symfony/symfony — pull request #5439 by Tobion (2012-09-05 14:35:30+00:00)
Title: [Routing] compile check for numeric named variables in pattern

Because PHP raises an error for such subpatterns in PCRE and thus would break matching, e.g. this is not allowed as regex '(?<123>.+)'.
So add a compile time check for a non-working pattern like '/{123}'.