Decrement errorState when recovering from -> error

It's likely that an error after -> will trigger another one due to
missing semicolon without shifting a single token. We prevent an
immediate failure in this case by manually setting errorState to 2,
which will suppress the duplicate error message, but allow error
recovery.

Author: nikic

grammar/php5.y

@@ -915,7 +915,7 @@ object_property:
       T_STRING                                              { $$ = $1; }
     | '{' expr '}'                                          { $$ = $2; }
     | variable_without_objects                              { $$ = $1; }
-    | error                                                 { $$ = Expr\Error[]; }
+    | error                                                 { $$ = Expr\Error[]; $this->errorState = 2; }
 ;
 
 list_expr:

grammar/php7.y

@@ -793,7 +793,7 @@ property_name:
       T_STRING                                              { $$ = $1; }
     | '{' expr '}'	                                        { $$ = $2; }
     | simple_variable	                                    { $$ = Expr\Variable[$1]; }
-    | error                                                 { $$ = Expr\Error[]; }
+    | error                                                 { $$ = Expr\Error[]; $this->errorState = 2; }
 ;
 
 list_expr:

lib/PhpParser/Parser/Php5.php

@@ -3009,7 +3009,7 @@ protected function reduceRule517() {
     }
 
     protected function reduceRule518() {
-         $this->semValue = new Expr\Error($this->startAttributeStack[$this->stackPos-(1-1)] + $this->endAttributes);
+         $this->semValue = new Expr\Error($this->startAttributeStack[$this->stackPos-(1-1)] + $this->endAttributes); $this->errorState = 2;
     }
 
     protected function reduceRule519() {

lib/PhpParser/Parser/Php7.php

@@ -2619,7 +2619,7 @@ protected function reduceRule452() {
     }
 
     protected function reduceRule453() {
-         $this->semValue = new Expr\Error($this->startAttributeStack[$this->stackPos-(1-1)] + $this->endAttributes);
+         $this->semValue = new Expr\Error($this->startAttributeStack[$this->stackPos-(1-1)] + $this->endAttributes); $this->errorState = 2;
     }
 
     protected function reduceRule454() {

lib/PhpParser/ParserAbstract.php

@@ -95,6 +95,8 @@ abstract class ParserAbstract implements Parser
     protected $throwOnError;
     /** @var Error[] Errors collected during last parse */
     protected $errors;
+    /** @var int Error state, used to avoid error floods */
+    protected $errorState;
 
     /**
      * Creates a parser instance.
@@ -157,7 +159,7 @@ public function parse($code) {
         // Current position in the stack(s)
         $this->stackPos = 0;
 
-        $errorState = 0;
+        $this->errorState = 0;
 
         for (;;) {
             //$this->traceNewState($state, $symbol);
@@ -216,8 +218,8 @@ public function parse($code) {
                         $this->endAttributes = $endAttributes;
                         $symbol = self::SYMBOL_NONE;
 
-                        if ($errorState) {
-                            --$errorState;
+                        if ($this->errorState) {
+                            --$this->errorState;
                         }
 
                         if ($action < $this->YYNLSTATES) {
@@ -274,7 +276,7 @@ public function parse($code) {
                     $this->semStack[$this->stackPos] = $this->semValue;
                 } else {
                     /* error */
-                    switch ($errorState) {
+                    switch ($this->errorState) {
                         case 0:
                             $msg = $this->getErrorMessage($symbol, $state);
                             $error = new Error($msg, $startAttributes + $endAttributes);
@@ -285,7 +287,7 @@ public function parse($code) {
                             // Break missing intentionally
                         case 1:
                         case 2:
-                            $errorState = 3;
+                            $this->errorState = 3;
 
                             // Pop until error-expecting state uncovered
                             while (!(

test/code/parser/errorHandling/recovery.test

@@ -254,4 +254,29 @@ array(
         name: Expr_Error(
         )
     )
+)
+-----
+<?php
+function foo() {
+    $bar->
+}
+-----
+Syntax error, unexpected '}' from 4:1 to 4:1
+array(
+    0: Stmt_Function(
+        byRef: false
+        name: foo
+        params: array(
+        )
+        returnType: null
+        stmts: array(
+            0: Expr_PropertyFetch(
+                var: Expr_Variable(
+                    name: bar
+                )
+                name: Expr_Error(
+                )
+            )
+        )
+    )
 )