PANIC triggered by simple assembly `require` function

[axic]

The line https://github.com/axic/solcore/blob/a14a61491592a710ea588050dd982ff9e816ac87/test/examples/dispatch/deposit.solc#L240 triggers this PANIC:

$ ./contest.sh test/examples/dispatch/deposit.json 
Processing: test/examples/dispatch/deposit.json
Compiling to Hull...
PANIC: spec(require<sum((), ()) -> $420408>(ne<uint256 -> uint256 -> sum((), ())>(callvalue<uint256>(), uint256<word -> uint256>(0)))): free type vars in sum((), ()) -> $420408: [TVar {var = $420408}] @ subst={$265579 |-> $420408, a |-> uint256, decodable |-> calldata(bytes), ty |-> (memory(string), (memory(string), (memory(string), uint256))), reader |-> CalldataWordReader, decoded |-> (memory(string), (memory(string), (memory(string), uint256))), b |-> (memory(string), (memory(string), uint256)), _s1 |-> NonPayable, _q1 |-> (memory(string), (memory(string), (memory(string), uint256))), _r1 |-> (), _p1 |-> t_deposit421831, name |-> DispatchNameTy_DepositContract_deposit, n |-> Method(DispatchNameTy_DepositContract_deposit, NonPayable, (memory(string), (memory(string), (memory(string), uint256))), (), t_deposit421831), m |-> Method(DispatchNameTy_DepositContract_supportsInterface, NonPayable, uint256, sum((), ()), t_supportsInterface292600), methods |-> (Method(DispatchNameTy_DepositContract_get_zero_hash, NonPayable, uint256, uint256, t_get_zero_hash410559), (Method(DispatchNameTy_DepositContract_get_deposit_root, NonPayable, (), uint256, t_get_deposit_root413685), (Method(DispatchNameTy_DepositContract_get_deposit_count, NonPayable, (), memory(string), t_get_deposit_count418663), (Method(DispatchNameTy_DepositContract_deposit, NonPayable, (memory(string), (memory(string), (memory(string), uint256))), (), t_deposit421831), Method(DispatchNameTy_DepositContract_supportsInterface, NonPayable, uint256, sum((), ()), t_supportsInterface292600))))), fallback |-> Fallback(NonPayable, (), (), t_revert_handler260167)}
Error: sol-core compilation failed

Removing that line allows for compilation. Prior to this a more complex require implementation (the one from ownable.solc) worked. Commenting out the assembly block in require makes it compile.

[mbenke]

I'll look into improving the error handling (a proper error message instead of PANIC), but the underlying problem is real

[mbenke]

#371 aims to provide better diagnostics. Suggested way of implementing require:

forall a.
function myrevert(offset:word, length:word) -> a {
        assembly {
            revert(offset, length)
        }

}
function require(cond: bool) -> () {
    if (!cond) {
     myrevert(0,0):();
    }
}

the key point is the type annotation in myrevert(0,0):();

[axic]

@mbenke is this still an outstanding bug?

[mbenke]

Not in the sense that the test mentioned fails, no. Related test fails but for different reasons.
Polymorphic require by itself seems to work:

forall a.
function requireNot(cond: bool) -> a {
    if (cond) {
        assembly {
            revert(0, 0)
        }
    }
}

contract PolyRequire {
  public function main() -> () {
      requireNot(true);
      return ();
  }
}