Squiz/NonExecutableCode: only ignore inline statements when PHP allows them

Aside from `T_EXIT`, PHP (prior to PHP 8.0) does not allow for the inline use of the other tokens this sniff registers.
While using those tokens inline would result in a parse error, that is not the concern of this sniff.

By ignoring these, the sniff causes false negatives.

This commit makes the sniff more selective and only ignores inline statements for tokens which are allowed in inline statements.

Includes unit test.

Author: jrfnl

src/Standards/Squiz/Sniffs/PHP/NonExecutableCodeSniff.php

@@ -16,6 +16,16 @@
 class NonExecutableCodeSniff implements Sniff
 {
 
+    /**
+     * Tokens for terminating expressions, which can be used inline.
+     *
+     * This is in contrast to terminating statements, which cannot be used inline
+     * and would result in a parse error (which is not the concern of this sniff).
+     *
+     * @var array
+     */
+    private $expressionTokens = [T_EXIT => T_EXIT];
+
 
     /**
      * Returns an array of tokens this test wants to listen for.
@@ -49,11 +59,15 @@ public function process(File $phpcsFile, $stackPtr)
     {
         $tokens = $phpcsFile->getTokens();
 
-        // If this token is preceded with an "or", it only relates to one line
-        // and should be ignored. For example: fopen() or die().
         $prev = $phpcsFile->findPrevious(Tokens::$emptyTokens, ($stackPtr - 1), null, true);
-        if ($tokens[$prev]['code'] === T_LOGICAL_OR || $tokens[$prev]['code'] === T_BOOLEAN_OR) {
-            return;
+
+        // Tokens which can be used in inline expressions need special handling.
+        if (isset($this->expressionTokens[$tokens[$stackPtr]['code']]) === true) {
+            // If this token is preceded with an "or", it only relates to one line
+            // and should be ignored. For example: fopen() or die().
+            if ($tokens[$prev]['code'] === T_LOGICAL_OR || $tokens[$prev]['code'] === T_BOOLEAN_OR) {
+                return;
+            }
         }
 
         // Check if this token is actually part of a one-line IF or ELSE statement.

src/Standards/Squiz/Tests/PHP/NonExecutableCodeUnitTest.1.inc

@@ -297,5 +297,16 @@ class TestAlternativeControlStructures {
 $var_after_class_in_global_space = 1;
 do_something_else();
 
+// These are parse errors, but that's not the concern of the sniff.
+function parseError1() {
+    defined('FOO') or return 'foo';
+    echo 'unreachable';
+}
+
+function parseError2() {
+    defined('FOO') || continue;
+    echo 'unreachable';
+}
+
 // Intentional syntax error.
 return array_map(

src/Standards/Squiz/Tests/PHP/NonExecutableCodeUnitTest.php

@@ -74,6 +74,8 @@ public function getWarningList($testFile='')
                 252 => 1,
                 253 => 1,
                 254 => 2,
+                303 => 1,
+                308 => 1,
             ];
             break;
         case 'NonExecutableCodeUnitTest.2.inc':