A hint: This file contains one or more very long lines, so maybe it is better readable using the pure text view mode that shows the contents as wrapped lines within the browser window.
To build Hugo from source you must:
The install directory is controlled by the GOPATH and GOBIN environment variables. If GOBIN is set, binaries are installed to that directory. If GOPATH is set, binaries are installed to the bin subdirectory of the first directory in the GOPATH list. Otherwise, binaries are installed to the bin subdirectory of the default GOPATH ($HOME/go or %USERPROFILE%\go).
Then build and test:
go install -tags extended github.com/gohugoio/hugo@latest
hugo version