Merge pull request #2177 from AntyMew/master

Allow `NULL` to be coerced to a pointer to a fused type

Cython/Compiler/ExprNodes.py

@@ -850,6 +850,9 @@ class ExprNode(Node):
 
             if src_type.is_fused:
                 error(self.pos, "Type is not specialized")
+            elif src_type.is_null_ptr and dst_type.is_ptr:
+                # NULL can be implicitly cast to any pointer type
+                return self
             else:
                 error(self.pos, "Cannot coerce to a type that is not specialized")
 

tests/run/fused_types.pyx

@@ -119,6 +119,38 @@ def test_fused_with_pointer():
     print
     print fused_with_pointer(string_array).decode('ascii')
 
+cdef fused_type1* fused_pointer_except_null(fused_type1 x) except NULL:
+    if fused_type1 is string_t:
+        assert(bool(x))
+    else:
+        assert(x < 10)
+    return &x
+
+def test_fused_pointer_except_null(value):
+    """
+    >>> test_fused_pointer_except_null(1)
+    1
+    >>> test_fused_pointer_except_null(2.0)
+    2.0
+    >>> test_fused_pointer_except_null(b'foo')
+    foo
+    >>> test_fused_pointer_except_null(16)
+    Traceback (most recent call last):
+    AssertionError
+    >>> test_fused_pointer_except_null(15.1)
+    Traceback (most recent call last):
+    AssertionError
+    >>> test_fused_pointer_except_null(b'')
+    Traceback (most recent call last):
+    AssertionError
+    """
+    if isinstance(value, int):
+        print fused_pointer_except_null(<cython.int>value)[0]
+    elif isinstance(value, float):
+        print fused_pointer_except_null(<cython.float>value)[0]
+    elif isinstance(value, bytes):
+        print fused_pointer_except_null(<string_t>value)[0].decode('ascii')
+
 include "cythonarrayutil.pxi"
 
 cpdef cython.integral test_fused_memoryviews(cython.integral[:, ::1] a):