Squashed 'sub/' content from commit 9d48549

git-subtree-dir: sub
git-subtree-split: 9d48549846e855c0e326b33401c3326c05309e3d
Merge commit 'bffb1fc3b56b2d1750d45a6eb5b27bb27983b3d5' as 'sub'
add b.cpp