Strange gcc-3.0.1 preprocessor

Strange gcc-3.0.1 preprocessor

[Nick Kurshev]

Hello!

I've tried to compile my project with new gcc-3.0.1 and got strange error. :(

command:
gcc -D__MACHINE__=ia32 ...

source code:
    #define _INLINES <biewlib/sysdep/##__MACHINE__/_inlines.h>
    #define __CONFIG <biewlib/sysdep/##__MACHINE__/__config.h>
    #include __CONFIG
    #include _INLINES

stderr output:
In file included from biewlib/biewlib.h:25,
                 from biewlib/bbio.h:21,
                 from biewlib/bbio.c:26:
biewlib/sysdep/_sys_dep.h:30:14: warning: pasting "/" and "__MACHINE__" does not give a valid preprocessing token
biewlib/sysdep/_sys_dep.h:30:22: biewlib/sysdep/__MACHINE__/__config.h: No such file or directory
biewlib/sysdep/_sys_dep.h:31:14: warning: pasting "/" and "__MACHINE__" does not give a valid preprocessing token
biewlib/sysdep/_sys_dep.h:31:22: biewlib/sysdep/__MACHINE__/_inlines.h: No such file or directory

Only one question: Is it a bug or is it a new feature of gcc-3.0.1?
Any previouse versions of gcc since 2.7.2.1 upto 2.95.3 handle this code correctly.

Best regards! Nick

Re: Strange gcc-3.0.1 preprocessor

[Neil Booth]

Nick Kurshev wrote:-

> In file included from biewlib/biewlib.h:25,
>                  from biewlib/bbio.h:21,
>                  from biewlib/bbio.c:26:
> biewlib/sysdep/_sys_dep.h:30:14: warning: pasting "/" and "__MACHINE__" does not give a valid preprocessing token
> biewlib/sysdep/_sys_dep.h:30:22: biewlib/sysdep/__MACHINE__/__config.h: No such file or directory
> biewlib/sysdep/_sys_dep.h:31:14: warning: pasting "/" and "__MACHINE__" does not give a valid preprocessing token
> biewlib/sysdep/_sys_dep.h:31:22: biewlib/sysdep/__MACHINE__/_inlines.h: No such file or directory
> 
> Only one question: Is it a bug or is it a new feature of gcc-3.0.1?

The warning tells you the problem.  Do you know what ## does?

> Any previouse versions of gcc since 2.7.2.1 upto 2.95.3 handle this
> code correctly.

They are incorrect; from the code it would appear they used to expand
__MACHINE__.  That macro should not be expanded, since it is being
operated on by ##.

I suspect you can get the result you want by losing the ##.

Neil.

Re: Strange gcc-3.0.1 preprocessor

[Nick Kurshev]

Hello, Neil!
On Sun, 14 Oct 2001 16:12:22 +0100, you wrote:

> Nick Kurshev wrote:-
> 
> > In file included from biewlib/biewlib.h:25,
> >                  from biewlib/bbio.h:21,
> >                  from biewlib/bbio.c:26:
> > biewlib/sysdep/_sys_dep.h:30:14: warning: pasting "/" and "__MACHINE__" does not give a valid preprocessing token
> > biewlib/sysdep/_sys_dep.h:30:22: biewlib/sysdep/__MACHINE__/__config.h: No such file or directory
> > biewlib/sysdep/_sys_dep.h:31:14: warning: pasting "/" and "__MACHINE__" does not give a valid preprocessing token
> > biewlib/sysdep/_sys_dep.h:31:22: biewlib/sysdep/__MACHINE__/_inlines.h: No such file or directory
> > 
> > Only one question: Is it a bug or is it a new feature of gcc-3.0.1?
> 
> The warning tells you the problem.  Do you know what ## does?
> 
It was only way to build such trick. Else how you will notice compiler to build preprocessor string
without space characters?
Well, the same code with space characters around __MACHINE__:
source:
    #define _INLINES <biewlib/sysdep/ __MACHINE__ /_inlines.h>
    #define __CONFIG <biewlib/sysdep/ __MACHINE__ /__config.h>
    #include __CONFIG
    #include _INLINES
output:
biewlib/sysdep/_sys_dep.h:30:22: biewlib/sysdep/ ia32 /__config.h: No such file or directory
biewlib/sysdep/_sys_dep.h:31:22: biewlib/sysdep/ ia32 /_inlines.h: No such file or directory
> > Any previouse versions of gcc since 2.7.2.1 upto 2.95.3 handle this
> > code correctly.
> 
> They are incorrect; from the code it would appear they used to expand
> __MACHINE__.  That macro should not be expanded, since it is being
> operated on by ##.
> 
> I suspect you can get the result you want by losing the ##.
Well, other trick:
command:
gcc -D__MACHINE__='"ia32"'
source:
    #define _INLINES <"biewlib/sysdep/"__MACHINE__"/_inlines.h">
    #define __CONFIG <"biewlib/sysdep/"__MACHINE__"/__config.h">
    #include __CONFIG
    #include _INLINES
output:
biewlib/sysdep/_sys_dep.h:30:22: "biewlib/sysdep/"ia32"/__config.h": No such file or directory
biewlib/sysdep/_sys_dep.h:31:22: "biewlib/sysdep/"ia32"/_inlines.h": No such file or directory

So I have no solutions with new gcc-3.x branch for now.
Need some other trick.
From other point - it's PREPROCESSOR but not C compiler which can concatenate several strings to one.
> 
> Neil.
> 
> 

Best regards! Nick

Re: Strange gcc-3.0.1 preprocessor

[Neil Booth]

Nick Kurshev wrote:-

> It was only way to build such trick. Else how you will notice
> compiler to build preprocessor string without space characters?

Like I told you.

> Well, the same code with space characters around __MACHINE__:
> source:
>     #define _INLINES <biewlib/sysdep/ __MACHINE__ /_inlines.h>
>     #define __CONFIG <biewlib/sysdep/ __MACHINE__ /__config.h>
>     #include __CONFIG
>     #include _INLINES

Why have you added spaces?  Of course it will now break:

> output:
> biewlib/sysdep/_sys_dep.h:30:22: biewlib/sysdep/ ia32 /__config.h: No such file or directory
> biewlib/sysdep/_sys_dep.h:31:22: biewlib/sysdep/ ia32 /_inlines.h: No such file or directory

The following works for me:

#define STDIO stdio
#define STDIO_H </usr/include/STDIO.h>
#include STDIO_H

Note that the preprocessor does not do string literal concatenation in
header names.

Neil.

Re: Strange gcc-3.0.1 preprocessor

[Nick Kurshev]

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Hello, Neil!
On Sun, 14 Oct 2001 18:59:34 +0100, you wrote:

> Nick Kurshev wrote:-
> 
> > It was only way to build such trick. Else how you will notice
> > compiler to build preprocessor string without space characters?
> 
> Like I told you.
> 
> > Well, the same code with space characters around __MACHINE__:
> > source:
> >     #define _INLINES <biewlib/sysdep/ __MACHINE__ /_inlines.h>
> >     #define __CONFIG <biewlib/sysdep/ __MACHINE__ /__config.h>
> >     #include __CONFIG
> >     #include _INLINES
> 
> Why have you added spaces?  Of course it will now break:
> 
> > output:
> > biewlib/sysdep/_sys_dep.h:30:22: biewlib/sysdep/ ia32 /__config.h: No such file or directory
> > biewlib/sysdep/_sys_dep.h:31:22: biewlib/sysdep/ ia32 /_inlines.h: No such file or directory
> 
> The following works for me:
> 
> #define STDIO stdio
> #define STDIO_H </usr/include/STDIO.h>
> #include STDIO_H
> 
> Note that the preprocessor does not do string literal concatenation in
> header names.
> 
> Neil.
> 
But for me - no.

#undef __MACHINE__
#define __MACHINE__ ia32
    #define _INLINES <biewlib/sysdep/__MACHINE__/_inlines.h>
    #define __CONFIG <biewlib/sysdep/__MACHINE__/__config.h>
    #include __CONFIG
    #include _INLINES

In file included from biewlib/biewlib.c:24:
biewlib/sysdep/__config.h:27:14: warning: pasting "/" and "__MACHINE__" does not give a valid preprocessing token
biewlib/sysdep/__config.h:27:22: biewlib/sysdep/__MACHINE__/__config.h: No such file or directory
make: *** [biewlib/biewlib.o] ïÛÉÂËÁ 1

Best regards! Nick

Re: Strange gcc-3.0.1 preprocessor

[Neil Booth]

Nick Kurshev wrote:-

> But for me - no.

I don't believe you.

> #undef __MACHINE__
> #define __MACHINE__ ia32
>     #define _INLINES <biewlib/sysdep/__MACHINE__/_inlines.h>
>     #define __CONFIG <biewlib/sysdep/__MACHINE__/__config.h>
>     #include __CONFIG
>     #include _INLINES
> 
> In file included from biewlib/biewlib.c:24:
> biewlib/sysdep/__config.h:27:14: warning: pasting "/" and "__MACHINE__" does not give a valid preprocessing token
> biewlib/sysdep/__config.h:27:22: biewlib/sysdep/__MACHINE__/__config.h: No such file or directory
> make: *** [biewlib/biewlib.o]  1

Why is it complaining about pasting?  I don't think the code you quote
above is not the code you are using; the code you are using still has
the ## that I asked you to remove.

Neil.

Re: Strange gcc-3.0.1 preprocessor

[Nick Kurshev]

Hello, Neil!
On Sun, 14 Oct 2001 19:09:04 +0100, you wrote:

> Nick Kurshev wrote:-
> 
> > But for me - no.
> 
> I don't believe you.
> 
> > #undef __MACHINE__
> > #define __MACHINE__ ia32
> >     #define _INLINES <biewlib/sysdep/__MACHINE__/_inlines.h>
> >     #define __CONFIG <biewlib/sysdep/__MACHINE__/__config.h>
> >     #include __CONFIG
> >     #include _INLINES
> > 
> > In file included from biewlib/biewlib.c:24:
> > biewlib/sysdep/__config.h:27:14: warning: pasting "/" and "__MACHINE__" does not give a valid preprocessing token
> > biewlib/sysdep/__config.h:27:22: biewlib/sysdep/__MACHINE__/__config.h: No such file or directory
> > make: *** [biewlib/biewlib.o]  1
> 
> Why is it complaining about pasting?  I don't think the code you quote
> above is not the code you are using; the code you are using still has
> the ## that I asked you to remove.
> 
Yes! You are perfectly right.
I cleaned not all such places.
Now it works. Thanks!
> Neil.
> 


Best regards! Nick