Generic/FunctionCallArgumentSpacing: prevent fixer conflict over PHP 7.3+ trailing comma's in function calls

src/Standards/Generic/Sniffs/Functions/FunctionCallArgumentSpacingSniff.php

@@ -156,10 +156,13 @@ public function checkSpacing(File $phpcsFile, $stackPtr, $openBracket)
                 }//end if
 
                 if ($tokens[($nextSeparator + 1)]['code'] !== T_WHITESPACE) {
-                    $error = 'No space found after comma in argument list';
-                    $fix   = $phpcsFile->addFixableError($error, $nextSeparator, 'NoSpaceAfterComma');
-                    if ($fix === true) {
-                        $phpcsFile->fixer->addContent($nextSeparator, ' ');
+                    // Ignore trailing comma's after last argument as that's outside the scope of this sniff.
+                    if (($nextSeparator + 1) !== $closeBracket) {
+                        $error = 'No space found after comma in argument list';
+                        $fix   = $phpcsFile->addFixableError($error, $nextSeparator, 'NoSpaceAfterComma');
+                        if ($fix === true) {
+                            $phpcsFile->fixer->addContent($nextSeparator, ' ');
+                        }
                     }
                 } else {
                     // If there is a newline in the space, then they must be formatting

src/Standards/Generic/Tests/Functions/FunctionCallArgumentSpacingUnitTest.inc

@@ -162,3 +162,13 @@ class Testing extends Bar
         $a = new parent($foo ,$bar);
     }
 }
+
+// Ignore spacing after PHP 7.3+ trailing comma in single-line function calls to prevent fixer conflicts.
+// This is something which should be decided by a sniff dealing with the function call parentheses.
+$foo = new MyClass($obj, 'getMethod',);
+$foo = new MyClass($obj, 'getMethod', );
+$foo = new MyClass($obj, 'getMethod',       );
+$foo = new MyClass(
+    $obj,
+    'getMethod',
+);

src/Standards/Generic/Tests/Functions/FunctionCallArgumentSpacingUnitTest.inc.fixed

@@ -162,3 +162,13 @@ class Testing extends Bar
         $a = new parent($foo, $bar);
     }
 }
+
+// Ignore spacing after PHP 7.3+ trailing comma in single-line function calls to prevent fixer conflicts.
+// This is something which should be decided by a sniff dealing with the function call parentheses.
+$foo = new MyClass($obj, 'getMethod',);
+$foo = new MyClass($obj, 'getMethod', );
+$foo = new MyClass($obj, 'getMethod', );
+$foo = new MyClass(
+    $obj,
+    'getMethod',
+);

src/Standards/Generic/Tests/Functions/FunctionCallArgumentSpacingUnitTest.php

@@ -55,6 +55,7 @@ public function getErrorList()
             154 => 2,
             155 => 1,
             162 => 2,
+            170 => 1,
         ];
 
     }//end getErrorList()