Nightly: Enabling LTO causes undefined symbols when using build-std

[newcomb-luke]

This bug occurs when I tried to build the example uefi app in a workspace of mine that enables LTO. I was able to replicate it using a standalone project:

Cargo.toml:

[package]
name = "bootloader-uefi"
version = "0.1.0"
edition = "2021"

[profile.dev]
lto = true

[dependencies]
log = "0.4"
uefi = "0.22"
uefi-services = "0.19"

main.rs:

#![no_std]
#![no_main]

use log::info;
use uefi::prelude::*;

#[entry]
fn main(_image_handle: Handle, mut system_table: SystemTable<Boot>) -> Status {
    uefi_services::init(&mut system_table).unwrap();
    info!("Hello, firmware!");
    system_table.boot_services().stall(10_000_000);
    Status::SUCCESS
}

I expected the crate to compile successfully, as it does when LTO is turned off.

Instead, the crate fails to link correctly, with many undefined symbols not only from compiler_builtins but also some from core.

I am forced to use build-std, so it could definitely be related to this issue, but it is slightly different in that even disabling share-generics doesn't help.

The full command that I am running to attempt the build is:

RUST_BACKTRACE=1 RUSTFLAGS="-Zshare-generics=n" cargo build -Zbuild-std=core,compiler_builtins -Zbuild-std-features=compiler-builtins-mem --target x86_64-unknown-uefi

Meta

rustc --version --verbose:

rustc 1.72.0-nightly (dd5d7c729 2023-06-02)
binary: rustc
commit-hash: dd5d7c729d4e8a59708df64002e09dbcbc4005ba
commit-date: 2023-06-02
host: x86_64-unknown-linux-gnu
release: 1.72.0-nightly
LLVM version: 16.0.4

Compiler output

   Compiling bootloader-uefi v0.1.0 (/home/luke/Documents/bootloader-uefi)
error: linking with rust-lld failed: exit status: 1
  = note: rust-lld: error: undefined symbol: core::panicking::panic::hb163aad4ddc55c9f
          >>> referenced by /home/luke/.cargo/registry/src/index.crates.io-6f17d22bba15001f/compiler_builtins-0.1.92/src/../libm/src/math/exp.rs:129
          >>>               libcompiler_builtins-0152c520d1c8b186.rlib(compiler_builtins-0152c520d1c8b186.compiler_builtins.75569f00fa09706c-cgu.10.rcgu.o):(compiler_builtins::math::libm::exp::exp::h02a4bfd20070f07c)
          >>> referenced by /home/luke/.cargo/registry/src/index.crates.io-6f17d22bba15001f/compiler_builtins-0.1.92/src/../libm/src/math/exp.rs:129
          >>>               libcompiler_builtins-0152c520d1c8b186.rlib(compiler_builtins-0152c520d1c8b186.compiler_builtins.75569f00fa09706c-cgu.10.rcgu.o):(compiler_builtins::math::libm::exp::exp::h02a4bfd20070f07c)
          >>> referenced by /home/luke/.cargo/registry/src/index.crates.io-6f17d22bba15001f/compiler_builtins-0.1.92/src/../libm/src/math/fmaf.rs:102
          >>>               libcompiler_builtins-0152c520d1c8b186.rlib(compiler_builtins-0152c520d1c8b186.compiler_builtins.75569f00fa09706c-cgu.10.rcgu.o):(compiler_builtins::math::libm::fmaf::fmaf::h64c4fdc39a6a9200)
          >>> referenced 581 more times

          rust-lld: error: undefined symbol: core::panicking::panic_fmt::hda82d1e6e39651a7
          >>> referenced by /home/luke/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/fmt/mod.rs:299
          >>>               libcompiler_builtins-0152c520d1c8b186.rlib(compiler_builtins-0152c520d1c8b186.compiler_builtins.75569f00fa09706c-cgu.2.rcgu.o):(core::fmt::Arguments::new_const::hb12de13e127e57a4)
          >>> referenced by /home/luke/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/ptr/const_ptr.rs:1567
          >>>               libcompiler_builtins-0152c520d1c8b186.rlib(compiler_builtins-0152c520d1c8b186.compiler_builtins.75569f00fa09706c-cgu.0.rcgu.o):(core::ptr::const_ptr::_$LT$impl$u20$$BP$const$u20$T$GT$::is_aligned_to::h14d9509bf7aaf5c9)
          >>> referenced by /home/luke/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/ptr/const_ptr.rs:1567
          >>>               libcompiler_builtins-0152c520d1c8b186.rlib(compiler_builtins-0152c520d1c8b186.compiler_builtins.75569f00fa09706c-cgu.0.rcgu.o):(core::ptr::const_ptr::_$LT$impl$u20$$BP$const$u20$T$GT$::is_aligned_to::h22908f059c723326)
          >>> referenced 2 more times

          rust-lld: error: undefined symbol: core::panicking::panic_nounwind::h0f909d7fd0d3bd3e
          >>> referenced by /home/luke/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/ptr/mod.rs:1539
          >>>               libcompiler_builtins-0152c520d1c8b186.rlib(compiler_builtins-0152c520d1c8b186.compiler_builtins.75569f00fa09706c-cgu.7.rcgu.o):(core::ptr::read_volatile::h2a19696369700077)
          >>> referenced by /home/luke/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/ptr/mod.rs:1539
          >>>               libcompiler_builtins-0152c520d1c8b186.rlib(compiler_builtins-0152c520d1c8b186.compiler_builtins.75569f00fa09706c-cgu.7.rcgu.o):(core::ptr::read_volatile::hd1a8b1667212015d)
          >>> referenced by /home/luke/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/ptr/mod.rs:1175
          >>>               libcompiler_builtins-0152c520d1c8b186.rlib(compiler_builtins-0152c520d1c8b186.compiler_builtins.75569f00fa09706c-cgu.7.rcgu.o):(core::ptr::read::h70c3ace9010db4c7)
          >>> referenced 12 more times

          rust-lld: error: undefined symbol: core::option::expect_failed::hc5188971195ae32b
          >>> referenced by /home/luke/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/option.rs:898
          >>>               libcompiler_builtins-0152c520d1c8b186.rlib(compiler_builtins-0152c520d1c8b186.compiler_builtins.75569f00fa09706c-cgu.12.rcgu.o):(core::option::Option$LT$T$GT$::expect::h63b03588bfa56574)

          rust-lld: error: undefined symbol: core::slice::index::slice_index_order_fail::h89839b514f12b875
          >>> referenced by /home/luke/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/slice/index.rs:406
          >>>               libcompiler_builtins-0152c520d1c8b186.rlib(compiler_builtins-0152c520d1c8b186.compiler_builtins.75569f00fa09706c-cgu.8.rcgu.o):(_$LT$core..ops..range..Range$LT$usize$GT$$u20$as$u20$core..slice..index..SliceIndex$LT$$u5b$T$u5d$$GT$$GT$::index::h088287bcb6971bb6)

          rust-lld: error: undefined symbol: core::slice::index::slice_end_index_len_fail::hc3c969f2bc3a976b
          >>> referenced by /home/luke/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/slice/index.rs:408
          >>>               libcompiler_builtins-0152c520d1c8b186.rlib(compiler_builtins-0152c520d1c8b186.compiler_builtins.75569f00fa09706c-cgu.8.rcgu.o):(_$LT$core..ops..range..Range$LT$usize$GT$$u20$as$u20$core..slice..index..SliceIndex$LT$$u5b$T$u5d$$GT$$GT$::index::h088287bcb6971bb6)

          rust-lld: error: undefined symbol: core::slice::index::slice_end_index_overflow_fail::h7c1f489fb05731b4
          >>> referenced by /home/luke/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/slice/index.rs:576
          >>>               libcompiler_builtins-0152c520d1c8b186.rlib(compiler_builtins-0152c520d1c8b186.compiler_builtins.75569f00fa09706c-cgu.8.rcgu.o):(_$LT$core..ops..range..RangeInclusive$LT$usize$GT$$u20$as$u20$core..slice..index..SliceIndex$LT$$u5b$T$u5d$$GT$$GT$::index::h981b17dba1d622a5)

error: could not compile `bootloader-uefi` (bin "bootloader-uefi") due to previous error

[newcomb-luke]

Unfortunately I just tested it with a blank cargo new --bin project, and it had the same issue.

Steps to reproduce:

cargo new --bin test-lto

Cargo.toml:

[package]
name = "test-lto"
version = "0.1.0"
edition = "2021"

[profile.dev]
lto = true

[dependencies]

main.rs:

fn main() {
    println!("Hello, world!");
}

Build command:

RUST_BACKTRACE=1 RUSTFLAGS="-Zshare-generics=n" cargo build -Zbuild-std=std --target x86_64-unknown-linux-gnu

Compiler output

   Compiling test-lto v0.1.0 (/home/luke/Documents/test-lto)
error: linking with `cc` failed: exit status: 1
  = note: /usr/bin/ld: /home/luke/Documents/test-lto/target/x86_64-unknown-linux-gnu/debug/deps/libcompiler_builtins-6a735d5bd3926b02.rlib(compiler_builtins-6a735d5bd3926b02.compiler_builtins.c6c212234179a561-cgu.6.rcgu.o): in function `compiler_builtins::int::shift::Ashl::ashl':
          /home/luke/.cargo/registry/src/index.crates.io-6f17d22bba15001f/compiler_builtins-0.1.92/src/int/shift.rs:9: undefined reference to `core::panicking::panic'
          /usr/bin/ld: /home/luke/Documents/test-lto/target/x86_64-unknown-linux-gnu/debug/deps/libcompiler_builtins-6a735d5bd3926b02.rlib(compiler_builtins-6a735d5bd3926b02.compiler_builtins.c6c212234179a561-cgu.6.rcgu.o): in function `compiler_builtins::int::shift::Ashr::ashr':
          /home/luke/.cargo/registry/src/index.crates.io-6f17d22bba15001f/compiler_builtins-0.1.92/src/int/shift.rs:31: undefined reference to `core::panicking::panic'
          /usr/bin/ld: /home/luke/Documents/test-lto/target/x86_64-unknown-linux-gnu/debug/deps/libcompiler_builtins-6a735d5bd3926b02.rlib(compiler_builtins-6a735d5bd3926b02.compiler_builtins.c6c212234179a561-cgu.6.rcgu.o): in function `compiler_builtins::int::shift::Lshr::lshr':
          /home/luke/.cargo/registry/src/index.crates.io-6f17d22bba15001f/compiler_builtins-0.1.92/src/int/shift.rs:55: undefined reference to `core::panicking::panic'
          /usr/bin/ld: /home/luke/Documents/test-lto/target/x86_64-unknown-linux-gnu/debug/deps/libcompiler_builtins-6a735d5bd3926b02.rlib(compiler_builtins-6a735d5bd3926b02.compiler_builtins.c6c212234179a561-cgu.9.rcgu.o): in function `compiler_builtins::float::extend::extend':
          /home/luke/.cargo/registry/src/index.crates.io-6f17d22bba15001f/compiler_builtins-0.1.92/src/float/extend.rs:61: undefined reference to `core::panicking::panic'
          /usr/bin/ld: /home/luke/.cargo/registry/src/index.crates.io-6f17d22bba15001f/compiler_builtins-0.1.92/src/float/extend.rs:63: undefined reference to `core::panicking::panic'
          /usr/bin/ld: /home/luke/Documents/test-lto/target/x86_64-unknown-linux-gnu/debug/deps/libcompiler_builtins-6a735d5bd3926b02.rlib(compiler_builtins-6a735d5bd3926b02.compiler_builtins.c6c212234179a561-cgu.9.rcgu.o):/home/luke/.cargo/registry/src/index.crates.io-6f17d22bba15001f/compiler_builtins-0.1.92/src/float/extend.rs:63: more undefined references to `core::panicking::panic' follow
          /usr/bin/ld: /home/luke/Documents/test-lto/target/x86_64-unknown-linux-gnu/debug/deps/libcompiler_builtins-6a735d5bd3926b02.rlib(compiler_builtins-6a735d5bd3926b02.compiler_builtins.c6c212234179a561-cgu.10.rcgu.o): in function `core::hint::unreachable_unchecked::runtime':
          /home/luke/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/intrinsics.rs:2510: undefined reference to `core::panicking::panic_nounwind'
          /usr/bin/ld: /home/luke/Documents/test-lto/target/x86_64-unknown-linux-gnu/debug/deps/libcompiler_builtins-6a735d5bd3926b02.rlib(compiler_builtins-6a735d5bd3926b02.compiler_builtins.c6c212234179a561-cgu.10.rcgu.o): in function `<u32 as core::ops::arith::AddAssign>::add_assign':
          /home/luke/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/ops/arith.rs:753: undefined reference to `core::panicking::panic'
          /usr/bin/ld: /home/luke/Documents/test-lto/target/x86_64-unknown-linux-gnu/debug/deps/libcompiler_builtins-6a735d5bd3926b02.rlib(compiler_builtins-6a735d5bd3926b02.compiler_builtins.c6c212234179a561-cgu.10.rcgu.o): in function `<u64 as core::ops::arith::AddAssign>::add_assign':
          /home/luke/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/ops/arith.rs:753: undefined reference to `core::panicking::panic'
          /usr/bin/ld: /home/luke/Documents/test-lto/target/x86_64-unknown-linux-gnu/debug/deps/libcompiler_builtins-6a735d5bd3926b02.rlib(compiler_builtins-6a735d5bd3926b02.compiler_builtins.c6c212234179a561-cgu.10.rcgu.o): in function `compiler_builtins::float::trunc::trunc':
          /home/luke/.cargo/registry/src/index.crates.io-6f17d22bba15001f/compiler_builtins-0.1.92/src/float/trunc.rs:36: undefined reference to `core::panicking::panic'
          /usr/bin/ld: /home/luke/.cargo/registry/src/index.crates.io-6f17d22bba15001f/compiler_builtins-0.1.92/src/float/trunc.rs:36: undefined reference to `core::panicking::panic'
          /usr/bin/ld: /home/luke/.cargo/registry/src/index.crates.io-6f17d22bba15001f/compiler_builtins-0.1.92/src/float/trunc.rs:37: undefined reference to `core::panicking::panic'
          /usr/bin/ld: /home/luke/Documents/test-lto/target/x86_64-unknown-linux-gnu/debug/deps/libcompiler_builtins-6a735d5bd3926b02.rlib(compiler_builtins-6a735d5bd3926b02.compiler_builtins.c6c212234179a561-cgu.10.rcgu.o):/home/luke/.cargo/registry/src/index.crates.io-6f17d22bba15001f/compiler_builtins-0.1.92/src/float/trunc.rs:37: more undefined references to `core::panicking::panic' follow
          collect2: error: ld returned 1 exit status

[saethlin]

rust/Cargo.toml

Lines 64 to 72 in 1e17cef

	[profile.release.package.compiler_builtins]
	# The compiler-builtins crate cannot reference libcore, and it's own CI will
	# verify that this is the case. This requires, however, that the crate is built
	# without overflow checks and debug assertions. Forcefully disable debug
	# assertions and overflow checks here which should ensure that even if these
	# assertions are enabled for libstd we won't enable them for compiler_builtins
	# which should ensure we still link everything correctly.
	debug-assertions = false
	overflow-checks = false