Allow @final class decorator in pure mode. Was previously rejected for Python...

Allow @final class decorator in pure mode. Was previously rejected for Python classes with an @cclass decorator.
Closes #2040.

CHANGES.rst

@@ -79,6 +79,9 @@ Bugs fixed
 * Some declaration types in ``libc.limits`` were corrected.
   Patch by Jeroen Demeyer.  (Github issue #2016)
 
+* ``@cython.final`` was not accepted on Python classes with an ``@cython.cclass``
+  decorator.  (Github issue #2040)
+
 Other changes
 -------------
 

Cython/Compiler/ParseTreeTransforms.py

@@ -1033,7 +1033,8 @@ class InterpretCompilerDirectives(CythonTransform):
         directives = []
         realdecs = []
         both = []
-        for dec in node.decorators:
+        # Decorators coming first take precedence.
+        for dec in node.decorators[::-1]:
             new_directives = self.try_to_parse_directives(dec.decorator)
             if new_directives is not None:
                 for directive in new_directives:
@@ -1043,15 +1044,17 @@ class InterpretCompilerDirectives(CythonTransform):
                             directives.append(directive)
                         if directive[0] == 'staticmethod':
                             both.append(dec)
+                    # Adapt scope type based on decorators that change it.
+                    if directive[0] == 'cclass' and scope_name == 'class':
+                        scope_name = 'cclass'
             else:
                 realdecs.append(dec)
-        if realdecs and isinstance(node, (Nodes.CFuncDefNode, Nodes.CClassDefNode, Nodes.CVarDefNode)):
+        if realdecs and (scope_name == 'cclass' or
+                         isinstance(node, (Nodes.CFuncDefNode, Nodes.CClassDefNode, Nodes.CVarDefNode))):
             raise PostParseError(realdecs[0].pos, "Cdef functions/classes cannot take arbitrary decorators.")
-        else:
-            node.decorators = realdecs + both
+        node.decorators = realdecs[::-1] + both[::-1]
         # merge or override repeated directives
         optdict = {}
-        directives.reverse() # Decorators coming first take precedence
         for directive in directives:
             name, value = directive
             if name in optdict:

tests/run/pure_py.py

@@ -341,3 +341,22 @@ def ccall_except_check_always(x):
     if x == 0:
         raise ValueError
     return x+1
+
+
+@cython.final
+@cython.cclass
+class CClass(object):
+    """
+    >>> c = CClass(2)
+    >>> c.get_attr()
+    int
+    2
+    """
+    cython.declare(attr=cython.int)
+
+    def __init__(self, attr):
+        self.attr = attr
+
+    def get_attr(self):
+        print(cython.typeof(self.attr))
+        return self.attr