Re: c compiler: Problems with constants

On Tuesday 23 March 2004 07:06 pm, Alan Jenkins wrote:
> gcc will compile the folowing code, but cscc produces errors for the last
> two statements:
>
> test.c:8: constant value required
> test.c:9: constant value required

Please log this "sizeof" problem in Savannah, so that I don't forget about it.

> I also discovered that the following compiles on gcc but not cscc (syntax
> error, unexpected 'int').  I don't know how important this is:
>
> main ()
> {
>         int i;
>         {
>                 /* do nothing*/
>         }
>         int j;
> }
>
> I guess this is because cscc assumes that something apart from variable
> declarations happens inside the subblock - which excludes futher variable
> declarations i.e. the declaration of j - at the parsing level.  Presumably
> gcc leaves this check until later when it can see that the subblock
> contains nothing that is not a variable declaration inside.

Traditional ANSI C only allows declarations at the head of a block.  C++ 
allows them anywhere in a block.  The latest version of gcc follows the C++ 
model.  Until recently, such code was considered invalid in C.

I personally think that it *should* be invalid because it causes sloppy coders 
to write C code that won't compile on most of the world's existing C 
compilers, harming code portability in the process.  This is why I do most of 
my development with gcc 2.x, not gcc 3.x - the resulting C code is more 
portable.

I'll think about it.

Cheers,

Rhys.