Add sniff to ensure we're not using Carbon or DateTime when we shouldn't be

.gitignore

@@ -1,2 +1,4 @@
 # 3rd party libraries
 /vendor
+
+*.swp

DatacodeStandard/Sniffs/Dates/CarbonInstansiationSniff.php

@@ -0,0 +1,119 @@
+<?php
+
+declare(strict_types=1);
+
+namespace DatacodeStandard\Sniffs\Dates;
+
+use PHP_CodeSniffer\Sniffs\Sniff;
+use PHP_CodeSniffer\Files\File;
+
+/**
+ * Class: Bans instansiation of, or static methods on, evil date objects
+ *
+ * @see Sniff
+ */
+class CarbonInstansiationSniff implements Sniff {
+
+	private static $evilClasses = [
+		'Carbon',
+		'CarbonImmutable',
+		'DateTime',
+		'DateTimeImmutable',
+	];
+
+	public function register() {
+		return [
+			T_NEW,
+			T_STRING,
+		];
+	}
+
+	/**
+	 * Processes this test, when one of its tokens is encountered.
+	 *
+	 * @param PHP_CodeSniffer_File $phpcsFile The file being scanned.
+	 * @param integer $stackPtr The position of the current token in the stack passed in $tokens.
+	 *
+	 * @return integer
+	 */
+	public function process(File $phpcsFile, $stackPtr) {
+		$this->file = $phpcsFile;
+
+		$tokens = $phpcsFile->getTokens();
+		$firstToken = $tokens[$stackPtr];
+
+		$classNamePointer = match ($firstToken['type']) {
+			"T_STRING" => $stackPtr,
+			"T_NEW" => $phpcsFile->findNext([ T_STRING ], $stackPtr + 1),
+		};
+
+		$className = $classNamePointer !== false
+			? $tokens[$classNamePointer]['content']
+			: null;
+
+		if (!in_array($className, self::$evilClasses)) {
+			return;
+		}
+
+		if ($firstToken['type'] === 'T_NEW') {
+			$phpcsFile->addError(
+				"Usage of 'new Carbon' is banned. Use the Date facade instead",
+				$stackPtr,
+				'NoNewCarbon',
+			);
+		}
+
+		$nextTokenPtr = $this->nextNonWhitespaceToken($classNamePointer + 1);
+
+		if (!$nextTokenPtr) {
+			return;
+		}
+
+		$nextToken = $tokens[$nextTokenPtr];
+		$nextTokenIsDoubleColon = $nextToken['type'] === 'T_DOUBLE_COLON';
+		$probablyStaticMethodNamePtr = $this->nextNonWhitespaceToken($nextTokenPtr + 1);
+
+		if (!$probablyStaticMethodNamePtr) {
+			return;
+		}
+
+		$afterProbableStaticMethodNamePtr = $this->nextNonWhitespaceToken($probablyStaticMethodNamePtr + 1);
+
+		if (!$afterProbableStaticMethodNamePtr) {
+			return;
+		}
+
+		$thenWeAreCallingTheMethod = $tokens[$afterProbableStaticMethodNamePtr]['type'] === 'T_OPEN_PARENTHESIS';
+		$isStaticMethodCall = $nextTokenIsDoubleColon && $thenWeAreCallingTheMethod;
+
+		if ($isStaticMethodCall) {
+			$phpcsFile->addError(
+				"Usage of static methods on Carbon is banned. Use Date facade instead",
+				$stackPtr,
+				'NoCarbonStaticMethods',
+			);
+		}
+	}
+
+	/**
+	 * Checks tokens from $start til EOF. Returns first pointer that isn't whitespace
+	 *
+	 * @param mixed $start The pointer we're starting at
+	 *
+	 * @return int|null
+	 */
+	private function nextNonWhitespaceToken(int $start): ?int
+	{
+		$tokens = $this->file->getTokens();
+		$end = $this->file->numTokens;
+
+		for ($i = $start; $i < $end; $i++) {
+			if ($tokens[$i]['type'] !== 'T_WHITESPACE') {
+				return $i;
+			}
+		}
+
+		return false;
+	}
+
+}