Auto merge of #109008 - clubby789:drop-elaborate-array, r=davidtwco

Drop array patterns using subslices

Fixes #109004
Drops contiguous subslices of an array when moving elements out with a pattern, which improves perf for large arrays
r? `@compiler-errors`

1 files changed, 16 insertions, 0 deletions

diff --git a/tests/ui/mir/issue-109004-drop-large-array.rs b/tests/ui/mir/issue-109004-drop-large-array.rs
new file mode 100644
index 00000000000..5e3361cef6e
--- /dev/null
+++ b/tests/ui/mir/issue-109004-drop-large-array.rs
@@ -0,0 +1,16 @@
+// check-pass
+
+const SZ: usize = 64_000_000;
+type BigDrop = [String; SZ];
+
+fn f(_dropme: BigDrop) {}
+
+fn f2(_moveme: BigDrop) -> String {
+    let [a, ..] = _moveme;
+    a
+}
+
+fn main() {
+    f(std::array::from_fn(|_| String::new()));
+    f2(std::array::from_fn(|_| String::new()));
+}