Backport official GLib iterator safety fix for Linux desktop

tools/glib-regression/src/lib.rs

@@ -0,0 +1,64 @@
+//! Optimized Linux regression for the reviewed GLib iterator backport.
+//! Borrowed strings must never escape their owning variant:
+//! ```compile_fail,E0597
+//! use glib::prelude::*;
+//! let escaped;
+//! {
+//!     let owner = ["hello"].to_variant();
+//!     escaped = owner.array_iter_str().unwrap().next().unwrap();
+//! }
+//! println!("{escaped}");
+//! ```
+
+#[cfg(test)]
+mod tests {
+    use glib::prelude::*;
+
+    #[test]
+    fn unicode_forward_reverse_and_last() {
+        let owner = ["Gemäß", "日本", "😀", "tail"].to_variant();
+        let expected = ["Gemäß", "日本", "😀", "tail"];
+        assert_eq!(
+            owner.array_iter_str().unwrap().collect::<Vec<_>>(),
+            expected
+        );
+        assert_eq!(
+            owner.array_iter_str().unwrap().rev().collect::<Vec<_>>(),
+            expected.into_iter().rev().collect::<Vec<_>>()
+        );
+        assert_eq!(owner.array_iter_str().unwrap().last(), Some("tail"));
+    }
+
+    #[test]
+    fn mixed_ends_exact_size_and_fused_exhaustion() {
+        let owner = ["zero", "one", "two", "three", "four", "five"].to_variant();
+        let mut iter = owner.array_iter_str().unwrap();
+        assert_eq!(iter.size_hint(), (6, Some(6)));
+        assert_eq!(iter.next(), Some("zero"));
+        assert_eq!(iter.next_back(), Some("five"));
+        assert_eq!(iter.nth(1), Some("two"));
+        assert_eq!(iter.nth_back(0), Some("four"));
+        assert_eq!(iter.len(), 1);
+        assert_eq!(iter.next(), Some("three"));
+        for _ in 0..3 {
+            assert_eq!(iter.next(), None);
+            assert_eq!(iter.next_back(), None);
+            assert_eq!(iter.len(), 0);
+        }
+    }
+
+    #[test]
+    fn empty_and_out_of_range() {
+        let empty: [&str; 0] = [];
+        let owner = empty.to_variant();
+        assert_eq!(owner.array_iter_str().unwrap().last(), None);
+        assert_eq!(owner.array_iter_str().unwrap().next_back(), None);
+        let owner = ["first", "second"].to_variant();
+        let mut iter = owner.array_iter_str().unwrap();
+        assert_eq!(iter.nth(usize::MAX), None);
+        assert_eq!(iter.next(), None);
+        let mut iter = owner.array_iter_str().unwrap();
+        assert_eq!(iter.nth_back(usize::MAX), None);
+        assert_eq!(iter.next_back(), None);
+    }
+}