Auto merge of #102297 - fee1-dead-contrib:rollup-2np0cre, r=fee1-dead

Rollup of 5 pull requests

Successful merges:

 - #102143 (Recover from struct nested in struct)
 - #102178 (bootstrap: the backtrace feature is stable, no need to allow it any more)
 - #102197 (Stabilize const `BTree{Map,Set}::new`)
 - #102267 (Don't set RUSTC in the bootstrap build script)
 - #102270 (Remove benches from `rustc_middle`)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup

3 files changed, 17 insertions, 2 deletions

diff --git a/src/test/ui/consts/issue-88071.rs b/src/test/ui/consts/issue-88071.rs
index 1c38c43e6c0..f58cdb5945e 100644
--- a/src/test/ui/consts/issue-88071.rs
+++ b/src/test/ui/consts/issue-88071.rs
@@ -2,8 +2,6 @@
 //
 // regression test for #88071
 
-#![feature(const_btree_new)]
-
 use std::collections::BTreeMap;
 
 pub struct CustomMap<K, V>(BTreeMap<K, V>);
diff --git a/src/test/ui/parser/issues/issue-101540.rs b/src/test/ui/parser/issues/issue-101540.rs
new file mode 100644
index 00000000000..328ec6f906b
--- /dev/null
+++ b/src/test/ui/parser/issues/issue-101540.rs
@@ -0,0 +1,7 @@
+struct S1 {
+    struct S2 {
+    //~^ ERROR structs are not allowed in struct definitions
+    }
+}
+
+fn main() {}
diff --git a/src/test/ui/parser/issues/issue-101540.stderr b/src/test/ui/parser/issues/issue-101540.stderr
new file mode 100644
index 00000000000..53c7c9590e6
--- /dev/null
+++ b/src/test/ui/parser/issues/issue-101540.stderr
@@ -0,0 +1,10 @@
+error: structs are not allowed in struct definitions
+  --> $DIR/issue-101540.rs:2:5
+   |
+LL |     struct S2 {
+   |     ^^^^^^^^^
+   |
+   = help: consider creating a new `struct` definition instead of nesting
+
+error: aborting due to previous error
+