GCC rejecting (I think) valid code

[Dale Johannesen]

On Jan 23, 2005, at 6:05 AM, Andreas Schwab wrote:

> "Sam Lauber" <sam124@operamail.com> writes:
>
>> I compile this pair of declarations with GCC (which would
>> probably be found in a stdint.h):
>>
>> typedef short int16_t;
>> typedef unsigned int16_t uint16_t;
>>
>> The first declaration is OK, but GCC gives me an error on
>> the second one. That dosen't make sense, because part of
>> the C89 grammar is
>>
>> type-name:
>> (some types) typedef-name
>>
>> typedef-declaration: something like
>> `typedef' type-name typedef-name
>
> There is more to C than the syntax.  The standard also contains 
> semantic
> constraints that are to be applied on top of the syntax.  I can't check
> C89, but in C99 section 6.7.2 contains an exhaustive list of allowed
> type-specifier sets in a type-name, and this list only allows a single
> typedef-name not mixed with other type-specifiers for each type-name.

C90 has the same list in 3.5.2.  An example in 3.5.6 sheds some light 
on why:
consider

struct {
    unsigned int16_t:4;
};