Internationalized Domain Name support in FILTER_VALIDATE_URL

Hello, I'm working on enhancing the FILTER_VALIDATE_URL filter ( https://github.com/php/php-src/pull/826). The current implementation does not support validation of internationalized domain names (i.e: http://www.académie-française.fr/ <http://www.xn--acadmie-franaise-npb1a.fr/>). Support of IDN validation can be easily added using ICU's uidna_toASCII() function. Is it acceptable to add a dependency to ICU for ext/filter? Another option is to add a HAVE_ICU constant in main/php_config.h and to validate IDN only if ICU is present. What strategy is preferred? -- Kévin Dunglas http://dunglas.fr