Generate custom conversion code for enums.

This not only fixes bugs like auto-conversion of std::map[enum, enum] but also
fixes a bug where the compiler-chosen type of int for the enum may not have been
long.

Cython/Compiler/PyrexTypes.py

@@ -3600,8 +3600,6 @@ class CEnumType(CType):
     is_enum = 1
     signed = 1
     rank = -1 # Ranks below any integer type
-    to_py_function = "PyInt_FromLong"
-    from_py_function = "PyInt_AsLong"
 
     def __init__(self, name, cname, typedef_flag):
         self.name = name
@@ -3629,6 +3627,22 @@ class CEnumType(CType):
             base_code = public_decl(base_code, dll_linkage)
         return self.base_declaration_code(base_code, entity_code)
 
+    def create_to_py_utility_code(self, env):
+        self.to_py_function = "__Pyx_PyInt_From_" + self.specialization_name()
+        env.use_utility_code(TempitaUtilityCode.load_cached(
+            "CIntToPy", "TypeConversion.c",
+            context={"TYPE": self.empty_declaration_code(),
+                     "TO_PY_FUNCTION": self.to_py_function}))
+        return True
+
+    def create_from_py_utility_code(self, env):
+        self.from_py_function = "__Pyx_PyInt_As_" + self.specialization_name()
+        env.use_utility_code(TempitaUtilityCode.load_cached(
+            "CIntFromPy", "TypeConversion.c",
+            context={"TYPE": self.empty_declaration_code(),
+                     "FROM_PY_FUNCTION": self.from_py_function}))
+        return True
+
     def from_py_call_code(self, source_code, result_code, error_pos, code,
                           from_py_function=None, error_condition=None):
         rhs = "%s(%s)" % (

Cython/Utility/TypeConversion.c

@@ -536,7 +536,7 @@ static CYTHON_INLINE PyObject* {{TO_PY_FUNCTION}}({{TYPE}} value);
 /////////////// CIntToPy ///////////////
 
 static CYTHON_INLINE PyObject* {{TO_PY_FUNCTION}}({{TYPE}} value) {
-    const {{TYPE}} neg_one = ({{TYPE}}) -1, const_zero = 0;
+    const {{TYPE}} neg_one = ({{TYPE}}) -1, const_zero = ({{TYPE}}) 0;
     const int is_unsigned = neg_one > const_zero;
     if (is_unsigned) {
         if (sizeof({{TYPE}}) < sizeof(long)) {
@@ -607,7 +607,7 @@ static CYTHON_INLINE {{TYPE}} {{FROM_PY_FUNCTION}}(PyObject *);
 {{py: from Cython.Utility import pylong_join }}
 
 static CYTHON_INLINE {{TYPE}} {{FROM_PY_FUNCTION}}(PyObject *x) {
-    const {{TYPE}} neg_one = ({{TYPE}}) -1, const_zero = 0;
+    const {{TYPE}} neg_one = ({{TYPE}}) -1, const_zero = ({{TYPE}}) 0;
     const int is_unsigned = neg_one > const_zero;
 #if PY_MAJOR_VERSION < 3
     if (likely(PyInt_Check(x))) {
@@ -627,7 +627,7 @@ static CYTHON_INLINE {{TYPE}} {{FROM_PY_FUNCTION}}(PyObject *x) {
 #if CYTHON_USE_PYLONG_INTERNALS
             const digit* digits = ((PyLongObject*)x)->ob_digit;
             switch (Py_SIZE(x)) {
-                case  0: return 0;
+                case  0: return ({{TYPE}}) 0;
                 case  1: __PYX_VERIFY_RETURN_INT({{TYPE}}, digit, digits[0])
                 {{for _size in (2, 3, 4)}}
                 case {{_size}}:
@@ -635,7 +635,7 @@ static CYTHON_INLINE {{TYPE}} {{FROM_PY_FUNCTION}}(PyObject *x) {
                         if (8 * sizeof(unsigned long) > {{_size}} * PyLong_SHIFT) {
                             __PYX_VERIFY_RETURN_INT({{TYPE}}, unsigned long, {{pylong_join(_size, 'digits')}})
                         } else if (8 * sizeof({{TYPE}}) >= {{_size}} * PyLong_SHIFT) {
-                            return {{pylong_join(_size, 'digits', TYPE)}};
+                            return ({{TYPE}}) {{pylong_join(_size, 'digits', TYPE)}};
                         }
                     }
                     break;
@@ -666,7 +666,7 @@ static CYTHON_INLINE {{TYPE}} {{FROM_PY_FUNCTION}}(PyObject *x) {
 #if CYTHON_USE_PYLONG_INTERNALS
             const digit* digits = ((PyLongObject*)x)->ob_digit;
             switch (Py_SIZE(x)) {
-                case  0: return 0;
+                case  0: return ({{TYPE}}) 0;
                 case -1: __PYX_VERIFY_RETURN_INT({{TYPE}}, sdigit, -(sdigit) digits[0])
                 case  1: __PYX_VERIFY_RETURN_INT({{TYPE}},  digit, +digits[0])
                 {{for _size in (2, 3, 4)}}
@@ -676,7 +676,7 @@ static CYTHON_INLINE {{TYPE}} {{FROM_PY_FUNCTION}}(PyObject *x) {
                         if (8 * sizeof(unsigned long) > {{_size}} * PyLong_SHIFT) {
                             __PYX_VERIFY_RETURN_INT({{TYPE}}, {{'long' if _case < 0 else 'unsigned long'}}, {{'-(long) ' if _case < 0 else ''}}{{pylong_join(_size, 'digits')}})
                         } else if (8 * sizeof({{TYPE}}) - 1 > {{_size}} * PyLong_SHIFT) {
-                            return {{'-' if _case < 0 else ''}}{{pylong_join(_size, 'digits', TYPE)}};
+                            return ({{TYPE}}) {{'-' if _case < 0 else ''}}{{pylong_join(_size, 'digits', TYPE)}};
                         }
                     }
                     break;

tests/run/cpp_stl_conversion.pyx

@@ -207,3 +207,16 @@ def test_nested(o):
     """
     cdef map[pair[double, double], vector[int]] m = o
     return m
+
+cpdef enum Color:
+    RED = 0
+    GREEN
+    BLUE
+
+def test_enum_map(o):
+    """
+    >>> test_enum_map({RED: GREEN})
+    {0: 1}
+    """
+    cdef map[Color, Color] m = o
+    return m