TLDR: git2 dependency update needed. Will post a PR shortly, this issue is just for the record.

Reproduction:

Ensure you have libgit2 version 1.4.0 or greater installed on your system (as is currently the case with Arch and Manjaro)
Run cargo install cargo-bisect-rustc. Do NOT set the RUST_SRC_REPO environment variable.
Prepare a crate to run a successful bisection with. For example, put this into main.rs (regression in nightly-2022-04-17):
```
fn f() {
g((), ());
}
```

pub fn g( a1: (), a2: bool, a3: bool, a4: bool, a5: bool, a6: () ) -> () { }

fn main() { }

- Run a successful bisection. Do NOT set the `RUST_SRC_REPO` environment variable here either. If you use the example from above run
`cargo bisect-rustc --regress=ice --start=2022-04-16 --end=2022-04-17`
The last output before the segfault should be `cloning rust repository`.
The segfault itself happens at this line:
https://github.com/rust-lang/cargo-bisect-rustc/blob/51b048455074007af6082918d065701e34e83935/src/git.rs#L95

The stacktrace for me was:

Stack trace of thread 170034:

0 0x00007f5edef15260 n/a (libgit2.so.1.4 + 0xa4260)

            #1  0x00007f5edef16d6e git_remote_fetch (libgit2.so.1.4 + 0xa5d6e)
            #2  0x00007f5edeea20ac n/a (libgit2.so.1.4 + 0x310ac)
            #3  0x000055ef51df2d15 n/a (/home/username/.cargo/bin/cargo-bisect-rustc + 0x18bd15)



Thankfully the problem was already reported to git2 in https://github.com/rust-lang/git2-rs/issues/813 and fixed. We just need to update the dependency. As mentioned at the beginning, I'll submit a PR shortly.

rust-lang / cargo-bisect-rustc

Segmentation fault when cloning rust repository on systems with libgit2 >= 1.4.0 #154

0 0x00007f5edef15260 n/a (libgit2.so.1.4 + 0xa4260)