Differences in the behaviour of sparse and gcc within cygwin environment

Differences in the behaviour of sparse and gcc within cygwin environment

[Thomas Schmid]

I use sparse in a cygwin environment to obtain pre-build info from 
sourcefiles which get comiled with gcc (also compiled with cygwin).

After some time of using sparse, I noticed some differences in the 
behaviour of sparse and gcc:
1. Symbolnames with "$" are accepted by gcc but not by sparse
2. #include "..\plc.h" is accepted by gcc but not by sparse => "\" is 
interpreted as escape- character
3. #include "D:\plc.h" is accepted by gcc but not by sparse

I know that number 2 and 3 are problems which only occur within an cygwin 
environment and number 3 isn't the best way to include files,
but is there any chance to get this fixed?


Best regards,
Thomas Schmid

Re: Differences in the behaviour of sparse and gcc within cygwin environment

[Al Viro]

On Fri, May 18, 2007 at 01:43:11PM +0200, Thomas Schmid wrote:
> I use sparse in a cygwin environment to obtain pre-build info from 
> sourcefiles which get comiled with gcc (also compiled with cygwin).
> 
> After some time of using sparse, I noticed some differences in the 
> behaviour of sparse and gcc:
> 1. Symbolnames with "$" are accepted by gcc but not by sparse

ewww...  It's not hard to change, but I strongly recommend making it
ifdefed and *not* included on sane boxen.  Rationale: that affects one
of the hottest paths in the entire thing.

Who uses $ in identifiers, anyway, when it's guaranteed to be non-portable?
gcc accepts it as a bloody misguided extension, but it's not standard C by
any stretch of imagination.  What are you working with, a bunch of old code
originating on VMS?

> 2. #include "..\plc.h" is accepted by gcc but not by sparse => "\" is 
> interpreted as escape- character
> 3. #include "D:\plc.h" is accepted by gcc but not by sparse

*argh*

sparse takes a shortcut - it treats header-name as string-literal.  In
principle, these are distinct tokens.  We could try to change that, but...
that makes tokenizer context-dependent in a fairly upleasant way.

Note that \ in header-name is explicitly undefined behaviour (6.4.7(3)),
and compilers I've seen on weird systems of that kind tend to remap / on \
in header names anyway before trying to look for files to include.

Antwort: Re: Differences in the behaviour of sparse and gcc within cygwin environment

[Thomas Schmid]

linux-sparse-owner@vger.kernel.org schrieb am 18.05.2007 22:47:35:

> On Fri, May 18, 2007 at 01:43:11PM +0200, Thomas Schmid wrote:
> > 1. Symbolnames with "$" are accepted by gcc but not by sparse
> 
> ewww...  It's not hard to change, but I strongly recommend making it
> ifdefed and *not* included on sane boxen.  Rationale: that affects one
> of the hottest paths in the entire thing.
> 
> Who uses $ in identifiers, anyway, when it's guaranteed to be 
non-portable?
> gcc accepts it as a bloody misguided extension, but it's not standard C 
by
> any stretch of imagination.  What are you working with, a bunch of old 
code
> originating on VMS?
> 
> > 2. #include "..\plc.h" is accepted by gcc but not by sparse => "\" is 
> > interpreted as escape- character
> > 3. #include "D:\plc.h" is accepted by gcc but not by sparse
> 
> *argh*
;-) Really that bad?
> 
> sparse takes a shortcut - it treats header-name as string-literal.  In
> principle, these are distinct tokens.  We could try to change that, 
but...
> that makes tokenizer context-dependent in a fairly upleasant way.
> 
> Note that \ in header-name is explicitly undefined behaviour (6.4.7(3)),
> and compilers I've seen on weird systems of that kind tend to remap / on 
\
> in header names anyway before trying to look for files to include.

The code which I like to use sparse with, is some sort of living 3rd party 
thing. 
I fear, these are not the only "misguided extensions" used, which work 
with cygwin GCC 2.95.3.

I also tried to pre-process that code with cpp - but then I lose the 
position-data of the declarations i try to get info from.
It's not possible to use cpp integrated in sparse, isn't it?


Best regards 
Thomas Schmid

Re: Antwort: Re: Differences in the behaviour of sparse and gcc within cygwin environment

[Josh Triplett]

[-- Attachment #1: Type: text/plain, Size: 460 bytes --]

Thomas Schmid wrote:
> I also tried to pre-process that code with cpp - but then I lose the 
> position-data of the declarations i try to get info from.
> It's not possible to use cpp integrated in sparse, isn't it?

In theory, we could add support for the line-number information provided by
the GCC preprocessor.  That seems useful, though it can't provide as much
information as Sparse's usual line-and-character information.

- Josh Triplett



[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 252 bytes --]