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Regression when using linker=arm-none-eabi-gcc #113597

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#113631
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Regression when using linker=arm-none-eabi-gcc#113597
#113631
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lqd
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A-CLIArea: Command-line interface (CLI) to the compilerA-linkageArea: linking into static, shared libraries and binariesC-bugCategory: This is a bug.P-mediumMedium priorityregression-from-stable-to-nightlyPerformance or correctness regression from stable to nightly.
Milestone
1.72.0

Description

@adamgreig
adamgreig
opened on Jul 12, 2023

The cortex-m CI tests building with all our supported linkers: Rust's provided lld, ARM GCC's arm-none-eabi-ld, and ARM GCC's arm-none-eabi-gcc. It recently encountered an error when using arm-none-eabi-gcc in nightly builds since #112910.

The most likely culprit is that the failing version has started added "-fuse-ld=lld" to the linker arguments, which was not present in previous working versions. @lqd, I wonder if we're meant to be adding some other argument to disable adding -fuse-ld=lld?

Code

The error occurs with the cortex-m-rt CI and can be reproduced like so:

git clone https://github.com/rust-embedded/cortex-m
cd cortex-m/cortex-m-rt
rustup toolchain install nightly-2023-07-03
rustup target add thumbv6m-none-eabi --toolchain nightly-2023-07-03
cargo +nightly-2023-07-03 rustc --target thumbv6m-none-eabi --example alignment --features cortex-m/critical-section-single-core -- -C linker=arm-none-eabi-gcc -C link-arg=-nostartfiles

Or viewed in CI here.

The error is:

error: linking with `arm-none-eabi-gcc` failed: exit status: 1
  |
  = note: LC_ALL="C" PATH="<snip>" VSLANG="1033" "arm-none-eabi-gcc" "/tmp/rustcFHUl0t/symbols.o" "/home/adam/Projects/re/cortex-m/target/thumbv6m-none-eabi/debug/examples/alignment-c363c9558a2fe06e.15yn3mrxz53m7uw7.rcgu.o" "/home/adam/Projects/re/cortex-m/target/thumbv6m-none-eabi/debug/examples/alignment-c363c9558a2fe06e.6wqau5vl49hu4fi.rcgu.o" "-Wl,--as-needed" "-L" "/home/adam/Projects/re/cortex-m/target/thumbv6m-none-eabi/debug/deps" "-L" "/home/adam/Projects/re/cortex-m/target/debug/deps" "-L" "/home/adam/Projects/re/cortex-m/target/thumbv6m-none-eabi/debug/build/cortex-m-rt-69b7ab10efe30aa1/out" "-L" "/home/adam/.rustup/toolchains/nightly-2023-07-03-x86_64-unknown-linux-gnu/lib/rustlib/thumbv6m-none-eabi/lib" "-Wl,-Bstatic" "/home/adam/Projects/re/cortex-m/target/thumbv6m-none-eabi/debug/deps/libpanic_halt-f60a67ec71296eeb.rlib" "/home/adam/Projects/re/cortex-m/target/thumbv6m-none-eabi/debug/deps/libcortex_m_rt-9a1a89eba3425cf7.rlib" "/home/adam/.rustup/toolchains/nightly-2023-07-03-x86_64-unknown-linux-gnu/lib/rustlib/thumbv6m-none-eabi/lib/librustc_std_workspace_core-cc16e9be0f247487.rlib" "/home/adam/.rustup/toolchains/nightly-2023-07-03-x86_64-unknown-linux-gnu/lib/rustlib/thumbv6m-none-eabi/lib/libcore-b9a65150d0351313.rlib" "/home/adam/.rustup/toolchains/nightly-2023-07-03-x86_64-unknown-linux-gnu/lib/rustlib/thumbv6m-none-eabi/lib/libcompiler_builtins-2769d4646d3d396e.rlib" "-Wl,-Bdynamic" "-fuse-ld=lld" "-Wl,--eh-frame-hdr" "-Wl,-z,noexecstack" "-L" "/home/adam/.rustup/toolchains/nightly-2023-07-03-x86_64-unknown-linux-gnu/lib/rustlib/thumbv6m-none-eabi/lib" "-o" "/home/adam/Projects/re/cortex-m/target/thumbv6m-none-eabi/debug/examples/alignment-c363c9558a2fe06e" "-Wl,--gc-sections" "-no-pie" "-nodefaultlibs" "-nostartfiles" "-Tlink.x"
  = note: collect2: fatal error: cannot find 'ld'
          compilation terminated.

Version it worked on

nightly-2023-07-02

Version with regression

nightly-2023-07-03

bisected to 8e2d5e3

from PR #112910

@rustbot modify labels: +regression-from-stable-to-nightly -regression-untriaged

Activity

  1. adamgreig
    added
    C-bugCategory: This is a bug.
    regression-untriagedUntriaged performance or correctness regression.
    on Jul 12, 2023
  2. rustbot
    added
    needs-triageThis issue may need triage. Remove when done. See docs forge.rust-lang.org/release/issue-triaging
    I-prioritizeIssue needs a team member to assess the impact. Will be replaced by P-{low,medium,high,critical}
    regression-from-stable-to-nightlyPerformance or correctness regression from stable to nightly.
    and removed
    regression-untriagedUntriaged performance or correctness regression.
    on Jul 12, 2023

  3. jyn514 commented on Jul 12, 2023

    @jyn514
    jyn514
    on Jul 12, 2023
    Member

    rust/compiler/rustc_target/src/spec/thumb_base.rs

    Line 37 in 993deaa

    linker: Some("rust-lld".into()),

    shows that the default for the target is rust-lld. i wonder if the new code uses the default instead of the linker in -C linker for some reason?

  4. jyn514
    added
    A-linkageArea: linking into static, shared libraries and binaries
    A-CLIArea: Command-line interface (CLI) to the compiler
    on Jul 12, 2023
  5. saethlin
    removed
    needs-triageThis issue may need triage. Remove when done. See docs forge.rust-lang.org/release/issue-triaging
    on Jul 12, 2023

  6. lqd commented on Jul 12, 2023

    @lqd
    lqd
    on Jul 12, 2023
    Member

    I wonder if we're meant to be adding some other argument to disable adding -fuse-ld=lld?

    You were not meant to do anything, sorry about that. I'll fix it.

  7. lqd
    self-assigned this
    on Jul 12, 2023

  8. lqd commented on Jul 12, 2023

    @lqd
    lqd
    on Jul 12, 2023
    Member

    I can't build a thumbv6m-none-eabi toolchain locally, via ./x build library/ --target thumbv6m-none-eabi, which would be complete enough for this cortex-m test to build. There are issues about missing core/std.

    I tried on a no_std example, and can also reproduce the arm-none-eabi-gcc issue and investigate more there, and that rust-lld and arm-none-eabi-ld work.

    The code I added in #112910 is asked to add CLI arguments for a Gnu(Cc::Yes, Lld::Yes) flavor: this asks to link using lld via a c/c++ compiler, and why -fuse-ld=lld is added. I assume that flavor is incorrect when using -C linker=arm-none-eabi-gcc -C link-arg=-nostartfiles @adamgreig ? (I don't know who the target maintainers are, so I'll also ping the other 2 people involved in the discovery: @hannobraun @thejpster)

    -C linker=arm-none-eabi-ld and -C linker=rust-lld still work because they result in a non-cc request, and we don't do anything there as expected.

    For my own understanding: does arm-none-eabi-gcc use arm-none-eabi-ld by default maybe ? And if so, I'd expect that explicitly specifying the linker would also fix the issue, à la -C linker=arm-none-eabi-gcc -C link-arg=-nostartfiles -C link-arg=-fuse-ld=bfd which seems to work for me ?

    I'll look into why this surprising flavor is used in this situation, as it seems to be the pre-existing issue here uncovered by the PR, and report back. It could be an issue in the flavor inference, or some information missing in the targets' definitions, and so on.

  9. workingjubilee
    added
    P-mediumMedium priority
    and removed
    I-prioritizeIssue needs a team member to assess the impact. Will be replaced by P-{low,medium,high,critical}
    on Jul 12, 2023

  10. 9 remaining items

  11. matthiaskrgr
    added a commit that references this issue on Jul 13, 2023

    Rollup merge of rust-lang#113631 - lqd:fix-113597, r=petrochenkov

    6d6bf6c

  12. lqd commented on Jul 13, 2023

    @lqd
    lqd
    on Jul 13, 2023
    Member

    Thanks for the information, it's very helpful.

    The good news is that using GCC as a linker is still working 😅. In the future where we switch to lld, maybe rustc will also need an explicit linker flavor here, to make sure the flavor it guesses actually matches your expectations. But that's a topic for another day/stabilization: in the more immediate future, things will return to normal for the target and cortex-m's tests in a day or two.

  13. matthiaskrgr
    added a commit that references this issue on Jul 13, 2023

    Rollup merge of rust-lang#113631 - lqd:fix-113597, r=petrochenkov

    fc1cb04

  14. thejpster commented on Jul 13, 2023

    @thejpster
    thejpster
    on Jul 13, 2023
    Contributor

    Thank you!

    Just to come back to this point:

    I don't know who the target maintainers are

    I was under the impression that Arm Ltd were maintaining the thumbv*m-none-eabi* targets. However, they don't appear to have the platform-support documentation that is required for more recently added targets. Maybe that could be addressed.

  15. bors
    closed this as completedin fc1cb04on Jul 13, 2023

  16. lqd commented on Jul 14, 2023

    @lqd
    lqd
    on Jul 14, 2023
    Member

    This is now on beta, reopening to track backport.

  17. lqd
    reopened this on Jul 14, 2023
  18. jyn514
    added this to the 1.72.0 milestone on Jul 14, 2023

  19. workingjubilee commented on Jul 16, 2023

    @workingjubilee
    workingjubilee
    on Jul 16, 2023
    Member

    @thejpster Pursuant to your concern I have opened #113739 to summarize the issue that affects indeed all our tier 2 targets.

  20. lqd commented on Aug 10, 2023

    @lqd
    lqd
    on Aug 10, 2023
    Member

    The backport of #113631 has landed on beta in #113938. We can close this issue as fixed.

  21. lqd
    closed this as completedon Aug 10, 2023
  22. matthiaskrgr
    added a commit that references this issue on Aug 15, 2023

    Rollup merge of rust-lang#114711 - lqd:linker-inference, r=petrochenkov

    17c47cf
  23. GuillaumeGomez
    added a commit that references this issue on Aug 15, 2023

    Rollup merge of rust-lang#114711 - lqd:linker-inference, r=petrochenkov

    f929741
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A-CLIArea: Command-line interface (CLI) to the compilerA-linkageArea: linking into static, shared libraries and binariesC-bugCategory: This is a bug.P-mediumMedium priorityregression-from-stable-to-nightlyPerformance or correctness regression from stable to nightly.

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