bug #28712 [Form] reverse transform RFC 3339 formatted dates (xabbuh)

This PR was merged into the 2.8 branch.

Discussion
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[Form] reverse transform RFC 3339 formatted dates

| Q             | A
| ------------- | ---
| Branch?       | 2.8
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #28699
| License       | MIT
| Doc PR        |

Technically, dates formatted according to the HTML specifications do not
contain any timezone information. But since our DateTimeType used to
contain this information in the passed, users had configure their JS
libraries to accept (and create) dates in that format.

To not break BC we should accept these dates and silently ignore the
additional timezone information.

Commits
-------

503239f75e reverse transform RFC 3339 formatted dates

Author: nicolas-grekas

Extension/Core/DataTransformer/DateTimeToHtml5LocalDateTimeTransformer.php

@@ -81,7 +81,9 @@ public function reverseTransform($dateTimeLocal)
             return;
         }
 
-        if (!preg_match('/^(\d{4})-(\d{2})-(\d{2})[T ]\d{2}:\d{2}(?::\d{2})?$/', $dateTimeLocal, $matches)) {
+        // to maintain backwards compatibility we do not strictly validate the submitted date
+        // see https://github.com/symfony/symfony/issues/28699
+        if (!preg_match('/^(\d{4})-(\d{2})-(\d{2})[T ]\d{2}:\d{2}(?::\d{2})?/', $dateTimeLocal, $matches)) {
             throw new TransformationFailedException(sprintf('The date "%s" is not a valid date.', $dateTimeLocal));
         }
 

Tests/Extension/Core/DataTransformer/DateTimeToHtml5LocalDateTimeTransformerTest.php

@@ -51,6 +51,10 @@ public function reverseTransformProvider()
             array('UTC', 'UTC', '2010-02-03 04:05:00 UTC', '2010-02-03T04:05'),
             array('America/New_York', 'Asia/Hong_Kong', '2010-02-03 04:05:00 America/New_York', '2010-02-03T17:05'),
             array('Europe/Amsterdam', 'Europe/Amsterdam', '2013-08-21 10:30:00 Europe/Amsterdam', '2013-08-21T10:30:00'),
+            array('UTC', 'UTC', '2018-09-15T10:00:00Z', '2018-09-15T10:00:00Z'),
+            array('Europe/Berlin', 'Europe/Berlin', '2018-09-15T10:00:00+02:00', '2018-09-15T10:00:00+02:00'),
+            array('Europe/Berlin', 'Europe/Berlin', '2018-09-15T10:00:00+0200', '2018-09-15T10:00:00+0200'),
+            array('UTC', 'UTC', '2018-10-03T10:00:00.000Z', '2018-10-03T10:00:00.000Z'),
         );
     }