Emit init code before body code (GH-3166)

The test crash in cdef_multiple_inheritance has to do with a change in the method assignment. In the old version, the code

cdef class Both(CBase, PyBase):
    cdef dict __dict__
    cdef c_method(self):
        return "Both"
    cpdef cp_method(self):
        return "Both"
    def call_c_method(self):
        return self.c_method()

would assign cp_method and call_c_method to a PyMethodDef struct. In the new code only call_c_method is assigned in the PyMethodDef struct, but both are assigned to the __pyx_ptype...Both->tp_dict inside __Pyx_Init_Globals which happens while __pyx_ptype...Both is still NULL. The assignment __pyx_ptype...Both = &__pyx_type...Both happens in the next fragment, a few lines down.

This PR reorders the fragments so that __pyx_type...Both is set up before the method assignments and does not seem to cause any new test failures.

Cython/Compiler/Nodes.py

@@ -5036,8 +5036,6 @@ class CClassDefNode(ClassDefNode):
         # This is needed to generate evaluation code for
         # default values of method arguments.
         code.mark_pos(self.pos)
-        if self.body:
-            self.body.generate_execution_code(code)
         if not self.entry.type.early_init:
             if self.type_init_args:
                 self.type_init_args.generate_evaluation_code(code)
@@ -5065,6 +5063,8 @@ class CClassDefNode(ClassDefNode):
                 self.type_init_args.free_temps(code)
 
             self.generate_type_ready_code(self.entry, code, True)
+        if self.body:
+            self.body.generate_execution_code(code)
 
     # Also called from ModuleNode for early init types.
     @staticmethod

tests/run/cdef_multiple_inheritance.pyx

+cimport cython
+
 cdef class CBase(object):
     cdef int a
     cdef c_method(self):
@@ -9,7 +11,8 @@ class PyBase(object):
     def py_method(self):
         return "PyBase"
 
-cdef class Both(CBase, PyBase):
+@cython.binding(True)
+cdef class BothBound(CBase, PyBase):
     cdef dict __dict__
     """
     >>> b = Both()
@@ -32,7 +35,7 @@ cdef class Both(CBase, PyBase):
     def call_c_method(self):
         return self.c_method()
 
-cdef class BothSub(Both):
+cdef class BothSub(BothBound):
     """
     >>> b = BothSub()
     >>> b.py_method()
@@ -43,3 +46,27 @@ cdef class BothSub(Both):
     'Both'
     """
     pass
+
+@cython.binding(False)
+cdef class BothUnbound(CBase, PyBase):
+    cdef dict __dict__
+    """
+    >>> b = Both()
+    >>> b.py_method()
+    'PyBase'
+    >>> b.cp_method()
+    'Both'
+    >>> b.call_c_method()
+    'Both'
+
+    >>> isinstance(b, CBase)
+    True
+    >>> isinstance(b, PyBase)
+    True
+    """
+    cdef c_method(self):
+        return "Both"
+    cpdef cp_method(self):
+        return "Both"
+    def call_c_method(self):
+        return self.c_method()