Fix functors (wrapped as __call__) when using -builtin -modern -fastunpack.

CHANGES.current

@@ -7,6 +7,9 @@ the issue number to the end of the URL: https://github.com/swig/swig/issues/
 Version 4.0.0 (in progress)
 ===========================
 
+2018-09-19: wsfulton
+            [Python] Fix functors (wrapped as __call__) when using -builtin -modern -fastunpack.
+
 2018-09-02: andreas.gaeer,tkrasnukha
             [Python] #1321 Fix assert in PyTuple_GET_SIZE in debug interpreter builds of python-3.7
             when calling tp_new.

Examples/test-suite/functors.i

@@ -0,0 +1,33 @@
+%module functors
+
+// Rename operator() only if the language does not already do this by default
+#if defined(SWIGCSHARP) || defined(SWIGGO) || defined(SWIGGUILE) || defined(SWIGJAVA) || defined(SWIGJAVASCRIPT) || defined(SWIGPHP) || defined(SWIGSCILAB) || defined(SWIGTCL)
+%rename(Funktor) operator();
+#endif
+
+%inline %{
+class Functor0 {
+  int num;
+public:
+  Functor0(int num) : num(num) {}
+  int operator()() { return -num; }
+  int operate() { return this->operator()(); }
+};
+
+class Functor1 {
+  int num;
+public:
+  Functor1(int num) : num(num) {}
+  int operator()(int x) { return num + x; }
+  int operate(int x) { return this->operator()(x); }
+};
+
+class Functor2 {
+  int num;
+public:
+  Functor2(int num) : num(num) {}
+  int operator()(int x, int x2) { return num + x + x2; }
+  int operate(int x, int x2) { return this->operator()(x, x2); }
+};
+%}
+

Examples/test-suite/python/functors_runme.py

@@ -0,0 +1,12 @@
+from functors import *
+
+a = Functor0(10)
+b = Functor1(10)
+c = Functor2(10)
+
+if a()!=-10:
+    raise RuntimeError("a failed")
+if b(1)!=11:
+    raise RuntimeError("b failed")
+if c(1, 2)!=13:
+    raise RuntimeError("c failed")

Examples/test-suite/python/operator_overload_runme.py

@@ -75,3 +75,10 @@ if not -a==a:
 if not -b==Op(-5):
   raise RuntimeError("-b==Op(-5)")
 
+# test functors
+if not b()==5:
+  raise RuntimeError("functor")
+if not b(1)==6:
+  raise RuntimeError("functor")
+if not b(1, 2)==8:
+  raise RuntimeError("functor")

Source/Modules/python.cxx

@@ -3020,8 +3020,9 @@ public:
 	  }
 	  Printf(parse_args, "if ((nobjs < %d) || (nobjs > %d)) SWIG_fail;\n", num_required, num_arguments);
 	} else {
+	  int is_tp_call = Equal(Getattr(n, "feature:python:slot"), "tp_call");
 	  Printv(f->def, linkage, wrap_return, wname, "(PyObject *", self_param, ", PyObject *args", builtin_kwargs, ") {", NIL);
-	  if (onearg && !builtin_ctor) {
+	  if (onearg && !builtin_ctor && !is_tp_call) {
 	    Printf(parse_args, "if (!args) SWIG_fail;\n");
 	    Append(parse_args, "swig_obj[0] = args;\n");
 	  } else if (!noargs) {