Add let-else test for pulling a copy type out of a non-copy

Author: cormacrelf

src/test/ui/let-else/let-else-non-copy.rs

@@ -0,0 +1,45 @@
+// run-pass
+//
+// This is derived from a change to compiler/rustc_codegen_llvm/src/debuginfo/metadata.rs, in
+// preparation for adopting let-else within the compiler (thanks @est31):
+//
+// ```
+// -    let place = if let mir::VarDebugInfoContents::Place(p) = var.value { p } else { continue };
+// +    let mir::VarDebugInfoContents::Place(place) = var.value else { continue };
+// ```
+//
+// The move was due to mir::Place being Copy, but mir::VarDebugInfoContents not being Copy.
+
+#![feature(let_else)]
+
+#[derive(Copy, Clone)]
+struct Copyable;
+
+enum NonCopy {
+    Thing(Copyable),
+    #[allow(unused)]
+    Other,
+}
+
+struct Wrapper {
+    field: NonCopy,
+}
+
+fn let_else() {
+    let vec = vec![Wrapper { field: NonCopy::Thing(Copyable) }];
+    for item in &vec {
+        let NonCopy::Thing(_copyable) = item.field else { continue };
+    }
+}
+
+fn if_let() {
+    let vec = vec![Wrapper { field: NonCopy::Thing(Copyable) }];
+    for item in &vec {
+        let _copyable = if let NonCopy::Thing(copyable) = item.field { copyable } else { continue };
+    }
+}
+
+fn main() {
+    let_else();
+    if_let();
+}