version: use buildinfo vcs revision

version.go

@@ -6,10 +6,20 @@ import (
 	"runtime/debug"
 	"strings"
 
+	"github.com/jzelinskie/stringz"
 	"github.com/spf13/cobra"
 	"github.com/spf13/pflag"
 )
 
+func vcsRevision(bi *debug.BuildInfo) string {
+	for _, setting := range bi.Settings {
+		if setting.Key == "vcs.revision" {
+			return setting.Value
+		}
+	}
+	return ""
+}
+
 // Version is variable that holds program's version string.
 // This should be set with the follow flags to the `go build` command:
 // -ldflags '-X github.com/jzelinskie/cobrautil.Version=$YOUR_VERSION_HERE'
@@ -23,11 +33,9 @@ func UsageVersion(programName string, includeDeps bool) string {
 		panic("failed to read BuildInfo because the program was compiled with Go " + runtime.Version())
 	}
 
-	if Version == "" {
-		// The version wasn't set by ldflags, so fallback to the Go module version.
-		// Although, this value is pretty much guaranteed to just be "(devel)".
-		Version = bi.Main.Version
-	}
+	// The version wasn't set by ldflags, so fallback to the VCS revision, and
+	// finally Go module version.
+	Version = stringz.DefaultEmpty(stringz.DefaultEmpty(Version, vcsRevision(bi)), bi.Main.Version)
 
 	if !includeDeps {
 		if Version == "(devel)" {