[5.3] Revert #16692 and make date_format work with ISO8601 again (#16845

)

* Revert "Merge pull request #16692 from rohitsubedi/rohitsubedi-patch-1"

This reverts commit 4c70ab0, reversing
changes made to e91f04b.

* validation: add a few more date_format tests

Showing off how Y-m-d\TH:i:sP matches multple valid ISO 8601 date formats.

* validation: add test showing 00-00-01 passes for Y-m-d

It's unexpected for Y to match two-digit dates

src/Illuminate/Validation/Validator.php

@@ -1841,9 +1841,9 @@ protected function validateDateFormat($attribute, $value, $parameters)
             return false;
         }
 
-        $date = DateTime::createFromFormat($parameters[0], $value);
+        $parsed = date_parse_from_format($parameters[0], $value);
 
-        return $date && $date->format($parameters[0]) === $value;
+        return $parsed['error_count'] === 0 && $parsed['warning_count'] === 0;
     }
 
     /**

tests/Validation/ValidationValidatorTest.php

@@ -2121,8 +2121,23 @@ public function testValidateDateAndFormat()
         $v = new Validator($trans, ['x' => '22000-01-01'], ['x' => 'date_format:Y-m-d']);
         $this->assertTrue($v->fails());
 
+        $v = new Validator($trans, ['x' => '00-01-01'], ['x' => 'date_format:Y-m-d']);
+        $this->assertTrue($v->passes());
+
         $v = new Validator($trans, ['x' => ['Not', 'a', 'date']], ['x' => 'date_format:Y-m-d']);
         $this->assertTrue($v->fails());
+
+        $v = new Validator($trans, ['x' => '2000-01-01T00:00:00Z'], ['x' => 'date_format:Y-m-d\TH:i:sP']);
+        $this->assertTrue($v->passes());
+
+        $v = new Validator($trans, ['x' => '2000-01-01T00:00:00Z'], ['x' => 'date_format:Y-m-d\TH:i:sP']);
+        $this->assertTrue($v->passes());
+
+        $v = new Validator($trans, ['x' => '2000-01-01T00:00:00+00'], ['x' => 'date_format:Y-m-d\TH:i:sP']);
+        $this->assertTrue($v->passes());
+
+        $v = new Validator($trans, ['x' => '2000-01-01T00:00:00+00:30'], ['x' => 'date_format:Y-m-d\TH:i:sP']);
+        $this->assertTrue($v->passes());
     }
 
     public function testBeforeAndAfter()