What types are convertible to std::any?

Question

While writing a clang plugin, I noticed that objects of type llvm::cl::opt<T> are not convertible to std::any, i.e. the following snippet does not compile:

#include <any> #include <string> #include "llvm/Support/CommandLine.h" int main() { llvm::cl::opt<std::string> opt("o"); std::any opt_any = opt; // doesn't work! }

I would like to know both why this isn't possible in this specific instance and what criteria a type has to fullfill in general in order to be convertible to std::any.

@idclev463035818: That depends on the compiler and is not very insightful for both gcc and clang. — Peter
– Peter, Commented Jul 8, 2020 at 14:04
somewhere hidden, the error message just says the same as the answer. Maybe you cannot read it, but perhaps others can and also others might get the similar error so including the error message would make the question more useful for future readers — 463035818_is_not_an_ai
– 463035818_is_not_an_ai, Commented Jul 8, 2020 at 14:05
note to what @ idclev said: because then others pass-in error in search engine, it would link to here. — apple apple
– apple apple, Commented Jul 8, 2020 at 15:13

NathanOliver · Accepted Answer · 2020-07-08 13:59:52Z

llvm::cl::opt is not copyable. Both the copy constrcutor and copy assignment operator are marked as delete.

std::any requires that in construction and assignment that the type be copyable.

You could use a std::unique_ptr<llvm::cl::opt<std::string>> or std::shared_ptr<llvm::cl::opt<std::string>> or even a std::reference_wrapper depending on how you want to handle the lifetime of the object.

Collectives™ on Stack Overflow

What types are convertible to std::any?

1 Answer 1

Comments

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Related