From 7a430237eea3e1d296e0d69e40f154a3727ba2fc Mon Sep 17 00:00:00 2001
From: Akshay <nerdy@peppe.rs>
Date: Sat, 2 Oct 2021 18:40:08 +0530
Subject: new lint: manual_inherit_from

---
 lib/src/lints.rs                     |  1 +
 lib/src/lints/manual_inherit.rs      |  2 +-
 lib/src/lints/manual_inherit_from.rs | 49 ++++++++++++++++++++++++++++++++++++
 lib/src/make.rs                      |  9 +++++++
 4 files changed, 60 insertions(+), 1 deletion(-)
 create mode 100644 lib/src/lints/manual_inherit_from.rs

diff --git a/lib/src/lints.rs b/lib/src/lints.rs
index 7d5cd30..30c1678 100644
--- a/lib/src/lints.rs
+++ b/lib/src/lints.rs
@@ -4,4 +4,5 @@ lint_map! {
     bool_comparison,
     empty_let_in,
     manual_inherit,
+    manual_inherit_from,
 }
diff --git a/lib/src/lints/manual_inherit.rs b/lib/src/lints/manual_inherit.rs
index 2f8367f..c1b10ec 100644
--- a/lib/src/lints/manual_inherit.rs
+++ b/lib/src/lints/manual_inherit.rs
@@ -9,7 +9,7 @@ use rnix::{
 
 #[lint(
     name = "manual inherit",
-    note = "Assignment instead of `inherit` keyword",
+    note = "Assignment instead of inherit",
     code = 3,
     match_with = SyntaxKind::NODE_KEY_VALUE
 )]
diff --git a/lib/src/lints/manual_inherit_from.rs b/lib/src/lints/manual_inherit_from.rs
new file mode 100644
index 0000000..055cba2
--- /dev/null
+++ b/lib/src/lints/manual_inherit_from.rs
@@ -0,0 +1,49 @@
+use crate::{make, Lint, Metadata, Report, Rule, Suggestion};
+
+use if_chain::if_chain;
+use macros::lint;
+use rnix::{
+    types::{KeyValue, Ident, Select, TypedNode, TokenWrapper},
+    NodeOrToken, SyntaxElement, SyntaxKind,
+};
+
+#[lint(
+    name = "manual inherit from",
+    note = "Assignment instead of inherit from",
+    code = 4,
+    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) = Select::cast(value_node);
+            if let Some(index_node) = value.index();
+            if let Some(index) = Ident::cast(index_node);
+
+            if key.as_str() == index.as_str();
+
+            then {
+                let at = node.text_range();
+                let replacement = {
+                    let set = value.set()?;
+                    make::inherit_from_stmt(set, &[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
+            }
+        }
+    }
+}
+
+
diff --git a/lib/src/make.rs b/lib/src/make.rs
index facd247..cf371a2 100644
--- a/lib/src/make.rs
+++ b/lib/src/make.rs
@@ -29,3 +29,12 @@ pub fn inherit_stmt<'a>(nodes: impl IntoIterator<Item = &'a types::Ident>) -> ty
         .join(" ");
     ast_from_text(&format!("{{ inherit {}; }}", inherited_idents))
 }
+
+pub fn inherit_from_stmt<'a>(from: SyntaxNode, nodes: impl IntoIterator<Item = &'a types::Ident>) -> types::Inherit {
+    let inherited_idents = nodes
+        .into_iter()
+        .map(|i| i.as_str().to_owned())
+        .collect::<Vec<_>>()
+        .join(" ");
+    ast_from_text(&format!("{{ inherit ({}) {}; }}", from, inherited_idents))
+}
-- 
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