Warning Invoking events without emit prefix is deprecated while truffle compile

Question

truffle compile outputs Warning: Invoking events without "emit" prefix is deprecated.

Compilation warnings encountered:

zeppelin-solidity/contracts/token/ERC20/BasicToken.sol:38:5: Warning: 
Invoking events without "emit" prefix is deprecated.
   Transfer(msg.sender, _to, _value);

Answer 1

As the warning mentions, add emit as a prefix like this:

emit Transfer(msg.sender, _to, _value);

The emit keyword is used to call the events explicitly. 

Answer 2

Try removing zeppelin-solidity and reinstalling version zeppelin-solidity 1.8.0

npm install --save zeppelin-solidity@1.8.0

This should help