regression: duplicate symbol definition

https://crater-reports.s3.amazonaws.com/beta-1.86-3/beta-2025-02-28/gh/ns6251.spin-cookie-token-sample/log.txt

Possibly expected / not actually a problem, but probably good to figure out where this came from.

[INFO] [stdout]   = note: /usr/bin/ld: /opt/rustwide/target/debug/deps/libwit_bindgen_rust-7b7d20e188069fd3.rlib(wit_bindgen_rust-7b7d20e188069fd3.wit_bindgen_rust.712e9c6990f0d8a7-cgu.0.rcgu.o): in function `canonical_abi_realloc':
[INFO] [stdout]           /opt/rustwide/cargo-home/git/checkouts/wit-bindgen-e92a7091d4f51398/2f46ce4/crates/rust-wasm/src/lib.rs:134: multiple definition of `canonical_abi_realloc'; /opt/rustwide/target/debug/deps/libwit_bindgen_rust-742545eb826378e5.rlib(wit_bindgen_rust-742545eb826378e5.wit_bindgen_rust.ceb23070018b5742-cgu.0.rcgu.o):/opt/rustwide/cargo-home/git/checkouts/wit-bindgen-e92a7091d4f51398/e9c7c0a/crates/rust-wasm/src/lib.rs:134: first defined here
[INFO] [stdout]           /usr/bin/ld: /opt/rustwide/target/debug/deps/libwit_bindgen_rust-7b7d20e188069fd3.rlib(wit_bindgen_rust-7b7d20e188069fd3.wit_bindgen_rust.712e9c6990f0d8a7-cgu.0.rcgu.o): in function `canonical_abi_free':
[INFO] [stdout]           /opt/rustwide/cargo-home/git/checkouts/wit-bindgen-e92a7091d4f51398/2f46ce4/crates/rust-wasm/src/lib.rs:158: multiple definition of `canonical_abi_free'; /opt/rustwide/target/debug/deps/libwit_bindgen_rust-742545eb826378e5.rlib(wit_bindgen_rust-742545eb826378e5.wit_bindgen_rust.ceb23070018b5742-cgu.0.rcgu.o):/opt/rustwide/cargo-home/git/checkouts/wit-bindgen-e92a7091d4f51398/e9c7c0a/crates/rust-wasm/src/lib.rs:158: first defined here

@Mark-Simulacrum

This may have been #137035 -- @Mark-Simulacrum, does the beta you're triaging include that PR or not? Not sure how the timing worked out.

I got some weird results when trying to bisect this. Looks like the build still fails on nightly so I don't think that PR is it.

Yeah, 137035 is included in beta (commit 42212a5 is what was tested here).

@rustbot

Assigning priority (discussion on Zulip).

@rustbot label -I-prioritize +P-high

The crate in question uses a proc macro, and with that expanded, I can minimize the crate to this:

use spin_sdk;

#[export_name = "handle-http-request"]
unsafe extern "C" fn __wit_bindgen_handle_http_request() {
    let layout = core::alloc::Layout::from_size_align_unchecked(1, 1);
    let result = std::alloc::alloc(layout);
    if result.is_null() {}

    wit_bindgen_rust::rt::as_i32(0);
    std::hint::black_box(RET_AREA);
}
static RET_AREA: u8 = 0;

with

[lib]
crate-type = [ "cdylib" ]

[dependencies]
spin-sdk = { git = "https://github.com/fermyon/spin", tag = "v0.3.0" }
wit-bindgen-rust = { git = "https://github.com/bytecodealliance/wit-bindgen", rev = "e9c7c0a3405845cecd3fe06f3c20ab413302fc73" }

Linkage minimizations are always trippy, so bear with me. We have a few layers to go.

Ah-ha! I tried a bunch of codegen-units settings and it looks like the reproducer is highly sensitive to the number of codegen-units used in building dependencies. That's probably why this error comes and goes sporadically.

Minimized a bit farther: (note that I turned spin-sdk into two of its transitive dependencies)

use spin_sdk;

#[export_name = "handle-http-request"]
pub unsafe extern "C" fn __wit_bindgen_handle_http_request() {
    let layout = core::alloc::Layout::from_size_align_unchecked(1, 1);
    let result = std::alloc::alloc(layout);
    if result.is_null() {}

    wit_bindgen_rust::rt::as_i32(0);
}

[lib]
crate-type = [ "cdylib" ]

[dependencies]
anyhow = "1" # required ???
wit-bindgen-rust = { git = "https://github.com/bytecodealliance/wit-bindgen", rev = "e9c7c0a3405845cecd3fe06f3c20ab413302fc73" }
spin-sdk = { git = "https://github.com/bytecodealliance/wit-bindgen", rev = "2f46ce4cc072107153da0cefe15bdc69aa5b84d0", package = "wit-bindgen-rust" }

The regressed crate is depending on multiple versions of wit-bindgen-rust, which has an rt module, which exports the canonical_abi_realloc and canonical_abi_free symbols.

So the bigger question here is how does this crate ever build?

I'm going to close this because the crate in question is simply buggy. In an ideal world we would be issuing a warning for this kind of situation; this is now the second time I've root-caused a crater link error regression to a crate which is mistakenly depending on two versions of a library that exports an unmangled symbol.

@saethlin

wow thanks @saethlin for the deep dive 👍

Should this crate be excluded from our crater runs?

@rustbot label -P-high

Ignore the regression from rust-lang/rust#137891

Yeah. Posted rust-lang/crater#766

Merge pull request #766 from saethlin/patch-1

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regression: duplicate symbol definition #137891

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compiler-errors commented on Mar 2, 2025

saethlin commented on Mar 2, 2025

Mark-Simulacrum commented on Mar 2, 2025

apiraino commented on Mar 4, 2025

saethlin commented on Mar 5, 2025

saethlin commented on Mar 5, 2025

saethlin commented on Mar 5, 2025

saethlin commented on Mar 5, 2025

saethlin commented on Mar 5, 2025

apiraino commented on Mar 5, 2025

saethlin commented on Mar 5, 2025

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