fix(noParametersOnlyUsedInRecursion): detect recursion in assignment expressions

Author: matanshavit

crates/biome_js_analyze/src/lint/nursery/no_parameters_only_used_in_recursion.rs

@@ -278,6 +278,7 @@ fn get_function_binding(
                     continue;
                 }
 
+                // Check for variable declarator: const foo = () => ...
                 if let Some(declarator) = JsVariableDeclarator::cast_ref(&ancestor)
                     && let Ok(id) = declarator.id()
                     && let Some(any_binding) = id.as_any_js_binding()
@@ -286,6 +287,18 @@ fn get_function_binding(
                     return Some(model.as_binding(js_id_binding));
                 }
 
+                // Check for assignment expression: foo = () => ...
+                if let Some(assignment) = JsAssignmentExpression::cast_ref(&ancestor)
+                    && let Ok(left) = assignment.left()
+                    && let Some(id_assignment) = left.as_any_js_assignment()
+                    && let Some(js_id_assignment) = id_assignment.as_js_identifier_assignment()
+                {
+                    // For assignment expressions, resolve the assignment target to its binding.
+                    // JsIdentifierAssignment implements HasDeclarationAstNode, so model.binding()
+                    // can resolve write references to their bindings.
+                    return model.binding(js_id_assignment);
+                }
+
                 if is_function_like(&ancestor) {
                     break;
                 }

crates/biome_js_analyze/tests/specs/nursery/noParametersOnlyUsedInRecursion/invalid.js

@@ -56,6 +56,13 @@ foo = (n, acc) => {
     return foo(n - 1, acc);
 };
 
+// Separate declaration and assignment with arrow function
+let bar;
+bar = (x, unused) => {
+    if (x === 0) return 0;
+    return bar(x - 1, unused);
+};
+
 // Logical AND operator
 function fnAnd(n, acc) {
     if (n === 0) return 0;