1/1000 events do happen sometimes...

src/tools/miri/tests/fail/unaligned_pointers/dyn_alignment.rs

@@ -7,7 +7,7 @@ struct MuchAlign;
 
 fn main() {
     // Try many times as this might work by chance.
-    for _ in 0..10 {
+    for _ in 0..20 {
         let buf = [0u32; 256];
         // `buf` is sufficiently aligned for `layout.align` on a `dyn Debug`, but not
         // for the actual alignment required by `MuchAlign`.

src/tools/miri/tests/fail/unaligned_pointers/reference_to_packed.rs

@@ -11,7 +11,7 @@ struct Foo {
 
 fn main() {
     // Try many times as this might work by chance.
-    for _ in 0..10 {
+    for _ in 0..20 {
         let foo = Foo { x: 42, y: 99 };
         let p = &foo.x;
         let i = *p; //~ERROR: alignment 4 is required

src/tools/miri/tests/fail/unaligned_pointers/unaligned_ptr3.rs

@@ -3,7 +3,7 @@
 
 fn main() {
     // Try many times as this might work by chance.
-    for _ in 0..10 {
+    for _ in 0..20 {
         let x = [2u16, 3, 4, 5]; // Make it big enough so we don't get an out-of-bounds error.
         let x = &x[0] as *const _ as *const *const u8; // cast to ptr-to-ptr, so that we load a ptr
         // This must fail because alignment is violated. Test specifically for loading pointers,

src/tools/miri/tests/fail/unaligned_pointers/unaligned_ptr4.rs

@@ -6,7 +6,7 @@ fn main() {
     // (This would be missed if u8 allocations are *always* at odd addresses.)
     //
     // Try many times as this might work by chance.
-    for _ in 0..10 {
+    for _ in 0..20 {
         let x = [0u8; 4];
         let ptr = x.as_ptr().wrapping_offset(1).cast::<u16>();
         let _val = unsafe { *ptr }; //~ERROR: but alignment

src/tools/miri/tests/fail/unaligned_pointers/unaligned_ptr_zst.rs

@@ -4,7 +4,7 @@
 
 fn main() {
     // Try many times as this might work by chance.
-    for i in 0..10 {
+    for i in 0..20 {
         let x = i as u8;
         let x = &x as *const _ as *const [u32; 0];
         // This must fail because alignment is violated. Test specifically for loading ZST.

src/tools/miri/tests/pass/align.rs

@@ -22,7 +22,7 @@ fn align_to() {
 
 fn main() {
     // Do this a couple times in a loop because it may work "by chance".
-    for _ in 0..10 {
+    for _ in 0..20 {
         manual_alignment();
         align_to();
     }