Make import libraries compatible with wholearchive

Author: ChrisDenton

Cargo.lock

@@ -205,9 +205,9 @@ dependencies = [
 
 [[package]]
 name = "ar_archive_writer"
-version = "0.4.0"
+version = "0.4.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "de11a9d32db3327f981143bdf699ade4d637c6887b13b97e6e91a9154666963c"
+checksum = "01667f6f40216b9a0b2945e05fed5f1ad0ab6470e69cb9378001e37b1c0668e4"
 dependencies = [
  "object 0.36.2",
 ]

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 = "0.4.2"
 arrayvec = { version = "0.7", default-features = false }
 bitflags = "2.4.1"
 cc = "1.0.90"

compiler/rustc_codegen_ssa/src/back/archive.rs

@@ -108,7 +108,11 @@ pub trait ArchiveBuilderBuilder {
                 &exports,
                 machine,
                 !sess.target.is_like_msvc,
-                /*comdat=*/ false,
+                // Enable compatibility with MSVC's `/WHOLEARCHIVE` flag.
+                // Without this flag a duplicate symbol error would be emitted
+                // when linking a rust staticlib using `/WHOLEARCHIVE`.
+                // See #129020
+                true,
             ) {
                 sess.dcx()
                     .emit_fatal(ErrorCreatingImportLibrary { lib_name, error: error.to_string() });