Make import libraries compatible with wholearchive

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() });