fix: Prevent panic in Remove Unused Parameter assist

Instead of calling `builder.delete` for every text range we find with
`process_usage`, we now ensure that the ranges do not overlap before removing
them. If a range is fully contained by a prior one, it is dropped.

fixes rust-lang#12784

Author: DorianListens

crates/ide-assists/src/handlers/remove_unused_param.rs

@@ -96,12 +96,20 @@ fn process_usages(
 ) {
     let source_file = ctx.sema.parse(file_id);
     builder.edit_file(file_id);
-    for usage in references {
-        if let Some(text_range) = process_usage(&source_file, usage, arg_to_remove, is_self_present)
-        {
-            builder.delete(text_range);
+    let possible_ranges = references
+        .into_iter()
+        .filter_map(|usage| process_usage(&source_file, usage, arg_to_remove, is_self_present));
+
+    let mut ranges_to_delete: Vec<TextRange> = vec![];
+    for range in possible_ranges {
+        if !ranges_to_delete.iter().any(|it| it.contains_range(range)) {
+            ranges_to_delete.push(range)
         }
     }
+
+    for range in ranges_to_delete {
+        builder.delete(range)
+    }
 }
 
 fn process_usage(
@@ -370,6 +378,31 @@ fn main() {
     S.f(92);
     S::f(&S);
 }
+"#,
+        )
+    }
+
+    #[test]
+    fn nested_call() {
+        check_assist(
+            remove_unused_param,
+            r#"
+fn foo(x: i32, $0y: i32) -> i32 {
+    x
+}
+
+fn bar() {
+    foo(1, foo(2, 3));
+}
+"#,
+            r#"
+fn foo(x: i32) -> i32 {
+    x
+}
+
+fn bar() {
+    foo(1);
+}
 "#,
         )
     }