Core build is broken when using build-std with custom cross-compile target

[KernelFreeze]

Hello. I'm using the nightly feature build-std to cross-compile core to a custom target. It always works as expected, however, today it suddenly stopped working and throws an error:

LLVM ERROR: EH registrations only live in functions using WinEH
error: could not compile `core`

I tried the same on Windows, and another error occurs:

Caused by:
process didn't exit successfully: `rustc --crate-name core --edition=2018 C:\Users\Kernel\.rustup\toolchains\nightly-x86_64-pc-windows-msvc\lib\rustlib\src\rust\library\core\src\lib.rs --error-format=json --json=diagnostic-rendered-ansi,artifacts --crate-type lib --emit=dep-info,metadata,link -C embed-bitcode=no -C debuginfo=2 -C metadata=f8246f0242b85744 -C extra-filename=-f8246f0242b85744 --out-dir C:\Users\Kernel\Documents\Proyectos\etheryal\kernel\target\x86_64\debug\deps --target \\?\C:\Users\Kernel\Documents\Proyectos\etheryal\kernel\targets\x86_64.json -Z force-unstable-if-unmarked -L dependency=C:\Users\Kernel\Documents\Proyectos\etheryal\kernel\target\x86_64\debug\deps -L dependency=C:\Users\Kernel\Documents\Proyectos\etheryal\kernel\target\debug\deps --cap-lints allow` (exit code: 0xc0000409, STATUS_STACK_BUFFER_OVERRUN)
warning: build failed, waiting for other jobs to finish...
error: build failed

Meta

rustc --version --verbose:

rustc --version --verbose
rustc 1.51.0-nightly (c0b64d97b 2021-01-28)
binary: rustc
commit-hash: c0b64d97beebb09325b5587abed39f4f1621026f
commit-date: 2021-01-28
host: x86_64-unknown-linux-gnu
release: 1.51.0-nightly
LLVM version: 11.0.1

Backtrace

   RUST_BACKTRACE=1 cargo build --verbose

   Compiling core v0.0.0 (/home/kernel/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core)
       Fresh autocfg v1.0.1
     Running `rustc --crate-name core --edition=2018 /home/kernel/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/lib.rs --error-format=json --json=diagnostic-rendered-ansi,artifacts --crate-type lib --emit=dep-info,metadata,link -C embed-bitcode=no -C debuginfo=2 -C metadata=6e4a9794a30e64e2 -C extra-filename=-6e4a9794a30e64e2 --out-dir /mnt/c/Users/Kernel/Documents/Proyectos/etheryal/kernel/target/x86_64/debug/deps --target /mnt/c/Users/Kernel/Documents/Proyectos/etheryal/kernel/targets/x86_64.json -Z force-unstable-if-unmarked -L dependency=/mnt/c/Users/Kernel/Documents/Proyectos/etheryal/kernel/target/x86_64/debug/deps -L dependency=/mnt/c/Users/Kernel/Documents/Proyectos/etheryal/kernel/target/debug/deps --cap-lints allow`
   Compiling rustc-std-workspace-core v1.99.0 (/home/kernel/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/rustc-std-workspace-core)
     Running `rustc --crate-name rustc_std_workspace_core --edition=2018 /home/kernel/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/rustc-std-workspace-core/lib.rs --error-format=json --json=diagnostic-rendered-ansi,artifacts --crate-type lib --emit=dep-info,metadata,link -C embed-bitcode=no -C debuginfo=2 -C metadata=de6d357e632aa5bc -C extra-filename=-de6d357e632aa5bc --out-dir /mnt/c/Users/Kernel/Documents/Proyectos/etheryal/kernel/target/x86_64/debug/deps --target /mnt/c/Users/Kernel/Documents/Proyectos/etheryal/kernel/targets/x86_64.json -Z force-unstable-if-unmarked -L dependency=/mnt/c/Users/Kernel/Documents/Proyectos/etheryal/kernel/target/x86_64/debug/deps -L dependency=/mnt/c/Users/Kernel/Documents/Proyectos/etheryal/kernel/target/debug/deps --extern core=/mnt/c/Users/Kernel/Documents/Proyectos/etheryal/kernel/target/x86_64/debug/deps/libcore-6e4a9794a30e64e2.rmeta --cap-lints allow`
   Compiling compiler_builtins v0.1.39
     Running `rustc --crate-name compiler_builtins /home/kernel/.cargo/registry/src/github.com-1ecc6299db9ec823/compiler_builtins-0.1.39/src/lib.rs --error-format=json --json=diagnostic-rendered-ansi,artifacts --crate-type lib --emit=dep-info,metadata,link -C embed-bitcode=no -C debuginfo=2 --cfg 'feature="compiler-builtins"' --cfg 'feature="core"' --cfg 'feature="default"' --cfg 'feature="mem"' --cfg 'feature="rustc-dep-of-std"' -C metadata=97388e1919ba9c5c -C extra-filename=-97388e1919ba9c5c --out-dir /mnt/c/Users/Kernel/Documents/Proyectos/etheryal/kernel/target/x86_64/debug/deps --target /mnt/c/Users/Kernel/Documents/Proyectos/etheryal/kernel/targets/x86_64.json -Z force-unstable-if-unmarked -L dependency=/mnt/c/Users/Kernel/Documents/Proyectos/etheryal/kernel/target/x86_64/debug/deps -L dependency=/mnt/c/Users/Kernel/Documents/Proyectos/etheryal/kernel/target/debug/deps --extern core=/mnt/c/Users/Kernel/Documents/Proyectos/etheryal/kernel/target/x86_64/debug/deps/librustc_std_workspace_core-de6d357e632aa5bc.rmeta --cap-lints allow --cfg 'feature="unstable"'`
LLVM ERROR: EH registrations only live in functions using WinEH
error: could not compile `core`

Caused by:
  process didn't exit successfully: `rustc --crate-name core --edition=2018 /home/kernel/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/lib.rs --error-format=json --json=diagnostic-rendered-ansi,artifacts --crate-type lib --emit=dep-info,metadata,link -C embed-bitcode=no -C debuginfo=2 -C metadata=6e4a9794a30e64e2 -C extra-filename=-6e4a9794a30e64e2 --out-dir /mnt/c/Users/Kernel/Documents/Proyectos/etheryal/kernel/target/x86_64/debug/deps --target /mnt/c/Users/Kernel/Documents/Proyectos/etheryal/kernel/targets/x86_64.json -Z force-unstable-if-unmarked -L dependency=/mnt/c/Users/Kernel/Documents/Proyectos/etheryal/kernel/target/x86_64/debug/deps -L dependency=/mnt/c/Users/Kernel/Documents/Proyectos/etheryal/kernel/target/debug/deps --cap-lints allow` (exit code: 101)
warning: build failed, waiting for other jobs to finish...
error: build failed

config.toml:

[unstable]
build-std = ["core", "compiler_builtins", "alloc"]
build-std-features = ["compiler-builtins-mem"]

Thank you for your great work!

[ehuss]

Can you post a copy of your target spec? Are there any other details about the custom target that are needed to reproduce?

[KernelFreeze]

My target spec is:

{
  "llvm-target": "x86_64-unknown-none",
  "data-layout": "e-m:e-i64:64-f80:128-n8:16:32:64-S128",
  "arch": "x86_64",
  "target-endian": "little",
  "target-pointer-width": "64",
  "target-c-int-width": "32",
  "os": "none",
  "executables": true,
  "linker-flavor": "ld.lld",
  "linker": "rust-lld",
  "panic-strategy": "abort",
  "disable-redzone": true,
  "features": "-mmx,-sse,+soft-float"
}

If I enable SSE and MMX, the build fails again

[ehuss]

Sorry, I'm a bit confused. Are you saying you see an error with "-mmx,-sse,+soft-float" or with "+mmx,+sse,+soft-float" or both?

I'm only able to reproduce with +sse,+soft-float, but I don't think that combination is really supported. See #36659, where one possibility is to have +soft-float imply -sse and friends.

[KernelFreeze]

I get this error with just +mmx,+sse

[Enselic]

Triage: I'm trying to reproduce this but I'm getting different errors now. I'm compiling hello world with your target JSON:

$ cargo +nightly build -Zbuild-std --target x86_64.json
   Compiling core v0.0.0 (/home/martin/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core)
   Compiling compiler_builtins v0.1.138
   Compiling libc v0.2.162
   Compiling std v0.0.0 (/home/martin/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std)
   Compiling rustc-std-workspace-core v1.99.0 (/home/martin/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/rustc-std-workspace-core)
error: data-layout for target `x86_64-1532950540624012415`, `e-m:e-i64:64-f80:128-n8:16:32:64-S128`, differs from LLVM target's `x86_64-unknown-none` default layout, `e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-f80:128-n8:16:32:64-S128`

error: could not compile `rustc-std-workspace-core` (lib) due to 1 previous error
warning: build failed, waiting for other jobs to finish...
error: could not compile `libc` (lib) due to 1 previous error
error: could not compile `core` (lib) due to 1 previous error
error: could not compile `compiler_builtins` (lib) due to 1 previous error

Did you find a workaround for the problem?

Can we close this issue as obsolete?

[ehuss]

@Enselic Over time the data-layout field has to be updated when new LLVM versions are introduced. The current target json reproduction is:

{
  "llvm-target": "x86_64-unknown-none",
  "data-layout": "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-f80:128-n8:16:32:64-S128",
  "arch": "x86_64",
  "target-endian": "little",
  "target-pointer-width": "64",
  "target-c-int-width": "32",
  "os": "none",
  "executables": true,
  "linker-flavor": "ld.lld",
  "linker": "rust-lld",
  "panic-strategy": "abort",
  "disable-redzone": true,
  "features": "+sse,+soft-float"
}

And cargo build -Zbuild-std=core --target target.json

I would guess that SSE is incompatible with soft-float. And neither rustc or llvm are really validating that the given options are compatible with one another.

rustc 1.85.0-nightly (5e1440ae5 2024-12-01)
binary: rustc
commit-hash: 5e1440ae514d98ddfcbf1607acb64d41e07ef616
commit-date: 2024-12-01
host: aarch64-apple-darwin
release: 1.85.0-nightly
LLVM version: 19.1.4

[Enselic]

I see, thanks. If SSE is incompatible with soft-float I suggest we close this as won't fix.