Auto merge of #66908 - Centril:rollup-26givp6, r=Centril

Rollup of 9 pull requests

Successful merges:

 - #66612 (Initial implementation of or-pattern usefulness checking)
 - #66705 (Atomic as_mut_ptr)
 - #66759 (impl TrustedLen for vec::Drain)
 - #66858 (Use LLVMAddAnalysisPasses instead of Rust's wrapper)
 - #66870 (SimplifyArmIdentity only for locals with the same type)
 - #66883 (rustc_typeck: gate AnonConst's generics on feature(const_generics).)
 - #66889 (Make python-generated source files compatible with rustfmt)
 - #66894 (Remove unneeded prelude imports in libcore tests)
 - #66895 (Feature gating *declarations* => new crate `rustc_feature`)

Failed merges:

 - #66905 (rustc_plugin: Remove some remaining plugin features)

r? @ghost

1 files changed, 75 insertions, 0 deletions

diff --git a/src/test/mir-opt/simplify-arm-identity.rs b/src/test/mir-opt/simplify-arm-identity.rs
new file mode 100644
index 00000000000..a8fa64255fb
--- /dev/null
+++ b/src/test/mir-opt/simplify-arm-identity.rs
@@ -0,0 +1,75 @@
+// Checks that `SimplifyArmIdentity` is not applied if enums have incompatible layouts.
+// Regression test for issue #66856.
+//
+// compile-flags: -Zmir-opt-level=2
+
+enum Src {
+    Foo(u8),
+    Bar,
+}
+
+enum Dst {
+    Foo(u8),
+}
+
+fn main() {
+    let e: Src = Src::Foo(0);
+    let _: Dst = match e {
+        Src::Foo(x) => Dst::Foo(x),
+        Src::Bar => Dst::Foo(0),
+    };
+}
+
+// END RUST SOURCE
+// START rustc.main.SimplifyArmIdentity.before.mir
+// fn main() -> () {
+//     ...
+//     bb0: {
+//         StorageLive(_1);
+//         ((_1 as Foo).0: u8) = const 0u8;
+//         discriminant(_1) = 0;
+//         StorageLive(_2);
+//         _3 = discriminant(_1);
+//         switchInt(move _3) -> [0isize: bb3, 1isize: bb1, otherwise: bb2];
+//     }
+//     bb1: {
+//         ((_2 as Foo).0: u8) = const 0u8;
+//         discriminant(_2) = 0;
+//         goto -> bb4;
+//     }
+//     ...
+//     bb3: {
+//         _4 = ((_1 as Foo).0: u8);
+//         ((_2 as Foo).0: u8) = move _4;
+//         discriminant(_2) = 0;
+//         goto -> bb4;
+//     }
+//     ...
+// }
+// END rustc.main.SimplifyArmIdentity.before.mir
+// START rustc.main.SimplifyArmIdentity.after.mir
+// fn main() -> () {
+//     ...
+//     bb0: {
+//         StorageLive(_1);
+//         ((_1 as Foo).0: u8) = const 0u8;
+//         discriminant(_1) = 0;
+//         StorageLive(_2);
+//         _3 = discriminant(_1);
+//         switchInt(move _3) -> [0isize: bb3, 1isize: bb1, otherwise: bb2];
+//     }
+//     bb1: {
+//         ((_2 as Foo).0: u8) = const 0u8;
+//         discriminant(_2) = 0;
+//         goto -> bb4;
+//     }
+//     ...
+//     bb3: {
+//         _4 = ((_1 as Foo).0: u8);
+//         ((_2 as Foo).0: u8) = move _4;
+//         discriminant(_2) = 0;
+//         goto -> bb4;
+//     }
+//     ...
+// }
+// END rustc.main.SimplifyArmIdentity.after.mir