Auto merge of #1927 - RalfJung:array-align-tests, r=RalfJung

add tests for alignment on array initialization

This adds regression tests for https://github.com/rust-lang/miri/issues/1925, https://github.com/rust-lang/miri/issues/1919.

rust-version

@@ -1 +1 @@
-686e313a9aa14107c8631ffe48fa09110a7692db
+58f9efd36de5669ab731ec7ebf565999ff17b159

tests/run-pass/async-fn.rs

@@ -45,6 +45,18 @@ async fn partial_init(x: u32) -> u32 {
     let _x: (String, !) = (String::new(), return async { x + x }.await);
 }
 
+async fn read_exact(_from: &mut &[u8], _to: &mut [u8]) -> Option<()> {
+    Some(())
+}
+
+async fn hello_world() {
+    let data = [0u8; 1];
+    let mut reader = &data[..];
+
+    let mut marker = [0u8; 1];
+    read_exact(&mut reader, &mut marker).await.unwrap();
+}
+
 fn run_fut<T>(fut: impl Future<Output = T>) -> T {
     use std::sync::Arc;
     use std::task::{Context, Poll, Wake, Waker};
@@ -74,4 +86,5 @@ fn main() {
     assert_eq!(run_fut(build_aggregate(1, 2, 3, 4)), 10);
     assert_eq!(run_fut(includes_never(false, 4)), 16);
     assert_eq!(run_fut(partial_init(4)), 8);
+    run_fut(hello_world());
 }

tests/run-pass/issue-miri-1925.rs

@@ -0,0 +1,33 @@
+// compile-flags: -Zmiri-symbolic-alignment-check
+
+use std::mem::size_of;
+
+fn main() {
+    let mut a = Params::new();
+    a.key_block = [0; BLOCKBYTES];
+}
+
+#[repr(C)]
+#[derive(Clone)]
+#[allow(unused)]
+pub struct Params {
+    hash_length: u8,
+    key_length: u8,
+    key_block: [u8; BLOCKBYTES],
+    max_leaf_length: u32,
+}
+
+pub const OUTBYTES: usize = 8 * size_of::<u64>();
+pub const KEYBYTES: usize = 8 * size_of::<u64>();
+pub const BLOCKBYTES: usize = 16 * size_of::<u64>();
+
+impl Params {
+    pub fn new() -> Self {
+        Self {
+            hash_length: OUTBYTES as u8,
+            key_length: 0,
+            key_block: [0; BLOCKBYTES],
+            max_leaf_length: 0,
+        }
+    }
+}