Validate functions in nested task closures

Author: realFlowControl

src/scheduler.c

@@ -158,6 +158,16 @@ static bool php_parallel_scheduler_functions(zend_function *function, php_parall
 				required = zend_fetch_function(Z_STR_P(name + 2));
 			}
 			break;
+		case ZEND_DECLARE_LAMBDA_FUNCTION: {
+			zend_string   *key;
+			zend_function *nested;
+
+			PARALLEL_COPY_OPLINE_TO_FUNCTION(function, opline, &key, &nested);
+
+			if (!php_parallel_scheduler_functions(nested, error)) {
+				return false;
+			}
+		} break;
 		}
 
 		if (name) {

tests/base/init_fcall_fix_004.phpt

@@ -0,0 +1,24 @@
+--TEST--
+Missing function in nested closure fails task before execution
+--SKIPIF--
+<?php
+if (!extension_loaded('parallel')) {
+	echo 'skip';
+}
+?>
+--FILE--
+<?php
+function dummy_func(): string { return 'value'; }
+
+$runtime = new \parallel\Runtime();
+try {
+	$runtime->run(function(){
+		echo "task executed\n";
+		return (static fn() => dummy_func())();
+	})->value();
+} catch (\parallel\Runtime\Error\IllegalInstruction $e) {
+	echo $e->getMessage();
+}
+?>
+--EXPECT--
+Task requires function dummy_func(), but dummy_func() is not defined in this Runtime. Define it in the Runtime bootstrap or pass it as a task argument with Closure::fromCallable('dummy_func').