Use protected visibility by default on ELF platforms

[pcc]

I noticed that the .so files built by x.py contain a lot of "unnecessary" PLT entries. The compiler should be using protected visibility on ELF platforms by default.

I was thinking we should be able to tie it to #[no_mangle] but on Zulip @bjorn3 proposed tying it to the SymbolExportLevel (Rust for mangled and unmangled but not exported from cdylib #[rustc_std_internal_symbol] symbols and C for #[no_mangle] symbols).

[danakj]

This is related to https://github.com/rust-lang/rust/issues/37530 and https://github.com/rust-lang/rust/issues/33221

[bjorn3]

Those issues are about which symbols are exported or not. This issue is not about which symbols are exported or not. Protected visibility will still export symbols. It merely prevents overwriting those symbols from other dylibs.

[danakj]

Ah ok thanks for the clarification!

[bjorn3]

Attempted to implement this in https://github.com/bjorn3/rust/tree/protected_visibility. It works fine for ld.gold and ld.lld, but with ld.bfd it results in:

error: linking with `cc` failed: exit status: 1
  |
  = note: LC_ALL="C" PATH="/home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1/lib/rustlib/aarch64-unknown-linux-gnu/bin:/home/gh-bjorn3/.local/bin:/home/gh-bjorn3/.cargo/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin" VSLANG="1033" "cc" "-Wl,--version-script=/tmp/rustcOHW0DQ/list" "-Wl,--no-undefined-version" "/tmp/rustcOHW0DQ/symbols.o" "/home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1-std/aarch64-unknown-linux-gnu/release/deps/std-415ef54566353f34.std.9bb3df1236a54be1-cgu.00.rcgu.o" "/home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1-std/aarch64-unknown-linux-gnu/release/deps/std-415ef54566353f34.std.9bb3df1236a54be1-cgu.01.rcgu.o" "/home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1-std/aarch64-unknown-linux-gnu/release/deps/std-415ef54566353f34.std.9bb3df1236a54be1-cgu.02.rcgu.o" "/home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1-std/aarch64-unknown-linux-gnu/release/deps/std-415ef54566353f34.std.9bb3df1236a54be1-cgu.03.rcgu.o" "/home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1-std/aarch64-unknown-linux-gnu/release/deps/std-415ef54566353f34.std.9bb3df1236a54be1-cgu.04.rcgu.o" "/home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1-std/aarch64-unknown-linux-gnu/release/deps/std-415ef54566353f34.std.9bb3df1236a54be1-cgu.05.rcgu.o" "/home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1-std/aarch64-unknown-linux-gnu/release/deps/std-415ef54566353f34.std.9bb3df1236a54be1-cgu.06.rcgu.o" "/home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1-std/aarch64-unknown-linux-gnu/release/deps/std-415ef54566353f34.std.9bb3df1236a54be1-cgu.07.rcgu.o" "/home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1-std/aarch64-unknown-linux-gnu/release/deps/std-415ef54566353f34.std.9bb3df1236a54be1-cgu.08.rcgu.o" "/home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1-std/aarch64-unknown-linux-gnu/release/deps/std-415ef54566353f34.std.9bb3df1236a54be1-cgu.09.rcgu.o" "/home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1-std/aarch64-unknown-linux-gnu/release/deps/std-415ef54566353f34.std.9bb3df1236a54be1-cgu.10.rcgu.o" "/home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1-std/aarch64-unknown-linux-gnu/release/deps/std-415ef54566353f34.std.9bb3df1236a54be1-cgu.11.rcgu.o" "/home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1-std/aarch64-unknown-linux-gnu/release/deps/std-415ef54566353f34.std.9bb3df1236a54be1-cgu.12.rcgu.o" "/home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1-std/aarch64-unknown-linux-gnu/release/deps/std-415ef54566353f34.std.9bb3df1236a54be1-cgu.13.rcgu.o" "/home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1-std/aarch64-unknown-linux-gnu/release/deps/std-415ef54566353f34.std.9bb3df1236a54be1-cgu.14.rcgu.o" "/home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1-std/aarch64-unknown-linux-gnu/release/deps/std-415ef54566353f34.std.9bb3df1236a54be1-cgu.15.rcgu.o" "/home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1-std/aarch64-unknown-linux-gnu/release/deps/std-415ef54566353f34.4jul3hyqzc65lxuh.rcgu.rmeta" "/home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1-std/aarch64-unknown-linux-gnu/release/deps/std-415ef54566353f34.3lo40xndxmc2j69n.rcgu.o" "-Wl,--as-needed" "-L" "/home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1-std/aarch64-unknown-linux-gnu/release/deps" "-L" "/home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1-std/release/deps" "-L" "/home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1/lib/rustlib/aarch64-unknown-linux-gnu/lib" "-Wl,-Bstatic" "/home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1-std/aarch64-unknown-linux-gnu/release/deps/libpanic_unwind-6539d23e93d602e2.rlib" "/home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1-std/aarch64-unknown-linux-gnu/release/deps/libobject-a47966ab81fae984.rlib" "/home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1-std/aarch64-unknown-linux-gnu/release/deps/libmemchr-1b930b63de7c56f6.rlib" "/home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1-std/aarch64-unknown-linux-gnu/release/deps/libaddr2line-eb24309d543fdabf.rlib" "/home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1-std/aarch64-unknown-linux-gnu/release/deps/libgimli-3b7990132945b345.rlib" "/home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1-std/aarch64-unknown-linux-gnu/release/deps/librustc_demangle-d091de4010eed9b8.rlib" "/home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1-std/aarch64-unknown-linux-gnu/release/deps/libstd_detect-1b1db080986b68cf.rlib" "/home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1-std/aarch64-unknown-linux-gnu/release/deps/libhashbrown-65245041fec002ce.rlib" "/home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1-std/aarch64-unknown-linux-gnu/release/deps/librustc_std_workspace_alloc-40b6828da573b833.rlib" "/home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1-std/aarch64-unknown-linux-gnu/release/deps/libminiz_oxide-dbf6b23630950e0f.rlib" "/home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1-std/aarch64-unknown-linux-gnu/release/deps/libadler-65b9b24cccb63b72.rlib" "/home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1-std/aarch64-unknown-linux-gnu/release/deps/libunwind-b6cb3762975e15c6.rlib" "/home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1-std/aarch64-unknown-linux-gnu/release/deps/libcfg_if-b0325152658f881c.rlib" "/home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1-std/aarch64-unknown-linux-gnu/release/deps/liblibc-7a5025d388fb2618.rlib" "/home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1-std/aarch64-unknown-linux-gnu/release/deps/liballoc-880cfc5ae7643f83.rlib" "/home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1-std/aarch64-unknown-linux-gnu/release/deps/librustc_std_workspace_core-3a5d24fbcee0e4fd.rlib" "/home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1-std/aarch64-unknown-linux-gnu/release/deps/libcore-3f87a9c32d25ec14.rlib" "/home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1-std/aarch64-unknown-linux-gnu/release/deps/libcompiler_builtins-30a15f09c31cdce0.rlib" "-Wl,-Bdynamic" "-lgcc_s" "-lutil" "-lrt" "-lpthread" "-lm" "-ldl" "-lc" "-Wl,--eh-frame-hdr" "-Wl,-z,noexecstack" "-L" "/home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1/lib/rustlib/aarch64-unknown-linux-gnu/lib" "-o" "/home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1-std/aarch64-unknown-linux-gnu/release/deps/libstd-415ef54566353f34.so" "-shared" "-Wl,-z,relro,-z,now" "-Wl,-O1" "-nodefaultlibs" "-Wl,-z,origin" "-Wl,-rpath,$ORIGIN/../lib"
  = note: /usr/bin/ld: /home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1-std/aarch64-unknown-linux-gnu/release/deps/std-415ef54566353f34.std.9bb3df1236a54be1-cgu.02.rcgu.o: relocation R_AARCH64_ADR_PREL_PG_HI21 against symbol `_ZN3std9backtrace9Backtrace7capture17hbe0ab5a5ae8a4d77E' which may bind externally can not be used when making a shared object; recompile with -fPIC
          /home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1-std/aarch64-unknown-linux-gnu/release/deps/std-415ef54566353f34.std.9bb3df1236a54be1-cgu.02.rcgu.o: in function `std::backtrace::Backtrace::capture':
          std.9bb3df1236a54be1-cgu.02:(.text._ZN3std9backtrace9Backtrace7capture17hbe0ab5a5ae8a4d77E+0x124): dangerous relocation: unsupported relocation
          /usr/bin/ld: /home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1-std/aarch64-unknown-linux-gnu/release/deps/std-415ef54566353f34.std.9bb3df1236a54be1-cgu.02.rcgu.o: relocation R_AARCH64_ADR_PREL_PG_HI21 against symbol `_ZN3std9backtrace9Backtrace13force_capture17hef3296f41bc64462E' which may bind externally can not be used when making a shared object; recompile with -fPIC
          /home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1-std/aarch64-unknown-linux-gnu/release/deps/std-415ef54566353f34.std.9bb3df1236a54be1-cgu.02.rcgu.o: in function `std::backtrace::Backtrace::force_capture':
          std.9bb3df1236a54be1-cgu.02:(.text._ZN3std9backtrace9Backtrace13force_capture17hef3296f41bc64462E+0x4): dangerous relocation: unsupported relocation
          /usr/bin/ld: /home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1-std/aarch64-unknown-linux-gnu/release/deps/std-415ef54566353f34.std.9bb3df1236a54be1-cgu.07.rcgu.o: relocation R_AARCH64_ADR_PREL_PG_HI21 against symbol `_ZN3std9panicking11panic_count18GLOBAL_PANIC_COUNT17h57a6bf59ff8b4107E' which may bind externally can not be used when making a shared object; recompile with -fPIC
          /home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1-std/aarch64-unknown-linux-gnu/release/deps/std-415ef54566353f34.std.9bb3df1236a54be1-cgu.07.rcgu.o: in function `std::panicking::panic_count::increase':
          std.9bb3df1236a54be1-cgu.07:(.text._ZN3std9panicking11panic_count8increase17hb67738ce4889cd48E+0x8): dangerous relocation: unsupported relocation
          /usr/bin/ld: /home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1-std/aarch64-unknown-linux-gnu/release/deps/std-415ef54566353f34.std.9bb3df1236a54be1-cgu.07.rcgu.o: relocation R_AARCH64_ADR_PREL_PG_HI21 against symbol `_ZN3std9panicking11panic_count18GLOBAL_PANIC_COUNT17h57a6bf59ff8b4107E' which may bind externally can not be used when making a shared object; recompile with -fPIC
          /home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1-std/aarch64-unknown-linux-gnu/release/deps/std-415ef54566353f34.std.9bb3df1236a54be1-cgu.07.rcgu.o: in function `std::panicking::panic_count::decrease':
          std.9bb3df1236a54be1-cgu.07:(.text._ZN3std9panicking11panic_count8decrease17h7032ce993a333a03E+0x4): dangerous relocation: unsupported relocation
          /usr/bin/ld: /home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1-std/aarch64-unknown-linux-gnu/release/deps/std-415ef54566353f34.std.9bb3df1236a54be1-cgu.07.rcgu.o: relocation R_AARCH64_ADR_PREL_PG_HI21 against symbol `_ZN3std9panicking11panic_count18GLOBAL_PANIC_COUNT17h57a6bf59ff8b4107E' which may bind externally can not be used when making a shared object; recompile with -fPIC
          /home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1-std/aarch64-unknown-linux-gnu/release/deps/std-415ef54566353f34.std.9bb3df1236a54be1-cgu.07.rcgu.o: in function `std::panicking::panic_count::set_always_abort':
          std.9bb3df1236a54be1-cgu.07:(.text._ZN3std9panicking11panic_count16set_always_abort17h4c2528c0ec6026dbE+0x4): dangerous relocation: unsupported relocation
          /usr/bin/ld: /home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1-std/aarch64-unknown-linux-gnu/release/deps/std-415ef54566353f34.std.9bb3df1236a54be1-cgu.13.rcgu.o: relocation R_AARCH64_ADR_PREL_PG_HI21 against symbol `_ZN91_$LT$std..sys_common..backtrace.._print..DisplayBacktrace$u20$as$u20$core..fmt..Display$GT$3fmt17hb8d1b111f7cc8252E' which may bind externally can not be used when making a shared object; recompile with -fPIC
          /home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1-std/aarch64-unknown-linux-gnu/release/deps/std-415ef54566353f34.std.9bb3df1236a54be1-cgu.13.rcgu.o: in function `std::sys_common::backtrace::print':
          std.9bb3df1236a54be1-cgu.13:(.text._ZN3std10sys_common9backtrace5print17hf7aac3e29d72f262E+0x98): dangerous relocation: unsupported relocation
          /usr/bin/ld: /home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1-std/aarch64-unknown-linux-gnu/release/deps/std-415ef54566353f34.std.9bb3df1236a54be1-cgu.13.rcgu.o: relocation R_AARCH64_ADR_PREL_PG_HI21 against symbol `_ZN3std9panicking4HOOK17h70a6060fe0d379ceE' which may bind externally can not be used when making a shared object; recompile with -fPIC
          /home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1-std/aarch64-unknown-linux-gnu/release/deps/std-415ef54566353f34.std.9bb3df1236a54be1-cgu.13.rcgu.o: in function `std::panicking::set_hook':
          std.9bb3df1236a54be1-cgu.13:(.text._ZN3std9panicking8set_hook17h8591ac4933ef13a8E+0x38): dangerous relocation: unsupported relocation
          /usr/bin/ld: /home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1-std/aarch64-unknown-linux-gnu/release/deps/std-415ef54566353f34.std.9bb3df1236a54be1-cgu.13.rcgu.o: relocation R_AARCH64_ADR_PREL_PG_HI21 against symbol `_ZN3std9panicking4HOOK17h70a6060fe0d379ceE' which may bind externally can not be used when making a shared object; recompile with -fPIC
          std.9bb3df1236a54be1-cgu.13:(.text._ZN3std9panicking8set_hook17h8591ac4933ef13a8E+0x58): dangerous relocation: unsupported relocation
          /usr/bin/ld: /home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1-std/aarch64-unknown-linux-gnu/release/deps/std-415ef54566353f34.std.9bb3df1236a54be1-cgu.13.rcgu.o: relocation R_AARCH64_ADR_PREL_PG_HI21 against symbol `_ZN3std9panicking4HOOK17h70a6060fe0d379ceE' which may bind externally can not be used when making a shared object; recompile with -fPIC
          /home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1-std/aarch64-unknown-linux-gnu/release/deps/std-415ef54566353f34.std.9bb3df1236a54be1-cgu.13.rcgu.o: in function `std::panicking::take_hook':
          std.9bb3df1236a54be1-cgu.13:(.text._ZN3std9panicking9take_hook17h6d3b290e8ed034f5E+0x24): dangerous relocation: unsupported relocation
          /usr/bin/ld: /home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1-std/aarch64-unknown-linux-gnu/release/deps/std-415ef54566353f34.std.9bb3df1236a54be1-cgu.13.rcgu.o: relocation R_AARCH64_ADR_PREL_PG_HI21 against symbol `_ZN3std9panicking4HOOK17h70a6060fe0d379ceE' which may bind externally can not be used when making a shared object; recompile with -fPIC
          std.9bb3df1236a54be1-cgu.13:(.text._ZN3std9panicking9take_hook17h6d3b290e8ed034f5E+0x150): dangerous relocation: unsupported relocation
          /usr/bin/ld: /home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1-std/aarch64-unknown-linux-gnu/release/deps/std-415ef54566353f34.std.9bb3df1236a54be1-cgu.13.rcgu.o: relocation R_AARCH64_ADR_PREL_PG_HI21 against symbol `_ZN3std9panicking4HOOK17h70a6060fe0d379ceE' which may bind externally can not be used when making a shared object; recompile with -fPIC
          /home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1-std/aarch64-unknown-linux-gnu/release/deps/std-415ef54566353f34.std.9bb3df1236a54be1-cgu.13.rcgu.o: in function `std::panicking::rust_panic_with_hook':
          std.9bb3df1236a54be1-cgu.13:(.text._ZN3std9panicking20rust_panic_with_hook17h3533559235359199E+0x54): dangerous relocation: unsupported relocation
          /usr/bin/ld: /home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1-std/aarch64-unknown-linux-gnu/release/deps/std-415ef54566353f34.std.9bb3df1236a54be1-cgu.13.rcgu.o: relocation R_AARCH64_ADR_PREL_PG_HI21 against symbol `_ZN3std9panicking4HOOK17h70a6060fe0d379ceE' which may bind externally can not be used when making a shared object; recompile with -fPIC
          std.9bb3df1236a54be1-cgu.13:(.text._ZN3std9panicking20rust_panic_with_hook17h3533559235359199E+0x64): dangerous relocation: unsupported relocation
          /usr/bin/ld: /home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1-std/aarch64-unknown-linux-gnu/release/deps/std-415ef54566353f34.std.9bb3df1236a54be1-cgu.13.rcgu.o: relocation R_AARCH64_ADR_PREL_PG_HI21 against symbol `_ZN3std9panicking4HOOK17h70a6060fe0d379ceE' which may bind externally can not be used when making a shared object; recompile with -fPIC
          std.9bb3df1236a54be1-cgu.13:(.text._ZN3std9panicking20rust_panic_with_hook17h3533559235359199E+0x88): dangerous relocation: unsupported relocation
          /usr/bin/ld: /home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1-std/aarch64-unknown-linux-gnu/release/deps/std-415ef54566353f34.std.9bb3df1236a54be1-cgu.13.rcgu.o: relocation R_AARCH64_ADR_PREL_PG_HI21 against symbol `_ZN3std9panicking4HOOK17h70a6060fe0d379ceE' which may bind externally can not be used when making a shared object; recompile with -fPIC
          std.9bb3df1236a54be1-cgu.13:(.text._ZN3std9panicking20rust_panic_with_hook17h3533559235359199E+0xa0): dangerous relocation: unsupported relocation
          /usr/bin/ld: /home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1-std/aarch64-unknown-linux-gnu/release/deps/std-415ef54566353f34.std.9bb3df1236a54be1-cgu.15.rcgu.o: relocation R_AARCH64_ADR_PREL_PG_HI21 against symbol `_ZN63_$LT$std..process..ExitStatus$u20$as$u20$core..fmt..Display$GT$3fmt17h227b634e4373fa20E' which may bind externally can not be used when making a shared object; recompile with -fPIC
          /home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1-std/aarch64-unknown-linux-gnu/release/deps/std-415ef54566353f34.std.9bb3df1236a54be1-cgu.15.rcgu.o: in function `<std::process::ExitStatusError as core::fmt::Display>::fmt':
          std.9bb3df1236a54be1-cgu.15:(.text._ZN68_$LT$std..process..ExitStatusError$u20$as$u20$core..fmt..Display$GT$3fmt17h25dd15edbda74edbE+0x8): dangerous relocation: unsupported relocation
          /usr/bin/ld: /home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1-std/aarch64-unknown-linux-gnu/release/deps/std-415ef54566353f34.std.9bb3df1236a54be1-cgu.15.rcgu.o: relocation R_AARCH64_ADR_PREL_PG_HI21 against symbol `_ZN58_$LT$std..io..error..Error$u20$as$u20$core..fmt..Debug$GT$3fmt17hd3cced40c18becd9E' which may bind externally can not be used when making a shared object; recompile with -fPIC
          /home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1-std/aarch64-unknown-linux-gnu/release/deps/std-415ef54566353f34.std.9bb3df1236a54be1-cgu.15.rcgu.o: in function `<std::sys::unix::fs::Dir as core::ops::drop::Drop>::drop':
          std.9bb3df1236a54be1-cgu.15:(.text._ZN65_$LT$std..sys..unix..fs..Dir$u20$as$u20$core..ops..drop..Drop$GT$4drop17h7ea69e9215da5a9fE+0x4c): dangerous relocation: unsupported relocation
          /usr/bin/ld: /home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1-std/aarch64-unknown-linux-gnu/release/deps/libstd_detect-1b1db080986b68cf.rlib(std_detect-1b1db080986b68cf.std_detect.8c82cd51d704ab52-cgu.1.rcgu.o): relocation R_AARCH64_ADR_PREL_PG_HI21 against symbol `_ZN10std_detect6detect5cache5CACHE17h1d43f563830256b8E' which may bind externally can not be used when making a shared object; recompile with -fPIC
          /home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1-std/aarch64-unknown-linux-gnu/release/deps/libstd_detect-1b1db080986b68cf.rlib(std_detect-1b1db080986b68cf.std_detect.8c82cd51d704ab52-cgu.1.rcgu.o): in function `std_detect::detect::cache::detect_and_initialize':
          std_detect.8c82cd51d704ab52-cgu.1:(.text.unlikely._ZN10std_detect6detect5cache21detect_and_initialize17h6b9853ffcd91f3c4E+0x14): dangerous relocation: unsupported relocation
          /usr/bin/ld: /home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1-std/aarch64-unknown-linux-gnu/release/deps/libcore-3f87a9c32d25ec14.rlib(core-3f87a9c32d25ec14.core.fb8474c54fa90b60-cgu.02.rcgu.o): relocation R_AARCH64_ADR_PREL_PG_HI21 against symbol `_ZN4core3num7flt2dec8strategy5grisu12CACHED_POW1017ha575f96fa2ca9354E' which may bind externally can not be used when making a shared object; recompile with -fPIC
          /home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1-std/aarch64-unknown-linux-gnu/release/deps/libcore-3f87a9c32d25ec14.rlib(core-3f87a9c32d25ec14.core.fb8474c54fa90b60-cgu.02.rcgu.o): in function `core::num::flt2dec::strategy::grisu::cached_power':
          core.fb8474c54fa90b60-cgu.02:(.text._ZN4core3num7flt2dec8strategy5grisu12cached_power17h5128fe17067d2382E+0x3c): dangerous relocation: unsupported relocation
          /usr/bin/ld: /home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1-std/aarch64-unknown-linux-gnu/release/deps/libcore-3f87a9c32d25ec14.rlib(core-3f87a9c32d25ec14.core.fb8474c54fa90b60-cgu.02.rcgu.o): relocation R_AARCH64_ADR_PREL_PG_HI21 against symbol `_ZN4core3num7flt2dec8strategy5grisu12CACHED_POW1017ha575f96fa2ca9354E' which may bind externally can not be used when making a shared object; recompile with -fPIC
          /home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1-std/aarch64-unknown-linux-gnu/release/deps/libcore-3f87a9c32d25ec14.rlib(core-3f87a9c32d25ec14.core.fb8474c54fa90b60-cgu.02.rcgu.o): in function `core::num::flt2dec::strategy::grisu::format_shortest_opt':
          core.fb8474c54fa90b60-cgu.02:(.text._ZN4core3num7flt2dec8strategy5grisu19format_shortest_opt17h754cfe6b872040c0E+0xf8): dangerous relocation: unsupported relocation
          /usr/bin/ld: /home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1-std/aarch64-unknown-linux-gnu/release/deps/libcore-3f87a9c32d25ec14.rlib(core-3f87a9c32d25ec14.core.fb8474c54fa90b60-cgu.02.rcgu.o): relocation R_AARCH64_ADR_PREL_PG_HI21 against symbol `_ZN4core3num7flt2dec8strategy5grisu12CACHED_POW1017ha575f96fa2ca9354E' which may bind externally can not be used when making a shared object; recompile with -fPIC
          /home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1-std/aarch64-unknown-linux-gnu/release/deps/libcore-3f87a9c32d25ec14.rlib(core-3f87a9c32d25ec14.core.fb8474c54fa90b60-cgu.02.rcgu.o): in function `core::num::flt2dec::strategy::grisu::format_exact_opt':
          core.fb8474c54fa90b60-cgu.02:(.text._ZN4core3num7flt2dec8strategy5grisu16format_exact_opt17h28bcd1f634583a4fE+0x94): dangerous relocation: unsupported relocation
          /usr/bin/ld: /home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1-std/aarch64-unknown-linux-gnu/release/deps/libcore-3f87a9c32d25ec14.rlib(core-3f87a9c32d25ec14.core.fb8474c54fa90b60-cgu.02.rcgu.o): relocation R_AARCH64_ADR_PREL_PG_HI21 against symbol `_ZN67_$LT$core..net..ip_addr..Ipv4Addr$u20$as$u20$core..fmt..Display$GT$3fmt17hd4e486673774bef8E' which may bind externally can not be used when making a shared object; recompile with -fPIC
          /home/gh-bjorn3/rust/build/aarch64-unknown-linux-gnu/stage1-std/aarch64-unknown-linux-gnu/release/deps/libcore-3f87a9c32d25ec14.rlib(core-3f87a9c32d25ec14.core.fb8474c54fa90b60-cgu.02.rcgu.o): in function `<core::net::ip_addr::Ipv6Addr as core::fmt::Display>::fmt':
          core.fb8474c54fa90b60-cgu.02:(.text._ZN67_$LT$core..net..ip_addr..Ipv6Addr$u20$as$u20$core..fmt..Display$GT$3fmt17h1126a36f89d04df3E+0x1f4): dangerous relocation: unsupported relocation
          collect2: error: ld returned 1 exit status

error: could not compile `std` (lib) due to previous error

[VorpalBlade]

@bjorn3 did you report the issue upstream to Binutils? This would be a nice thing to have.

[bjorn3]

I didn't. I don't even know if the latest binutils has the same issue.

[davidlattimore]

I just published a blog post on this topic: https://davidlattimore.github.io/posts/2024/08/27/rust-dylib-rabbit-holes.html

The situation has improved significantly with GNU ld from binutils 2.40 and later, which went into distros late last year. I'd say that we can't justify breaking linking for users that have GNU ld < 2.40 for quite some time. So that means this would need to be behind a flag. The good news is that we could consider defaulting that flag to true when LLD is selected as the linker.

I'm happy to have a go at this, unless @bjorn3 or someone else wants to?

[mati865]

This might be a bit unexpected, so I'm posting it for your information. This flag will also affect windows-gnu* targets because of https://github.com/llvm/llvm-project/commit/c5b3de6745c37dd991430b9b88ff97c35b6fc455. So, it's not an ELF only flag.