bpo-24234: implement complex.__complex__ (GH-27887)

Co-authored-by: Dong-hee Na <donghee.na92@gmail.com>

2 files changed, 40 insertions, 1 deletions

diff --git a/Objects/clinic/complexobject.c.h b/Objects/clinic/complexobject.c.h
index 557fbf9..e7d8065 100644
--- a/Objects/clinic/complexobject.c.h
+++ b/Objects/clinic/complexobject.c.h
@@ -69,6 +69,24 @@ exit:
     return return_value;
 }
 
+PyDoc_STRVAR(complex___complex____doc__,
+"__complex__($self, /)\n"
+"--\n"
+"\n"
+"Convert this value to exact type complex.");
+
+#define COMPLEX___COMPLEX___METHODDEF    \
+    {"__complex__", (PyCFunction)complex___complex__, METH_NOARGS, complex___complex____doc__},
+
+static PyObject *
+complex___complex___impl(PyComplexObject *self);
+
+static PyObject *
+complex___complex__(PyComplexObject *self, PyObject *Py_UNUSED(ignored))
+{
+    return complex___complex___impl(self);
+}
+
 PyDoc_STRVAR(complex_new__doc__,
 "complex(real=0, imag=0)\n"
 "--\n"
@@ -113,4 +131,4 @@ skip_optional_pos:
 exit:
     return return_value;
 }
-/*[clinic end generated code: output=056cac3226d94967 input=a9049054013a1b77]*/
+/*[clinic end generated code: output=6d85094ace15677e input=a9049054013a1b77]*/
diff --git a/Objects/complexobject.c b/Objects/complexobject.c
index 3e47949..cfe6c73 100644
--- a/Objects/complexobject.c
+++ b/Objects/complexobject.c
@@ -693,8 +693,29 @@ complex___format___impl(PyComplexObject *self, PyObject *format_spec)
     return _PyUnicodeWriter_Finish(&writer);
 }
 
+/*[clinic input]
+complex.__complex__
+
+Convert this value to exact type complex.
+[clinic start generated code]*/
+
+static PyObject *
+complex___complex___impl(PyComplexObject *self)
+/*[clinic end generated code: output=e6b35ba3d275dc9c input=3589ada9d27db854]*/
+{
+    if (PyComplex_CheckExact(self)) {
+        Py_INCREF(self);
+        return (PyObject *)self;
+    }
+    else {
+        return PyComplex_FromCComplex(self->cval);
+    }
+}
+
+
 static PyMethodDef complex_methods[] = {
     COMPLEX_CONJUGATE_METHODDEF
+    COMPLEX___COMPLEX___METHODDEF
     COMPLEX___GETNEWARGS___METHODDEF
     COMPLEX___FORMAT___METHODDEF
     {NULL,              NULL}           /* sentinel */