Wrong glibc linked in building crates using proc_macro with linuxbrew

[dalance]

If the versions of system glibc and linuxbrew glibc are different, building crates using proc_macro (ex. serde_derive, structopt_derive) is failed at Rust 1.32.0.
In Rust 1.31.1, this issue don't occur.

Environment

CentOS Linux release 7.6.1810 (Core)
Rust 1.32.0, 1.31.1
System glibc: 2.17
linuxbrew glibc: 2.23

Step

Source code

Cargo.toml

[package]
name = "temp"
version = "0.1.0"

[dependencies]
structopt    = "0.2.14"

src/main.rs

#[macro_use]
extern crate structopt;
use structopt::StructOpt;

#[derive(Debug, StructOpt)]
pub struct Opt {}

fn main() {
    let _ = Opt::from_args();
    println!("Hello, world!");
}

Build result

$ rustup override set 1.32.0
$ cargo clean; cargo run

   Compiling structopt v0.2.14
error: /lib64/libc.so.6: version `GLIBC_2.18' not found (required by /home/dalance/work/repos/temp/target/debug/deps/libstructopt_derive-cdf0ae629ff7e333.so)
   --> /home/dalance/.cargo/registry/src/github.com-1ecc6299db9ec823/structopt-0.2.14/src/lib.rs:490:1
    |
490 | extern crate structopt_derive;
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error: aborting due to previous error

error: Could not compile `structopt`.

The ldd result of libstructopt_derive....so is below.
In this result, linker should search to linuxbrew's glibc, but actually search to system glibc.

$ ldd /home/dalance/work/repos/temp/target/debug/deps/libstructopt_derive-cdf0ae629ff7e333.so
        linux-vdso.so.1 (0x00007fffac483000)
        libdl.so.2 => /home/dalance/.linuxbrew/lib/libdl.so.2 (0x00007f2c95292000)
        librt.so.1 => /home/dalance/.linuxbrew/lib/librt.so.1 (0x00007f2c95288000)
        libpthread.so.0 => /home/dalance/.linuxbrew/lib/libpthread.so.0 (0x00007f2c95268000)
        libgcc_s.so.1 => /home/dalance/.linuxbrew/lib/libgcc_s.so.1 (0x00007f2c95051000)
        libc.so.6 => /home/dalance/.linuxbrew/lib/libc.so.6 (0x00007f2c94eb3000)
        /home/dalance/.linuxbrew/Cellar/glibc/2.23/lib64/ld-linux-x86-64.so.2 (0x00007f2c9566a000)

Workaround

If .cargo/config set to below, build is passed at Rust 1.32.0.

[target.x86_64-unknown-linux-gnu]
linker = "/usr/bin/cc"

Broken revision

I run git bisect from 1.31.1 to 1.32.0. The result is below.

188d2dafcdd4d0dbd54315412503fb8011d716b6 is the first bad commit
commit 188d2dafcdd4d0dbd54315412503fb8011d716b6
Author: Eduard-Mihai Burtescu <edy.burt@gmail.com>
Date:   Thu Apr 26 14:11:08 2018 +0300

    Statically link proc_macro into proc macros.

:040000 040000 a218f2092aad86632374db4fc3ba0effe6705d7f b8357a8a11394a8ab0f6e20875802930dd0ecc9f M      src
bisect run success

git bisect log is below.

# bad: [9fda7c2237db910e41d6a712e9a2139b352e558b] Auto merge of #57600 - rust-lang:stable-next, r=alexcrichton
# good: [b6c32da9b0481e3e9d737153286b3ff8aa39a22c] Auto merge of #56960 - pietroalbini:gpg-stable, r=pietroalbini
git bisect start '1.32.0' '1.31.1'
# good: [4bd4e4130ed531a644263db26bf8461704215c77] Auto merge of #54490 - wesleywiser:rewrite_it_in_mir, r=oli-obk
git bisect good 4bd4e4130ed531a644263db26bf8461704215c77
# good: [6ca7bc0eb8648abc8673a971c85b777a6bc62e16] Rollup merge of #55781 - pnkfelix:issue-54382-more-precise-spans-for-temps-and-their-drops, r=davidtwco
git bisect good 6ca7bc0eb8648abc8673a971c85b777a6bc62e16
# good: [45e5a856a6551ae1b77fe8c5585e80f886b44b6e] Rollup merge of #56100 - RalfJung:visiting-generators, r=oli-obk
git bisect good 45e5a856a6551ae1b77fe8c5585e80f886b44b6e
# bad: [fb2b2f5582b9eff3ee5d98ec5c9461847b6f0b2d] Rollup merge of #56367 - alexreg:move-feature-gate-tests-1, r=Centril
git bisect bad fb2b2f5582b9eff3ee5d98ec5c9461847b6f0b2d
# good: [5d7717360c8f343f70a33455029355f00e39dea2] fix test
git bisect good 5d7717360c8f343f70a33455029355f00e39dea2
# good: [1fe2085441c5c9afc1523c19c1c1ddbf86bae462] Rollup merge of #56322 - petrochenkov:edlints, r=eddyb
git bisect good 1fe2085441c5c9afc1523c19c1c1ddbf86bae462
# bad: [b8198da4d2a9e643a9863bf4cddd82d01ebc3f71] Rollup merge of #55821 - ljedrz:cached_key_sorts, r=michaelwoerister
git bisect bad b8198da4d2a9e643a9863bf4cddd82d01ebc3f71
# good: [67afeef9e472812ba85341114c21289c75790a3e] proc_macro: move to a dependency of libtest.
git bisect good 67afeef9e472812ba85341114c21289c75790a3e
# bad: [eb2c71cdf2d154a217e155d96474f4988e04a253] bootstrap: don't use libraries from MUSL_ROOT on non-musl targets.
git bisect bad eb2c71cdf2d154a217e155d96474f4988e04a253
# bad: [fcca22cb4072097fc2cd1ae78ff84c7d59aacda2] tests: move all proc_macro tests from -fulldeps.
git bisect bad fcca22cb4072097fc2cd1ae78ff84c7d59aacda2
# bad: [d3ab4a74efad266155fcd402c8d159af9e443e3d] tests: remove ignore-stage1 where possible in proc_macro tests.
git bisect bad d3ab4a74efad266155fcd402c8d159af9e443e3d
# bad: [188d2dafcdd4d0dbd54315412503fb8011d716b6] Statically link proc_macro into proc macros.
git bisect bad 188d2dafcdd4d0dbd54315412503fb8011d716b6
# first bad commit: [188d2dafcdd4d0dbd54315412503fb8011d716b6] Statically link proc_macro into proc macros.

Related issue

This issue seems to be the same.
rust-lang/cargo#6582

[sfackler]

Compiler plugins are dlopened by the compiler. Is the dynamic linker even willing to load two copies of glibc into the same process?

This may be an intrinsic issue with linuxbrew's approach. You could try out making some C code that dlopens a linuxbrew library.

[dalance]

Thanks.
The linker used to build libstructopt_derive-cdf0ae629ff7e333.so is ~/.linuxbrew/bin/cc.
But dlopen of compiler plugin seems to be use system loader?
System loader don't know the linuxbrew's library path which is not included in /etc/ld.so*.

I'll investigate more.

[dalance]

I understood as below:

• libstructopt_derive-cdf0ae629ff7e333.so is linked by cc. In linuxbrew environment, cc becomes ~/.linuxbrew/bin/cc by PATH environment variable. Therefore libstructopt_derive-cdf0ae629ff7e333.so is linked to ~/.linuxbrew/lib/libc.so.6.
• rustc loads libstructopt_derive-cdf0ae629ff7e333.so by libc::dlopen. The official rustc from rustup is linked to /lib64/libc.so.6, so libc::dlopen use /etc/ld.so.(config|cache) as library search path. Therefore libc::dlopen is failed because ~/.linuxbrew/lib/libc.so.6 can't be found.

I think the root cause of this issue is that linker may be changed by user environment but loader is fixed.
If both follow PATH or both are fixed, this issue can be resolved, but it seems to be difficult...

[sfackler]

Yes, you'll either need to adjust the Rust distribution to point to the linuxbrew environment via an rpath or LD_LIBRARY_PATH, or use the system linker when working with the compiler.

[dalance]

OK. Linuxbrew don't recommend LD_LIBRARY_PATH modification.
So I think linker specification by ~/.cargo/config is a reasonable solution.

[asdetrefle]

Yes, you'll either need to adjust the Rust distribution to point to the linuxbrew environment via an rpath or LD_LIBRARY_PATH, or use the system linker when working with the compiler.

Would you please describe how to adjust the rust distribution? I could not find any rustup documentation on how to link a specific version of libc