Patch-Source: https://github.com/open-telemetry/opentelemetry-php-instrumentation/pull/153

diff --git a/ext/otel_observer.c b/ext/otel_observer.c
index b3138d1..080db36 100644
--- ext/otel_observer.c
+++ ext/otel_observer.c
@@ -152,6 +152,23 @@ static bool func_has_withspan_attribute(zend_execute_data *ex) {
     return attr != NULL;
 }
 
+/*
+ * OpenTelemetry attribute values may only be of limited types
+ */
+static bool is_valid_attribute_value(zval *val) {
+    switch (Z_TYPE_P(val)) {
+    case IS_STRING:
+    case IS_LONG:   // Numeric (integer)
+    case IS_DOUBLE: // Numeric (floating point)
+    case IS_TRUE:
+    case IS_FALSE: // Boolean
+    case IS_ARRAY:
+        return true;
+    default:
+        return false;
+    }
+}
+
 // get function args. any args with the
 // SpanAttributes attribute are added to the attributes HashTable
 static void func_get_args(zval *zv, HashTable *attributes,
@@ -198,7 +215,7 @@ static void func_get_args(zval *zv, HashTable *attributes,
                     zend_string *arg_name = ex->func->op_array.vars[i];
                     zend_attribute *attribute =
                         find_spanattribute_attribute(ex->func, i);
-                    if (attribute != NULL) {
+                    if (attribute != NULL && is_valid_attribute_value(p)) {
                         if (attribute->argc) {
                             zend_string *key = Z_STR(attribute->args[0].value);
                             zend_hash_del(attributes, key);
@@ -1149,5 +1166,8 @@ void opentelemetry_observer_init(INIT_FUNC_ARGS) {
         zend_observer_fcall_register(observer_fcall_init);
         op_array_extension =
             zend_get_op_array_extension_handle("opentelemetry");
+#if PHP_VERSION_ID >= 80400
+        zend_get_internal_function_extension_handle("opentelemetry");
+#endif
     }
 }
diff --git a/ext/tests/span_attribute/function_params_non_simple.phpt b/ext/tests/span_attribute/function_params_non_simple.phpt
index f637ab1..fc53f51 100644
--- ext/tests/span_attribute/function_params_non_simple.phpt
+++ ext/tests/span_attribute/function_params_non_simple.phpt
@@ -1,5 +1,5 @@
 --TEST--
-Check if function non-simple types can be passed as function params
+Check if function non-simple types are ignored
 --SKIPIF--
 <?php if (PHP_VERSION_ID < 80100) die('skip requires PHP >= 8.1'); ?>
 --EXTENSIONS--
@@ -28,28 +28,20 @@ function foo(
 }
 
 foo(
-    ['foo' => 'bar'],
-    new \stdClass(),
-    function(){return 'fn';},
-    null,
+    one: ['foo' => 'bar'],
+    two: new \stdClass(),
+    three: function(){return 'fn';},
+    four: null,
 );
 ?>
 --EXPECTF--
 string(3) "pre"
-array(4) {
+array(1) {
   ["one"]=>
   array(1) {
     ["foo"]=>
     string(3) "bar"
   }
-  ["two"]=>
-  object(stdClass)#1 (0) {
-  }
-  ["three"]=>
-  object(Closure)#2 (0) {
-  }
-  ["four"]=>
-  NULL
 }
 string(3) "foo"
 string(4) "post"
\ No newline at end of file