NAME

std::rethrow_exception - std::rethrow_exception

Synopsis

Defined in header <exception>
[[noreturn]] void rethrow_exception( std::exception_ptr p ); (since C++11)

Throws the previously captured exception object referred-to by the exception pointer
p, or a copy of that object.

It is unspecified whether a copy is made. If a copy is made, the storage for it is
allocated in an unspecified way.

The behavior is undefined if p is null.

Parameters

p - non-null std::exception_ptr

Return value

(none)

Exceptions

The exception object referred-to by p if no copy is made.

Otherwise, a copy of such exception object if the implementation successfully copied
the exception object.

Otherwise, std::bad_alloc or the exception thrown when copying the exception object,
if allocation or copying fails, respectively.

Notes

Before P1675R2, rethrow_exception was not allowed to copy the exception object,
which is unimplementable on some platforms where exception objects are allocated on
the stack.

Example

// Run this code

#include <iostream>
#include <string>
#include <exception>
#include <stdexcept>

void handle_eptr(std::exception_ptr eptr) // passing by value is ok
{
try {
if (eptr) {
std::rethrow_exception(eptr);
}
} catch(const std::exception& e) {
std::cout << "Caught exception \"" << e.what() << "\"\n";
}
}

int main()
{
std::exception_ptr eptr;
try {
std::string().at(1); // this generates an std::out_of_range
} catch(...) {
eptr = std::current_exception(); // capture
}
handle_eptr(eptr);
} // destructor for std::out_of_range called here, when the eptr is destructed

Possible output:

Caught exception "basic_string::at"