Lyd/underflow constraints#494
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Wei-257
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Jul 14, 2026
| node.expression?.leftHandSide?.typeName === 'bool' | ||
| ? 'bool' | ||
| : 'field'; | ||
| return withUnderflowGuardAssertions( |
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line 390, case 'InternalFunctionCall', is there any reason that we do not wrap it with "withUnderflowGuardAssertions(...)"?
for example, what if in solidity, we have something like "helper(a - amount);" which rejects when amount is greater than a. but in the circuit, this would not be enforced based on the current behaviour.
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We get an unrelated compiler error for inputs to internal function calls such as these. In commit d011d87 I have therefore added this as unsupported.
…th parameters that are expressions
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Summary
Currently in the circuits in Starlight, there are no checks to prevent underflows. Say we have a decrementation:
c -= a, we do not currently check that c > a first in the circuits. This means that c could underflow to the field modulus minus a. In contracts like Escrow.zol, this will lead to a user having a very high balance.
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