7 Expressions [expr]

7.6 Compound expressions [expr.compound]

7.6.18 Throwing an exception [expr.throw]

1
#
A throw-expression is of type void.
2
#
Evaluating a throw-expression with an operand throws an exception; the type of the exception object is determined by removing any top-level cv-qualifiers from the static type of the operand and adjusting the type from “array of T” or function type T to “pointer to T”.
3
#
A throw-expression with no operand rethrows the currently handled exception.
The exception is reactivated with the existing exception object; no new exception object is created.
The exception is no longer considered to be caught.
[Example 1: 
An exception handler that cannot completely handle the exception itself can be written like this: try { // ... } catch (...) { // catch all exceptions // respond (partially) to exception throw; // pass the exception to some other handler }
— end example]
4
#
If no exception is presently being handled, evaluating a throw-expression with no operand calls std​::​​terminate().