`include-libs`: export all global symbols from selected uptream c static libraries #150992

cezarbbb · 2026-01-12T07:23:30Z

In order to be able to export symbols from a specified upstream C static library, I redesigned a solution that, compared to a previous PR #150335 I submitted, will not have any extra symbols leaking out.
If LTO compilation is enabled for C static libraries, --include-libs behaves the same as the default.
The test code is the same as the PR #150335.
Here are the results:

cargo +include-libs rustc --release -- -L ./ -Z include-libs=libc_add.a

                 U abort@GLIBC_2.2.5
                 U bcmp@GLIBC_2.2.5
0000000000014f60 T c_add
                 U calloc@GLIBC_2.2.5
                 U close@GLIBC_2.2.5
0000000000014f70 T c_sub
                 w __cxa_finalize@GLIBC_2.2.5
                 w __cxa_thread_atexit_impl@GLIBC_2.18
                 U dl_iterate_phdr@GLIBC_2.2.5
0000000000014ee0 T downstream_add
                 U __errno_location@GLIBC_2.2.5
                 U free@GLIBC_2.2.5
                 U fstat64@GLIBC_2.33
                 U getcwd@GLIBC_2.2.5
                 U getenv@GLIBC_2.2.5
                 w __gmon_start__
                 w _ITM_deregisterTMCloneTable
                 w _ITM_registerTMCloneTable
                 U lseek64@GLIBC_2.2.5
                 U malloc@GLIBC_2.2.5
                 U memcpy@GLIBC_2.14
                 U memmove@GLIBC_2.2.5
                 U memset@GLIBC_2.2.5
                 U mmap64@GLIBC_2.2.5
                 U munmap@GLIBC_2.2.5
                 U open64@GLIBC_2.2.5
                 U posix_memalign@GLIBC_2.2.5
                 U pthread_key_create@GLIBC_2.34
                 U pthread_key_delete@GLIBC_2.34
                 U pthread_setspecific@GLIBC_2.34
                 U read@GLIBC_2.2.5
                 U readlink@GLIBC_2.2.5
                 U realloc@GLIBC_2.2.5
                 U realpath@GLIBC_2.3
                 U stat64@GLIBC_2.33
                 w statx@GLIBC_2.28
                 U strlen@GLIBC_2.2.5
                 U syscall@GLIBC_2.2.5
                 U __tls_get_addr@GLIBC_2.3
                 U _Unwind_Backtrace@GCC_3.3
                 U _Unwind_DeleteException@GCC_3.0
                 U _Unwind_GetDataRelBase@GCC_3.0
                 U _Unwind_GetIP@GCC_3.0
                 U _Unwind_GetIPInfo@GCC_4.2.0
                 U _Unwind_GetLanguageSpecificData@GCC_3.0
                 U _Unwind_GetRegionStart@GCC_3.0
                 U _Unwind_GetTextRelBase@GCC_3.0
                 U _Unwind_RaiseException@GCC_3.0
                 U _Unwind_Resume@GCC_3.0
                 U _Unwind_SetGR@GCC_3.0
                 U _Unwind_SetIP@GCC_3.0
                 U write@GLIBC_2.2.5
                 U writev@GLIBC_2.2.5

cargo +nightly rustc --release -- -L ./

                 U abort@GLIBC_2.2.5
                 U bcmp@GLIBC_2.2.5
                 U calloc@GLIBC_2.2.5
                 U close@GLIBC_2.2.5
                 w __cxa_finalize@GLIBC_2.2.5
                 w __cxa_thread_atexit_impl@GLIBC_2.18
                 U dl_iterate_phdr@GLIBC_2.2.5
0000000000011e10 T downstream_add
                 U __errno_location@GLIBC_2.2.5
                 U free@GLIBC_2.2.5
                 U fstat64@GLIBC_2.33
                 U getcwd@GLIBC_2.2.5
                 U getenv@GLIBC_2.2.5
                 w gettid@GLIBC_2.30
                 w __gmon_start__
                 w _ITM_deregisterTMCloneTable
                 w _ITM_registerTMCloneTable
                 U lseek64@GLIBC_2.2.5
                 U malloc@GLIBC_2.2.5
                 U memcpy@GLIBC_2.14
                 U memmove@GLIBC_2.2.5
                 U memset@GLIBC_2.2.5
                 U mmap64@GLIBC_2.2.5
                 U munmap@GLIBC_2.2.5
                 U open64@GLIBC_2.2.5
                 U posix_memalign@GLIBC_2.2.5
                 U pthread_key_create@GLIBC_2.34
                 U pthread_key_delete@GLIBC_2.34
                 U pthread_setspecific@GLIBC_2.34
                 U read@GLIBC_2.2.5
                 U readlink@GLIBC_2.2.5
                 U realloc@GLIBC_2.2.5
                 U realpath@GLIBC_2.3
                 U stat64@GLIBC_2.33
                 w statx@GLIBC_2.28
                 U strlen@GLIBC_2.2.5
                 U syscall@GLIBC_2.2.5
                 U __tls_get_addr@GLIBC_2.3
                 U _Unwind_Backtrace@GCC_3.3
                 U _Unwind_GetDataRelBase@GCC_3.0
                 U _Unwind_GetIP@GCC_3.0
                 U _Unwind_GetIPInfo@GCC_4.2.0
                 U _Unwind_GetLanguageSpecificData@GCC_3.0
                 U _Unwind_GetRegionStart@GCC_3.0
                 U _Unwind_GetTextRelBase@GCC_3.0
                 U _Unwind_RaiseException@GCC_3.0
                 U _Unwind_Resume@GCC_3.0
                 U _Unwind_SetGR@GCC_3.0
                 U _Unwind_SetIP@GCC_3.0
                 U write@GLIBC_2.2.5
                 U writev@GLIBC_2.2.5

r? @bjorn3

…tream c staticlibs when building cdylib

rustbot · 2026-01-12T07:23:35Z

⚠️ Warning ⚠️

This PR is based on an upstream commit that is older than 28 days.

It's recommended to update your branch according to the rustc-dev-guide.

bjorn3 · 2026-01-12T12:49:33Z

compiler/rustc_session/src/options.rs

        "display unnamed regions as `'<id>`, using a non-ident unique id (default: no)"),
    ignore_directory_in_diagnostics_source_blocks: Vec<String> = (Vec::new(), parse_string_push, [UNTRACKED],
        "do not display the source code block in diagnostics for files in the directory"),
+    include_libs: Vec<String> = (Vec::new(), parse_comma_list, [TRACKED],


I would call this -Zexport-staticlib-symbols or something like that.

bjorn3 · 2026-01-12T12:51:31Z

compiler/rustc_codegen_ssa/src/back/link.rs

+                let data = member.data(&*archive_data).unwrap();
+
+                // clang LTO: raw LLVM bitcode
+                if data.len() >= 4 && &data[0..4] == b"BC\xc0\xde" {


Suggested change

if data.len() >= 4 && &data[0..4] == b"BC\xc0\xde" {

if data.starts_with(b"BC\xc0\xde") {

bjorn3 · 2026-01-12T12:52:19Z

compiler/rustc_codegen_ssa/src/back/link.rs

+                .expect("wanted an c staticlib");
+            for member in archive.members() {
+                let member = member.unwrap();
+                let data = member.data(&*archive_data).unwrap();


When parsing the staticlib fails we should report nice errors rather than ICE.

bjorn3 · 2026-01-12T12:55:15Z

compiler/rustc_codegen_ssa/src/back/link.rs

+                let symbol = symbol.unwrap();
+                out.push((
+                    String::from_utf8(symbol.name().to_vec()).unwrap(),
+                    SymbolExportKind::Text,


We do need to distinguish between text and data symbols. Also on Windows I believe and on macOS I know we currently use the pre-C mangling names in exported_symbols. I think the post mangling name is fine here too for Windows, but you did need to check. On macOS however it is definitively not ok. The symbol names in the object file are prefixed with _, but the linker doesn't accept this.

After testing, the symbol does have a prefix _ on macos, but not on windows. I have removed the prefix symbol (I don’t know why it was added back in the export_symbols function?)

64-bit Windows symbols do not use special mangling, but 32-bit symbols are prefixed with an additional leading underscore.

So:

int foo() { return 42; }

Would be foo symbol on 64-bit Windows, and _foo on 32-bit Windows.

And extern "stdcall" has extra mangling, right?

Not only that, all calling conventions have their own mangling: https://learn.microsoft.com/en-us/cpp/error-messages/tool-errors/name-decoration?view=msvc-170

I don't remember whether linkers can export symbols using .DEF files if the symbol doesn't exactly match calling convention. IIRC, GNU ld and LLD (not so sure about this one) can handle it, at least in some cases.

bjorn3 · 2026-01-12T12:56:25Z

compiler/rustc_codegen_ssa/src/back/link.rs

+                }
+            }
+            for symbol in archive.symbols().unwrap().unwrap() {
+                let symbol = symbol.unwrap();


Make sure to only add symbols with SymbolScope::Dynamic. Otherwise the linker will complain.

bjorn3 · 2026-01-12T12:57:29Z

I think this is a reasonable approach. This will need a test though.

cezarbbb · 2026-01-14T01:14:28Z

I think this is a reasonable approach. This will need a test though.我认为这是一个合理的做法。不过这需要测试。

Working on it.

support --include-libs to export all global symbols from selected ups…

f800b03

…tream c staticlibs when building cdylib

rustbot assigned bjorn3 Jan 12, 2026

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Jan 12, 2026

This comment has been minimized.

Sign in to view

cezarbbb added 2 commits January 12, 2026 15:33

update

aa32f62

update

4afd993

This comment has been minimized.

Sign in to view

update

f4c91ab

This comment has been minimized.

Sign in to view

bjorn3 reviewed Jan 12, 2026

View reviewed changes

JayanAXHF added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Jan 12, 2026

	if data.len() >= 4 && &data[0..4] == b"BC\xc0\xde" {
	if data.starts_with(b"BC\xc0\xde") {

Uh oh!

include-libs: export all global symbols from selected uptream c static libraries #150992

Are you sure you want to change the base?

include-libs: export all global symbols from selected uptream c static libraries #150992

Conversation

cezarbbb commented Jan 12, 2026 • edited by rustbot Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

rustbot commented Jan 12, 2026

Uh oh!

This comment has been minimized.

This comment has been minimized.

This comment has been minimized.

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

bjorn3 commented Jan 12, 2026

Uh oh!

cezarbbb commented Jan 14, 2026

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

6 participants

`include-libs`: export all global symbols from selected uptream c static libraries #150992

`include-libs`: export all global symbols from selected uptream c static libraries #150992

cezarbbb commented Jan 12, 2026 •

edited by rustbot

Loading