export_name with unusual utf8 breaks new version script based linker

[m4b]

Unfortunately it looks like the awesome changes in #38117 caused breakage while linking when a weird export name is used (probably due to the version script requiring ascii, or some other esoterica):

        #[export_name="bad_∢"]
        pub extern fn bad(i: usize) {}

NOTE haven't checked this particular version, but certain combinations of values cause linker error complaining about invalid chars in version script.

[michaelwoerister]

I guess, we should just restrict export_name to ASCII.

cc @rust-lang/compiler

[m4b]

So this is an artificial restriction, for no technical merit. I'd really like utf8 support for symbol names, just on principle.

Nevertheless it doesn't work as is now (and used to) (albeit entirely because of a broken linker toolchain), so ASCII might be required... Iirc, swift re-encodes utf symbols in their name mangler, but that's not the same as real utf8 symbol names in the binary, which is just literally the coolest. I don't know of another language that allows that and can run (and the dynamic linker doesn't have any problem with it, because it just sees null terminated bytes, which utf8 preserves.)

[michaelwoerister]

With which linkers do you run into the problem?

[m4b]

Both gold and ld (-fuse-ld=bfd) are broken for me:

#[export_name="󠆷∀🢫"]
#[no_mangle]
pub extern fn whatever() {
    println!("nothing");
}

I guess unicode is too hard for C ppls.

rustc --crate-type=cdylib src/lib.rs 
error: linking with `cc` failed: exit code: 1
  |
  = note: "cc" "-Wl,--as-needed" "-Wl,-z,noexecstack" "-m64" "-L" "/home/m4b/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib" "lib.0.o" "-o" "liblib.so" "-Wl,--version-script=/tmp/rustc.AxbnbIEKM7Z3/list" "-Wl,--gc-sections" "-nodefaultlibs" "-L" "/home/m4b/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib" "-Wl,-Bstatic" "-Wl,-Bdynamic" "/home/m4b/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib/libstd-b4054fae3db32020.rlib" "/home/m4b/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib/librand-1c6ed188684e7d33.rlib" "/home/m4b/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib/libcollections-63f7707126c5a809.rlib" "/home/m4b/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib/libstd_unicode-a9711770523833d4.rlib" "/home/m4b/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib/libpanic_unwind-d2ecc8049920bea8.rlib" "/home/m4b/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib/libunwind-5837d7d3490e00c5.rlib" "/home/m4b/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib/liballoc-0720511b45a7223a.rlib" "/home/m4b/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib/liballoc_system-34e7f110f175a258.rlib" "/home/m4b/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib/liblibc-ab203041f1ec5313.rlib" "/home/m4b/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib/libcore-93f19628b61beb76.rlib" "/home/m4b/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib/libcompiler_builtins-35d2bc471c7ce467.rlib" "-l" "dl" "-l" "rt" "-l" "pthread" "-l" "gcc_s" "-l" "pthread" "-l" "c" "-l" "m" "-l" "rt" "-l" "util" "-shared"
  = note: /usr/bin/ld:/tmp/rustc.AxbnbIEKM7Z3/list:3: ignoring invalid character `\363' in script
/usr/bin/ld:/tmp/rustc.AxbnbIEKM7Z3/list:3: ignoring invalid character `\240' in script
/usr/bin/ld:/tmp/rustc.AxbnbIEKM7Z3/list:3: ignoring invalid character `\206' in script
/usr/bin/ld:/tmp/rustc.AxbnbIEKM7Z3/list:3: ignoring invalid character `\267' in script
/usr/bin/ld:/tmp/rustc.AxbnbIEKM7Z3/list:3: ignoring invalid character `\342' in script
/usr/bin/ld:/tmp/rustc.AxbnbIEKM7Z3/list:3: ignoring invalid character `\210' in script
/usr/bin/ld:/tmp/rustc.AxbnbIEKM7Z3/list:3: ignoring invalid character `\200' in script
/usr/bin/ld:/tmp/rustc.AxbnbIEKM7Z3/list:3: ignoring invalid character `\360' in script
/usr/bin/ld:/tmp/rustc.AxbnbIEKM7Z3/list:3: ignoring invalid character `\237' in script
/usr/bin/ld:/tmp/rustc.AxbnbIEKM7Z3/list:3: ignoring invalid character `\242' in script
/usr/bin/ld:/tmp/rustc.AxbnbIEKM7Z3/list:3: ignoring invalid character `\253' in script
/usr/bin/ld:/tmp/rustc.AxbnbIEKM7Z3/list:3: syntax error in VERSION script
collect2: error: ld returned 1 exit status

rustc --crate-type=cdylib -C link-args="-fuse-ld=gold" src/lib.rs 
error: linking with `cc` failed: exit code: 1
  |
  = note: "cc" "-Wl,--as-needed" "-Wl,-z,noexecstack" "-m64" "-L" "/home/m4b/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib" "lib.0.o" "-o" "liblib.so" "-Wl,--version-script=/tmp/rustc.5LjCdyxrgOsb/list" "-Wl,--gc-sections" "-nodefaultlibs" "-L" "/home/m4b/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib" "-Wl,-Bstatic" "-Wl,-Bdynamic" "/home/m4b/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib/libstd-b4054fae3db32020.rlib" "/home/m4b/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib/librand-1c6ed188684e7d33.rlib" "/home/m4b/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib/libcollections-63f7707126c5a809.rlib" "/home/m4b/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib/libstd_unicode-a9711770523833d4.rlib" "/home/m4b/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib/libpanic_unwind-d2ecc8049920bea8.rlib" "/home/m4b/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib/libunwind-5837d7d3490e00c5.rlib" "/home/m4b/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib/liballoc-0720511b45a7223a.rlib" "/home/m4b/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib/liballoc_system-34e7f110f175a258.rlib" "/home/m4b/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib/liblibc-ab203041f1ec5313.rlib" "/home/m4b/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib/libcore-93f19628b61beb76.rlib" "/home/m4b/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib/libcompiler_builtins-35d2bc471c7ce467.rlib" "-l" "dl" "-l" "rt" "-l" "pthread" "-l" "gcc_s" "-l" "pthread" "-l" "c" "-l" "m" "-l" "rt" "-l" "util" "-shared" "-fuse-ld=gold"
  = note: /usr/bin/ld.gold: error: /tmp/rustc.5LjCdyxrgOsb/list:3:5: invalid character
/usr/bin/ld.gold: error: /tmp/rustc.5LjCdyxrgOsb/list:3:5: syntax error, unexpected $end, expecting STRING or QUOTED_STRING or EXTERN
/usr/bin/ld.gold: fatal error: unable to parse version script file /tmp/rustc.5LjCdyxrgOsb/list
collect2: error: ld returned 1 exit status

[DemiMarie]

I think we should report this as a bug against GNU LD, unless there is a way to quote symbol names.

[steveklabnik]

Triage: not aware of any changes