#[link(kind = "static", name = "c")] segfaults on run

[GuillaumeGomez]

While working on #123974, I had a failure when running doctests of the unstable book. Rustdoc generates this code:

#![allow(unused_extern_crates)]
#![allow(internal_features)]
#![feature(test)]
#![feature(rustc_attrs)]
#![feature(coverage_attribute)]
#![feature(link_arg_attribute)]

#![allow(unused)]
extern crate test;
mod __doctest_0 {

fn main()  {
    #[link(kind = "link-arg", name = "--start-group")]
#[link(kind = "static", name = "c")] // Causing the segfault
#[link(kind = "static", name = "gcc")]
#[link(kind = "link-arg", name = "--end-group")]
extern "C" {}
}
#[rustc_test_marker = "/home/imperio/rust/rust/src/doc/unstable-book/src/language-features/link-arg-attribute.md - The_tracking_issue_for_this_feature_is__ (line 11)"]
pub const TEST: test::TestDescAndFn = test::TestDescAndFn {
    desc: test::TestDesc {
        name: test::StaticTestName("/home/imperio/rust/rust/src/doc/unstable-book/src/language-features/link-arg-attribute.md - The_tracking_issue_for_this_feature_is__ (line 11)"),
        ignore: false,
        ignore_message: None,
        source_file: "_home_imperio_rust_rust_src_doc_unstable_book_src_language_features_link_arg_attribute_md",
        start_line: 11,
        start_col: 0,
        end_line: 0,
        end_col: 0,
        compile_fail: false,
        no_run: true,
        should_panic: test::ShouldPanic::No,
        test_type: test::TestType::UnitTest,
    },
    testfn: test::StaticTestFn(
        #[coverage(off)]
        || test::assert_test_result(Ok::<(), String>(())),
    )
};
}

#[rustc_main]
#[coverage(off)]
fn main() {
    test::test_main(&["rustdoctest".to_string(),], vec![__doctest_0::TEST], None);
}

If you compile and run this program (on linux x86_64), it'll segfault. Commenting #[link(kind = "static", name = "c")] will make it run without problem.

[Noratrieb]

I'd just like to interject for a moment. What you're refering to as Linux, is in fact, GNU/Linux, or as I've recently taken to calling it, GNU plus Linux.
No but if you're on GNU/Linux then I do expect that to end badly, because glibc is not supposed to be linked statically.
I also don't know how rustc deals with having several linkages to "c" (as the standard library also links to it) but probably not very well either.
it would be interesting to know where it segfaults, but this certainly isn't supposed to work :D.

[bjorn3]

You have to use -Ctarget-feature=+crt-static to statically link libc. Otherwise you will still be producing a dynamically linked executable.