From b98e25a949cc7b79490ef9f89b049b2c3942c45b Mon Sep 17 00:00:00 2001
From: Andreas Schempp <andreas.schempp@terminal42.ch>
Date: Sun, 15 Apr 2018 08:28:27 +0200
Subject: [PATCH] Correctly merge mix of public and private responses

If a response is flagged as public and others are flagged private,
the merged response can be considered private-cacheable.
---
 .../HttpCache/ResponseCacheStrategy.php        | 18 ++++++++++++++++--
 .../HttpCache/ResponseCacheStrategyTest.php    |  2 --
 2 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/src/Symfony/Component/HttpKernel/HttpCache/ResponseCacheStrategy.php b/src/Symfony/Component/HttpKernel/HttpCache/ResponseCacheStrategy.php
index 6737bfd839af5..eda29158627b7 100644
--- a/src/Symfony/Component/HttpKernel/HttpCache/ResponseCacheStrategy.php
+++ b/src/Symfony/Component/HttpKernel/HttpCache/ResponseCacheStrategy.php
@@ -36,7 +36,7 @@ class ResponseCacheStrategy implements ResponseCacheStrategyInterface
     /**
      * Cache-Control headers that are sent to the final response if the appear in ALL of the responses.
      */
-    private static $inheritDirectives = array('public', 'private', 'immutable');
+    private static $inheritDirectives = array('immutable');
 
     private $embeddedResponses = 0;
     private $isNotCacheableResponseEmbedded = false;
@@ -76,6 +76,14 @@ public function add(Response $response)
             }
         }
 
+        if (false !== $this->flagDirectives['public']) {
+            $this->flagDirectives['public'] = $response->headers->hasCacheControlDirective('public');
+        }
+
+        if (false !== $this->flagDirectives['private']) {
+            $this->flagDirectives['private'] = $response->headers->hasCacheControlDirective('private') || $response->headers->hasCacheControlDirective('public');
+        }
+
         $age = $response->getAge();
         $this->age = max($this->age, $age);
 
@@ -124,7 +132,13 @@ public function update(Response $response)
             return;
         }
 
-        $response->headers->set('Cache-Control', implode(', ', array_keys(array_filter($this->flagDirectives))));
+        $flags = array_filter($this->flagDirectives);
+
+        if (isset($flags['public'], $flags['private'])) {
+            unset($flags['private']);
+        }
+
+        $response->headers->set('Cache-Control', implode(', ', array_keys($flags)));
 
         if ($this->ageDirectives['max-age']) {
             $response->headers->addCacheControlDirective('max-age', $this->ageDirectives['max-age'] + $this->age);
diff --git a/src/Symfony/Component/HttpKernel/Tests/HttpCache/ResponseCacheStrategyTest.php b/src/Symfony/Component/HttpKernel/Tests/HttpCache/ResponseCacheStrategyTest.php
index 061c88fc501b1..2cd3c5023eb10 100644
--- a/src/Symfony/Component/HttpKernel/Tests/HttpCache/ResponseCacheStrategyTest.php
+++ b/src/Symfony/Component/HttpKernel/Tests/HttpCache/ResponseCacheStrategyTest.php
@@ -112,8 +112,6 @@ public function testValidationOnMasterResponseIsNotPossibleWhenItContainsEmbedde
         $this->assertFalse($masterResponse->isValidateable());
         $this->assertFalse($masterResponse->headers->has('Last-Modified'));
         $this->assertFalse($masterResponse->headers->has('ETag'));
-//        $this->assertTrue($masterResponse->headers->hasCacheControlDirective('no-cache'));
-//        $this->assertTrue($masterResponse->headers->hasCacheControlDirective('must-revalidate'));
     }
 
     public function testMasterResponseWithValidationIsUnchangedWhenThereIsNoEmbeddedResponse()