Question

Following gives error as expected:

int* const const p = new int; // g++ error: duplicate cv-qualifier

But below doesn’t give any error, even though it’s equivalent to above one:

typedef int* const intp_const;
intp_const const p = new int;  // ok !
        // ^^^^^ duplicate ?

Why does compiler ignores the extra const ?

[Note: intp_const const is not same as const char* const, because *p = <value>; is possible.]

Answer 1

In 7.1.5 [dcl.type] (C++03), it is stated that redundant cv-qualifiers are allowed when introduced through a typedef:

const or volatile can be combined with any other type-specifier. However, redundant cv-
qualifiers are prohibited except when introduced through the use of typedefs (7.1.3) or template type
arguments (14.3), in which case the redundant cv-qualifiers are ignored.