Compatibility with GCC 6

ChangeLog.txt

@@ -8,6 +8,7 @@ Fixed Bugs:
 Improvements:
 * When mounting an old file system, CryFS will ask before migrating it to the newest version.
 * Operating system tools like the mount command or /proc/self/mountinfo report correct file system type and also report the base directory.
+* Compatibility with GCC 6
 
 Version 0.9.4
 ---------------

src/blockstore/implementations/inmemory/InMemoryBlockStore.h

@@ -7,10 +7,10 @@
 
 #include <mutex>
 #include <unordered_map>
+#include "InMemoryBlock.h"
 
 namespace blockstore {
 namespace inmemory {
-class InMemoryBlock;
 
 class InMemoryBlockStore final: public BlockStoreWithRandomKeys {
 public: