proc-macro-srv: make usage of RTLD_DEEPBIND portable

[Fabian-Gruenbichler]

the constant is wrong on some platforms (e.g., on mips64el it's 0x10, and 0x8 is RTLD_NOLOAD which makes all this functionality broken), the libc crate takes care of those differences for us.

fallback to old hard-coded value for non-glibc environments (which might or might not have RTLD_DEEPBIND support).

[rustbot]

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[rustbot]

rust-analyzer is developed in its own repository. If possible, consider making this change to rust-lang/rust-analyzer instead.

cc @rust-lang/rust-analyzer

[Mark-Simulacrum]

rust-analyzer is developed in its own repository. If possible, consider making this change to rust-lang/rust-analyzer instead.

Why is this change being proposed here, instead of in rust-analyzer?

r? @bjorn3 since you started reviewing the previous PR (I don't have much context here but it seems like not using a non-declared context is OK, though probably a better comment referencing whether we care is good).

[Fabian-Gruenbichler]

Why is this change being proposed here, instead of in rust-analyzer?

because AFAICT the test cases exercising this only run when built as part of the rustc tree. but if you prefer it coming in the other way, that's fine by me as well :)

[Veykril]

The proc-macro server tests do run in the rust-analyzer CI (when relevant source files are changed, as is the case here). Unless you mean some other specific test with relevant.

[Fabian-Gruenbichler]

I didn't manage to get them to run locally (except via ./x.py test rust-analyzer), and from the rust-analyzer CI output it seems they don't run there either:

     Running unittests src/lib.rs (target/debug/deps/proc_macro_srv-ce7345e9fe0e53b0)

running 0 tests

test result: ok. 0 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.00s

     Running unittests src/main.rs (target/debug/deps/rust_analyzer_proc_macro_srv-bdf12f69c82496e0)

running 0 tests

test result: ok. 0 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.00s

     Running unittests src/lib.rs (target/debug/deps/proc_macro_test-22a583937d8810d1)

running 0 tests

test result: ok. 0 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.00s

whereas the CI run for this PR:

       Running unittests src/lib.rs (obj/build/x86_64-unknown-linux-gnu/stage2-tools/x86_64-unknown-linux-gnu/release/deps/proc_macro_srv-3d134170492b442b)
  
  running 17 tests
  12%  --  2/17,  2 passed, 0 failed, 0 ignored
  24%  --  4/17,  4 passed, 0 failed, 0 ignored
  35%  --  6/17,  6 passed, 0 failed, 0 ignored
  41%  --  7/17,  7 passed, 0 failed, 0 ignored
  53%  --  9/17,  9 passed, 0 failed, 0 ignored
  65%  -- 11/17, 11 passed, 0 failed, 0 ignored
  71%  -- 12/17, 12 passed, 0 failed, 0 ignored
  82%  -- 14/17, 14 passed, 0 failed, 0 ignored
  94%  -- 16/17, 16 passed, 0 failed, 0 ignored
  100% -- 17/17, 17 passed, 0 failed, 0 ignored
  
  
  test result: ok. 17 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 2.82ms

[Veykril]

They require the nightly toolchain so they only run on r-a CI when proc-macro things change. To run them locally you'll need to pass a feature flag sysroot-abi as otherwise the proc-macro-srv crate is empty.

[Fabian-Gruenbichler]

that was the missing piece, thanks :) I will move this over to R-A then!

[Fabian-Gruenbichler]

closed in favour of rust-lang/rust-analyzer#18981