Unexpected behaviour when mutating variables in if-clauses

[RickardCardell]

Bug Report

Bug(s) related to variable-scopes and if-else clauses.
We discovered it when we had a composition that were supposed to create 3 resources but were creating 6.
The closest examples are example 5 and example 6 in the comments below.

1. Minimal reproduce step (Required)

Execute this KCL-code:

_counter = 0

if _counter == 0:
    _counter += 1
else:
    _counter += 1

assert _counter == 1, "Error: counter should be 1 but was ${_counter}"

2. What did you expect to see? (Required)

_counter should be 1.

3. What did you see instead (Required)

Error: counter should be 1 but was 2

4. What is your KCL components version? (Required)

0.11.1

kcl version
0.11.1-darwin-arm64

[RickardCardell]

Example2 - Unexpected order of execution

_items = []

if len(_items) == 1:
    print("This line should NOT be executed")

if len(_items) == 0:
    print("This line should be executed")

_items += [{"last": "bar"}]

Expects: "This line should be executed"
Was: "This line should NOT be executed"

[RickardCardell]

Example3 - similar to example2

_items = []

if len(_items) > 0:
    print("This line should NOT be executed")
    _items += [{"two": "bar"}]            # The above line is printed but where does these items go?

if len(_items) == 0:
    print("This line should be executed")
    _items += [{"zero": "bar"}]

_items += [{"last": "bar"}]
_items

Expected:

This line should be executed
zero: bar
---
last: bar

Was:

This line should be executed
This line should NOT be executed
zero: bar
---
last: bar

[RickardCardell]

Example 4 - lambda and variable scopes

_counter = 42

f = lambda {
  #_counter = 0                        # Uncomment and result becomes 1042
  if _counter == 0:
    _counter += 1
  else:
    _counter += 1

  _counter
}

f()

if True:
    _counter += 1000
else:
    _counter = 10000000         # uncomment and result becomes 1042

assert _counter == 1042, "Error: _counter should be 1042, but was ${_counter}"

Expected: _counter should be 1042
Was: Error: _counter should be 1042, but was 42

[RickardCardell]

Example 5 - duplicate items are added
This is close to what happened in our composition.

_items = []

if False:
    _items += [{kind: "NotToBeAdded"}]  # Required. This item is not added as expected.

if True:
    _items += [{kind: "One_of_this_kind", rand: crypto.uuid() }]  # Two of these are added! 'rand' is not really needed

the_len = len(_items)    # Some kind of access to the list seems to be required

_items += [{kind: "LastItems"}]   # This is also needed

#print([ i for i in _items if i.kind == "One_of_this_kind"])
assert len([ i for i in _items if i.kind == "One_of_this_kind"]) == 1, 'len was ${len([ i for i in _items if i.kind == "One_of_this_kind"])}'

Expected: assertion is passed, since only one of that item should be added.
Actual: assert outputs: Error: len was 2

[RickardCardell]

Example 6 - very close to our composition.

_items = []

if True:  # 'Check from config that we should create the resource'
    if True:  # 'Lookup some settings based on condition'
        _foo = [1,2,3]
    else:
        _foo = []

    if len(_foo) > 0:  # 'Only create if we have something to create'
        _items += [{kind: "One_of_this_kind"}]  # Two of these are added!

_items += [{kind: "LastItem"}]

assert len([ i for i in _items if i.kind == "One_of_this_kind"]) == 1, 'Error: len was ${len([ i for i in _items if i.kind == "One_of_this_kind"])}'
items = _items

Expected: assertion is passed, since only one of that item should be added.
Actual: assert outputs: Error: len was 2