fix gh-43: type func_num_args expressions

src/Optimizer/FuncCallOptimizer.php

@@ -1137,10 +1137,15 @@ trait FuncCallOptimizer
         $funcDef = $this->functionDef;
         foreach ($funcDef->argInfoList as $i => $argInfo) {
             if ($argInfo->variadic) {
-                return '(' . $argInfo->name . '.count() + ' . $i . ')';
+                // Array::count() is size_t, while func_num_args() is a PHP
+                // integer. Keep the folded expression in the exact native
+                // type so a surrounding toInt() cannot hit ambiguous C++
+                // scalar overloads.
+                return '(static_cast<' . Type::INT . '>(' . $argInfo->name . '.count()) + '
+                    . $this->genIntegerLiteral($i) . ')';
             }
         }
-        return (string) count($funcDef->argInfoList);
+        return $this->genIntegerLiteral(count($funcDef->argInfoList));
     }
 
     protected function genFunctionExists(string $name, Node\Expr\FuncCall $expr, array $config): string|false

tests/compiler/functions/func_num_args-return.phpt

@@ -0,0 +1,59 @@
+--TEST--
+func_num_args static count can be returned without leaking an ambiguous C++ integer literal
+--FILE--
+<?php
+
+function staticArgumentCountUntyped($value = null)
+{
+    return func_num_args();
+}
+
+function staticArgumentCountTyped($first = null, $second = 5): int
+{
+    return func_num_args();
+}
+
+function staticVariadicArgumentCount($first = null, ...$rest)
+{
+    return func_num_args();
+}
+
+class StaticArgumentCount
+{
+    public function method($value = null)
+    {
+        return func_num_args();
+    }
+
+    public static function staticMethod($value = null): int
+    {
+        return func_num_args();
+    }
+}
+
+function main(): void
+{
+    // TypePHP intentionally reports the statically materialized parameter
+    // slots, including omitted optional parameters filled by their defaults.
+    var_dump(staticArgumentCountUntyped());
+    var_dump(staticArgumentCountUntyped(10));
+    var_dump(staticArgumentCountTyped());
+    var_dump(staticArgumentCountTyped(10));
+
+    var_dump(staticVariadicArgumentCount());
+    var_dump(staticVariadicArgumentCount(10, 20, 30));
+
+    $object = new StaticArgumentCount();
+    var_dump($object->method());
+    var_dump(StaticArgumentCount::staticMethod());
+}
+?>
+--EXPECT--
+int(1)
+int(1)
+int(2)
+int(2)
+int(1)
+int(3)
+int(1)
+int(1)