Prefix AST symbols with _Py_. Fixes #1637022.

Misc/NEWS

@@ -12,6 +12,8 @@ What's New in Python 2.5.1c1?
 Core and builtins
 -----------------
 
+- Bug #1637022: Prefix AST symbols with _Py_.
+
 - Prevent seg fault on shutdown which could occur if an object
   raised a warning.
 

Parser/asdl_c.py

@@ -260,7 +260,12 @@ class PrototypeVisitor(EmitVisitor):
             argstr += ", PyArena *arena"
         else:
             argstr = "PyArena *arena"
-        self.emit("%s %s(%s);" % (ctype, name, argstr), 0)
+        margs = "a0"
+        for i in range(1, len(args)+1):
+            margs += ", a%d" % i
+        self.emit("#define %s(%s) _Py_%s(%s)" % (name, margs, name, margs), 0,
+                reflow = 0)
+        self.emit("%s _Py_%s(%s);" % (ctype, name, argstr), 0)
 
     def visitProduct(self, prod, name):
         self.emit_function(name, get_c_type(name),