generic_const_exprs: associated type with const parameter set by associated const gives "undefined reference" linker errors

[shelvacu]

MVCE:

#![allow(incomplete_features)]
#![feature(generic_const_exprs)]

trait TraitOne {
    const MY_NUM:usize;
    type MyErr : std::fmt::Debug;

    fn do_one_stuff(arr: [u8; Self::MY_NUM]) -> Result<(), Self::MyErr>;
}

trait TraitTwo {
    fn do_two_stuff();
}

impl<O: TraitOne> TraitTwo for O
where [(); Self::MY_NUM]: {
    fn do_two_stuff() { O::do_one_stuff([5; Self::MY_NUM]).unwrap() }
}

struct Blargotron;

#[derive(Debug)]
struct ErrTy<const N:usize> ([(); N]);

impl TraitOne for Blargotron {
    const MY_NUM:usize = 3;
    type MyErr = ErrTy<{Self::MY_NUM}>;

    fn do_one_stuff(_arr: [u8; Self::MY_NUM]) -> Result<(), Self::MyErr> { Ok(()) }
}

fn main() {
    Blargotron::do_two_stuff();
}

(longer than I'd usually like an MVCE to be, but I couldn't find any more ways to shorten it)

Output with linker error:

$ cargo +nightly run
   Compiling rustbugrepro v0.1.0 (/home/shelvacu/rustbugrepro)
error: linking with `cc` failed: exit status: 1
  |
  = note: "cc" "-m64" "/tmp/rustcpdm3oV/symbols.o" "/home/shelvacu/rustbugrepro/target/debug/deps/rustbugrepro-b454c4cbfd8105b6.1ihqumwagrufjop0.rcgu.o" "/home/shelvacu/rustbugrepro/target/debug/deps/rustbugrepro-b454c4cbfd8105b6.1mup2xyy24n4gk36.rcgu.o" "/home/shelvacu/rustbugrepro/target/debug/deps/rustbugrepro-b454c4cbfd8105b6.23s252vpk659ujid.rcgu.o" "/home/shelvacu/rustbugrepro/target/debug/deps/rustbugrepro-b454c4cbfd8105b6.2stlozizc5uxjd7b.rcgu.o" "/home/shelvacu/rustbugrepro/target/debug/deps/rustbugrepro-b454c4cbfd8105b6.32r5fw7gu7hn650.rcgu.o" "/home/shelvacu/rustbugrepro/target/debug/deps/rustbugrepro-b454c4cbfd8105b6.3m9r4hpnytp8i5eg.rcgu.o" "/home/shelvacu/rustbugrepro/target/debug/deps/rustbugrepro-b454c4cbfd8105b6.3y6kclqhz0icogsf.rcgu.o" "/home/shelvacu/rustbugrepro/target/debug/deps/rustbugrepro-b454c4cbfd8105b6.4gqxo0wsc252b81i.rcgu.o" "/home/shelvacu/rustbugrepro/target/debug/deps/rustbugrepro-b454c4cbfd8105b6.5gj6i7t0wm9u39r7.rcgu.o" "/home/shelvacu/rustbugrepro/target/debug/deps/rustbugrepro-b454c4cbfd8105b6.8gtzyztqdis5wfk.rcgu.o" "/home/shelvacu/rustbugrepro/target/debug/deps/rustbugrepro-b454c4cbfd8105b6.b2wiaz2930r642i.rcgu.o" "/home/shelvacu/rustbugrepro/target/debug/deps/rustbugrepro-b454c4cbfd8105b6.h4vu5fvuiuflzws.rcgu.o" "/home/shelvacu/rustbugrepro/target/debug/deps/rustbugrepro-b454c4cbfd8105b6.20c23rlj3dtxnb5h.rcgu.o" "-Wl,--as-needed" "-L" "/home/shelvacu/rustbugrepro/target/debug/deps" "-L" "/home/shelvacu/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib" "-Wl,--start-group" "-Wl,-Bstatic" "/home/shelvacu/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib/libstd-9a60c77fcb3cb120.rlib" "/home/shelvacu/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib/libpanic_unwind-5b44c7aad80856ae.rlib" "/home/shelvacu/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib/libobject-ff65b550b4dcd2ac.rlib" "/home/shelvacu/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib/libmemchr-7f1169f253822fce.rlib" "/home/shelvacu/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib/libaddr2line-a981dbda6aeca1f9.rlib" "/home/shelvacu/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib/libgimli-fc1281d9e6392569.rlib" "/home/shelvacu/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib/librustc_demangle-1fbfdea3abefe497.rlib" "/home/shelvacu/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib/libstd_detect-9c50e59a7c82c7d4.rlib" "/home/shelvacu/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib/libhashbrown-49ab78c1bdf400c6.rlib" "/home/shelvacu/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib/libminiz_oxide-640f18ffcf376a48.rlib" "/home/shelvacu/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib/libadler-8448e4d3e976ee3c.rlib" "/home/shelvacu/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib/librustc_std_workspace_alloc-cb13682f9c2a7246.rlib" "/home/shelvacu/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib/libunwind-cfa8f6cd7fbf314f.rlib" "/home/shelvacu/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib/libcfg_if-0f3268324638da83.rlib" "/home/shelvacu/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib/liblibc-9dba3f083c9eb142.rlib" "/home/shelvacu/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib/liballoc-aaaa00ed48be7dc8.rlib" "/home/shelvacu/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib/librustc_std_workspace_core-522518611024dce5.rlib" "/home/shelvacu/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib/libcore-05898138a596088a.rlib" "-Wl,--end-group" "/home/shelvacu/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib/libcompiler_builtins-6088bc0426d36242.rlib" "-Wl,-Bdynamic" "-lgcc_s" "-lutil" "-lrt" "-lpthread" "-lm" "-ldl" "-lc" "-Wl,--eh-frame-hdr" "-Wl,-znoexecstack" "-L" "/home/shelvacu/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib" "-o" "/home/shelvacu/rustbugrepro/target/debug/deps/rustbugrepro-b454c4cbfd8105b6" "-Wl,--gc-sections" "-pie" "-Wl,-zrelro,-znow" "-nodefaultlibs"
  = note: /usr/lib/gcc/x86_64-pc-linux-gnu/11.2.0/../../../../x86_64-pc-linux-gnu/bin/ld: /home/shelvacu/rustbugrepro/target/debug/deps/rustbugrepro-b454c4cbfd8105b6.b2wiaz2930r642i.rcgu.o: in function `<O as rustbugrepro::TraitTwo>::do_two_stuff':
          /home/shelvacu/rustbugrepro/src/main.rs:17: undefined reference to `core::result::Result<T,E>::unwrap'
          /usr/lib/gcc/x86_64-pc-linux-gnu/11.2.0/../../../../x86_64-pc-linux-gnu/bin/ld: /home/shelvacu/rustbugrepro/target/debug/deps/rustbugrepro-b454c4cbfd8105b6: hidden symbol `_ZN4core6result19Result$LT$T$C$E$GT$6unwrap17h3f789d9c8ef9bb3fE' isn't defined
          /usr/lib/gcc/x86_64-pc-linux-gnu/11.2.0/../../../../x86_64-pc-linux-gnu/bin/ld: final link failed: bad value
          collect2: error: ld returned 1 exit status
          
  = help: some `extern` functions couldn't be found; some native libraries may need to be installed or have their path specified
  = note: use the `-l` flag to specify native libraries to link
  = note: use the `cargo:rustc-link-lib` directive to specify the native libraries to link with Cargo (see https://doc.rust-lang.org/cargo/reference/build-scripts.html#cargorustc-link-libkindname)

error: could not compile `rustbugrepro` due to previous error

Rustc version:

$ rustc +nightly -vV
rustc 1.65.0-nightly (2befdefdd 2022-08-06)
binary: rustc
commit-hash: 2befdefdda0f2bc5ff93f7f95633c98841409098
commit-date: 2022-08-06
host: x86_64-unknown-linux-gnu
release: 1.65.0-nightly
LLVM version: 14.0.6

Also looked at other issues, one of these may be a dupe but none match the structure of the MVCE or the same linker error:

• const_generics: link fails with undefined reference, hidden symbol isn't defined #83972 - also tried with RUSTC_FLAGS="-Zsymbol-mangling-version=v0", no difference
• more generic const expr linker errors #84669
• Link fails with hidden symbol isn't defined #86710
• linker error with feature(generic_const_exprs) #82268
• "error: linking with cc failed: exit code: 1" regression in release build with const generics #73298

[shelvacu]

Also repro's on windows:

Windows linker error

> cargo +nightly run
   Compiling rustbugrepro v0.1.0 (C:\Dev\rustbugrepro)
error: linking with `link.exe` failed: exit code: 1120
  |
  = note: "C:\\Program Files (x86)\\Microsoft Visual Studio\\2019\\BuildTools\\VC\\Tools\\MSVC\\14.28.29910\\bin\\HostX64\\x64\\link.exe" "/NOLOGO" "C:\\Users\\Shelvacu\\AppData\\Local\\Temp\\rustcRQUigQ\\symbols.o" "C:\\Dev\\rustbugrepro\\target\\debug\\deps\\rustbugrepro.1udni13he2xyym0b.rcgu.o" "C:\\Dev\\rustbugrepro\\target\\debug\\deps\\rustbugrepro.2s6b7q3vkeq1d64i.rcgu.o" "C:\\Dev\\rustbugrepro\\target\\debug\\deps\\rustbugrepro.3c0cr0eh1zukshsb.rcgu.o" "C:\\Dev\\rustbugrepro\\target\\debug\\deps\\rustbugrepro.3e6jxlkjoc5gzna9.rcgu.o" "C:\\Dev\\rustbugrepro\\target\\debug\\deps\\rustbugrepro.3eyd2duakhmjtemq.rcgu.o" "C:\\Dev\\rustbugrepro\\target\\debug\\deps\\rustbugrepro.3x2wpsi5dzeyr9uo.rcgu.o" "C:\\Dev\\rustbugrepro\\target\\debug\\deps\\rustbugrepro.4f1h8qdlhhqmrp7n.rcgu.o" "C:\\Dev\\rustbugrepro\\target\\debug\\deps\\rustbugrepro.51cqp6hddvxj1d9k.rcgu.o" "C:\\Dev\\rustbugrepro\\target\\debug\\deps\\rustbugrepro.5a201y9vd5xd6ruq.rcgu.o" "C:\\Dev\\rustbugrepro\\target\\debug\\deps\\rustbugrepro.5b08j8gri1710q23.rcgu.o" "C:\\Dev\\rustbugrepro\\target\\debug\\deps\\rustbugrepro.8i8rqrj0zicqix1.rcgu.o" "C:\\Dev\\rustbugrepro\\target\\debug\\deps\\rustbugrepro.kvlka6m9mh6xz16.rcgu.o" "C:\\Dev\\rustbugrepro\\target\\debug\\deps\\rustbugrepro.3zpxynnxwesoe9xt.rcgu.o" "/LIBPATH:C:\\Dev\\rustbugrepro\\target\\debug\\deps" "/LIBPATH:C:\\Users\\Shelvacu\\.rustup\\toolchains\\nightly-x86_64-pc-windows-msvc\\lib\\rustlib\\x86_64-pc-windows-msvc\\lib" "C:\\Users\\Shelvacu\\.rustup\\toolchains\\nightly-x86_64-pc-windows-msvc\\lib\\rustlib\\x86_64-pc-windows-msvc\\lib\\libstd-8f2958805c366b35.rlib" "C:\\Users\\Shelvacu\\.rustup\\toolchains\\nightly-x86_64-pc-windows-msvc\\lib\\rustlib\\x86_64-pc-windows-msvc\\lib\\libpanic_unwind-fed034f75e1fd7b9.rlib" "C:\\Users\\Shelvacu\\.rustup\\toolchains\\nightly-x86_64-pc-windows-msvc\\lib\\rustlib\\x86_64-pc-windows-msvc\\lib\\librustc_demangle-dec7786bc54848e7.rlib" "C:\\Users\\Shelvacu\\.rustup\\toolchains\\nightly-x86_64-pc-windows-msvc\\lib\\rustlib\\x86_64-pc-windows-msvc\\lib\\libstd_detect-fd5241549c83eef9.rlib" "C:\\Users\\Shelvacu\\.rustup\\toolchains\\nightly-x86_64-pc-windows-msvc\\lib\\rustlib\\x86_64-pc-windows-msvc\\lib\\libhashbrown-5688c8846aadbd5c.rlib" "C:\\Users\\Shelvacu\\.rustup\\toolchains\\nightly-x86_64-pc-windows-msvc\\lib\\rustlib\\x86_64-pc-windows-msvc\\lib\\libminiz_oxide-ea5978b20cdb3144.rlib" "C:\\Users\\Shelvacu\\.rustup\\toolchains\\nightly-x86_64-pc-windows-msvc\\lib\\rustlib\\x86_64-pc-windows-msvc\\lib\\libadler-5095f98b1de89a77.rlib" "C:\\Users\\Shelvacu\\.rustup\\toolchains\\nightly-x86_64-pc-windows-msvc\\lib\\rustlib\\x86_64-pc-windows-msvc\\lib\\librustc_std_workspace_alloc-806aa9f85f297b4a.rlib" "C:\\Users\\Shelvacu\\.rustup\\toolchains\\nightly-x86_64-pc-windows-msvc\\lib\\rustlib\\x86_64-pc-windows-msvc\\lib\\libunwind-6401deea286d934a.rlib" "C:\\Users\\Shelvacu\\.rustup\\toolchains\\nightly-x86_64-pc-windows-msvc\\lib\\rustlib\\x86_64-pc-windows-msvc\\lib\\libcfg_if-5a2a92015c9f63a6.rlib" "C:\\Users\\Shelvacu\\.rustup\\toolchains\\nightly-x86_64-pc-windows-msvc\\lib\\rustlib\\x86_64-pc-windows-msvc\\lib\\liblibc-68fca0524476f675.rlib" "C:\\Users\\Shelvacu\\.rustup\\toolchains\\nightly-x86_64-pc-windows-msvc\\lib\\rustlib\\x86_64-pc-windows-msvc\\lib\\liballoc-bd07379605777ddb.rlib" "C:\\Users\\Shelvacu\\.rustup\\toolchains\\nightly-x86_64-pc-windows-msvc\\lib\\rustlib\\x86_64-pc-windows-msvc\\lib\\librustc_std_workspace_core-69892fa511d5a698.rlib" "C:\\Users\\Shelvacu\\.rustup\\toolchains\\nightly-x86_64-pc-windows-msvc\\lib\\rustlib\\x86_64-pc-windows-msvc\\lib\\libcore-798bc7c2d986ac97.rlib" "C:\\Users\\Shelvacu\\.rustup\\toolchains\\nightly-x86_64-pc-windows-msvc\\lib\\rustlib\\x86_64-pc-windows-msvc\\lib\\libcompiler_builtins-d2245e599df4d1e5.rlib" "advapi32.lib" "userenv.lib" "kernel32.lib" "ws2_32.lib" "bcrypt.lib" "msvcrt.lib" "/NXCOMPAT" "/LIBPATH:C:\\Users\\Shelvacu\\.rustup\\toolchains\\nightly-x86_64-pc-windows-msvc\\lib\\rustlib\\x86_64-pc-windows-msvc\\lib" "/OUT:C:\\Dev\\rustbugrepro\\target\\debug\\deps\\rustbugrepro.exe" "/OPT:REF,NOICF" "/DEBUG" "/NATVIS:C:\\Users\\Shelvacu\\.rustup\\toolchains\\nightly-x86_64-pc-windows-msvc\\lib\\rustlib\\etc\\intrinsic.natvis" "/NATVIS:C:\\Users\\Shelvacu\\.rustup\\toolchains\\nightly-x86_64-pc-windows-msvc\\lib\\rustlib\\etc\\liballoc.natvis" "/NATVIS:C:\\Users\\Shelvacu\\.rustup\\toolchains\\nightly-x86_64-pc-windows-msvc\\lib\\rustlib\\etc\\libcore.natvis" "/NATVIS:C:\\Users\\Shelvacu\\.rustup\\toolchains\\nightly-x86_64-pc-windows-msvc\\lib\\rustlib\\etc\\libstd.natvis"
  = note: rustbugrepro.kvlka6m9mh6xz16.rcgu.o : error LNK2019: unresolved external symbol _ZN4core6result19Result$LT$T$C$E$GT$6unwrap17h12707c38822a18b6E referenced in function _ZN44_$LT$O$u20$as$u20$rustbugrepro..TraitTwo$GT$12do_two_stuff17hce79e834541c2b02E
          C:\Dev\rustbugrepro\target\debug\deps\rustbugrepro.exe : fatal error LNK1120: 1 unresolved externals


error: could not compile `rustbugrepro` due to previous error

rustc version:

> rustc +nightly -vV
rustc 1.64.0-nightly (affe0d3a0 2022-08-05)
binary: rustc
commit-hash: affe0d3a00e92fa7885e3f5d2c5073fde432d154
commit-date: 2022-08-05
host: x86_64-pc-windows-msvc
release: 1.64.0-nightly
LLVM version: 14.0.6