Merge branch '5.0' into 5.1

* 5.0: (28 commits)
  [Cache] $lifetime cannot be null
  [Serializer] minor cleanup
  fix merge
  Run PHP 8 as 7.4.99
  Remove calls to deprecated ReflectionParameter::getClass().
  [VarDumper] fix PHP 8 support
  Add php 8 to travis.
  [Cache] Accessing undefined constants raises an Error in php8
  [Cache] allow DBAL v3
  Skip Doctrine DBAL on php 8 until we have a compatible version.
  [DomCrawler] Catch expected ValueError.
  Made method signatures compatible with their corresponding traits.
  [ErrorHandler] Apply php8 fixes from Debug component.
  [DomCrawler] Catch expected ValueError.
  [Validator] Catch expected ValueError.
  [VarDumper] ReflectionFunction::isDisabled() is deprecated.
  [BrowserKit] Raw body with custom Content-Type header
  [PropertyAccess] Parse php 8 TypeErrors correctly.
  [Intl] Fix call to ReflectionProperty::getValue() for static properties.
  [HttpKernel] Prevent calling method_exists() with non-string values.
  ...

Author: nicolas-grekas

Constraints/LengthValidator.php

@@ -44,8 +44,14 @@ public function validate($value, Constraint $constraint)
             $stringValue = ($constraint->normalizer)($stringValue);
         }
 
-        if (!$invalidCharset = !@mb_check_encoding($stringValue, $constraint->charset)) {
-            $length = mb_strlen($stringValue, $constraint->charset);
+        try {
+            $invalidCharset = !@mb_check_encoding($stringValue, $constraint->charset);
+        } catch (\ValueError $e) {
+            if (!str_starts_with($e->getMessage(), 'mb_check_encoding(): Argument #2 ($encoding) must be a valid encoding')) {
+                throw $e;
+            }
+
+            $invalidCharset = true;
         }
 
         if ($invalidCharset) {
@@ -59,6 +65,8 @@ public function validate($value, Constraint $constraint)
             return;
         }
 
+        $length = mb_strlen($stringValue, $constraint->charset);
+
         if (null !== $constraint->max && $length > $constraint->max) {
             $this->context->buildViolation($constraint->min == $constraint->max ? $constraint->exactMessage : $constraint->maxMessage)
                 ->setParameter('{{ value }}', $this->formatValue($stringValue))