Test gdb pretty printing more and fix overzealous type substitution

[ssomers]

Adresses a problem concerning printing BTreeMap / BTreeSet data in gdb: when the key or value type name contains substring "LeafNode", and the map has multiple nodes (e.g. more than 11 elements), printing causes an exception. E.g.

rustc -g - <<EOF
    use std::collections::BTreeMap;

    struct MyLeafNode(i8);

    fn main() {
        let m: BTreeMap<i8, MyLeafNode> = (0..12).map(|i| (i, MyLeafNode(i))).collect();
        assert!(!m.is_empty());
    }
EOF

$ rust-gdb rust_out
(gdb) b 7
(gdb) r
(gdb) p m
$1 = BTreeMap<i8, rust_out::MyLeafNode>(len: 12)Python Exception <class 'gdb.error'> No type named alloc::collections::btree::node::InternalNode<i8, rust_out::MyInternalNode>.:
use std::collections::BTreeMap;

The code was written in #56144 by @tromey (and later touched upon by @RalfJung in #57045, but I think that had nothing to do with the issues in this PR).

[rust-highfive]

r? @nikomatsakis

(rust_highfive has picked a reviewer for you, use r? to override)

[Mark-Simulacrum]

I think someone recently looked into our gdb pretty printing -- maybe @pnkfelix? Or @michaelwoerister?

[Dylan-DPC-zz]

r? @pnkfelix

[tromey]

FWIW this patch looks reasonable to me.

[ssomers]

Last push is a (very late) rebase that I had already prepared for #67980

[pnkfelix]

(This will need to be rebased atop PR #60826 after that lands.)

[pnkfelix]

r=me after PR #60826 lands and you do subsequent rebase.

[ssomers]

Last commit removed the part that isn't in the title and would interfere with #70111.

[tromey]

Thank you for doing this. FWIW this still looks reasonable to me.

[Mark-Simulacrum]

r=me but would like to wait on #70111 landing I think

[bors]

☔ The latest upstream changes (presumably #70205) made this pull request unmergeable. Please resolve the merge conflicts.

[ssomers]

I noticed that if the key type is (), and you insert an element (the only one ever), pretty printing says the type is undefined. I guess civilization can survive without me logging that as a bug.

r? @msimulacrum

[Mark-Simulacrum]

It looks like #60826 is still a bit stalled and should be fairly easy to rebase atop this given the minimal nature of this patch. @bors r+

Thanks!

[bors]

📌 Commit d8a136f has been approved by Mark-Simulacrum

[bors]

⌛ Testing commit d8a136f with merge 94d43d6...

[bors]

☀️ Test successful - checks-azure
Approved by: Mark-Simulacrum
Pushing 94d43d6 to master...