I'm getting mixed signals. In the comment elsewhere you say the original poster linked #14875, but here you refer to #19776. It's also the case that #19776 isn't even a problem, because using "leak" here is a misnomer. The "still reachable" section doesn't indicate memory that was leaked, but memory that could have been freed but that nobody bothered to. And the reason that this isn't a problem is because failing to explicitly free memory during process exit doesn't matter because the act of exiting will free that memory by definition. There's no leak here; the only reason that issue exists is because it makes the valgrind output slightly annoying when run with certain settings. It's a tooling issue, not a language issue.
Alex Crichton, one of Rust's top contributors, confirmed that the problem is still present a day ago. He acknowledged this on one of the very issues the original comment was in reference to.
See https://github.com/rust-lang/rust/issues/19776
alexcrichton commented a day ago @huonw did you test on linux? You may have been using the ELF TLS instead of pthread tls. I just built a compiler with --disable-elf-tls and it looks like the leak is still present:
It's exceptionally too bad the person who originally pointed this out in the comments here felt the need to delete their comment.