Message The type "<type>" is declared nested within "<enclosing type>". In C, the nesting is ignored and <type> can be accessed as if it were not nested. <However, the type is a member in C++>. <Fix>. Description C allows types to be declared within other types. For example: struct S { int x; struct S1 { int a; int b; } y; }; In C++ the struct S1 would not be accessible without using the :: operator. User Action Declare the nested type before declaring the enclosing type.