# HG changeset patch
# User Julien Cristau <julien.cristau@logilab.fr>
# Date 1446053970 0
# Node ID 3d948d35d94fdd6c0d9f2df0b4e44c8e0673f4a1
# Parent  b4beaf0bccea668636b2e22df00e2f6c9434f212
[migration] re-try without print_function when compiling a script fails

As part of the python3 porting we added the __future__.print_function import to
cubicweb.migration.  That started affecting all migration scripts it runs,
which may not be prepared.  So if compiling a script results in SyntaxError,
try again without the print_function flag.

Closes #7935030

diff -r b4beaf0bccea -r 3d948d35d94f migration.py
--- a/migration.py	Wed Sep 23 15:32:17 2015 +0200
+++ b/migration.py	Wed Oct 28 17:39:30 2015 +0000
@@ -26,6 +26,7 @@
 import tempfile
 from os.path import exists, join, basename, splitext
 from itertools import chain
+from warnings import warn
 
 from six import string_types
 
@@ -350,7 +351,14 @@
                 pyname = splitext(basename(migrscript))[0]
             scriptlocals['__name__'] = pyname
             with open(migrscript, 'rb') as fobj:
-                code = compile(fobj.read(), migrscript, 'exec')
+                fcontent = fobj.read()
+            try:
+                code = compile(fcontent, migrscript, 'exec')
+            except SyntaxError:
+                # try without print_function
+                code = compile(fcontent, migrscript, 'exec', 0, True)
+                warn('[3.22] script %r should be updated to work with print_function'
+                     % migrscript, DeprecationWarning)
             exec(code, scriptlocals)
             if funcname is not None:
                 try: