std::variant::operator=
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                    | variant& operator=(const variant& rhs); | (1) | (since C++17) | 
| variant& operator=(variant&& rhs) noexcept(/* see below */); | (2) | (since C++17) | 
| template <class T> variant& operator=(T&& t) noexcept(/* see below */); | (3) | (since C++17) | 
Assigns a new value to an existing variant object
1) Copy-assignment:
-  If both *thisandrhsare valueless by exception, does nothing.
-  Otherwise, if rhsis valueless, but*thisis not, destroys the value contained in*thisand makes it valueless.
-  Otherwise, if rhsholds the same alternative as*this, assigns the value contained inrhsto the value contained in*this. If an exception is thrown,*thisdoes not become valueless: the value depends on the exception safety guarantee of the alternative's copy assignment.
-  Otherwise, if the alternative held by otheris either nothrow copy constructible or not nothrow move constructible (as determined by std::is_nothrow_copy_constructible and std::is_nothrow_move_constructible, respectively), equivalent to this->emplace<other.index()>(get<other.index()>(other)).
- Otherwise, equivalent to this->operator=(variant(rhs)).
 This overload only participates in overload resolution if 
std::is_copy_constructible_v<T_i> && std::is_copy_assignable_v<T_i> is true for all T_i in Types... 2) Move-assignment:
-  If both *thisandrhsare valueless by exception, does nothing
-  Otherwise, if rhsis valueless, but*thisis not, destroys the value contained in*thisand makes it valueless
-  Otherwise, if rhsholds the same alternative as*this, assigns std::get<j>(std::move(rhs)) to the value contained in*this, withjbeingindex(). If an exception is thrown,*thisdoes not become valueless: the value depends on the exception safety guarantee of the alternative's move assignment.
-  Otherwise (if rhsand*thishold different alternatives), equivalent to this->emplace<other.index()>(get<other.index()>(std::move(other))). If an exception is thrown byT_i's move constructor,*thisbecomes valueless_by_exception.
 This overload only participates in overload resolution if 
std::is_move_constructible_v<T_i> && std::is_move_assignable_v<T_i> is true for all T_i in Types.... 3) Converting assignment. 
-  Determines the alternative type T_jthat would be selected by overload resolution for the expression F(std::forward<T>(t)) if there was an overload of imaginary function F(T_i) for everyT_ifromTypes...in scope at the same time.
-  If *thisalready holds aT_j, assigns std::forward<T>(t) to the value contained in*this. If an exception is thrown,*thisdoes not become valueless: the value depends on the exception safety guarantee of the assignment called.
- Otherwise, if std::is_nothrow_constructible_v<T_j, T> || !std::is_nothrow_move_constructible_v<T_j> is true, equivalent to this->emplace<j>(std::forward<T>(t));
- Otherwise, equivalent to this->operator=(variant(std::forward<T>(t))).
This overload only participates in overload resolution if std::is_same_v<std::decay_t<T>, variant> is false and  std::is_assignable_v<T_j&, T> is true and std::is_constructible_v<T_j, T> is true and the expression F(std::forward<T>(t)) (with F being the above-mentioned set of imaginary functions) is well formed
variant<string> v1; v1 = "abc"; // OK variant<string, string> v2; v2 = "abc"; // Error variant <string, bool> v3; v3 = "abc"; // OK but chooses bool
| Contents | 
[edit] Parameters
| rhs | - | another variant | 
| t | - | a value convertible to one of the variant's alternatives | 
[edit] Return value
*this
[edit] Exceptions
1) May throw any exception thrown by assignment and copy/move initialization of any alternative
2) 
noexcept specification:  
noexcept(((std::is_nothrow_move_constructible_v<Types> && std::is_nothrow_move_assignable_v<Types>) && ...))
3) 
noexcept specification:  
noexcept(std::is_nothrow_assignable_v<T_j&, T> && std::is_nothrow_constructible_v<T_j, T>)
[edit] Example
| This section is incomplete Reason: no example | 
[edit] See also
| constructs a value in the variant, in place (public member function) | 


