Remove the old std::optional based Result class, replace uses with the
new std::variant based Result class.
Test: make idmap2_tests
Change-Id: I401cb36e5af06133a2872d835cf29bfb0b106597
Add a new version of the Result class that functions like the old
Result, but in case of an error, also encodes a string detailing the
error. This will allow us to write the following type of code:
Result<Foo> CreateFoo() {
if (...) {
return Error("errno=%d", errno());
}
return Foo(...);
}
auto foo = CreateFoo();
if (!foo) {
std::cerr << "error: " << foo.GetErrorMessage() << std::endl;
abort();
}
std::cout << "foo=" << *foo << std::endl;
This commit only adds the new Result class. A later change will replace
uses of the old version.
Test: make idmap2_tests
Change-Id: I674d8a06866402adedf85f8514400f25840d5eda
