No exception is thrown on overflow during testing via Anchor Framework

[YanhuiJessica]

Describe the bug
I started a project following Getting started with Solang. I have tried some math calculations that would overflow, but found that all tests passed.

To Reproduce
Steps to reproduce the behavior:

1. anchor init example --solidity
2. Overwrite the flip() function with the following lines (example/solidity/example.sol)

function flip() public {
   uint32 x = 2147483648;
   uint32 y = 2147483648;
   uint32 z = x + y;
   print("z: {}".format(z));
   value = !value;
}

3. anchor test All tests passed
4. example/.anchor/program-logs/F1ipperKF9EfD821ZbbYjS319LXYiBmjhzkkf5a26rC.example.log

Streaming transaction logs mentioning F1ipperKF9EfD821ZbbYjS319LXYiBmjhzkkf5a26rC. Confirmed commitment
Transaction executed in slot 2:
  Signature: N3wupwfD5JcQLAVznxcqLXYB5wqqzoGGzmNyqMRwSqMjVsXJt8FZqu6ZjUg51pqdcMRMgBuut2kUvHwGGt5g97K
  Status: Ok
  Log Messages:
    ...
    Program log: Hello, World!
    ...
Transaction executed in slot 3:
  Signature: 4pL9WzzwpVp8CVbzFarEgcyXhCAUW7b661VGqWeUGHbwD8M4XT6ccprzu6nKXcCv7vCrS883jaBaptJ5Yg56orJJ
  Status: Ok
  Log Messages:
    Program F1ipperKF9EfD821ZbbYjS319LXYiBmjhzkkf5a26rC invoke [1]
    Program log: z: 0
    ...

Expected behavior
Throws an exception on overflow.

Hyperledger Solang version
v0.3.1

[seanyoung]

The const folding pass is at fault here. The addition is done at compile time, but the overflow is not detected.