Archlinux:golang不能使用go build

i installed archlinux few days ago, and i want to configure golang but there is some problem, I installed go from pacman :

pacman -S go

and i export some env var in my .bashrc

export PATH=$PATH:/usr/lib/go
export GOPATH=$HOME/go
export GOBIN=$GOPATH/bin

But when i build with "go build" i've got the error message :

main.go:11:2: no buildable Go source files in /usr/lib/go/src/go

go env includes:

GOBIN="/home/thomas/go/bin" GOEXE="" GOPATH="/home/thomas/go" GOROOT="/usr/lib/go" 

From the error message it seems like you might be trying to import the "go" package in main.go on line 11.

Removing that import statement should fix the problem.