Fix drop handling for `if let` expressions

MIR lowering for `if let` expressions is now more complicated now that
`if let` exists in HIR. This PR adds a scope for the variables bound in
an `if let` expression and then uses an approach similar to how we
handle loops to ensure that we reliably drop the correct variables.

1 files changed, 7 insertions, 0 deletions

diff --git a/src/test/ui/drop/drop-if-let-binding.rs b/src/test/ui/drop/drop-if-let-binding.rs
new file mode 100644
index 00000000000..9c1ac4e0c7f
--- /dev/null
+++ b/src/test/ui/drop/drop-if-let-binding.rs
@@ -0,0 +1,7 @@
+// build-pass
+// regression test for issue #88307
+// compile-flags: -C opt-level=s
+
+fn main() {
+    if let Some(_val) = Option::<String>::None {}
+}