PHP 8.1 | PSR12/ConstantVisibility: allow for class constants to be final

PHP 8.1 introduces the ability to declare class constants as `final`.

The tokenization of the `final` keyword in this context appears to be consistent PHPCS cross-version, so AFAICS no changes are needed to the PHP tokenizer.

However, the `PSR12.Properties.ConstantVisibility` sniff does need to allow for them.

Includes unit tests.

Ref: https://wiki.php.net/rfc/final_class_const

Author: jrfnl

src/Standards/PSR12/Sniffs/Properties/ConstantVisibilitySniff.php

@@ -47,7 +47,10 @@ public function process(File $phpcsFile, $stackPtr)
             return;
         }
 
-        $prev = $phpcsFile->findPrevious(Tokens::$emptyTokens, ($stackPtr - 1), null, true);
+        $ignore   = Tokens::$emptyTokens;
+        $ignore[] = T_FINAL;
+
+        $prev = $phpcsFile->findPrevious($ignore, ($stackPtr - 1), null, true);
         if (isset(Tokens::$scopeModifiers[$tokens[$prev]['code']]) === true) {
             return;
         }

src/Standards/PSR12/Tests/Properties/ConstantVisibilityUnitTest.inc

@@ -5,3 +5,13 @@ class Foo {
 }
 
 const APPLICATION_ENV = 'development';
+
+// Issue 3526, PHP 8.1 final constants.
+class SampleEnum
+{
+    final const FOO = 'SAMPLE';
+
+    public final const BAR = 'SAMPLE';
+
+    final private const BAZ = 'SAMPLE';
+}

src/Standards/PSR12/Tests/Properties/ConstantVisibilityUnitTest.php

@@ -40,7 +40,10 @@ public function getErrorList()
      */
     public function getWarningList()
     {
-        return [4 => 1];
+        return [
+            4  => 1,
+            12 => 1,
+        ];
 
     }//end getWarningList()