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Where does the JLS specify that the result of an addition is int if its operands are of smaller type?

With reference to Why i am getting type mismatch: cannot convert from int to byte, I tried a quick search in the JLS to find where is it mentioned that the result of an addition between byte operands is automatically widened to int.

The best I found was this tutorial, but I didnt' find anything in the JLS.

The Conversions chapter does not mention anything about the addition operator, at least I couldn't find something. The Additive Operators paragraph does not mention automatic widening of byte. It mentions that the type of each of the operands of the binary - operator must be a type that is convertible (§5.1.8) to a primitive numeric type, but nothing about widening. And byte is a numeric data type.

What am I missing?

Solution

  • You were almost there, it is in 15.18.2:

    Binary numeric promotion is performed on the operands (§5.6.2).