Fix formatting preservation for alternative elseif/else syntax

Test taken from PR #797.

(cherry picked from commit 9b46dff)

Author: nikic

grammar/php7.y

@@ -518,7 +518,8 @@ new_elseif_list:
 ;
 
 new_elseif:
-     T_ELSEIF '(' expr ')' ':' inner_statement_list         { $$ = Stmt\ElseIf_[$3, $6]; }
+     T_ELSEIF '(' expr ')' ':' inner_statement_list
+         { $$ = Stmt\ElseIf_[$3, $6]; $this->fixupAlternativeElse($$); }
 ;
 
 else_single:
@@ -528,7 +529,8 @@ else_single:
 
 new_else_single:
       /* empty */                                           { $$ = null; }
-    | T_ELSE ':' inner_statement_list                       { $$ = Stmt\Else_[$3]; }
+    | T_ELSE ':' inner_statement_list
+          { $$ = Stmt\Else_[$3]; $this->fixupAlternativeElse($$); }
 ;
 
 foreach_variable:

lib/PhpParser/Parser/Php7.php

@@ -1826,7 +1826,7 @@ protected function initReduceCallbacks() {
                  $this->semStack[$stackPos-(2-1)][] = $this->semStack[$stackPos-(2-2)]; $this->semValue = $this->semStack[$stackPos-(2-1)];
             },
             266 => function ($stackPos) {
-                 $this->semValue = new Stmt\ElseIf_($this->semStack[$stackPos-(6-3)], $this->semStack[$stackPos-(6-6)], $this->startAttributeStack[$stackPos-(6-1)] + $this->endAttributes);
+                 $this->semValue = new Stmt\ElseIf_($this->semStack[$stackPos-(6-3)], $this->semStack[$stackPos-(6-6)], $this->startAttributeStack[$stackPos-(6-1)] + $this->endAttributes); $this->fixupAlternativeElse($this->semValue);
             },
             267 => function ($stackPos) {
                  $this->semValue = null;
@@ -1838,7 +1838,7 @@ protected function initReduceCallbacks() {
                  $this->semValue = null;
             },
             270 => function ($stackPos) {
-                 $this->semValue = new Stmt\Else_($this->semStack[$stackPos-(3-3)], $this->startAttributeStack[$stackPos-(3-1)] + $this->endAttributes);
+                 $this->semValue = new Stmt\Else_($this->semStack[$stackPos-(3-3)], $this->startAttributeStack[$stackPos-(3-1)] + $this->endAttributes); $this->fixupAlternativeElse($this->semValue);
             },
             271 => function ($stackPos) {
                  $this->semValue = array($this->semStack[$stackPos-(1-1)], false);

lib/PhpParser/ParserAbstract.php

@@ -16,9 +16,12 @@
 use PhpParser\Node\Stmt\Class_;
 use PhpParser\Node\Stmt\ClassConst;
 use PhpParser\Node\Stmt\ClassMethod;
+use PhpParser\Node\Stmt\Else_;
+use PhpParser\Node\Stmt\ElseIf_;
 use PhpParser\Node\Stmt\Enum_;
 use PhpParser\Node\Stmt\Interface_;
 use PhpParser\Node\Stmt\Namespace_;
+use PhpParser\Node\Stmt\Nop;
 use PhpParser\Node\Stmt\Property;
 use PhpParser\Node\Stmt\TryCatch;
 use PhpParser\Node\Stmt\UseUse;
@@ -876,6 +879,24 @@ protected function createCommentNopAttributes(array $comments) {
         return $attributes;
     }
 
+    /** @param ElseIf_|Else_ $node */
+    protected function fixupAlternativeElse($node) {
+        // Make sure a trailing nop statement carrying comments is part of the node.
+        $numStmts = \count($node->stmts);
+        if ($numStmts !== 0 && $node->stmts[$numStmts - 1] instanceof Nop) {
+            $nopAttrs = $node->stmts[$numStmts - 1]->getAttributes();
+            if (isset($nopAttrs['endLine'])) {
+                $node->setAttribute('endLine', $nopAttrs['endLine']);
+            }
+            if (isset($nopAttrs['endFilePos'])) {
+                $node->setAttribute('endFilePos', $nopAttrs['endFilePos']);
+            }
+            if (isset($nopAttrs['endTokenPos'])) {
+                $node->setAttribute('endTokenPos', $nopAttrs['endTokenPos']);
+            }
+        }
+    }
+
     protected function checkClassModifier($a, $b, $modifierPos) {
         try {
             Class_::verifyClassModifier($a, $b);

test/code/formatPreservation/comments.test

@@ -49,4 +49,4 @@ class Test {
     public function test() {
         // some code
     }
-}
+}

test/code/prettyPrinter/comments.test

@@ -64,4 +64,28 @@ function test()
 function test()
 {
     // empty
-}
+}
+-----
+<?php
+
+function noDuplicateComment()
+{
+    if (true):
+        // TEST 1
+    elseif (true):
+        // TEST 2
+    else:
+        // TEST 3
+    endif;
+}
+-----
+function noDuplicateComment()
+{
+    if (true) {
+        // TEST 1
+    } elseif (true) {
+        // TEST 2
+    } else {
+        // TEST 3
+    }
+}