C99 parsing error?

C99 parsing error?

[Jamie Lokier]

Is it really not permitted to write this in C99?:

	while (--length >= 0)
	  {
	  loop:
	    int byte = *data++;

GCC 3.2.2 reports: parse error before "int"
If I replace "loop:" with "loop:;", it's fine.
Perhaps GCC is correct to reject this, but it is surprising.

-- Jamie

Re: C99 parsing error?

[Neil Booth]

Jamie Lokier wrote:-

> Is it really not permitted to write this in C99?:
> 
> 	while (--length >= 0)
> 	  {
> 	  loop:
> 	    int byte = *data++;
> 
> GCC 3.2.2 reports: parse error before "int"
> If I replace "loop:" with "loop:;", it's fine.
> Perhaps GCC is correct to reject this, but it is surprising.

No, your code is fine.

Neil.

Re: C99 parsing error?

[Joseph S. Myers]

On Sun, 18 May 2003, Jamie Lokier wrote:

> Is it really not permitted to write this in C99?:
> 
> 	while (--length >= 0)
> 	  {
> 	  loop:
> 	    int byte = *data++;
> 
> GCC 3.2.2 reports: parse error before "int"
> If I replace "loop:" with "loop:;", it's fine.
> Perhaps GCC is correct to reject this, but it is surprising.

A compound statement is a sequence of statements and declarations; only
statements can have labels; see 6.8.1 and 6.8.2.  The existing GCC
extension of attributes on labels means that we don't accept labels on
declarations as an extension either.

-- 
Joseph S. Myers
jsm28@cam.ac.uk

Re: C99 parsing error?

[Falk Hueffner]

Jamie Lokier <jamie@shareable.org> writes:

> Is it really not permitted to write this in C99?:
> 
> 	while (--length >= 0)
> 	  {
> 	  loop:
> 	    int byte = *data++;
> 
> GCC 3.2.2 reports: parse error before "int"
> If I replace "loop:" with "loop:;", it's fine.

That is indeed not permitted. C99 allows mixing statements and
declarations within blocks, but a declaration *is* not a statement,
and a label must be followed by a statement.

-- 
	Falk