Add "output" options to the Taskfile

Also, fix handling of Taskfile by making the version an instance of
`semver.Constraints` instead of `semver.Version`. This makes the version
works as described on TASKFILE_VERSIONS.md document, i.e. version "2" will
include "2.x" features but version "2.0" not.

internal/taskfile/taskfile.go

@@ -4,6 +4,7 @@ package taskfile
 type Taskfile struct {
 	Version    string
 	Expansions int
+	Output     string
 	Vars       Vars
 	Tasks      Tasks
 }
@@ -18,6 +19,7 @@ func (tf *Taskfile) UnmarshalYAML(unmarshal func(interface{}) error) error {
 	var taskfile struct {
 		Version    string
 		Expansions int
+		Output     string
 		Vars       Vars
 		Tasks      Tasks
 	}
@@ -26,6 +28,7 @@ func (tf *Taskfile) UnmarshalYAML(unmarshal func(interface{}) error) error {
 	}
 	tf.Version = taskfile.Version
 	tf.Expansions = taskfile.Expansions
+	tf.Output = taskfile.Output
 	tf.Vars = taskfile.Vars
 	tf.Tasks = taskfile.Tasks
 	if tf.Expansions <= 0 {

internal/taskfile/version/version.go

@@ -5,27 +5,30 @@ import (
 )
 
 var (
-	v1 = mustVersion("1")
+	v1  = mustVersion("1")
-	v2 = mustVersion("2")
+	v2  = mustVersion("2")
-
+	v21 = mustVersion("2.1")
-	isV1  = mustConstraint("= 1")
+	v22 = mustVersion("2.2")
-	isV2  = mustConstraint(">= 2")
-	isV21 = mustConstraint(">= 2.1")
 )
 
 // IsV1 returns if is a given Taskfile version is version 1
-func IsV1(v *semver.Version) bool {
+func IsV1(v *semver.Constraints) bool {
-	return isV1.Check(v)
+	return v.Check(v1)
 }
 
 // IsV2 returns if is a given Taskfile version is at least version 2
-func IsV2(v *semver.Version) bool {
+func IsV2(v *semver.Constraints) bool {
-	return isV2.Check(v)
+	return v.Check(v2)
 }
 
-// IsV21 returns if is a given Taskfile version is at least version 2
+// IsV21 returns if is a given Taskfile version is at least version 2.1
-func IsV21(v *semver.Version) bool {
+func IsV21(v *semver.Constraints) bool {
-	return isV21.Check(v)
+	return v.Check(v21)
+}
+
+// IsV22 returns if is a given Taskfile version is at least version 2.2
+func IsV22(v *semver.Constraints) bool {
+	return v.Check(v22)
 }
 
 func mustVersion(s string) *semver.Version {
@@ -35,11 +38,3 @@ func mustVersion(s string) *semver.Version {
 	}
 	return v
 }
-
-func mustConstraint(s string) *semver.Constraints {
-	c, err := semver.NewConstraint(s)
-	if err != nil {
-		panic(err)
-	}
-	return c
-}

task.go

@@ -79,7 +79,7 @@ func (e *Executor) Setup() error {
 		return err
 	}
 
-	v, err := semver.NewVersion(e.Taskfile.Version)
+	v, err := semver.NewConstraint(e.Taskfile.Version)
 	if err != nil {
 		return fmt.Errorf(`task: could not parse taskfile version "%s": %v`, e.Taskfile.Version, err)
 	}
@@ -108,7 +108,7 @@ func (e *Executor) Setup() error {
 			Vars:   e.taskvars,
 			Logger: e.Logger,
 		}
-	case version.IsV2(v):
+	case version.IsV2(v), version.IsV21(v):
 		e.Compiler = &compilerv2.CompilerV2{
 			Dir:          e.Dir,
 			Taskvars:     e.taskvars,
@@ -116,8 +116,11 @@ func (e *Executor) Setup() error {
 			Expansions:   e.Taskfile.Expansions,
 			Logger:       e.Logger,
 		}
-	case version.IsV21(v):
+	case version.IsV22(v):
-		return fmt.Errorf(`task: Taskfile versions greater than v2 not implemented in the version of Task`)
+		return fmt.Errorf(`task: Taskfile versions greater than v2.1 not implemented in the version of Task`)
+	}
+	if !version.IsV21(v) && e.Taskfile.Output != "" {
+		return fmt.Errorf(`task: Taskfile option "output" is only available starting on Taskfile version v2.1`)
 	}
 
 	e.taskCallCount = make(map[string]*int32, len(e.Taskfile.Tasks))