From 627f7214dbe6d21487f1ce6800c6b433be92518e Mon Sep 17 00:00:00 2001
From: William S Fulton <wsf@fultondesigns.co.uk>
Date: Tue, 11 Jan 2022 23:33:22 +0000
Subject: [PATCH] [Python] Add missing Python kwargs builtin support

Accept keyword arguments accessing C++ static member functions when
using -builtin and kwargs feature and Python class staticmethod syntax.
The missing keyword argument support was only when using the
class staticmethod syntax, not when using the flat static method
syntax.
---
 CHANGES.current                                    | 7 +++++++
 Examples/test-suite/kwargs_feature.i               | 1 +
 Examples/test-suite/python/kwargs_feature_runme.py | 3 +++
 Source/Modules/python.cxx                          | 4 ++--
 4 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/CHANGES.current b/CHANGES.current
index 6632f0126..a5a7b8c34 100644
--- a/CHANGES.current
+++ b/CHANGES.current
@@ -7,6 +7,13 @@ the issue number to the end of the URL: https://github.com/swig/swig/issues/
 Version 4.1.0 (in progress)
 ===========================
 
+2022-01-11: wsfulton
+            [Python] Accept keyword arguments accessing static member functions when
+            using -builtin and kwargs feature and Python class staticmethod syntax.
+            The missing keyword argument support was only when using the
+            class staticmethod syntax, such as Klass.memberfunction, and not when
+            using the flat static method syntax, such as Klass_memberfunction.
+
 2022-01-04: juierror
             [Go] #2045 Add support for std::array in std_array.i.
 
diff --git a/Examples/test-suite/kwargs_feature.i b/Examples/test-suite/kwargs_feature.i
index dd5b2638d..6db4d407b 100644
--- a/Examples/test-suite/kwargs_feature.i
+++ b/Examples/test-suite/kwargs_feature.i
@@ -27,6 +27,7 @@
 
     virtual int foo(int a = 1, int b = 0) {return a + b; }
     static int statfoo(int a = 1, int b = 0) {return a + b; }
+    static int statfoo_onearg(int x = 10) {return x + x; }
 
     static Foo *create(int a = 1, int b = 0) 
     {
diff --git a/Examples/test-suite/python/kwargs_feature_runme.py b/Examples/test-suite/python/kwargs_feature_runme.py
index d07525ffc..677c9ebd8 100644
--- a/Examples/test-suite/python/kwargs_feature_runme.py
+++ b/Examples/test-suite/python/kwargs_feature_runme.py
@@ -18,6 +18,9 @@ if f.foo(b=1, a=2) != 3:
 if Foo.statfoo(b=2) != 3:
     raise RuntimeError
 
+if Foo.statfoo_onearg(x=4) != 8:
+    raise RuntimeError
+
 if f.efoo(b=2) != 3:
     raise RuntimeError
 
diff --git a/Source/Modules/python.cxx b/Source/Modules/python.cxx
index 8682e6917..9046edcfb 100644
--- a/Source/Modules/python.cxx
+++ b/Source/Modules/python.cxx
@@ -4727,6 +4727,7 @@ public:
       Swig_restore(n);
     }
 
+    int kw = (check_kwargs(n) && !Getattr(n, "sym:overloaded")) ? 1 : 0;
     if (builtin && in_class) {
       if ((GetFlagAttr(n, "feature:extend") || checkAttribute(n, "access", "public"))
 	  && !Getattr(class_members, symname)) {
@@ -4741,7 +4742,7 @@ public:
 	else if (funpack && argcount == 1)
 	  Append(pyflags, "METH_O");
 	else
-	  Append(pyflags, "METH_VARARGS");
+	  Append(pyflags, kw ? "METH_VARARGS|METH_KEYWORDS" : "METH_VARARGS");
 	// Cast via void(*)(void) to suppress GCC -Wcast-function-type warning.
 	// Python should always call the function correctly, but the Python C
 	// API requires us to store it in function pointer of a different type.
@@ -4767,7 +4768,6 @@ public:
       String *staticfunc_name = NewString(fastproxy ? "_swig_new_static_method" : "staticmethod");
       bool fast = (fastproxy && !have_addtofunc(n)) || Getattr(n, "feature:callback");
       if (!fast || olddefs) {
-	int kw = (check_kwargs(n) && !Getattr(n, "sym:overloaded")) ? 1 : 0;
 	String *parms = make_pyParmList(n, false, false, kw);
 	String *callParms = make_pyParmList(n, false, true, kw);
 	Printv(f_shadow, "\n", tab4, "@staticmethod", NIL);