vipa | Virtual Intelligent Publishing Assistant : A | Content Management System library

TL;DR:

• In (1), do the 1st and 2nd volatile qualifiers both refer to int, thus being "duplicate" in gcc terms? (I'm looking at C99 6.7.3.4 here.)

yes, they both qualify the int and they're the duplicate.

• In (2), does one of the volatile qualifiers refer to the type of the array, and not the int or the pointer itself, so that C99 6.7.3.8 holds:

C99 6.7.3.8 does not hold here. The qualifier already applies to the element type. It is possible to apply a qualifier to an array with a typedef, but that also qualifies the element type (see below)

c. If the answer to b is negative, how do I declare a volatile array type that is described in C99 6.7.3.8?

With a typedef for example.

The C standard explicitly allows qualifiers to occur more than once. C11 n1570 6.7.3p5:

If the same qualifier appears more than once in the same specifier-qualifier-list, either directly or via one or more typedefs, the behavior is the same as if it appeared only once.

i.e. what -Wduplicate-decl-specifier is not an error as such, but such code verbatim is suspicious - should it be volatile int *volatile that was misspelt as volatile int volatile * causing the pointer to be unqualified...

The qualifiers apply to type of the left left of the qualifier, except if the qualifier itself is the leftmost one, in which case it is as if it was right of the base type i.e.