src/xatu/BUILD

@@ -8,6 +8,8 @@ rust_library(
         "file_store.rs",
         "parser.rs",
         "rules.rs",
+        "rules/manual_inherit.rs",
+        "rules/manual_inherit_from.rs",
         "rules/unquoted_uri.rs",
         "xatu.rs",
     ],

src/xatu/ast.rs

@@ -28,20 +28,26 @@ impl std::fmt::Display for SourceRange {
 
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub enum NodeData {
-    Apply(Apply),
-    LetIn(LetIn),
-    Inherit(Inherit),
+    Binding(Binding),
 }
 
 #[derive(Debug, Clone, PartialEq, Eq)]
-pub struct Apply {
-    pub function: Expr,
+pub struct Binding {
+    pub path: Vec<Attr>,
+    pub value: Expr,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum Attr {
+    Ident(Ident),
+    Other,
 }
 
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub enum Expr {
     Ident(Ident),
     Select(Box<Select>),
+    Other,
 }
 
 #[derive(Debug, Clone, PartialEq, Eq)]
@@ -52,17 +58,8 @@ pub struct Ident {
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub struct Select {
     pub receiver: Expr,
-    pub attrs: Vec<Ident>,
-}
-
-#[derive(Debug, Clone, PartialEq, Eq)]
-pub struct LetIn {
-    pub binding_count: usize,
-}
-
-#[derive(Debug, Clone, PartialEq, Eq)]
-pub struct Inherit {
-    pub attr_count: usize,
+    pub path: Vec<Attr>,
+    pub has_default: bool,
 }
 
 #[derive(Debug, Clone, PartialEq, Eq)]

src/xatu/parser.rs

@@ -1,4 +1,3 @@
-use rnix::ast::HasEntry;
 use rowan::ast::AstNode;
 
 use crate::{FileId, ast};
@@ -37,42 +36,51 @@ fn convert_syntax(syntax: rnix::SyntaxNode) -> (Vec<ast::Node>, Vec<ast::Token>)
 
 fn convert_node(node: rnix::SyntaxNode) -> Option<ast::Node> {
     match node.kind() {
-        rnix::SyntaxKind::NODE_APPLY => convert_apply(node),
-        rnix::SyntaxKind::NODE_LET_IN => convert_let_in(node),
-        rnix::SyntaxKind::NODE_INHERIT => convert_inherit(node),
+        rnix::SyntaxKind::NODE_ATTRPATH_VALUE => convert_binding(node),
         _ => None,
     }
 }
 
-fn convert_apply(node: rnix::SyntaxNode) -> Option<ast::Node> {
-    let apply = rnix::ast::Apply::cast(node)?;
-    let range = apply.syntax().text_range().into();
-    let data = apply.try_into().ok()?;
+fn convert_binding(node: rnix::SyntaxNode) -> Option<ast::Node> {
+    let binding = rnix::ast::AttrpathValue::cast(node)?;
+    let range = binding.syntax().text_range().into();
+    let data = binding.into();
 
     Some(ast::Node {
         range,
-        data: ast::NodeData::Apply(data),
+        data: ast::NodeData::Binding(data),
     })
 }
 
-impl TryFrom<rnix::ast::Apply> for ast::Apply {
-    type Error = ();
-
-    fn try_from(apply: rnix::ast::Apply) -> Result<Self, Self::Error> {
-        Ok(Self {
-            function: apply.lambda().ok_or(())?.try_into()?,
-        })
+impl From<rnix::ast::AttrpathValue> for ast::Binding {
+    fn from(binding: rnix::ast::AttrpathValue) -> Self {
+        Self {
+            path: binding
+                .attrpath()
+                .into_iter()
+                .flat_map(|path| path.attrs())
+                .map(Into::into)
+                .collect(),
+            value: binding.value().map(Into::into).unwrap_or(ast::Expr::Other),
+        }
     }
 }
 
-impl TryFrom<rnix::ast::Expr> for ast::Expr {
-    type Error = ();
+impl From<rnix::ast::Attr> for ast::Attr {
+    fn from(attr: rnix::ast::Attr) -> Self {
+        match attr {
+            rnix::ast::Attr::Ident(ident) => Self::Ident(ident.into()),
+            _ => Self::Other,
+        }
+    }
+}
 
-    fn try_from(expr: rnix::ast::Expr) -> Result<Self, Self::Error> {
+impl From<rnix::ast::Expr> for ast::Expr {
+    fn from(expr: rnix::ast::Expr) -> Self {
         match expr {
-            rnix::ast::Expr::Ident(ident) => Ok(Self::Ident(ident.into())),
-            rnix::ast::Expr::Select(select) => Ok(Self::Select(Box::new(select.try_into()?))),
-            _ => Err(()),
+            rnix::ast::Expr::Ident(ident) => Self::Ident(ident.into()),
+            rnix::ast::Expr::Select(select) => Self::Select(Box::new(select.into())),
+            _ => Self::Other,
         }
     }
 }
@@ -85,59 +93,17 @@ impl From<rnix::ast::Ident> for ast::Ident {
     }
 }
 
-impl TryFrom<rnix::ast::Select> for ast::Select {
-    type Error = ();
-
-    fn try_from(select: rnix::ast::Select) -> Result<Self, Self::Error> {
-        Ok(Self {
-            receiver: select.expr().ok_or(())?.try_into()?,
-            attrs: select
+impl From<rnix::ast::Select> for ast::Select {
+    fn from(select: rnix::ast::Select) -> Self {
+        Self {
+            receiver: select.expr().map(Into::into).unwrap_or(ast::Expr::Other),
+            path: select
                 .attrpath()
-                .ok_or(())?
-                .attrs()
-                .map(|attr| match attr {
-                    rnix::ast::Attr::Ident(ident) => Ok(ident.into()),
-                    _ => Err(()),
-                })
-                .collect::<Result<Vec<_>, _>>()?,
-        })
-    }
-}
-
-fn convert_let_in(node: rnix::SyntaxNode) -> Option<ast::Node> {
-    let let_in = rnix::ast::LetIn::cast(node)?;
-
-    Some(ast::Node {
-        range: let_in.syntax().text_range().into(),
-        data: ast::NodeData::LetIn(let_in.into()),
-    })
-}
-
-impl From<rnix::ast::LetIn> for ast::LetIn {
-    fn from(let_in: rnix::ast::LetIn) -> Self {
-        Self {
-            binding_count: let_in.attrpath_values().count()
-                + let_in
-                    .inherits()
-                    .map(|inherit| inherit.attrs().count())
-                    .sum::<usize>(),
-        }
-    }
-}
-
-fn convert_inherit(node: rnix::SyntaxNode) -> Option<ast::Node> {
-    let inherit = rnix::ast::Inherit::cast(node)?;
-
-    Some(ast::Node {
-        range: inherit.syntax().text_range().into(),
-        data: ast::NodeData::Inherit(inherit.into()),
-    })
-}
-
-impl From<rnix::ast::Inherit> for ast::Inherit {
-    fn from(inherit: rnix::ast::Inherit) -> Self {
-        Self {
-            attr_count: inherit.attrs().count(),
+                .into_iter()
+                .flat_map(|path| path.attrs())
+                .map(Into::into)
+                .collect(),
+            has_default: select.or_token().is_some(),
         }
     }
 }

src/xatu/rules.rs

@@ -1,7 +1,11 @@
 use crate::FileId;
 use crate::ast;
+use crate::rules::manual_inherit::ManualInherit;
+use crate::rules::manual_inherit_from::ManualInheritFrom;
 use crate::rules::unquoted_uri::UnquotedUri;
 
+pub mod manual_inherit;
+pub mod manual_inherit_from;
 pub mod unquoted_uri;
 
 #[derive(Debug)]
@@ -27,7 +31,6 @@ impl std::fmt::Display for Diagnostic {
     }
 }
 
-#[expect(dead_code, reason = "retained for planned node rules")]
 pub trait NodeRule {
     type Node;
 
@@ -47,7 +50,16 @@ pub trait TokenRule {
 }
 
 pub fn run_rules(file: &ast::ParsedFile) -> Vec<Diagnostic> {
-    let node_diagnostics = file.nodes.iter().flat_map(|_| std::iter::empty());
+    let node_diagnostics = file
+        .nodes
+        .iter()
+        .flat_map(|node| {
+            [
+                run_node_rule::<ManualInherit>(node),
+                run_node_rule::<ManualInheritFrom>(node),
+            ]
+        })
+        .flatten();
     let token_diagnostics = file
         .tokens
         .iter()
@@ -63,7 +75,6 @@ pub fn run_rules(file: &ast::ParsedFile) -> Vec<Diagnostic> {
         .collect()
 }
 
-#[expect(dead_code, reason = "retained for planned node rules")]
 fn run_node_rule<R>(node: &ast::Node) -> Option<Finding>
 where
     R: NodeRule,

src/xatu/rules/manual_inherit.rs

@@ -0,0 +1,25 @@
+use crate::{ast, rules::NodeRule};
+
+pub struct ManualInherit;
+
+impl NodeRule for ManualInherit {
+    type Node = ast::Binding;
+
+    const ID: &'static str = "manual_inherit";
+
+    fn select(data: &ast::NodeData) -> Option<&Self::Node> {
+        let ast::NodeData::Binding(binding) = data;
+        Some(binding)
+    }
+
+    fn check(binding: &Self::Node) -> Option<&'static str> {
+        let [ast::Attr::Ident(name)] = binding.path.as_slice() else {
+            return None;
+        };
+        let ast::Expr::Ident(value) = &binding.value else {
+            return None;
+        };
+
+        (name == value).then_some("Use `inherit` for this binding")
+    }
+}

src/xatu/rules/manual_inherit_from.rs

@@ -0,0 +1,34 @@
+use crate::{ast, rules::NodeRule};
+
+pub struct ManualInheritFrom;
+
+impl NodeRule for ManualInheritFrom {
+    type Node = ast::Binding;
+
+    const ID: &'static str = "manual_inherit_from";
+
+    fn select(data: &ast::NodeData) -> Option<&Self::Node> {
+        let ast::NodeData::Binding(binding) = data;
+        Some(binding)
+    }
+
+    fn check(binding: &Self::Node) -> Option<&'static str> {
+        let [ast::Attr::Ident(name)] = binding.path.as_slice() else {
+            return None;
+        };
+        let ast::Expr::Select(select) = &binding.value else {
+            return None;
+        };
+        let ast::Expr::Ident(_) = &select.receiver else {
+            return None;
+        };
+        let [ast::Attr::Ident(selected)] = select.path.as_slice() else {
+            return None;
+        };
+        if select.has_default {
+            return None;
+        }
+
+        (name == selected).then_some("Use `inherit (source)` for this binding")
+    }
+}

src/xatu/testdata/lint_findings.nix

@@ -1,3 +1,5 @@
 {
+  package = package;
+  sourcePackage = source.sourcePackage;
   url = https://example.com;
 }

src/xatu/xatu_test.rs

@@ -41,6 +41,44 @@ fn xatu_rejects_invalid_source() -> googletest::Result<()> {
     Ok(())
 }
 
+#[gtest]
+fn xatu_reports_manual_inherit() -> googletest::Result<()> {
+    let report = xatu::future_sight(vec![fixture_source("testdata/lint_findings.nix")?]).or_fail()?;
+
+    let findings = report
+        .diagnostics
+        .iter()
+        .map(|diagnostic| diagnostic.finding.rule_id)
+        .collect::<Vec<_>>();
+    expect_that!(findings, contains(eq(&"manual_inherit")));
+    Ok(())
+}
+
+#[gtest]
+fn xatu_reports_manual_inherit_from() -> googletest::Result<()> {
+    let report = xatu::future_sight(vec![fixture_source("testdata/lint_findings.nix")?]).or_fail()?;
+
+    let findings = report
+        .diagnostics
+        .iter()
+        .map(|diagnostic| diagnostic.finding.rule_id)
+        .collect::<Vec<_>>();
+    expect_that!(findings, contains(eq(&"manual_inherit_from")));
+    Ok(())
+}
+
+#[gtest]
+fn xatu_ignores_other_binding_forms() -> googletest::Result<()> {
+    let report = xatu::future_sight(vec![SourceFile {
+        path: PathBuf::from("other_binding_forms.nix"),
+        source: "{ nested = source.group.nested; target.path = path; defaulted = source.defaulted or null; renamed = source.original; }".into(),
+    }])
+    .or_fail()?;
+
+    expect_that!(report.is_clean(), is_true());
+    Ok(())
+}
+
 #[gtest]
 fn xatu_reports_unquoted_uri() -> googletest::Result<()> {
     let report = xatu::future_sight(vec![fixture_source("testdata/lint_findings.nix")?]).or_fail()?;