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Handle division by zero error in const evaluator #2333

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4c18bf3
add division by zero error to const evaluator
orpuente-MS Apr 24, 2025
3288c17
add float division error
orpuente-MS Apr 24, 2025
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43 changes: 33 additions & 10 deletions compiler/qsc_qasm/src/semantic/const_eval.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -25,6 +25,9 @@ use thiserror::Error;

#[derive(Clone, Debug, Diagnostic, Eq, Error, PartialEq)]
pub enum ConstEvalError {
#[error("division by error during const evaluation")]
#[diagnostic(code("Qasm.Lowerer.DivisionByZero"))]
DivisionByZero(#[label] Span),
#[error("expression must be const")]
#[diagnostic(code("Qasm.Lowerer.ExprMustBeConst"))]
ExprMustBeConst(#[label] Span),
Expand Down Expand Up @@ -457,25 +460,45 @@ impl BinaryOpExpr {
},
BinOp::Div => match lhs_ty {
Type::Int(..) | Type::UInt(..) => {
rewrap_lit!((lhs, rhs), (Int(lhs), Int(rhs)), Int(lhs / rhs))
rewrap_lit!((lhs, rhs), (Int(lhs), Int(rhs)), {
if rhs == 0 {
ctx.push_const_eval_error(ConstEvalError::DivisionByZero(self.span()));
return None;
}
Int(lhs / rhs)
})
}
Type::Float(..) => {
rewrap_lit!((lhs, rhs), (Float(lhs), Float(rhs)), Float(lhs / rhs))
rewrap_lit!((lhs, rhs), (Float(lhs), Float(rhs)), {
if rhs == 0. {
ctx.push_const_eval_error(ConstEvalError::DivisionByZero(self.span()));
return None;
}
Float(lhs / rhs)
})
}
Type::Angle(..) => match &self.rhs.ty {
Type::UInt(..) => {
rewrap_lit!(
(lhs, rhs),
(Angle(lhs), Int(rhs)),
rewrap_lit!((lhs, rhs), (Angle(lhs), Int(rhs)), {
if rhs == 0 {
ctx.push_const_eval_error(ConstEvalError::DivisionByZero(
self.span(),
));
return None;
}
Angle(lhs / u64::try_from(rhs).ok()?)
)
})
}
Type::Angle(..) => {
rewrap_lit!(
(lhs, rhs),
(Angle(lhs), Angle(rhs)),
rewrap_lit!((lhs, rhs), (Angle(lhs), Angle(rhs)), {
if rhs.value == 0 {
ctx.push_const_eval_error(ConstEvalError::DivisionByZero(
self.span(),
));
return None;
}
Int((lhs / rhs).try_into().ok()?)
)
})
}
_ => None,
},
Expand Down
7 changes: 7 additions & 0 deletions compiler/qsc_qasm/src/tests/fuzz.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -77,3 +77,10 @@ fn fuzz_2313() {
super::compare_qasm_and_qasharp_asts(source);
compile_qasm_best_effort(source, Profile::Unrestricted);
}

#[test]
fn fuzz_2332() {
let source = r#"ctrl(0/0)@s"#;
super::compare_qasm_and_qasharp_asts(source);
compile_qasm_best_effort(source, Profile::Unrestricted);
}
147 changes: 147 additions & 0 deletions compiler/qsc_qasm/src/tests/statement/const_eval.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -2186,3 +2186,150 @@ fn binary_op_with_non_supported_types_fails() {
"#]]
.assert_eq(&errs_string);
}

#[test]
fn division_of_int_by_zero_int_errors() {
let source = r#"
const int a = 2 / 0;
def f() { a; }
"#;

let Err(errs) = compile_qasm_to_qsharp(source) else {
panic!("should have generated an error");
};
let errs: Vec<_> = errs.iter().map(|e| format!("{e:?}")).collect();
let errs_string = errs.join("\n");
expect![[r#"
Qasm.Lowerer.DivisionByZero

x division by error during const evaluation
,-[Test.qasm:2:23]
1 |
2 | const int a = 2 / 0;
: ^^^^^
3 | def f() { a; }
`----

Qasm.Lowerer.ExprMustBeConst

x a captured variable must be a const expression
,-[Test.qasm:3:19]
2 | const int a = 2 / 0;
3 | def f() { a; }
: ^
4 |
`----
"#]]
.assert_eq(&errs_string);
}

#[test]
fn division_of_angle_by_zero_int_errors() {
let source = r#"
const angle a = 2.0;
const angle b = a / 0;
def f() { b; }
"#;

let Err(errs) = compile_qasm_to_qsharp(source) else {
panic!("should have generated an error");
};
let errs: Vec<_> = errs.iter().map(|e| format!("{e:?}")).collect();
let errs_string = errs.join("\n");
expect![[r#"
Qasm.Lowerer.DivisionByZero

x division by error during const evaluation
,-[Test.qasm:3:25]
2 | const angle a = 2.0;
3 | const angle b = a / 0;
: ^^^^^
4 | def f() { b; }
`----

Qasm.Lowerer.ExprMustBeConst

x a captured variable must be a const expression
,-[Test.qasm:4:19]
3 | const angle b = a / 0;
4 | def f() { b; }
: ^
5 |
`----
"#]]
.assert_eq(&errs_string);
}

#[test]
fn division_by_zero_float_errors() {
let source = r#"
const float a = 2.0 / 0.0;
def f() { a; }
"#;

let Err(errs) = compile_qasm_to_qsharp(source) else {
panic!("should have generated an error");
};
let errs: Vec<_> = errs.iter().map(|e| format!("{e:?}")).collect();
let errs_string = errs.join("\n");
expect![[r#"
Qasm.Lowerer.DivisionByZero

x division by error during const evaluation
,-[Test.qasm:2:25]
1 |
2 | const float a = 2.0 / 0.0;
: ^^^^^^^^^
3 | def f() { a; }
`----

Qasm.Lowerer.ExprMustBeConst

x a captured variable must be a const expression
,-[Test.qasm:3:19]
2 | const float a = 2.0 / 0.0;
3 | def f() { a; }
: ^
4 |
`----
"#]]
.assert_eq(&errs_string);
}

#[test]
fn division_by_zero_angle_errors() {
let source = r#"
const angle a = 2.0;
const angle b = 0.0;
const uint c = a / b;
def f() { c; }
"#;

let Err(errs) = compile_qasm_to_qsharp(source) else {
panic!("should have generated an error");
};
let errs: Vec<_> = errs.iter().map(|e| format!("{e:?}")).collect();
let errs_string = errs.join("\n");
expect![[r#"
Qasm.Lowerer.DivisionByZero

x division by error during const evaluation
,-[Test.qasm:4:24]
3 | const angle b = 0.0;
4 | const uint c = a / b;
: ^^^^^
5 | def f() { c; }
`----

Qasm.Lowerer.ExprMustBeConst

x a captured variable must be a const expression
,-[Test.qasm:5:19]
4 | const uint c = a / b;
5 | def f() { c; }
: ^
6 |
`----
"#]]
.assert_eq(&errs_string);
}
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