It's been a while since I had to fiddle with my dev setup but I recently created a new separate go repo in my home directory and it took me a while to untangle where which binaries got installed. Specifically when it comes to uses of $GOBIN for which the documentation is a bit vague. It says that if $GOBIN is set, the go command installs all commands there. Well, that's not what I am observing.

I have no Go specific environment variables set but for GOPATH which is set to $HOME. So no GOBIN, or GOROOT per the usual recommendation.

In a brand-new local repo of the Go distribution, after running make.bash, the two tools go and gofmt are built and installed in $GOROOT/bin where $GOROOT is the repo directory (per documentation). It doesn't matter if $GOBIN is set or not.

go install of a new "command", that is a main package under $GOROOT/src/cmd, appears to be installed in $GOTOOLDIR no matter if $GOBIN is set or not. $GOTOOLDIR is $GOROOT/pkg/tool/GOOS_$GOARCH.

Only for binaries (main packages) outside $GOROOTsrc/cmd does $GOBIN apply: Those end up in $GOBIN if it set, or in GOROOT/bin if $GOBIN is not set.

(This is all based in empirical evidence, I haven't studied the code. Happy to be corrected if I got this wrong.)

The documentation should be more clear. Right now we have lists of environment variables and respective documentation which is referred to from various places but it's not consistent.

More generally, it would be useful to document the recommended basic dev setup for people who want to work on the std lib. Specifically, where what is installed. Note that go help install doesn't say anything about what "install" actually means or where things go. It refers to go help build and go help packages which only makes things complicated.

cc: @bcmills