-            let line = line.trim();
-            if line.is_empty() || line.starts_with("//") {
-                None
-            } else {
-                Some(line)
-            }
-        })
-        .collect();
+        .expect("failed to read list");
+    args.extend(buffer.lines().filter_map(|line| {
+        let line = line.trim();
+        if line.is_empty() || line.starts_with("//") {
+            None
+        } else {
+            Some(line)
+        }
+    }));
+
+    // Generate bindings.
+    windows_bindgen::bindgen(&args).expect("running bindgen failed");
 
-    // Write the bindings to windows-sys.rs
-    let bindings =
-        windows_bindgen::standalone_std(&names).replace("::core::ptr::invalid_mut", "invalid_mut");
+    let mut bindings = String::new();
+    fs::File::open(temp_file.path())
+        .expect("failed to open temp windows_sys.rs")
+        .read_to_string(&mut bindings)
+        .expect("failed to read temp windows_sys.rs");
 
     let mut f = fs::File::create(format!("{manifest_dir}/../../src/windows/windows_sys.rs"))
         .expect("failed to create windows_sys.rs");
     f.write_all(PRELUDE.as_bytes())?;
     f.write_all(bindings.as_bytes())?;
-    f.write_all(POSTLUDE.as_bytes())?;
 
     Ok(())
 }

dev-tools/gen-windows-sys-binding/windows_sys.list

@@ -11,6 +11,7 @@ Windows.Win32.Foundation.WAIT_OBJECT_0
 Windows.Win32.Foundation.WAIT_TIMEOUT
 Windows.Win32.Foundation.WAIT_FAILED
 Windows.Win32.Foundation.WAIT_ABANDONED
+Windows.Win32.Foundation.FreeLibrary
 
 Windows.Win32.System.Com.SAFEARRAY
 Windows.Win32.System.Com.SAFEARRAYBOUND
@@ -19,6 +20,9 @@ Windows.Win32.System.Com.COINIT_MULTITHREADED
 Windows.Win32.System.Com.CoCreateInstance
 Windows.Win32.System.Com.CoInitializeEx
 
+Windows.Win32.System.LibraryLoader.GetProcAddress
+Windows.Win32.System.LibraryLoader.LoadLibraryA
+
 Windows.Win32.System.Pipes.PeekNamedPipe
 
 Windows.Win32.System.Registry.RegCloseKey
@@ -31,9 +35,13 @@ Windows.Win32.System.Registry.KEY_READ
 Windows.Win32.System.Registry.KEY_WOW64_32KEY
 Windows.Win32.System.Registry.REG_SZ
 
+Windows.Win32.System.SystemInformation.IMAGE_FILE_MACHINE_AMD64
+
+Windows.Win32.System.Threading.GetMachineTypeAttributes
 Windows.Win32.System.Threading.ReleaseSemaphore
 Windows.Win32.System.Threading.WaitForSingleObject
 Windows.Win32.System.Threading.SEMAPHORE_MODIFY_STATE
 Windows.Win32.System.Threading.THREAD_SYNCHRONIZE
+Windows.Win32.System.Threading.UserEnabled
 
 Windows.Win32.System.WindowsProgramming.OpenSemaphoreA

src/windows/com.rs

@@ -15,6 +15,7 @@ use crate::windows::{
     },
 };
 use std::{
+    convert::TryInto,
     ffi::{OsStr, OsString},
     mem::ManuallyDrop,
     ops::Deref,
@@ -24,7 +25,7 @@ use std::{
 };
 
 pub fn initialize() -> Result<(), HRESULT> {
-    let err = unsafe { CoInitializeEx(null(), COINIT_MULTITHREADED) };
+    let err = unsafe { CoInitializeEx(null(), COINIT_MULTITHREADED.try_into().unwrap()) };
     if err != S_OK && err != S_FALSE {
         // S_FALSE just means COM is already initialized
         Err(err)

src/windows/find_tools.rs

@@ -163,6 +163,10 @@ mod impl_ {
     use crate::windows::registry::{RegistryKey, LOCAL_MACHINE};
     use crate::windows::setup_config::SetupConfiguration;
     use crate::windows::vs_instances::{VsInstances, VswhereInstance};
+    use crate::windows::windows_sys::{
+        FreeLibrary, GetMachineTypeAttributes, GetProcAddress, LoadLibraryA, UserEnabled, HMODULE,
+        IMAGE_FILE_MACHINE_AMD64, MACHINE_ATTRIBUTES, S_OK,
+    };
     use std::convert::TryFrom;
     use std::env;
     use std::ffi::OsString;
@@ -173,6 +177,8 @@ mod impl_ {
     use std::path::{Path, PathBuf};
     use std::process::Command;
     use std::str::FromStr;
+    use std::sync::atomic::{AtomicBool, Ordering};
+    use std::sync::Once;
 
     use super::MSVC_FAMILY;
     use crate::Tool;
@@ -199,6 +205,71 @@ mod impl_ {
         include: Vec<PathBuf>,
     }
 
+    struct LibraryHandle(HMODULE);
+
+    impl LibraryHandle {
+        fn new(name: &[u8]) -> Option<Self> {
+            let handle = unsafe { LoadLibraryA(name.as_ptr() as _) };
+            (!handle.is_null()).then(|| Self(handle))
+        }
+
+        /// Get a function pointer to a function in the library.
+        /// SAFETY: The caller must ensure that the function signature matches the actual function.
+        /// The easiest way to do this is to add an entry to windows_sys_no_link.list and use the
+        /// generated function for `func_signature`.
+        unsafe fn get_proc_address<F>(&self, name: &[u8]) -> Option<F> {
+            let symbol = unsafe { GetProcAddress(self.0, name.as_ptr() as _) };
+            symbol.map(|symbol| unsafe { mem::transmute_copy(&symbol) })
+        }
+    }
+
+    impl Drop for LibraryHandle {
+        fn drop(&mut self) {
+            unsafe { FreeLibrary(self.0) };
+        }
+    }
+
+    type GetMachineTypeAttributesFuncType =
+        unsafe extern "system" fn(u16, *mut MACHINE_ATTRIBUTES) -> i32;
+    const _: () = {
+        // Ensure that our hand-written signature matches the actual function signature.
+        // We can't use `GetMachineTypeAttributes` outside of a const scope otherwise we'll end up statically linking to
+        // it, which will fail to load on older versions of Windows.
+        let _: GetMachineTypeAttributesFuncType = GetMachineTypeAttributes;
+    };
+
+    fn is_amd64_emulation_supported_inner() -> Option<bool> {
+        // GetMachineTypeAttributes is only available on Win11 22000+, so dynamically load it.
+        let kernel32 = LibraryHandle::new(b"kernel32.dll\0")?;
+        // SAFETY: GetMachineTypeAttributesFuncType is checked to match the real function signature.
+        let get_machine_type_attributes = unsafe {
+            kernel32
+                .get_proc_address::<GetMachineTypeAttributesFuncType>(b"GetMachineTypeAttributes\0")
+        }?;
+        let mut attributes = Default::default();
+        if unsafe { get_machine_type_attributes(IMAGE_FILE_MACHINE_AMD64, &mut attributes) } == S_OK
+        {
+            Some((attributes & UserEnabled) != 0)
+        } else {
+            Some(false)
+        }
+    }
+
+    fn is_amd64_emulation_supported() -> bool {
+        // TODO: Replace with a OnceLock once MSRV is 1.70.
+        static LOAD_VALUE: Once = Once::new();
+        static IS_SUPPORTED: AtomicBool = AtomicBool::new(false);
+
+        // Using Relaxed ordering since the Once is providing synchronization.
+        LOAD_VALUE.call_once(|| {
+            IS_SUPPORTED.store(
+                is_amd64_emulation_supported_inner().unwrap_or(false),
+                Ordering::Relaxed,
+            );
+        });
+        IS_SUPPORTED.load(Ordering::Relaxed)
+    }
+
     impl MsvcTool {
         fn new(tool: PathBuf) -> MsvcTool {
             MsvcTool {
@@ -226,7 +297,6 @@ mod impl_ {
 
     /// Checks to see if the `VSCMD_ARG_TGT_ARCH` environment variable matches the
     /// given target's arch. Returns `None` if the variable does not exist.
-    #[cfg(windows)]
     fn is_vscmd_target(target: TargetArch<'_>) -> Option<bool> {
         let vscmd_arch = env::var("VSCMD_ARG_TGT_ARCH").ok()?;
         // Convert the Rust target arch to its VS arch equivalent.
@@ -482,27 +552,41 @@ mod impl_ {
     ) -> Option<(PathBuf, PathBuf, PathBuf, PathBuf, Option<PathBuf>, PathBuf)> {
         let version = vs15plus_vc_read_version(instance_path)?;
 
-        let host = match host_arch() {
-            X86 => "X86",
-            X86_64 => "X64",
-            // There is no natively hosted compiler on ARM64.
-            // Instead, use the x86 toolchain under emulation (there is no x64 emulation).
-            AARCH64 => "X86",
+        let hosts = match host_arch() {
+            X86 => &["X86"],
+            X86_64 => &["X64"],
+            // Starting with VS 17.4, there is a natively hosted compiler on ARM64:
+            // https://devblogs.microsoft.com/visualstudio/arm64-visual-studio-is-officially-here/
+            // On older versions of VS, we use x64 if running under emulation is supported,
+            // otherwise use x86.
+            AARCH64 => {
+                if is_amd64_emulation_supported() {
+                    &["ARM64", "X64", "X86"][..]
+                } else {
+                    &["ARM64", "X86"]
+                }
+            }
             _ => return None,
         };
         let target = lib_subdir(target)?;
         // The directory layout here is MSVC/bin/Host$host/$target/
         let path = instance_path.join(r"VC\Tools\MSVC").join(version);
+        // We use the first available host architecture that can build for the target
+        let (host_path, host) = hosts.iter().find_map(|&x| {
+            let candidate = path.join("bin").join(format!("Host{}", x));
+            if candidate.join(target).exists() {
+                Some((candidate, x))
+            } else {
+                None
+            }
+        })?;
         // This is the path to the toolchain for a particular target, running
         // on a given host
-        let bin_path = path.join("bin").join(format!("Host{}", host)).join(target);
+        let bin_path = host_path.join(target);
         // But! we also need PATH to contain the target directory for the host
         // architecture, because it contains dlls like mspdb140.dll compiled for
         // the host architecture.
-        let host_dylib_path = path
-            .join("bin")
-            .join(format!("Host{}", host))
-            .join(host.to_lowercase());
+        let host_dylib_path = host_path.join(host.to_lowercase());
         let lib_path = path.join("lib").join(target);
         let alt_lib_path = (target == "arm64ec").then(|| path.join("lib").join("arm64ec"));
         let include_path = path.join("include");