Add support for raw-dylib

Author: dpaoliello

Cargo.lock

@@ -17,6 +17,7 @@ cranelift-object = { version = "0.110.1" }
 target-lexicon = "0.12.0"
 gimli = { version = "0.28", default-features = false, features = ["write"]}
 object = { version = "0.36", default-features = false, features = ["std", "read_core", "write", "archive", "coff", "elf", "macho", "pe"] }
+ar_archive_writer = "0.3"
 
 indexmap = "2.0.0"
 libloading = { version = "0.8.0", optional = true }

Cargo.toml

@@ -106,6 +106,7 @@ const BASE_SYSROOT_SUITE: &[TestCase] = &[
         ]);
         runner.run_out_command("gen_block_iterate", &[]);
     }),
+    TestCase::build_bin_and_run("aot.raw-dylib", "example/raw-dylib.rs", &[]),
 ];
 
 pub(crate) static RAND_REPO: GitRepo = GitRepo::github(

build_system/tests.rs

@@ -45,6 +45,7 @@ aot.issue-59326
 aot.polymorphize_coroutine
 aot.neon
 aot.gen_block_iterate
+aot.raw-dylib
 
 testsuite.extended_sysroot
 test.rust-random/rand

config.txt

@@ -0,0 +1,31 @@
+// Tests the raw-dylib feature for Windows.
+// https://doc.rust-lang.org/reference/items/external-blocks.html#the-link-attribute
+
+fn main() {
+    #[cfg(windows)]
+    {
+        #[link(name = "kernel32", kind = "raw-dylib")]
+        extern "C" {
+            fn GetModuleFileNameA(
+                module: *mut std::ffi::c_void,
+                filename: *mut u8,
+                size: u32,
+            ) -> u32;
+        }
+
+        // Get the filename of the current executable....
+        let mut buffer = [0u8; 1024];
+        let size = unsafe {
+            GetModuleFileNameA(core::ptr::null_mut(), buffer.as_mut_ptr(), buffer.len() as u32)
+        };
+        if size == 0 {
+            eprintln!("failed to get module file name: {}", std::io::Error::last_os_error());
+            return;
+        } else {
+            // ...and make sure that it matches the test name.
+            let filename =
+                std::ffi::CStr::from_bytes_with_nul(&buffer[..size as usize + 1]).unwrap();
+            assert!(filename.to_str().unwrap().ends_with("raw-dylib.exe"));
+        }
+    }
+}

example/raw-dylib.rs

@@ -1,8 +1,13 @@
+use std::borrow::Borrow;
+use std::fs;
 use std::path::Path;
 
+use ar_archive_writer::{COFFShortExport, MachineTypes};
 use rustc_codegen_ssa::back::archive::{
-    ArArchiveBuilder, ArchiveBuilder, ArchiveBuilderBuilder, DEFAULT_OBJECT_READER,
+    create_mingw_dll_import_lib, ArArchiveBuilder, ArchiveBuilder, ArchiveBuilderBuilder,
+    DEFAULT_OBJECT_READER,
 };
+use rustc_codegen_ssa::common::is_mingw_gnu_toolchain;
 use rustc_session::Session;
 
 pub(crate) struct ArArchiveBuilderBuilder;
@@ -15,10 +20,74 @@ impl ArchiveBuilderBuilder for ArArchiveBuilderBuilder {
     fn create_dll_import_lib(
         &self,
         sess: &Session,
-        _lib_name: &str,
-        _import_name_and_ordinal_vector: Vec<(String, Option<u16>)>,
-        _output_path: &Path,
+        lib_name: &str,
+        import_name_and_ordinal_vector: Vec<(String, Option<u16>)>,
+        output_path: &Path,
     ) {
-        sess.dcx().fatal("raw-dylib is not yet supported by rustc_codegen_cranelift");
+        if is_mingw_gnu_toolchain(&sess.target) {
+            // The binutils linker used on -windows-gnu targets cannot read the import
+            // libraries generated by LLVM: in our attempts, the linker produced an .EXE
+            // that loaded but crashed with an AV upon calling one of the imported
+            // functions. Therefore, use binutils to create the import library instead,
+            // by writing a .DEF file to the temp dir and calling binutils's dlltool.
+            create_mingw_dll_import_lib(
+                sess,
+                lib_name,
+                import_name_and_ordinal_vector,
+                output_path,
+            );
+        } else {
+            let mut file =
+                match fs::OpenOptions::new().write(true).create_new(true).open(&output_path) {
+                    Ok(file) => file,
+                    Err(error) => {
+                        sess.dcx().fatal(format!(
+                            "failed to create import library file `{path}`: {error}",
+                            path = output_path.display(),
+                        ));
+                    }
+                };
+
+            let machine = match sess.target.arch.borrow() {
+                "x86" => MachineTypes::I386,
+                "x86_64" => MachineTypes::AMD64,
+                "arm" => MachineTypes::ARMNT,
+                "aarch64" => MachineTypes::ARM64,
+                _ => {
+                    sess.dcx().fatal(format!(
+                        "unsupported target architecture `{arch}`",
+                        arch = sess.target.arch,
+                    ));
+                }
+            };
+
+            let exports = import_name_and_ordinal_vector
+                .iter()
+                .map(|(name, ordinal)| COFFShortExport {
+                    name: name.to_string(),
+                    ext_name: None,
+                    symbol_name: None,
+                    alias_target: None,
+                    ordinal: ordinal.unwrap_or(0),
+                    noname: ordinal.is_some(),
+                    data: false,
+                    private: false,
+                    constant: false,
+                })
+                .collect::<Vec<_>>();
+
+            if let Err(error) = ar_archive_writer::write_import_library(
+                &mut file,
+                lib_name,
+                &exports,
+                machine,
+                !sess.target.is_like_msvc,
+            ) {
+                sess.dcx().fatal(format!(
+                    "failed to create import library `{path}`: `{error}`",
+                    path = output_path.display(),
+                ));
+            }
+        }
     }
 }