linkme crate not supported by Miri

[nazar-pc]

This is probably related to #2757, but I'm less interested in suppressing it and more in being able to use it.

Specifically, I'm using linkme crate and would like to be able to run tests under Miri. Right now I'm getting this instead:

test basic ... error: unsupported operation: extern static `__start_linkme_CONTRACTS_METHODS_FN_POINTERS` is not supported by Miri
   --> /web/github/abundance/crates/contracts/ab-contracts-executor/src/lib.rs:803:13
    |
803 |             CONTRACTS_METHODS_FN_POINTERS
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ extern static `__start_linkme_CONTRACTS_METHODS_FN_POINTERS` is not supported by Miri
    |
    = help: this is likely not a bug in the program; it indicates that the program performed an operation that Miri does not support
    = note: BACKTRACE on thread `basic`:
    = note: inside `ab_contracts_executor::NativeExecutor::in_memory` at /web/github/abundance/crates/contracts/ab-contracts-executor/src/lib.rs:803:13: 803:42
note: inside `basic`
   --> crates/contracts/ab-contract-example/tests/basic.rs:13:24
    |
13  |     let mut executor = NativeExecutor::in_memory(shard_index).unwrap();
    |                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
note: inside closure
   --> crates/contracts/ab-contract-example/tests/basic.rs:9:11
    |
8   | #[test]
    | ------- in this procedural macro expansion
9   | fn basic() {
    |           ^
    = note: inside `<{closure@crates/contracts/ab-contract-example/tests/basic.rs:9:1: 27:2} as std::ops::FnOnce<()>>::call_once - shim` at /home/nazar-pc/.rustup/toolchains/nightly-2024-12-24-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/ops/function.rs:250:5: 250:71
    = note: inside `<fn() -> std::result::Result<(), std::string::String> as std::ops::FnOnce<()>>::call_once - shim(fn() -> std::result::Result<(), std::string::String>)` at /home/nazar-pc/.rustup/toolchains/nightly-2024-12-24-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/ops/function.rs:250:5: 250:71
    = note: inside `test::__rust_begin_short_backtrace::<std::result::Result<(), std::string::String>, fn() -> std::result::Result<(), std::string::String>>` at /home/nazar-pc/.rustup/toolchains/nightly-2024-12-24-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/test/src/lib.rs:632:18: 632:21
    = note: inside `test::types::RunnableTest::run` at /home/nazar-pc/.rustup/toolchains/nightly-2024-12-24-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/test/src/types.rs:145:40: 145:71
    = note: inside closure at /home/nazar-pc/.rustup/toolchains/nightly-2024-12-24-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/test/src/lib.rs:655:60: 655:79
    = note: inside `<std::panic::AssertUnwindSafe<{closure@test::run_test_in_process::{closure#0}}> as std::ops::FnOnce<()>>::call_once` at /home/nazar-pc/.rustup/toolchains/nightly-2024-12-24-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/panic/unwind_safe.rs:272:9: 272:19
    = note: inside `std::panicking::r#try::do_call::<std::panic::AssertUnwindSafe<{closure@test::run_test_in_process::{closure#0}}>, std::result::Result<(), std::string::String>>` at /home/nazar-pc/.rustup/toolchains/nightly-2024-12-24-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/panicking.rs:568:40: 568:43
    = note: inside `std::panicking::r#try::<std::result::Result<(), std::string::String>, std::panic::AssertUnwindSafe<{closure@test::run_test_in_process::{closure#0}}>>` at /home/nazar-pc/.rustup/toolchains/nightly-2024-12-24-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/panicking.rs:531:19: 531:88
    = note: inside `std::panic::catch_unwind::<std::panic::AssertUnwindSafe<{closure@test::run_test_in_process::{closure#0}}>, std::result::Result<(), std::string::String>>` at /home/nazar-pc/.rustup/toolchains/nightly-2024-12-24-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/panic.rs:358:14: 358:33
    = note: inside `test::run_test_in_process` at /home/nazar-pc/.rustup/toolchains/nightly-2024-12-24-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/test/src/lib.rs:655:27: 655:81
    = note: inside closure at /home/nazar-pc/.rustup/toolchains/nightly-2024-12-24-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/test/src/lib.rs:576:43: 584:18
    = note: inside closure at /home/nazar-pc/.rustup/toolchains/nightly-2024-12-24-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/test/src/lib.rs:606:41: 606:83
    = note: inside `std::sys::backtrace::__rust_begin_short_backtrace::<{closure@test::run_test::{closure#1}}, ()>` at /home/nazar-pc/.rustup/toolchains/nightly-2024-12-24-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/sys/backtrace.rs:152:18: 152:21
    = note: inside closure at /home/nazar-pc/.rustup/toolchains/nightly-2024-12-24-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/thread/mod.rs:564:17: 564:71
    = note: inside `<std::panic::AssertUnwindSafe<{closure@std::thread::Builder::spawn_unchecked_<'_, {closure@test::run_test::{closure#1}}, ()>::{closure#1}::{closure#0}}> as std::ops::FnOnce<()>>::call_once` at /home/nazar-pc/.rustup/toolchains/nightly-2024-12-24-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/panic/unwind_safe.rs:272:9: 272:19
    = note: inside `std::panicking::r#try::do_call::<std::panic::AssertUnwindSafe<{closure@std::thread::Builder::spawn_unchecked_<'_, {closure@test::run_test::{closure#1}}, ()>::{closure#1}::{closure#0}}>, ()>` at /home/nazar-pc/.rustup/toolchains/nightly-2024-12-24-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/panicking.rs:568:40: 568:43
    = note: inside `std::panicking::r#try::<(), std::panic::AssertUnwindSafe<{closure@std::thread::Builder::spawn_unchecked_<'_, {closure@test::run_test::{closure#1}}, ()>::{closure#1}::{closure#0}}>>` at /home/nazar-pc/.rustup/toolchains/nightly-2024-12-24-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/panicking.rs:531:19: 531:88
    = note: inside `std::panic::catch_unwind::<std::panic::AssertUnwindSafe<{closure@std::thread::Builder::spawn_unchecked_<'_, {closure@test::run_test::{closure#1}}, ()>::{closure#1}::{closure#0}}>, ()>` at /home/nazar-pc/.rustup/toolchains/nightly-2024-12-24-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/panic.rs:358:14: 358:33
    = note: inside closure at /home/nazar-pc/.rustup/toolchains/nightly-2024-12-24-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/thread/mod.rs:562:30: 565:16
    = note: inside `<{closure@std::thread::Builder::spawn_unchecked_<'_, {closure@test::run_test::{closure#1}}, ()>::{closure#1}} as std::ops::FnOnce<()>>::call_once - shim(vtable)` at /home/nazar-pc/.rustup/toolchains/nightly-2024-12-24-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/ops/function.rs:250:5: 250:71
    = note: inside `<std::boxed::Box<dyn std::ops::FnOnce()> as std::ops::FnOnce<()>>::call_once` at /home/nazar-pc/.rustup/toolchains/nightly-2024-12-24-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/alloc/src/boxed.rs:1970:9: 1970:52
    = note: inside `<std::boxed::Box<std::boxed::Box<dyn std::ops::FnOnce()>> as std::ops::FnOnce<()>>::call_once` at /home/nazar-pc/.rustup/toolchains/nightly-2024-12-24-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/alloc/src/boxed.rs:1970:9: 1970:52
    = note: inside `std::sys::pal::unix::thread::Thread::new::thread_start` at /home/nazar-pc/.rustup/toolchains/nightly-2024-12-24-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/sys/pal/unix/thread.rs:106:17: 106:64
    = note: this error originates in the attribute macro `test` (in Nightly builds, run with -Z macro-backtrace for more info)

$ cargo miri --version
miri 0.1.0 (bdc6b3de48 2024-12-23)

[oli-obk]

Miri doesn't support the linker hacks that linkme is using. Few platforms do. We'd either have to have some sort of impl for all the platforms linkme supports or we'd add one impl and linkme would need to cfg(miri) that one on all platforms

[nazar-pc]

One impl and custom support in linkme makes much more sense to me than supporting linker hacks in Miri

[RalfJung]

The even better approach would be Rust getting native support for "distributed slices". This has been discussed though I am not sure whether it reached the RFC stage.

[nazar-pc]

Switched to inventory that works even better for my needs, which works under Miri

[RalfJung]

Miri will probably not execute the "inventory::submit!" calls though, so the list will stay empty.

[nazar-pc]

Indeed, spoke too soon 😅
But there is already #450 for that.