[Bug c++/87016] New: std::optional::operator= in constexpr context

[bobogu at atlas dot cz]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87016

            Bug ID: 87016
           Summary: std::optional::operator= in constexpr context
           Product: gcc
           Version: 8.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: bobogu at atlas dot cz
  Target Milestone: ---

Created attachment 44558
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=44558&action=edit
preprocessed TU

According to the standard, there is no assignment operator that should work in
a constexpr context, however, I am able to successfully compile and use the
following snippet:

// gcc -lstdc++ -std=c++17 main.cpp @Linux laptop 4.17.11-arch1 x86_64

constexpr std::optional<int> foo() {
    std::optional<int> bar = 3;
    bar = 10;
    return bar;
}