It used to be a unique pointer, and there could be a case where ClangASTSource
held onto a copy of the pointer but Target::Destroy destroyed the unique pointer
in the mean time.
I also ensured that there is a validity check on the target (which confirms that
a ClangASTImporter can be generated) before the target's shared pointer is
copied into ClangASTSource.
This race condition caused a crash if Target::Destroy was called and then later
the target objecct was deleted.
llvm-svn: 252665
There are still a bunch of dependencies on the plug-in, but this helps to
identify them.
There are also a few more bits we need to move (and abstract, for example the
ClangPersistentVariables).
llvm-svn: 248612