C++: Fix crash after triggering completion and closing editor

Fix use-after-free for the following case:
  1. Open an editor
  2. Trigger a long processing completion
     (e.g. simulate with QThread::msleep in
      CppCompletionAssistInterface::getCppSpecifics)
  3. ...and immediately close the editor (e.g. with Ctrl+W)
  4. Wait until it crashes.

The completion thread relied on the BuiltinEditorDocumentParser object,
which is deleted once the editor is closed. Fixed by sharing the
ownership of that object between the *EditorDocumentProcessor and the
completion assist interface.

This case came up when doing tests for the bug report below.

Task-number: QTCREATORBUG-14991
Change-Id: I0b009229e68fc6b7838740858cdc41a32403fe6f
Reviewed-by: David Schulz <david.schulz@theqtcompany.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/src/plugins/cpptools/cppcompletionassist.h b/src/plugins/cpptools/cppcompletionassist.h
index 9de04d69e4..01fd44e5b8 100644
--- a/src/plugins/cpptools/cppcompletionassist.h
+++ b/src/plugins/cpptools/cppcompletionassist.h
@@ -31,6 +31,7 @@
 #ifndef CPPCOMPLETIONASSIST_H
 #define CPPCOMPLETIONASSIST_H
 
+#include "builtineditordocumentparser.h"
 #include "cppcompletionassistprocessor.h"
 #include "cppcompletionassistprovider.h"
 #include "cppmodelmanager.h"
@@ -171,11 +172,13 @@ class CppCompletionAssistInterface : public TextEditor::AssistInterface
 public:
     CppCompletionAssistInterface(const QString &filePath,
                                  const TextEditor::TextEditorWidget *textEditorWidget,
+                                 BuiltinEditorDocumentParser::Ptr parser,
                                  const CPlusPlus::LanguageFeatures &languageFeatures,
                                  int position,
                                  TextEditor::AssistReason reason,
                                  const WorkingCopy &workingCopy)
         : TextEditor::AssistInterface(textEditorWidget->document(), position, filePath, reason)
+        , m_parser(parser)
         , m_gotCppSpecifics(false)
         , m_workingCopy(workingCopy)
         , m_languageFeatures(languageFeatures)
@@ -204,6 +207,7 @@ public:
 private:
     void getCppSpecifics() const;
 
+    BuiltinEditorDocumentParser::Ptr m_parser;
     mutable bool m_gotCppSpecifics;
     WorkingCopy m_workingCopy;
     mutable CPlusPlus::Snapshot m_snapshot;