Generic/CharacterBeforePHPOpeningTag: prevent false positive in mixed PHP/HTML files

package.xml

@@ -720,6 +720,8 @@ http://pear.php.net/dtd/package-2.0.xsd">
         <file baseinstalldir="PHP/CodeSniffer" name="CharacterBeforePHPOpeningTagUnitTest.1.inc" role="test" />
         <file baseinstalldir="PHP/CodeSniffer" name="CharacterBeforePHPOpeningTagUnitTest.2.inc" role="test" />
         <file baseinstalldir="PHP/CodeSniffer" name="CharacterBeforePHPOpeningTagUnitTest.3.inc" role="test" />
+        <file baseinstalldir="PHP/CodeSniffer" name="CharacterBeforePHPOpeningTagUnitTest.4.inc" role="test" />
+        <file baseinstalldir="PHP/CodeSniffer" name="CharacterBeforePHPOpeningTagUnitTest.5.inc" role="test" />
         <file baseinstalldir="PHP/CodeSniffer" name="CharacterBeforePHPOpeningTagUnitTest.php" role="test" />
         <file baseinstalldir="PHP/CodeSniffer" name="ClosingPHPTagUnitTest.1.inc" role="test" />
         <file baseinstalldir="PHP/CodeSniffer" name="ClosingPHPTagUnitTest.2.inc" role="test" />

src/Standards/Generic/Sniffs/PHP/CharacterBeforePHPOpeningTagSniff.php

@@ -36,7 +36,10 @@ class CharacterBeforePHPOpeningTagSniff implements Sniff
      */
     public function register()
     {
-        return [T_OPEN_TAG];
+        return [
+            T_OPEN_TAG,
+            T_OPEN_TAG_WITH_ECHO,
+        ];
 
     }//end register()
 
@@ -52,10 +55,15 @@ public function register()
      */
     public function process(File $phpcsFile, $stackPtr)
     {
+        $tokens = $phpcsFile->getTokens();
+        if ($tokens[$stackPtr]['code'] === T_OPEN_TAG_WITH_ECHO) {
+            // Mixed PHP/HTML file, ignore.
+            return $phpcsFile->numTokens;
+        }
+
         $expected = 0;
         if ($stackPtr > 0) {
             // Allow a byte-order mark.
-            $tokens = $phpcsFile->getTokens();
             foreach ($this->bomDefinitions as $bomName => $expectedBomHex) {
                 $bomByteLength = (strlen($expectedBomHex) / 2);
                 $htmlBomHex    = bin2hex(substr($tokens[0]['content'], 0, $bomByteLength));

src/Standards/Generic/Tests/PHP/CharacterBeforePHPOpeningTagUnitTest.4.inc

@@ -0,0 +1,5 @@
+Foo
+<?= $var ?>
+
+
+ <?= $var ?>

src/Standards/Generic/Tests/PHP/CharacterBeforePHPOpeningTagUnitTest.5.inc

@@ -0,0 +1,4 @@
+<?= $var ?>
+
+<?php
+// Some code