Create v3 compiler which respects declaration order of variables

Also, fix "<no value>" been printed when a non-existing variable is printed.

testdata/checksum/Taskfile.yml

@@ -1,4 +1,4 @@
-version: '2'
+version: '3'
 
 tasks:
   build:

testdata/cyclic/Taskfile.yml

@@ -1,4 +1,4 @@
-version: '2'
+version: '3'
 
 tasks:
   task-1:

testdata/deps/Taskfile.yml

@@ -1,4 +1,4 @@
-version: '2'
+version: '3'
 
 tasks:
   default:

testdata/dir/Taskfile.yml

@@ -1,4 +1,4 @@
-version: '2'
+version: '3'
 
 tasks:
   whereami:

testdata/dir/explicit_doesnt_exist/Taskfile.yml

@@ -1,4 +1,4 @@
-version: '2'
+version: '3'
 
 tasks:
   whereami:

testdata/dir/explicit_exists/Taskfile.yml

@@ -1,4 +1,4 @@
-version: '2'
+version: '3'
 
 tasks:
   whereami:

testdata/dry/Taskfile.yml

@@ -1,4 +1,4 @@
-version: '2'
+version: '3'
 
 tasks:
   build:

testdata/dry_checksum/Taskfile.yml

@@ -1,4 +1,4 @@
-version: '2'
+version: '3'
 
 tasks:
   default:

testdata/env/Taskfile.yml

@@ -1,4 +1,4 @@
-version: '2'
+version: '3'
 
 vars:
   BAZ:

testdata/expand/Taskfile.yml

@@ -1,4 +1,4 @@
-version: '2'
+version: '3'
 
 tasks:
   pwd:

testdata/generates/Taskfile.yml

@@ -1,4 +1,7 @@
-version: '2'
+version: '3'
+
+vars:
+  BUILD_DIR: $pwd
 
 tasks:
   abs.txt:

testdata/generates/Taskvars.yml

@@ -1 +0,0 @@
-BUILD_DIR: $pwd

testdata/ignore_errors/Taskfile.yml

@@ -1,4 +1,4 @@
-version: '2'
+version: '3'
 
 tasks:
   task-should-pass:

testdata/includes_call_root_task/Taskfile.yml

@@ -1,4 +1,4 @@
-version: '2'
+version: '3'
 
 includes:
   included: Taskfile2.yml

testdata/includes_call_root_task/Taskfile2.yml

@@ -1,4 +1,4 @@
-version: '2'
+version: '3'
 
 tasks:
   call-root:

testdata/includes_deps/Taskfile.yml

@@ -1,4 +1,4 @@
-version: '2'
+version: '3'
 
 includes:
   included: Taskfile2.yml

testdata/includes_deps/Taskfile2.yml

@@ -1,4 +1,4 @@
-version: '2'
+version: '3'
 
 tasks:
   default:

testdata/includes_empty/Taskfile.yml

@@ -1,4 +1,4 @@
-version: '2'
+version: '3'
 
 includes:
   included: Taskfile2.yml

testdata/includes_empty/Taskfile2.yml

@@ -1,4 +1,4 @@
-version: '2'
+version: '3'
 
 vars:
   FILE: file.txt

testdata/params/Taskfile.yml

@@ -1,4 +1,8 @@
-version: '2'
+version: '3'
+
+vars:
+  PORTUGUESE_HELLO_WORLD: Olá, mundo!
+  GERMAN: Hello
 
 tasks:
   default:

testdata/params/Taskvars.yml

@@ -1,2 +0,0 @@
-PORTUGUESE_HELLO_WORLD: Olá, mundo!
-GERMAN: "Hello"

testdata/precondition/Taskfile.yml

@@ -1,4 +1,4 @@
-version: '2'
+version: '3'
 
 tasks:
   foo:

testdata/status/Taskfile.yml

@@ -1,4 +1,4 @@
-version: '2'
+version: '3'
 
 tasks:
   gen-foo:

testdata/summary/Taskfile.yml

@@ -1,4 +1,4 @@
-version: '2'
+version: '3'
 
 tasks:
   task-with-summary:

testdata/vars/v3/.gitignore

@@ -0,0 +1 @@
+*.txt

testdata/vars/v3/Taskfile.yml

@@ -0,0 +1,46 @@
+version: '3'
+
+vars:
+  VAR_A: A
+  VAR_B: '{{.VAR_A}}B'
+  VAR_C: '{{.VAR_B}}C'
+
+  VAR_1: {sh: echo 1}
+  VAR_2: {sh: 'echo "{{.VAR_1}}2"'}
+  VAR_3: {sh: 'echo "{{.VAR_2}}3"'}
+
+tasks:
+  default:
+    - task: missing-var
+    - task: var-order
+    - task: dependent-sh
+    - task: with-call
+
+  missing-var: echo '{{.NON_EXISTING_VAR}}' > missing-var.txt
+
+  var-order:
+    vars:
+      VAR_D: '{{.VAR_C}}D'
+      VAR_E: '{{.VAR_D}}E'
+      VAR_F: '{{.VAR_E}}F'
+    cmds:
+      - echo '{{.VAR_F}}' > var-order.txt
+
+  dependent-sh:
+    vars:
+      VAR_4: {sh: 'echo "{{.VAR_3}}4"'}
+      VAR_5: {sh: 'echo "{{.VAR_4}}5"'}
+      VAR_6: {sh: 'echo "{{.VAR_5}}6"'}
+    cmds:
+      - echo '{{.VAR_6}}' > dependent-sh.txt
+
+  with-call:
+    - task: called-task
+      vars:
+        ABC123: '{{.VAR_C}}{{.VAR_3}}'
+
+  called-task:
+    vars:
+      MESSAGE: Hi, {{.ABC123}}!
+    cmds:
+      - echo "{{.MESSAGE}}" > with-call.txt