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TPE: Simplify <residual> && false to false when <residual> cannot error #2091

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TPE: Simplify <residual> && false to false when <residual> cannot error #2091

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0ffea1f
TPE: Simplify `<residual> && false` to `false` and `<residual> || tru…
luxas Jan 9, 2026
918bdc6
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luxas Jan 9, 2026
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160 changes: 160 additions & 0 deletions cedar-policy-core/src/tpe/evaluator.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -136,6 +136,34 @@ impl Evaluator<'_> {
},
..
} => left,
Residual::Concrete {
value:
Value {
value: ValueKind::Lit(ast::Literal::Bool(false)),
..
},
..
} => {
if !left.can_error_assuming_well_formed() {
// simplify <error-free> && false == false
Residual::Concrete {
value: false.into(),
ty,
}
} else {
// cannot simplify <non-error-free> && false
Residual::Partial {
kind: ResidualKind::And {
left: Arc::new(left),
right: Arc::new(Residual::Concrete {
value: false.into(),
ty: ty.clone(),
}),
},
ty,
}
}
}
right => Residual::Partial {
kind: ResidualKind::And {
left: Arc::new(left),
Expand Down Expand Up @@ -179,6 +207,34 @@ impl Evaluator<'_> {
},
..
} => left,
Residual::Concrete {
value:
Value {
value: ValueKind::Lit(ast::Literal::Bool(true)),
..
},
..
} => {
if !left.can_error_assuming_well_formed() {
// simplify <error-free> || true == true
Residual::Concrete {
value: true.into(),
ty,
}
} else {
// cannot simplify <non-error-free> || true
Residual::Partial {
kind: ResidualKind::Or {
left: Arc::new(left),
right: Arc::new(Residual::Concrete {
value: true.into(),
ty: ty.clone(),
}),
},
ty,
}
}
}
right => Residual::Partial {
kind: ResidualKind::Or {
left: Arc::new(left),
Expand Down Expand Up @@ -843,6 +899,58 @@ mod tests {
..
}
);
// <error-free> && false => false
// principal.name like "lucas-*" && 41 == 42 => false
assert_matches!(
eval.interpret_expr(
&builder().and(
builder().like(
builder().get_attr(builder().var(Var::Principal), "name".parse().unwrap()),
vec![
PatternElem::Char('l'),
PatternElem::Char('u'),
PatternElem::Char('c'),
PatternElem::Char('a'),
PatternElem::Char('s'),
PatternElem::Char('-'),
PatternElem::Wildcard
]
.into()
),
builder().is_eq(builder().val(41), builder().val(42))
)
)
.unwrap(),
Residual::Concrete {
value: Value {
value: ValueKind::Lit(Literal::Bool(false)),
..
},
..
},
);
// <non-error-free> && false cannot be simplified, e.g.
// principal.foo + 1 == 100 && 41 == 42
assert_matches!(
eval.interpret_expr(&builder().and(
builder().is_eq(
builder().add(
builder().get_attr(builder().var(Var::Principal), "foo".parse().unwrap()),
builder().val(1)
),
builder().val(100)
),
builder().is_eq(builder().val(41), builder().val(42))
))
.unwrap(),
// cannot match against the full residual, because of the Arc in the And enum variant,
// and due to Residual not implementing the Eq trait, but this shows that the evaluator
// kept the residual partial and with an And clause.
Residual::Partial {
kind: ResidualKind::And { .. },
..
}
);
}

#[test]
Expand Down Expand Up @@ -917,6 +1025,58 @@ mod tests {
..
}
);
// <error-free> || true => true
// principal.name like "lucas-*" || 42 == 42 => true
assert_matches!(
eval.interpret_expr(
&builder().or(
builder().like(
builder().get_attr(builder().var(Var::Principal), "name".parse().unwrap()),
vec![
PatternElem::Char('l'),
PatternElem::Char('u'),
PatternElem::Char('c'),
PatternElem::Char('a'),
PatternElem::Char('s'),
PatternElem::Char('-'),
PatternElem::Wildcard
]
.into()
),
builder().is_eq(builder().val(42), builder().val(42))
)
)
.unwrap(),
Residual::Concrete {
value: Value {
value: ValueKind::Lit(Literal::Bool(true)),
..
},
..
},
);
// <non-error-free> || true cannot be simplified, e.g.
// principal.foo + 1 == 100 || 42 == 42
assert_matches!(
eval.interpret_expr(&builder().or(
builder().is_eq(
builder().add(
builder().get_attr(builder().var(Var::Principal), "foo".parse().unwrap()),
builder().val(1)
),
builder().val(100)
),
builder().is_eq(builder().val(42), builder().val(42))
))
.unwrap(),
// cannot match against the full residual, because of the Arc in the Or enum variant,
// and due to Residual not implementing the Eq trait, but this shows that the evaluator
// kept the residual partial and with an Or clause.
Residual::Partial {
kind: ResidualKind::Or { .. },
..
}
);
}

#[test]
Expand Down
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