Auto merge of #106458 - albertlarsan68:move-tests, r=jyn514

Move src/test to the root

See MCP at rust-lang/compiler-team#573

There may be more changes needed.

The first commit is just the move of the files:
You can check that the first commit did not do anything else than renames by running
```
git diff --diff-filter=r -M100% <rust-lang remote>/master <first commit hash>
```
The output should be empty, because the filter excludes renames, and the match threshold for qualifying a rename is 100%.

The second one is mostly a "find and replace" of `src/test` to `tests` and whatever is needed to make CI pass.

What is left to do:
---

- [x] Move directory
- [ ] Change references to `src/test`
    - [x] Change references in-tree
    - [ ] Change references in submodules / out-of-tree docs
- [x] Make CI pass:
    - [x] Fix tidy
    - [x] Fix tests
    - [x] Bless tests if needed (shouldn't normally)
- [ ] Merge it !

1 files changed, 53 insertions, 0 deletions

diff --git a/tests/ui/array-slice-vec/slice-of-zero-size-elements.rs b/tests/ui/array-slice-vec/slice-of-zero-size-elements.rs
new file mode 100644
index 00000000000..83b08a3db4c
--- /dev/null
+++ b/tests/ui/array-slice-vec/slice-of-zero-size-elements.rs
@@ -0,0 +1,53 @@
+// run-pass
+#![allow(stable_features)]
+
+// compile-flags: -C debug-assertions
+
+#![feature(iter_to_slice)]
+
+use std::slice;
+
+fn foo<T>(v: &[T]) -> Option<&[T]> {
+    let mut it = v.iter();
+    for _ in 0..5 {
+        let _ = it.next();
+    }
+    Some(it.as_slice())
+}
+
+fn foo_mut<T>(v: &mut [T]) -> Option<&mut [T]> {
+    let mut it = v.iter_mut();
+    for _ in 0..5 {
+        let _ = it.next();
+    }
+    Some(it.into_slice())
+}
+
+pub fn main() {
+    // In a slice of zero-size elements the pointer is meaningless.
+    // Ensure iteration still works even if the pointer is at the end of the address space.
+    let slice: &[()] = unsafe { slice::from_raw_parts(-5isize as *const (), 10) };
+    assert_eq!(slice.len(), 10);
+    assert_eq!(slice.iter().count(), 10);
+
+    // .nth() on the iterator should also behave correctly
+    let mut it = slice.iter();
+    assert!(it.nth(5).is_some());
+    assert_eq!(it.count(), 4);
+
+    // Converting Iter to a slice should never have a null pointer
+    assert!(foo(slice).is_some());
+
+    // Test mutable iterators as well
+    let slice: &mut [()] = unsafe { slice::from_raw_parts_mut(-5isize as *mut (), 10) };
+    assert_eq!(slice.len(), 10);
+    assert_eq!(slice.iter_mut().count(), 10);
+
+    {
+        let mut it = slice.iter_mut();
+        assert!(it.nth(5).is_some());
+        assert_eq!(it.count(), 4);
+    }
+
+    assert!(foo_mut(slice).is_some())
+}