Auto merge of #137371 - matthiaskrgr:rollup-3qkdqar, r=matthiaskrgr

Rollup of 8 pull requests

Successful merges:

 - #128080 (Specify scope in `out_of_scope_macro_calls` lint)
 - #135630 (add more `s390x` target features)
 - #136089 (Reduce `Box::default` stack copies in debug mode)
 - #137204 (Clarify MIR dialects and phases)
 - #137299 (Simplify `Postorder` customization.)
 - #137302 (Use a probe to avoid registering stray region obligations when re-checking drops in MIR typeck)
 - #137305 (Tweaks in and around `rustc_middle`)
 - #137313 (Some codegen_llvm cleanups)

r? `@ghost`
`@rustbot` modify labels: rollup

1 files changed, 28 insertions, 0 deletions

diff --git a/tests/codegen/box-default-debug-copies.rs b/tests/codegen/box-default-debug-copies.rs
new file mode 100644
index 00000000000..06cc41b21c0
--- /dev/null
+++ b/tests/codegen/box-default-debug-copies.rs
@@ -0,0 +1,28 @@
+//@ compile-flags: -Copt-level=0
+
+// Test to make sure that `<Box<T>>::default` does not create too many copies of `T` on the stack.
+// in debug mode. This regressed in dd0620b86721ae8cae86736443acd3f72ba6fc32 to
+// four `T` allocas.
+//
+// See https://github.com/rust-lang/rust/issues/136043 for more context.
+//
+// FIXME: This test only wants to ensure that there are at most two allocas of `T` created, instead
+// of checking for exactly two.
+
+#![crate_type = "lib"]
+
+#[allow(dead_code)]
+pub struct Thing([u8; 1000000]);
+
+impl Default for Thing {
+    fn default() -> Self {
+        Thing([0; 1000000])
+    }
+}
+
+// CHECK-COUNT-2: %{{.*}} = alloca {{.*}}1000000
+// CHECK-NOT: %{{.*}} = alloca {{.*}}1000000
+#[no_mangle]
+pub fn box_default_single_copy() -> Box<Thing> {
+    Box::default()
+}