bug symfony#36859 [Validator] allow passing a validator to Validation::createCallable() (nicolas-grekas)

This PR was merged into the 5.1 branch.

Discussion
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[Validator] allow passing a validator to Validation::createCallable()

| Q             | A
| ------------- | ---
| Branch?       | 5.1
| Bug fix?      | yes
| New feature?  | no
| Deprecations? | no
| Tickets       | -
| License       | MIT
| Doc PR        | -

As spotted by @stof in symfony#31466 (comment)

Commits
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1357cbf [Validator] allow passing a validator to Validation::createCallable()

Author: nicolas-grekas

src/Symfony/Component/Validator/Validation.php

@@ -23,10 +23,21 @@ final class Validation
 {
     /**
      * Creates a callable chain of constraints.
+     *
+     * @param Constraint|ValidatorInterface|null $constraintOrValidator
      */
-    public static function createCallable(Constraint ...$constraints): callable
+    public static function createCallable($constraintOrValidator = null, Constraint ...$constraints): callable
     {
-        $validator = self::createValidator();
+        $validator = $constraintOrValidator;
+
+        if ($constraintOrValidator instanceof Constraint) {
+            $constraints = \func_get_args();
+            $validator = null;
+        } elseif (null !== $constraintOrValidator && !$constraintOrValidator instanceof ValidatorInterface) {
+            throw new \TypeError(sprintf('Argument 1 passed to "%s()" must be a "%s" or a "%s" object, "%s" given.', __METHOD__, Constraint::class, ValidatorInterface::class, get_debug_type($constraintOrValidator)));
+        }
+
+        $validator = $validator ?? self::createValidator();
 
         return static function ($value) use ($constraints, $validator) {
             $violations = $validator->validate($value, $constraints);