cmd: use omitzero option for time.Time

The doc of time.Time says:
Programs using times should typically store and pass them as values,
not pointers. That is, time variables and struct fields should be of type
time.Time, not *time.Time.

Since CL 615676 added omitzero option to encoding/json package, we can
just replace (*time.Time + omitempty) with (time.Time + omitzero).

Change-Id: I5593c4b45af291d015433bd1d164f1c1378db642

Author: callthingsoff

src/cmd/go/internal/cache/prog.go

@@ -129,10 +129,10 @@ type ProgResponse struct {
 
 	// For Get requests.
 
-	Miss     bool       `json:",omitempty"` // cache miss
-	OutputID []byte     `json:",omitempty"`
-	Size     int64      `json:",omitempty"` // in bytes
-	Time     *time.Time `json:",omitempty"` // an Entry.Time; when the object was added to the docs
+	Miss     bool      `json:",omitempty"` // cache miss
+	OutputID []byte    `json:",omitempty"`
+	Size     int64     `json:",omitempty"` // in bytes
+	Time     time.Time `json:",omitzero"`  // an Entry.Time; when the object was added to the docs
 
 	// DiskPath is the absolute path on disk of the ObjectID corresponding
 	// a "get" request's ActionID (on cache hit) or a "put" request's
@@ -339,8 +339,8 @@ func (c *ProgCache) Get(a ActionID) (Entry, error) {
 	e := Entry{
 		Size: res.Size,
 	}
-	if res.Time != nil {
-		e.Time = *res.Time
+	if !res.Time.IsZero() {
+		e.Time = res.Time
 	} else {
 		e.Time = time.Now()
 	}

src/cmd/go/internal/modinfo/info.go

@@ -19,7 +19,7 @@ type ModulePublic struct {
 	Query      string           `json:",omitempty"` // version query corresponding to this version
 	Versions   []string         `json:",omitempty"` // available module versions
 	Replace    *ModulePublic    `json:",omitempty"` // replaced by this module
-	Time       *time.Time       `json:",omitempty"` // time version was created
+	Time       time.Time        `json:",omitzero"`  // time version was created
 	Update     *ModulePublic    `json:",omitempty"` // available update (with -u)
 	Main       bool             `json:",omitempty"` // is this the main module?
 	Indirect   bool             `json:",omitempty"` // module is only indirectly needed by main module

src/cmd/go/internal/modload/build.go

@@ -156,7 +156,7 @@ func addUpdate(ctx context.Context, m *modinfo.ModulePublic) {
 		m.Update = &modinfo.ModulePublic{
 			Path:    m.Path,
 			Version: info.Version,
-			Time:    &info.Time,
+			Time:    info.Time,
 		}
 	}
 }
@@ -344,7 +344,7 @@ func moduleInfo(ctx context.Context, rs *Requirements, m module.Version, mode Li
 				m.Error = &modinfo.ModuleError{Err: err.Error()}
 			} else {
 				m.Version = q.Version
-				m.Time = &q.Time
+				m.Time = q.Time
 			}
 		}
 

src/cmd/go/internal/modload/query.go

@@ -234,8 +234,8 @@ func queryProxy(ctx context.Context, proxy, path, query, current string, allowed
 				Version: old.Version,
 				Origin:  old.Origin,
 			}
-			if old.Time != nil {
-				info.Time = *old.Time
+			if !old.Time.IsZero() {
+				info.Time = old.Time
 			}
 			return info, nil
 		}

src/cmd/go/internal/work/action.go

@@ -173,9 +173,9 @@ type actionJSON struct {
 	NeedBuild  bool      `json:",omitempty"`
 	ActionID   string    `json:",omitempty"`
 	BuildID    string    `json:",omitempty"`
-	TimeReady  time.Time `json:",omitempty"`
-	TimeStart  time.Time `json:",omitempty"`
-	TimeDone   time.Time `json:",omitempty"`
+	TimeReady  time.Time `json:",omitzero"`
+	TimeStart  time.Time `json:",omitzero"`
+	TimeDone   time.Time `json:",omitzero"`
 
 	Cmd     []string      // `json:",omitempty"`
 	CmdReal time.Duration `json:",omitempty"`

src/cmd/internal/test2json/test2json.go

@@ -29,7 +29,7 @@ const (
 
 // event is the JSON struct we emit.
 type event struct {
-	Time    *time.Time `json:",omitempty"`
+	Time    time.Time `json:",omitzero"`
 	Action  string
 	Package string     `json:",omitempty"`
 	Test    string     `json:",omitempty"`
@@ -387,8 +387,7 @@ func (c *Converter) writeOutputEvent(out []byte) {
 func (c *Converter) writeEvent(e *event) {
 	e.Package = c.pkg
 	if c.mode&Timestamp != 0 {
-		t := time.Now()
-		e.Time = &t
+		e.Time = time.Now()
 	}
 	if e.Test == "" {
 		e.Test = c.testName