SHAMap::snapShot maybe exist an error

[NewChinese]

std::shared_ptr
SHAMap::snapShot (bool isMutable) const
{
auto ret = std::make_shared (type_, f_, get_version());
SHAMap& newMap = *ret;

if (!isMutable)
    newMap.state_ = SHAMapState::Immutable;

newMap.seq_ = seq_ + 1;
newMap.ledgerSeq_ = ledgerSeq_;
newMap.root_ = root_;
newMap.backed_ = backed_;

**if ((state_ != SHAMapState::Immutable) || !isMutable)**
{
    // If either map may change, they cannot share nodes
    newMap.unshare ();
}

return ret;

}

In the above codes, this line "if ((state_ != SHAMapState::Immutable) || !isMutable)" ,
it seems that it should be "if ((state_ != SHAMapState::Immutable) || isMutable)"

[HowardHinnant]

Thanks for submitting this issue!

[JoelKatz]

The code does look wrong. I think it's not hurting us because I don't believe the code ever tries to take a mutable snapshot of a ledger that isn't already unshared. But I suspect it would be possible to create a unit test that fails with the current code and works correctly with this fixed.