Stack outputs executable in source directory?

It’s really weird. I have a minimal project here: aaya ~/g/really-weird> ls -a . .. .gitignore package.yaml src stack.yaml aaya ~/g/really-weird> ls src -a . .. Lib.hs Main.hs cat stack.yaml snapshot: lts-24.63 packages: - . cat package.yaml name: really-weird version: 0.1.0.0 dependencies: base: ">= 4.7 && < 5" library: source-dirs: src executable: main: Main.hs source-dirs: src ghc-options: - -threaded - -rtsopts ...