UnknownVariables doesn't return unknown variables defined in files

[dustdfg]

Running scons will print {}, while running scons my_var="cli_value" will print {'my_var': 'cli_value'}

#custom.py
my_var="value"

import SCons
from SCons.Variables import *

env = Environment()

options = Variables(["custom.py"], ARGUMENTS)
options.Add("my_option", "", "")

options.Update(env)

print(options.UnknownVariables())

[mwichmann]

The current manpage wording suggests "unknown" variables from files should indeed be flagged:

Returns a dictionary containing any variables that were specified in the files and/or args parameters when Variables was called, but the object was not actually configured for.

[mwichmann]

I can confirm there's no processing of unknowns in the variables-file reading section. It just does an exec to add the assignments to the dict.