Fix mir-cfg dumps

[osa1]

Fixes #81918
Fixes #82326 (duplicate)
Fixes #82325

---

r? @oli-obk

[osa1]

Should I add a test to this? I have a minimal repro:

const TAG: &'static str = "ABCD";

fn main() {
    if TAG == "" {}
}

but I couldn't find a way to accept a test based on rustc exit code (without comparing stdout contents), and I'm not sure if we want to check dot outputs.

[oli-obk]

but I couldn't find a way to accept a test based on rustc exit code (without comparing stdout contents), and I'm not sure if we want to check dot outputs.

we already have pretty printing tests in https://github.com/rust-lang/rust/tree/master/src/test/pretty I think you should be able to just add it there

[osa1]

@oli-obk I couldn't put this in test/pretty because outputs of tests in that directory is passed to the compiler again, to check the the printer prints valid Rust. I realized that stdouts of tests in test/mir-opt are not checked so I put the test there. Let me know if you want me to move it elsewhere.

[oli-obk]

Heh that's a neat trick. Please leave the explanation on why it is here and not in the ui test suite in a comment in that file, otherwise someone will be confused by that test in the future

[osa1]

Sigh.. it seems like you can't easily ignore stdout contents of a test.. Putting the test in mir-opt just to ignore stdout seemed hacky so I moved the test once again, and committed stdout contents. Ping @oli-obk

[osa1]

@oli-obk nvm, figured it out. Could you review?

[oli-obk]

@bors r+ rollup

[bors]

📌 Commit 2145a87 has been approved by oli-obk