Use strict sorted and union for NoQA mapping insertion

crates/ruff/src/directives.rs

@@ -461,6 +461,18 @@ y = \
                 TextRange::new(TextSize::from(77), TextSize::from(83)),
             ])
         );
+
+        // https://github.com/astral-sh/ruff/issues/7530
+        let contents = r"
+assert foo, \
+    '''triple-quoted
+    string'''
+"
+        .trim();
+        assert_eq!(
+            noqa_mappings(contents),
+            NoqaMapping::from_iter([TextRange::new(TextSize::from(0), TextSize::from(48))])
+        );
     }
 
     #[test]

crates/ruff/src/noqa.rs

@@ -764,15 +764,17 @@ impl NoqaMapping {
     pub(crate) fn push_mapping(&mut self, range: TextRange) {
         if let Some(last_range) = self.ranges.last_mut() {
             // Strictly sorted insertion
-            if last_range.end() <= range.start() {
+            if last_range.end() < range.start() {
                 // OK
-            }
-            // Try merging with the last inserted range
-            else if let Some(intersected) = last_range.intersect(range) {
-                *last_range = intersected;
-                return;
-            } else {
+            } else if range.end() < last_range.start() {
+                // Incoming range is strictly before the last range which violates
+                // the function's contract.
                 panic!("Ranges must be inserted in sorted order")
+            } else {
+                // Here, it's guaranteed that `last_range` and `range` overlap
+                // in some way. We want to merge them into a single range.
+                *last_range = last_range.cover(range);
+                return;
             }
         }