staticlib symbol renaming: add -Zstaticlib-rename-internal-symbols

Author: cezarbbb

compiler/rustc_codegen_ssa/src/back/archive.rs

@@ -525,15 +525,23 @@ fn link_staticlib(
         sess.dcx().emit_fatal(e);
     }
 
-    if sess.opts.unstable_opts.staticlib_hide_internal_symbols {
+    if sess.opts.unstable_opts.staticlib_rename_internal_symbols {
         if !matches!(&*sess.target.archive_format, "gnu" | "bsd") {
-            sess.dcx().emit_warn(errors::StaticlibHideInternalSymbolsUnsupported {
+            sess.dcx().emit_warn(errors::StaticlibRenameInternalSymbolsUnsupported {
                 archive_format: sess.target.archive_format.to_string(),
             });
         } else if let Some(symbols) = crate_info.exported_symbols.get(&CrateType::StaticLib) {
             use rustc_data_structures::fx::FxHashSet;
             let keep: FxHashSet<String> = symbols.iter().map(|(s, _)| s.clone()).collect();
-            ab.set_keep_symbols(keep);
+            // Generate a unique suffix from the crate name and a short hash
+            // extracted from the metadata symbol (format: rust_metadata_{name}_{hash:08x}).
+            let short_hash = crate_info
+                .metadata_symbol
+                .rsplit_once('_')
+                .map(|(_, hash)| hash.to_string())
+                .unwrap_or_else(|| format!("{:08x}", crate_info.local_crate_name.as_u32()));
+            let suffix = format!("_rs{}", short_hash);
+            ab.set_rename_symbols(keep, suffix);
         }
     }
 

compiler/rustc_codegen_ssa/src/back/link.rs

@@ -677,9 +677,9 @@ pub(crate) struct BpfStaticlibNotSupported;
 
 #[derive(Diagnostic)]
 #[diag(
-    "-Zstaticlib-hide-internal-symbols only supports ELF archive formats (gnu/bsd), but the target uses `{$archive_format}`"
+    "-Zstaticlib-rename-internal-symbols only supports ELF archive formats (gnu/bsd), but the target uses `{$archive_format}`"
 )]
-pub(crate) struct StaticlibHideInternalSymbolsUnsupported {
+pub(crate) struct StaticlibRenameInternalSymbolsUnsupported {
     pub archive_format: String,
 }
 

compiler/rustc_codegen_ssa/src/errors.rs

@@ -869,7 +869,7 @@ fn test_unstable_options_tracking_hash() {
     tracked!(split_lto_unit, Some(true));
     tracked!(src_hash_algorithm, Some(SourceFileHashAlgorithm::Sha1));
     tracked!(stack_protector, StackProtector::All);
-    tracked!(staticlib_hide_internal_symbols, true);
+    tracked!(staticlib_rename_internal_symbols, true);
     tracked!(teach, true);
     tracked!(thinlto, Some(true));
     tracked!(tiny_const_eval_limit, true);

compiler/rustc_interface/src/tests.rs

@@ -2474,10 +2474,11 @@ pub fn build_session_options(early_dcx: &mut EarlyDiagCtxt, matches: &getopts::M
 
     let mut unstable_opts = UnstableOptions::build(early_dcx, matches, &mut collected_options);
 
-    if unstable_opts.staticlib_hide_internal_symbols && !crate_types.contains(&CrateType::StaticLib)
+    if unstable_opts.staticlib_rename_internal_symbols
+        && !crate_types.contains(&CrateType::StaticLib)
     {
         early_dcx.early_fatal(
-            "-Zstaticlib-hide-internal-symbols can only be used with `--crate-type staticlib`",
+            "-Zstaticlib-rename-internal-symbols can only be used with `--crate-type staticlib`",
         );
     }
 

compiler/rustc_session/src/config.rs

@@ -2764,8 +2764,8 @@ written to standard error output)"),
         "control stack smash protection strategy (`rustc --print stack-protector-strategies` for details)"),
     staticlib_allow_rdylib_deps: bool = (false, parse_bool, [TRACKED],
         "allow staticlibs to have rust dylib dependencies"),
-    staticlib_hide_internal_symbols: bool = (false, parse_bool, [TRACKED],
-        "hide Rust internal symbols when building staticlibs"),
+    staticlib_rename_internal_symbols: bool = (false, parse_bool, [TRACKED],
+        "rename Rust internal symbols when building staticlibs to avoid conflicts"),
     staticlib_prefer_dynamic: bool = (false, parse_bool, [TRACKED],
         "prefer dynamic linking to static linking for staticlibs (default: no)"),
     strict_init_checks: bool = (false, parse_bool, [TRACKED],

compiler/rustc_session/src/options.rs

@@ -0,0 +1,16 @@
+# `staticlib-rename-internal-symbols`
+
+When building a `staticlib`, this option renames all non-exported Rust-internal
+symbols by appending a `_rs{hash}` suffix and setting their ELF visibility to
+`STV_HIDDEN`. This prevents symbol collisions when multiple Rust static
+libraries are linked into the same final binary.
+
+Only symbols explicitly exported via `#[no_mangle]` or `#[export_name]` are left
+unchanged. All other `GLOBAL`/`WEAK` symbols (including `pub(crate)` and `pub`
+items without `#[no_mangle]`) are renamed.
+
+This option can only be used with `--crate-type staticlib`. Using it with
+other crate types will result in a compilation error.
+
+Currently only ELF targets are supported (Linux, BSD, etc.). On non-ELF
+targets (macOS, Windows), a warning is emitted and the flag has no effect.