Add test for Future inflating arg size to 3x

This adds one more test that should track improvements to generator
layout, like #62958 and #62575.

In particular, this test highlights suboptimal layout, as the storage
for the argument future is not being reused across its usage as `upvar`,
`local` and `awaitee` (being polled to completion).

2 files changed, 96 insertions, 0 deletions

diff --git a/tests/ui/async-await/future-sizes/async-awaiting-fut.rs b/tests/ui/async-await/future-sizes/async-awaiting-fut.rs
new file mode 100644
index 00000000000..1816d842d6c
--- /dev/null
+++ b/tests/ui/async-await/future-sizes/async-awaiting-fut.rs
@@ -0,0 +1,24 @@
+// compile-flags: -Z print-type-sizes --crate-type lib
+// edition:2021
+// build-pass
+// ignore-pass
+
+async fn wait() {}
+
+async fn big_fut(arg: [u8; 1024]) {}
+
+async fn calls_fut(fut: impl std::future::Future<Output = ()>) {
+    loop {
+        wait().await;
+        if true {
+            return fut.await;
+        } else {
+            wait().await;
+        }
+    }
+}
+
+pub async fn test() {
+    let fut = big_fut([0u8; 1024]);
+    calls_fut(fut).await;
+}
diff --git a/tests/ui/async-await/future-sizes/async-awaiting-fut.stdout b/tests/ui/async-await/future-sizes/async-awaiting-fut.stdout
new file mode 100644
index 00000000000..eaf3e4b61e3
--- /dev/null
+++ b/tests/ui/async-await/future-sizes/async-awaiting-fut.stdout
@@ -0,0 +1,72 @@
+print-type-size type: `[async fn body@$DIR/async-awaiting-fut.rs:21:21: 24:2]`: 3078 bytes, alignment: 1 bytes
+print-type-size     discriminant: 1 bytes
+print-type-size     variant `Unresumed`: 0 bytes
+print-type-size     variant `Suspend0`: 3077 bytes
+print-type-size         local `.__awaitee`: 3077 bytes, offset: 0 bytes, alignment: 1 bytes
+print-type-size     variant `Returned`: 0 bytes
+print-type-size     variant `Panicked`: 0 bytes
+print-type-size type: `[async fn body@$DIR/async-awaiting-fut.rs:10:64: 19:2]`: 3077 bytes, alignment: 1 bytes
+print-type-size     discriminant: 1 bytes
+print-type-size     variant `Unresumed`: 2051 bytes
+print-type-size         padding: 1026 bytes
+print-type-size         upvar `.fut`: 1025 bytes, alignment: 1 bytes
+print-type-size     variant `Suspend0`: 2052 bytes
+print-type-size         local `.fut`: 1025 bytes, offset: 0 bytes, alignment: 1 bytes
+print-type-size         local `..generator_field4`: 1 bytes
+print-type-size         padding: 1 bytes
+print-type-size         upvar `.fut`: 1025 bytes, alignment: 1 bytes
+print-type-size         local `.__awaitee`: 1 bytes
+print-type-size     variant `Suspend1`: 3076 bytes
+print-type-size         padding: 1024 bytes
+print-type-size         local `..generator_field4`: 1 bytes, alignment: 1 bytes
+print-type-size         padding: 1 bytes
+print-type-size         upvar `.fut`: 1025 bytes, alignment: 1 bytes
+print-type-size         local `.__awaitee`: 1025 bytes
+print-type-size     variant `Suspend2`: 2052 bytes
+print-type-size         local `.fut`: 1025 bytes, offset: 0 bytes, alignment: 1 bytes
+print-type-size         local `..generator_field4`: 1 bytes
+print-type-size         padding: 1 bytes
+print-type-size         upvar `.fut`: 1025 bytes, alignment: 1 bytes
+print-type-size         local `.__awaitee`: 1 bytes
+print-type-size     variant `Returned`: 2051 bytes
+print-type-size         padding: 1026 bytes
+print-type-size         upvar `.fut`: 1025 bytes, alignment: 1 bytes
+print-type-size     variant `Panicked`: 2051 bytes
+print-type-size         padding: 1026 bytes
+print-type-size         upvar `.fut`: 1025 bytes, alignment: 1 bytes
+print-type-size type: `std::mem::ManuallyDrop<[async fn body@$DIR/async-awaiting-fut.rs:10:64: 19:2]>`: 3077 bytes, alignment: 1 bytes
+print-type-size     field `.value`: 3077 bytes
+print-type-size type: `std::mem::MaybeUninit<[async fn body@$DIR/async-awaiting-fut.rs:10:64: 19:2]>`: 3077 bytes, alignment: 1 bytes
+print-type-size     variant `MaybeUninit`: 3077 bytes
+print-type-size         field `.uninit`: 0 bytes
+print-type-size         field `.value`: 3077 bytes
+print-type-size type: `[async fn body@$DIR/async-awaiting-fut.rs:8:35: 8:37]`: 1025 bytes, alignment: 1 bytes
+print-type-size     discriminant: 1 bytes
+print-type-size     variant `Unresumed`: 1024 bytes
+print-type-size         upvar `.arg`: 1024 bytes, offset: 0 bytes, alignment: 1 bytes
+print-type-size     variant `Returned`: 1024 bytes
+print-type-size         upvar `.arg`: 1024 bytes, offset: 0 bytes, alignment: 1 bytes
+print-type-size     variant `Panicked`: 1024 bytes
+print-type-size         upvar `.arg`: 1024 bytes, offset: 0 bytes, alignment: 1 bytes
+print-type-size type: `std::mem::ManuallyDrop<[async fn body@$DIR/async-awaiting-fut.rs:8:35: 8:37]>`: 1025 bytes, alignment: 1 bytes
+print-type-size     field `.value`: 1025 bytes
+print-type-size type: `std::mem::MaybeUninit<[async fn body@$DIR/async-awaiting-fut.rs:8:35: 8:37]>`: 1025 bytes, alignment: 1 bytes
+print-type-size     variant `MaybeUninit`: 1025 bytes
+print-type-size         field `.uninit`: 0 bytes
+print-type-size         field `.value`: 1025 bytes
+print-type-size type: `[async fn body@$DIR/async-awaiting-fut.rs:6:17: 6:19]`: 1 bytes, alignment: 1 bytes
+print-type-size     discriminant: 1 bytes
+print-type-size     variant `Unresumed`: 0 bytes
+print-type-size     variant `Returned`: 0 bytes
+print-type-size     variant `Panicked`: 0 bytes
+print-type-size type: `std::mem::ManuallyDrop<bool>`: 1 bytes, alignment: 1 bytes
+print-type-size     field `.value`: 1 bytes
+print-type-size type: `std::mem::MaybeUninit<bool>`: 1 bytes, alignment: 1 bytes
+print-type-size     variant `MaybeUninit`: 1 bytes
+print-type-size         field `.uninit`: 0 bytes
+print-type-size         field `.value`: 1 bytes
+print-type-size type: `std::task::Poll<()>`: 1 bytes, alignment: 1 bytes
+print-type-size     discriminant: 1 bytes
+print-type-size     variant `Ready`: 0 bytes
+print-type-size         field `.0`: 0 bytes
+print-type-size     variant `Pending`: 0 bytes