feat(natu): lint direct listToAttrs maps

src/dotfiles/registry.nix

@@ -5,10 +5,8 @@
   util,
 }:
 let
-  definitions = lib.listToAttrs (
+  definitions = lib.genAttrs' (util.collectNixFiles root) (
-    map (path: lib.nameValuePair (util.removeNixSuffix path) (mkRegistry path)) (
+    path: lib.nameValuePair (util.removeNixSuffix path) (mkRegistry path)
-      util.collectNixFiles root
-    )
   );
 
   mkRegistry =

src/natu/BUILD

@@ -10,6 +10,7 @@ rust_library(
         "parser.rs",
         "rules.rs",
         "rules/let_order.rs",
+        "rules/list_to_attrs_map.rs",
         "rules/manual_inherit.rs",
         "rules/manual_inherit_from.rs",
         "rules/unquoted_uri.rs",

src/natu/ast.rs

@@ -48,6 +48,7 @@ pub struct Ident {
 pub enum Expr {
     Ident(Ident),
     Select(Select),
+    Apply(Apply),
     Let {
         range: SourceRange,
         bindings: Vec<Binding>,
@@ -67,6 +68,12 @@ pub struct Select {
     pub attr: Ident,
 }
 
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct Apply {
+    pub lambda: Box<Expr>,
+    pub argument: Box<Expr>,
+}
+
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub struct Token {
     pub range: SourceRange,

src/natu/natu_test.rs

@@ -77,6 +77,63 @@ fn natu_preserves_suppressed_bindings() -> googletest::Result<()> {
     Ok(())
 }
 
+#[gtest]
+fn natu_reports_select_dependency_order() -> googletest::Result<()> {
+    let report = natu::future_sight(vec![SourceFile {
+        path: PathBuf::from("testdata/select_dependencies.nix"),
+        source: r#"
+let
+  dependency = { value = 1; };
+  entry = dependency.value;
+in
+entry
+"#
+        .into(),
+    }])
+    .or_fail()?;
+
+    let count = report
+        .diagnostics
+        .iter()
+        .filter(|diagnostic| diagnostic.finding.rule_id == "let_order")
+        .count();
+    expect_that!(count, eq(1));
+    Ok(())
+}
+
+#[gtest]
+fn natu_reports_list_to_attrs_after_map() -> googletest::Result<()> {
+    let report = natu::future_sight(vec![SourceFile {
+        path: PathBuf::from("testdata/list_to_attrs.nix"),
+        source: r#"
+let
+  generated = lib.listToAttrs (
+    map (item: lib.nameValuePair item item) items
+  );
+  generated_pairs = lib.listToAttrs (
+    concatLists (
+      mapAttrsToList (name: _: lib.nameValuePair name name) attrs
+    )
+  );
+  precomputed = lib.listToAttrs pairs;
+in
+{
+  inherit generated generated_pairs precomputed;
+}
+"#
+        .into(),
+    }])
+    .or_fail()?;
+
+    let count = report
+        .diagnostics
+        .iter()
+        .filter(|diagnostic| diagnostic.finding.rule_id == "list_to_attrs_map")
+        .count();
+    expect_that!(count, eq(1));
+    Ok(())
+}
+
 #[gtest]
 fn natu_reports_unquoted_uri() -> googletest::Result<()> {
     let report = natu::future_sight(vec![fixture_source("testdata/lint_findings.nix")?]).or_fail()?;

src/natu/parser.rs

@@ -42,6 +42,13 @@ fn convert_syntax(syntax: rnix::SyntaxNode) -> (Vec<ast::Node>, Vec<ast::Token>)
 fn convert_expr(expr: rnix::ast::Expr) -> ast::Expr {
     match expr {
         rnix::ast::Expr::Ident(ident) => ast::Expr::Ident(ident.into()),
+        rnix::ast::Expr::Select(select) => convert_select_expr(select),
+        rnix::ast::Expr::Apply(apply) => ast::Expr::Apply(ast::Apply {
+            lambda: Box::new(convert_expr(apply.lambda().expect("applications have a lambda"))),
+            argument: Box::new(convert_expr(
+                apply.argument().expect("applications have an argument"),
+            )),
+        }),
         rnix::ast::Expr::LetIn(let_in) => ast::Expr::Let {
             range: let_in.syntax().text_range().into(),
             bindings: let_in
@@ -67,6 +74,19 @@ fn convert_expr(expr: rnix::ast::Expr) -> ast::Expr {
     }
 }
 
+fn convert_select_expr(select: rnix::ast::Select) -> ast::Expr {
+    select.clone().try_into().map(ast::Expr::Select).unwrap_or_else(|_| {
+        ast::Expr::Other(
+            select
+                .syntax()
+                .children()
+                .filter_map(rnix::ast::Expr::cast)
+                .map(convert_expr)
+                .collect(),
+        )
+    })
+}
+
 fn convert_binding_ast(binding: rnix::ast::AttrpathValue) -> Option<ast::Binding> {
     let mut attrs = binding.attrpath()?.attrs();
     let Attr::Ident(key) = attrs.next()? else {
@@ -139,11 +159,21 @@ fn convert_node(node: rnix::SyntaxNode) -> Option<ast::Node> {
 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.try_into().ok()?;
+    let mut attrs = binding.attrpath()?.attrs();
+    let Attr::Ident(key) = attrs.next()? else {
+        return None;
+    };
+    if attrs.next().is_some() {
+        return None;
+    }
 
     Some(ast::Node {
         range,
-        data: ast::NodeData::Binding(data),
+        data: ast::NodeData::Binding(ast::Binding {
+            range,
+            key: key.into(),
+            value: convert_expr(binding.value()?),
+        }),
     })
 }
 

src/natu/rules.rs

@@ -1,11 +1,13 @@
 use crate::FileId;
 use crate::ast;
+use crate::rules::list_to_attrs_map::ListToAttrsMap;
 use crate::rules::manual_inherit::ManualInherit;
 use crate::rules::manual_inherit_from::ManualInheritFrom;
 use crate::rules::unquoted_uri::UnquotedUri;
 use crate::scope_graph::ScopeGraph;
 
 pub mod let_order;
+pub mod list_to_attrs_map;
 pub mod manual_inherit;
 pub mod manual_inherit_from;
 pub mod unquoted_uri;
@@ -65,6 +67,7 @@ pub fn run_rules(file: &ast::ParsedFile, graph: &ScopeGraph, source: &str) -> Ve
         .iter()
         .flat_map(|node| {
             [
+                run_node_rule::<ListToAttrsMap>(node),
                 run_node_rule::<ManualInherit>(node),
                 run_node_rule::<ManualInheritFrom>(node),
             ]

src/natu/rules/list_to_attrs_map.rs

@@ -0,0 +1,58 @@
+use crate::{ast, rules::NodeRule};
+
+pub struct ListToAttrsMap;
+
+impl NodeRule for ListToAttrsMap {
+    type Node = ast::Binding;
+
+    const ID: &'static str = "list_to_attrs_map";
+
+    fn select(data: &ast::NodeData) -> Option<&Self::Node> {
+        let ast::NodeData::Binding(binding) = data;
+
+        Some(binding)
+    }
+
+    fn check(node: &Self::Node) -> Option<&'static str> {
+        matches_list_to_attrs_map(&node.value)
+            .then_some("Use `lib.genAttrs'` instead of `lib.listToAttrs` after `map`")
+    }
+}
+
+fn matches_list_to_attrs_map(expr: &ast::Expr) -> bool {
+    let ast::Expr::Apply(application) = unwrap_expr(expr) else {
+        return false;
+    };
+
+    is_lib_list_to_attrs(&application.lambda) && is_map_application(&application.argument)
+}
+
+fn unwrap_expr(expr: &ast::Expr) -> &ast::Expr {
+    match expr {
+        ast::Expr::Other(expressions) if expressions.len() == 1 => unwrap_expr(&expressions[0]),
+        _ => expr,
+    }
+}
+
+fn is_lib_list_to_attrs(expr: &ast::Expr) -> bool {
+    matches!(
+        unwrap_expr(expr),
+        ast::Expr::Select(select) if select.receiver == "lib" && select.attr.name == "listToAttrs"
+    )
+}
+
+fn is_map_application(expr: &ast::Expr) -> bool {
+    let ast::Expr::Apply(application) = unwrap_expr(expr) else {
+        return false;
+    };
+
+    is_map(&application.lambda)
+}
+
+fn is_map(expr: &ast::Expr) -> bool {
+    match unwrap_expr(expr) {
+        ast::Expr::Ident(ident) => ident.name == "map",
+        ast::Expr::Apply(application) => is_map(&application.lambda),
+        _ => false,
+    }
+}

src/natu/scope_graph.rs

@@ -42,11 +42,16 @@ impl ScopeGraph {
                 }
                 self.build_expr(body, scope)
             }
+            ast::Expr::Apply(application) => [
+                self.build_expr(&application.lambda, scope),
+                self.build_expr(&application.argument, scope),
+            ]
+            .concat(),
             ast::Expr::Other(expressions) => expressions
                 .iter()
                 .flat_map(|expression| self.build_expr(expression, scope))
                 .collect(),
-            ast::Expr::Select(_) => Vec::new(),
+            ast::Expr::Select(select) => vec![self.add_reference(&select.receiver, scope)],
         }
     }