cmd/go: add flag values to counter for buildmode

Usually, when we increment counters for flags, the counter only contains
the flag name. For the buildmode flag, we now include the flag value
because there's a limited set of values.

We can't use CountFlags directly anymore since we have different
behavior for buildmode.

Change-Id: I956a1a97d62850df3199b5514ad507ea51355c9f
Reviewed-on: https://go-review.googlesource.com/c/go/+/582896
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Sam Thanawalla <samthanawalla@google.com>

diff --git a/src/cmd/go/main.go b/src/cmd/go/main.go
index dc2a8fd49c034fe6dfd88c99d371605ca26cce25..86f3c65a92db91cdd6b4b9c6cbcd25875414fcc7 100644 (file)
--- a/src/cmd/go/main.go
+++ b/src/cmd/go/main.go
@@ -252,7 +252,14 @@ func invoke(cmd *base.Command, args []string) {
        } else {
                base.SetFromGOFLAGS(&cmd.Flag)
                cmd.Flag.Parse(args[1:])
-               telemetry.CountFlags("go/flag:"+strings.ReplaceAll(cfg.CmdName, " ", "-")+"-", cmd.Flag)
+               prefix := "go/flag:" + strings.ReplaceAll(cfg.CmdName, " ", "-") + "-"
+               cmd.Flag.Visit(func(f *flag.Flag) {
+                       counterName := prefix + f.Name
+                       if f.Name == "buildmode" { // Special case: there is a limited set of buildmode values
+                               counterName += "-" + f.Value.String()
+                       }
+                       telemetry.Inc(counterName)
+               })
                args = cmd.Flag.Args()
        }