Set DT_SONAME when building dylibs

Forwarded: no

In Rust, library filenames include a version-specific hash to help
the run-time linker find the correct version.  Unlike in C/C++, the
compiler looks for all libraries matching a glob that ignores the
hash and reads embedded metadata to work out versions, etc.

The upshot is that there is no need for the usual "libfoo.so ->
libfoo-1.2.3.so" symlink common with C/C++ when building with Rust,
and no need to communicate an alternate filename to use at run-time
vs compile time.  If linking to a Rust dylib from C/C++ however, a
"libfoo.so -> libfoo-$hash.so" symlink may well be useful and in
this case DT_SONAME=libfoo-$hash.so would be required.  More
mundanely, various tools (eg: dpkg-shlibdeps) complain if they don't
find DT_SONAME on shared libraries in public directories.

This patch passes -Wl,-soname=$outfile when building dylibs (and
using a GNU linker).

Gbp-Pq: Name d-add-soname.patch

diff --git a/compiler/rustc_codegen_ssa/src/back/link.rs b/compiler/rustc_codegen_ssa/src/back/link.rs
index 8bc4e64422370425bfd31dad23ab4680d572e541..1e9d5835cbb09c6d27f586117bab297e5801e652 100644 (file)
--- a/compiler/rustc_codegen_ssa/src/back/link.rs
+++ b/compiler/rustc_codegen_ssa/src/back/link.rs
@@ -1747,6 +1747,13 @@ fn linker_with_args<'a, B: ArchiveBuilder<'a>>(
     // OBJECT-FILES-NO, AUDIT-ORDER
     add_rpath_args(cmd, sess, codegen_results, out_filename);
 
+    if (crate_type == config::CrateType::Dylib || crate_type == config::CrateType::Cdylib)
+       && sess.target.linker_is_gnu {
+        let filename = String::from(out_filename.file_name().unwrap().to_str().unwrap());
+        let soname = [String::from("-Wl,-soname=") + &filename];
+        cmd.args(&soname);
+    }
+
     // OBJECT-FILES-MAYBE, CUSTOMIZATION-POINT
     add_user_defined_link_args(cmd, sess, codegen_results);