rustc_mir: don't run the deaggregator on arrays for now.

Author: eddyb

src/librustc_mir/transform/deaggregator.rs

@@ -41,7 +41,11 @@ impl MirPass for Deaggregator {
 
         let can_deaggregate = |statement: &Statement| {
             if let StatementKind::Assign(_, ref rhs) = statement.kind {
-                if let Rvalue::Aggregate(..) = *rhs {
+                if let Rvalue::Aggregate(ref kind, _) = *rhs {
+                    // FIXME(#48193) Deaggregate arrays when it's cheaper to do so.
+                    if let AggregateKind::Array(_) = **kind {
+                        return false;
+                    }
                     return true;
                 }
             }

src/test/mir-opt/deaggregator_test_multiple.rs

@@ -52,8 +52,7 @@ fn main() {
 //     ((_4 as A).0: i32) = move _5;
 //     discriminant(_4) = 0;
 //     ...
-//     _0[0 of 1] = move _2;
-//     _0[1 of 2] = move _4;
+//     _0 = [move _2, move _4];
 //     ...
 //     return;
 // }