new lint: manual_inherit

2 files changed, 44 insertions, 2 deletions

diff --git a/lib/src/lints/empty_let_in.rs b/lib/src/lints/empty_let_in.rs
index 4b074e7..207d253 100644
--- a/lib/src/lints/empty_let_in.rs
+++ b/lib/src/lints/empty_let_in.rs
@@ -3,8 +3,7 @@ use crate::{Lint, Metadata, Report, Rule, Suggestion};
 use if_chain::if_chain;
 use macros::lint;
 use rnix::{
-    types::{LetIn, TypedNode, 
-        EntryHolder},
+    types::{LetIn, TypedNode, EntryHolder},
     NodeOrToken, SyntaxElement, SyntaxKind,
 };
 
diff --git a/lib/src/lints/manual_inherit.rs b/lib/src/lints/manual_inherit.rs
new file mode 100644
index 0000000..2f8367f
--- /dev/null
+++ b/lib/src/lints/manual_inherit.rs
@@ -0,0 +1,43 @@
+use crate::{make, Lint, Metadata, Report, Rule, Suggestion};
+
+use if_chain::if_chain;
+use macros::lint;
+use rnix::{
+    types::{KeyValue, Ident, TypedNode, TokenWrapper},
+    NodeOrToken, SyntaxElement, SyntaxKind,
+};
+
+#[lint(
+    name = "manual inherit",
+    note = "Assignment instead of `inherit` keyword",
+    code = 3,
+    match_with = SyntaxKind::NODE_KEY_VALUE
+)]
+struct ManualInherit;
+
+impl Rule for ManualInherit {
+    fn validate(&self, node: &SyntaxElement) -> Option<Report> {
+        if_chain! {
+            if let NodeOrToken::Node(key_value_node) = node;
+            if let Some(key_value_stmt) = KeyValue::cast(key_value_node.clone());
+            if let Some(key_path) = key_value_stmt.key();
+            if let Some(key_node) = key_path.path().next();
+            if let Some(key) = Ident::cast(key_node);
+
+            if let Some(value_node) = key_value_stmt.value();
+            if let Some(value) = Ident::cast(value_node);
+
+            if key.as_str() == value.as_str();
+
+            then {
+                let at = node.text_range();
+                let replacement = make::inherit_stmt(&[key]).node().clone();
+                let message = format!("The assignment `{}` is better written with `inherit`", node);
+                Some(Self::report().suggest(at, message, Suggestion::new(at, replacement)))
+            } else {
+                None
+            }
+        }
+    }
+}
+