Nested include vars overridden by ancestor include vars

[daeh]

Nested include vars overridden by ancestor include vars

Description

This issue may be related to the Variables Megathread discussion (#2034) and the scoping proposal in #2035, but I want to report a specific behavior that appears to contradict the fix in PR #1256 ("fix: propagate include vars in multi-level includes").

I believe the behavior described here is an edge case not covered by #1256 or a regression of that PR, but apologies if this is the expected behavior or a duplicate issue.

Summary

In nested includes (A → B → C), vars explicitly passed in the child include (B → C) are overridden by vars from the ancestor include (A → B). The immediate parent's explicit vars declaration is ignored. This seems inconsistent with PR #1256's intent to properly propagate include vars in multi-level includes.

Minimal Reproduction

minimal_test/
├── Taskfile.yml      # includes TasksLevel1 with EGVAR='INHERITED-root-value'
├── TasksLevel1.yml   # includes TasksLevel2 with EGVAR='PASSED-via-includes-in-level1'
└── TasksLevel2.yml   # expects 'PASSED-via-includes-in-level1', gets 'INHERITED-root-value'

Taskfile.yml

version: '3'

includes:
  level1:
    taskfile: './TasksLevel1.yml'
    vars:
      EGVAR: 'INHERITED-root-value'

TasksLevel1.yml

version: '3'

includes:
  level2:
    taskfile: './TasksLevel2.yml'
    vars:
      EGVAR: 'PASSED-via-includes-in-level1'  # IGNORED when invoked via root

tasks:
  show:
    cmds:
      - echo "EGVAR={{.EGVAR}}"

  call-level2-workaround:
    cmds:
      - task: level2:show
        vars:
          EGVAR: 'PASSED-via-task-in-level1'

TasksLevel2.yml

version: '3'

vars:
  DERIVED_EGVAR: '{{.EGVAR}}-derived'  # Computed at parse time

tasks:
  show:
    cmds:
      - echo "EGVAR={{.EGVAR}}"
      - echo "DERIVED_EGVAR={{.DERIVED_EGVAR}}"

Observed Behavior

# Nested includes: ancestor var overrides immediate parent's explicit var
$ task level1:level2:show
EGVAR=INHERITED-root-value
DERIVED_EGVAR=INHERITED-root-value-derived

# Direct invocation: immediate include var works correctly
$ task -t TasksLevel1.yml level2:show
EGVAR=PASSED-via-includes-in-level1
DERIVED_EGVAR=PASSED-via-includes-in-level1-derived

Expected Behavior

TasksLevel2.yml should receive EGVAR='PASSED-via-includes-in-level1' because that is what TasksLevel1.yml explicitly passes in its includes.

Task-Call-Time Vars Do Not Resolve This

Passing vars at task-call time (rather than include time) does not fully resolve this issue:

$ task level1:call-level2-workaround
EGVAR=PASSED-via-task-in-level1        # Task-call var works
DERIVED_EGVAR=INHERITED-root-value-derived  # Global var still wrong

Task-call vars override EGVAR for task execution, but cannot affect DERIVED_EGVAR, which was already evaluated at include time using the (incorrect) ancestor value.

Why This Seems Like a Bug

1. Explicit declarations ignored: vars: { EGVAR: '...' } in an include statement is an explicit override. Silent replacement by an ancestor's value violates least-surprise.

2. Entry-point-dependent behavior: The same taskfile behaves differently depending on whether it is the root or included from a parent.

3. Contradicts fix: propagate include vars in multi-level includes #1256: PR fix: propagate include vars in multi-level includes #1256 fixed multi-level include var propagation. Vars now propagate, but with incorrect precedence—ancestor wins over immediate parent.

Related Issues

Issue	Problem	This Bug
#996	Vars nil/lost	Vars propagate, wrong precedence
#1800	Child vars override parent	Opposite: ancestor overrides child
#2595	Race condition	Deterministic

• fix: propagate include vars in multi-level includes #1256 - PR that fixed multi-level include var propagation
• Variables Megathread #2034 - Variables Megathread
• Variable scope and inheritance experiment #2035 - Variable Scope and Inheritance Proposal

Version

3.46.3

Operating system

macOS 14.8.3

Experiments Enabled

No response

Example Taskfile

See above

[trulede]

@daeh the tasks are merged in the following sequence:

• level2:show - sets FOO=bar from includes vars (on intermediate task)
• level1:show - sets FOO=foo from includes vars
• level1:level2:show - FOO=bar which is overwritten with FOO=foo from includes vars

So, it is clear that the merge process applies the includes vars at each include level, and that the variable merge overwrites existing values.

Changing that behaviour is not so difficult (3-4 lines of code) ... however it does break quite a few tests, so we must assume this behaviour is intentional, and its fairly easy to make an equally good argument (as yours) for it to work the way it does.

I will close this a duplicate of #2035 as its one of the many cases where includes and vars do not operate well.

My own approach to this kind of behaviour is to "namespace" my taskfile vars with a useful prefix. That way, such variable name collisions are avoided.