Go build不构建自定义库

my working tree is like this:

/opt/go/src/tb-to-composer/
├── apis
│   └── rtb.go
├── config.yaml
├── jsondef
│   └── structures.go
├── LICENSE.md
├── README.md
├── tb-to-composer
└── thingsToComposer.go

when I do go build inside /opt/go/src/tb-to-composer/ the build doesn't recompile rtb.go and structures.go even though there was changes in them. In order to achieve build I need to run go build -a every time I do a change to rtb.go or structures.go, is that the expected behavior from go build? How to I recompile only custom libs inside my package folder without recompile the whole /opt/go/src tree?

You can try the -i flag, or (this does not work, sorry) specify the files in the directories explicitly as arguments to go build, i.e. go build thingsToComposer.go apis/rtb.go jsondef/structures.go