Remove deprecated "$" and "^" prefixes

`$` was a variable prefix that make it being evaluated as shell. It was
replaced with `sh:`.

`^` is a command prefix that make it run another task. It was replaced
with `task:`.

These were added long ago when we were experimenting with stuff and kept for
some time for backward compatibility reasons, but sometimes causes confusion
and I think the time to remove the code came.

Closes #644
Closes #645
Ref #642

Co-authored-by: Trite <60318513+Trite8Q1@users.noreply.github.com>

CHANGELOG.md

@@ -2,7 +2,12 @@
 
 ## Unreleased
 
-- Add support for yaml extension ([#584](https://github.com/go-task/task/issues/584))
+- Remove long deprecated and undocumented `$` variable prefix and `^` command
+  prefix
+  ([#642](https://github.com/go-task/task/issues/642), [#644](https://github.com/go-task/task/issues/644), [#645](https://github.com/go-task/task/pull/645)).
+- Add support for `.yaml` extension (as an alternative to `.yml`).
+  This was requested multiple times throughout the years. Enjoy!
+  ([#183](https://github.com/go-task/task/issues/183), [#184](https://github.com/go-task/task/pull/184), [#369](https://github.com/go-task/task/issues/369), [#584](https://github.com/go-task/task/issues/584), [#621](https://github.com/go-task/task/pull/621)).
 
 ## v3.9.2 - 2021-12-02
 

taskfile/cmd.go

@@ -1,9 +1,5 @@
 package taskfile
 
-import (
-	"strings"
-)
-
 // Cmd is a task command
 type Cmd struct {
 	Cmd         string
@@ -23,11 +19,7 @@ type Dep struct {
 func (c *Cmd) UnmarshalYAML(unmarshal func(interface{}) error) error {
 	var cmd string
 	if err := unmarshal(&cmd); err == nil {
-		if strings.HasPrefix(cmd, "^") {
-			c.Task = strings.TrimPrefix(cmd, "^")
-		} else {
 		c.Cmd = cmd
-		}
 		return nil
 	}
 	var cmdStruct struct {

taskfile/var.go

@@ -2,7 +2,6 @@ package taskfile
 
 import (
 	"errors"
-	"strings"
 
 	"gopkg.in/yaml.v3"
 )
@@ -108,11 +107,7 @@ type Var struct {
 func (v *Var) UnmarshalYAML(unmarshal func(interface{}) error) error {
 	var str string
 	if err := unmarshal(&str); err == nil {
-		if strings.HasPrefix(str, "$") {
-			v.Sh = strings.TrimPrefix(str, "$")
-		} else {
 		v.Static = str
-		}
 		return nil
 	}
 

testdata/vars/v2/Taskfile.yml

@@ -35,7 +35,8 @@ tasks:
       - echo '{{.TASK}}' > task_name.txt
     vars:
       FOO: foo
-      BAR: $echo bar
+      BAR:
+        sh: echo bar
       BAZ:
         sh: echo baz
       TMPL_FOO: "{{.FOO}}"

testdata/vars/v2/Taskvars.yml

@@ -1,5 +1,6 @@
 FOO2: foo2
-BAR2: $echo bar2
+BAR2:
+  sh: echo bar2
 BAZ2:
   sh: echo baz2
 TMPL2_FOO: "{{.FOO}}"