The main package of Elvish is cmd/elvish, and you can build it like any other
Go application.
You can set some variables in the src.elv.sh/pkg/buildinfo package using
linker flags to enhance the Elvish's version information. See the
package's API doc for
details.
They don't affect any other aspect of Elvish's behavior, so it's infeasible to pass those linker flags, it's fine to leave them as is.
Note: The names and usage of these variables have changed several time in
Elvish's history. If your build script has -ldflags '-X $symbol=$value' where
$symbol is not documented in the linked API doc, those flags no longer do
anything and should be removed.