From 417bfbc2fc73b17431b09e7fae6235367140f434 Mon Sep 17 00:00:00 2001
From: Dhruv Manilawala <dhruvmanila@gmail.com>
Date: Mon, 23 Dec 2024 15:46:48 +0530
Subject: [PATCH] [red-knot] Infer value expr for empty list / tuple target

---
 crates/red_knot_python_semantic/src/types/infer.rs | 10 ++++++++--
 crates/red_knot_workspace/tests/check.rs           |  6 ++----
 2 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/crates/red_knot_python_semantic/src/types/infer.rs b/crates/red_knot_python_semantic/src/types/infer.rs
index 6111eaf72f6cc..aee508c91fdea 100644
--- a/crates/red_knot_python_semantic/src/types/infer.rs
+++ b/crates/red_knot_python_semantic/src/types/infer.rs
@@ -1826,11 +1826,14 @@ impl<'db> TypeInferenceBuilder<'db> {
         }
     }
 
-    /// Infer the definition type involved in a `target` expression.
+    /// Infer the definition types involved in a `target` expression.
     ///
     /// This is used for assignment statements, for statements, etc. with a single or multiple
     /// targets (unpacking).
-    // TODO: Remove the `value` argument once we handle all possible assignment targets.
+    ///
+    /// # Panics
+    ///
+    /// If the `value` is not a standalone expression.
     fn infer_target(&mut self, target: &ast::Expr, value: &ast::Expr) {
         match target {
             ast::Expr::Name(name) => self.infer_definition(name),
@@ -1839,6 +1842,9 @@ impl<'db> TypeInferenceBuilder<'db> {
                 for element in elts {
                     self.infer_target(element, value);
                 }
+                if elts.is_empty() {
+                    self.infer_standalone_expression(value);
+                }
             }
             _ => {
                 // TODO: Remove this once we handle all possible assignment targets.
diff --git a/crates/red_knot_workspace/tests/check.rs b/crates/red_knot_workspace/tests/check.rs
index d7d0a14b11d39..04a1ba1c07e7d 100644
--- a/crates/red_knot_workspace/tests/check.rs
+++ b/crates/red_knot_workspace/tests/check.rs
@@ -207,14 +207,12 @@ impl SourceOrderVisitor<'_> for PullTypesVisitor<'_> {
                 for target in &assign.targets {
                     self.visit_target(target);
                 }
-                // TODO
-                //self.visit_expr(&assign.value);
+                self.visit_expr(&assign.value);
                 return;
             }
             Stmt::For(for_stmt) => {
                 self.visit_target(&for_stmt.target);
-                // TODO
-                //self.visit_expr(&for_stmt.iter);
+                self.visit_expr(&for_stmt.iter);
                 self.visit_body(&for_stmt.body);
                 self.visit_body(&for_stmt.orelse);
                 return;