What is type of lambda expression?
The type of a lambda expression (the so-called closure) is an unnamed class type with a function call operator automatically generated by the compiler. The internal name the compiler will give it is unspecified.
According to Paragraph 5.1.2/3 of the C++11 Standard:
The type of the lambda-expression (which is also the type of the closure object) is a unique, unnamed nonunion
class type — called the closure type — whose properties are described below. This class type is not
an aggregate (8.5.1). The closure type is declared in the smallest block scope, class scope, or namespace
scope that contains the corresponding lambda-expression. [...]
Also notice, that the name()
member function of the type_info
class (the type returned by typeid()
) is also implementation-dependent, and the Standard does not require it to be meaningful for a human.
Per Paragraph 18.7.1:
const char* name() const noexcept;
9 Returns: An implementation-defined NTBS.
10 Remarks: The message may be a null-terminated multibyte string (17.5.2.1.4.2), suitable for conversion and display as a wstring (21.3, 22.4.1.4)