Keep a list whose elements carry comments

Author: thesiti92

src/config/prune.rs

@@ -111,13 +111,32 @@ fn has_comment(table: &dyn TableLike, key: &str, item: &Item) -> bool {
         .key(key)
         .is_some_and(|key| commented(key.leaf_decor()));
     let item = match item {
-        Item::Value(value) => commented(value.decor()),
+        Item::Value(value) => value_has_comment(value),
         Item::Table(table) => commented(table.decor()),
         _ => false,
     };
     key || item
 }
 
+/// A comment on the value or anywhere inside it: between an array's
+/// elements, after its last one, or on an inline table's entries.
+fn value_has_comment(value: &toml_edit::Value) -> bool {
+    let note = |raw: &toml_edit::RawString| raw.as_str().is_some_and(|text| text.contains('#'));
+    commented(value.decor())
+        || match value {
+            toml_edit::Value::Array(array) => {
+                note(array.trailing()) || array.iter().any(value_has_comment)
+            }
+            toml_edit::Value::InlineTable(table) => table.iter().any(|(key, value)| {
+                table
+                    .key(key)
+                    .is_some_and(|key| commented(key.leaf_decor()))
+                    || value_has_comment(value)
+            }),
+            _ => false,
+        }
+}
+
 fn commented(decor: &toml_edit::Decor) -> bool {
     [decor.prefix(), decor.suffix()]
         .into_iter()

src/config/prune/tests.rs

@@ -234,7 +234,15 @@ fn generate(rng: &mut Rng, settings: &[(String, Value)]) -> (DocumentMut, Vec<St
             table = table[segment].as_table_mut().unwrap();
         }
         let leaf = path[path.len() - 1];
-        table.insert(leaf, toml_edit::value(edit_value(&value)));
+        let mut value = edit_value(&value);
+        if let Some(first) = value.as_array_mut().and_then(|array| array.get_mut(0)) {
+            if rng.chance(20) {
+                let comment = format!("# in list {}", comments.len());
+                first.decor_mut().set_prefix(format!("\n  {comment}\n  "));
+                comments.push(comment);
+            }
+        }
+        table.insert(leaf, toml_edit::value(value));
         if rng.chance(10) {
             let comment = format!("# note {}", comments.len());
             table

src/config/store.rs

@@ -557,6 +557,22 @@ mod sparse_tests {
         }
     }
 
+    #[test]
+    fn a_comment_inside_a_default_list_keeps_it() {
+        let dir = tempfile::tempdir().unwrap();
+        let path = dir.path().join("config.toml");
+        std::fs::write(
+            &path,
+            "[plugins.bundled.hide-files]\ntags = [\n  # keep generated code out\n  \"generated\",\n  \"vendored\",\n  \"test\", # tests too\n]\n",
+        )
+        .unwrap();
+        set(&path, "diff.graph_limit", "42").unwrap();
+        let text = std::fs::read_to_string(&path).unwrap();
+        for comment in ["# keep generated code out", "# tests too"] {
+            assert!(text.contains(comment), "{comment} in {text}");
+        }
+    }
+
     #[test]
     fn tables_left_empty_by_pruning_go_too() {
         let dir = tempfile::tempdir().unwrap();