Structured binding on const

Question

Is the following code supposed to compile? #include void foo() { const std::pair x = {1, 2}; auto [a, b] = x; static_assert(std::is_const_v); static_assert(std::is_const_v); } MSVC says "yes!". GCC says "oh no, man!". Clang says "no way!". So, is this an MSVC bug? The standard is not straightforward here (I had a quick look), but considering the rules for auto, I suppose, a and b should be copied discarding cv-qualifier. JavaScript questions and answers, JavaScript questions pdf, JavaScript question bank, JavaScript questions and answers pdf, mcq on JavaScript pdf, JavaScript questions and solutions, JavaScript mcq Test , Interview JavaScript questions, JavaScript Questions for Interview, JavaScript MCQ (Multiple Choice Questions)

Answer 1

Is the following code supposed to compile? It is not. This is an MSVC bug. A structured binding declaration introduces a new name (for specification only), e, that is declared like: auto e = x; The type of e is called E, and since the initializer is tuple-like, the types of the bindings are given by tuple_element_t. In this case E is pair, so the two types are just int. The rule for decltype of a structured binding is to give the referenced type, so decltype(a) and decltype(b) are both int. The important part here is that a and b (the structured bindings) come from the invented variable (e), and not its initializer (x). e is not const because you just declared it auto. What we're doing is copying x, and then taking bindings into this (non-const) copy.