Merge branch '6.4' into 7.2

* 6.4:
  [VarExporter] Fix support for hooks and asymmetric visibility
  fix(process): use a pipe for stderr in pty mode to avoid mixed output between stdout and stderr
  [Cache] fix data collector

Author: nicolas-grekas

Pipes/UnixPipes.php

@@ -70,7 +70,7 @@ public function getDescriptors(): array
             return [
                 ['pty'],
                 ['pty'],
-                ['pty'],
+                ['pipe', 'w'], // stderr needs to be in a pipe to correctly split error and output, since PHP will use the same stream for both
             ];
         }
 

Tests/ProcessTest.php

@@ -559,6 +559,20 @@ public function testExitCodeTextIsNullWhenExitCodeIsNull()
         $this->assertNull($process->getExitCodeText());
     }
 
+    public function testStderrNotMixedWithStdout()
+    {
+        if (!Process::isPtySupported()) {
+            $this->markTestSkipped('PTY is not supported on this operating system.');
+        }
+
+        $process = $this->getProcess('echo "foo" && echo "bar" >&2');
+        $process->setPty(true);
+        $process->run();
+
+        $this->assertSame("foo\r\n", $process->getOutput());
+        $this->assertSame("bar\n", $process->getErrorOutput());
+    }
+
     public function testPTYCommand()
     {
         if (!Process::isPtySupported()) {