Auto merge of #129257 - ChrisDenton:rename-null-descriptor, r=<try>

Allow rust staticlib to work with MSVC's /WHOLEARCHIVE

This renames the `__NULL_IMPORT_DESCRIPTOR` to prevent conflicts.

try-job: x86_64-msvc
try-job: i686-msvc

r? ghost

Author: bors

Diff for: Cargo.lock

@@ -205,9 +205,8 @@ dependencies = [
 
 [[package]]
 name = "ar_archive_writer"
-version = "0.4.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "de11a9d32db3327f981143bdf699ade4d637c6887b13b97e6e91a9154666963c"
+version = "0.3.3"
+source = "git+https://github.com/ChrisDenton/ar_archive_writer.git?branch=rename2#a5b424a6ef9d6416b299ac27c2dba224e2470253"
 dependencies = [
  "object 0.36.2",
 ]

Diff for: compiler/rustc_codegen_ssa/Cargo.toml

@@ -5,7 +5,7 @@ edition = "2021"
 
 [dependencies]
 # tidy-alphabetical-start
-ar_archive_writer = "0.4.0"
+ar_archive_writer = { git = 'https://github.com/ChrisDenton/ar_archive_writer.git', branch = "rename2" }
 arrayvec = { version = "0.7", default-features = false }
 bitflags = "2.4.1"
 cc = "1.0.90"
@@ -52,7 +52,17 @@ libc = "0.2.50"
 [dependencies.object]
 version = "0.36.2"
 default-features = false
-features = ["read_core", "elf", "macho", "pe", "xcoff", "unaligned", "archive", "write", "wasm"]
+features = [
+    "read_core",
+    "elf",
+    "macho",
+    "pe",
+    "xcoff",
+    "unaligned",
+    "archive",
+    "write",
+    "wasm",
+]
 
 [target.'cfg(windows)'.dependencies.windows]
 version = "0.52.0"

Diff for: compiler/rustc_codegen_ssa/src/back/archive.rs

@@ -108,7 +108,11 @@ pub trait ArchiveBuilderBuilder {
                 &exports,
                 machine,
                 !sess.target.is_like_msvc,
-                /*comdat=*/ false,
+                // Tell the import library writer to make `.idata$3` a COMDAT section.
+                // This prevents duplicate symbol errors when using /WHOLEARCHIVE
+                // to link a staticlib with the MSVC linker.
+                // See #129020
+                true,
             ) {
                 sess.dcx()
                     .emit_fatal(ErrorCreatingImportLibrary { lib_name, error: error.to_string() });

Diff for: src/tools/tidy/src/extdeps.rs

@@ -8,6 +8,7 @@ const ALLOWED_SOURCES: &[&str] = &[
     r#""registry+https://github.com/rust-lang/crates.io-index""#,
     // This is `rust_team_data` used by `site` in src/tools/rustc-perf,
     r#""git+https://github.com/rust-lang/team#a5260e76d3aa894c64c56e6ddc8545b9a98043ec""#,
+    r#""git+https://github.com/ChrisDenton/ar_archive_writer.git?branch=rename2#a5b424a6ef9d6416b299ac27c2dba224e2470253""#,
 ];
 
 /// Checks for external package sources. `root` is the path to the directory that contains the

Diff for: tests/run-make/msvc-wholearchive/c.c

@@ -0,0 +1 @@
+// This page is intentionally left blank

Diff for: tests/run-make/msvc-wholearchive/dll.def

@@ -0,0 +1,4 @@
+LIBRARY dll
+EXPORTS
+        hello
+        number

Diff for: tests/run-make/msvc-wholearchive/rmake.rs

@@ -0,0 +1,41 @@
+//@ only-msvc
+// Reason: this is testing the MSVC linker
+
+// This is a regression test for #129020
+// It ensures we can link a rust staticlib into DLL using the MSVC linker
+
+use std::path::Path;
+
+use run_make_support::{cc, env_var, extra_c_flags, rustc};
+
+fn main() {
+    // FIXME: Make this test either work with or ignore LLVM.
+    if false {
+        return;
+    }
+    // Build the staticlib
+    rustc().crate_type("staticlib").input("static.rs").output("static.lib").run();
+    // Create an empty obj file (using the C compiler)
+    // Then use it to link in the staticlib using `/WHOLEARCHIVE` and produce a DLL.
+    // We test for `cl.exe` to ensure we're using MSVC's tools and not the LLVM equivalents.
+
+    if env_var("CC").ends_with("cl.exe") {
+        cc().input("c.c")
+            .args([
+                "-MT",
+                "-link",
+                "-WHOLEARCHIVE:./static.lib",
+                "-dll",
+                "-def:dll.def",
+                "-out:dll.dll",
+            ])
+            .args(extra_c_flags())
+            .run();
+    }
+
+    // As a sanity check, make sure it works without /WHOLEARCHIVE
+    cc().input("c.c")
+        .args(["-MT", "-link", "./static.lib", "-dll", "-def:dll.def", "-out:dll2.dll"])
+        .args(extra_c_flags())
+        .run();
+}

Diff for: tests/run-make/msvc-wholearchive/static.rs

@@ -0,0 +1,9 @@
+#[no_mangle]
+pub extern "C" fn hello() {
+    println!("Hello world!");
+}
+
+#[no_mangle]
+pub extern "C" fn number() -> u32 {
+    42
+}