Question about include path

Question about include path

[yann]

Hi,

I build gcc (4.5.2) from scratch, and i have a question with include 
path.

when i want to include "limits.h" (the good one is at 
/LFS2011/include/limits.h), gcc uses 
/LFS2011/bin/../lib/gcc/i686-pc-linux-gnu/4.5.1/include-fixed/limits.h

When i add "-I/LFS2011/include" it does not look for  
/LFS2011/include/limits.h (bad ?) but when I add "-I/tmp", it looks for 
/tmp/limits.h (good)

What is wrong, where can i look into gcc source code to debug it ?

Thank you.

Yann Le Doaré

***************************************

my test.c :

#include "limits.h"

int main()
{
}

*******************************************************************
strace -f -e open -o logs gcc -I/LFS2011/include test.c
bash-3.2# grep limits.h logs
5469  open("limits.h", O_RDONLY|O_NOCTTY) = -1 ENOENT (No such file or 
directory)
5469  
open("/LFS2011/bin/../lib/gcc/i586-pc-linux/4.5.2/include/limits.h", 
O_RDONLY|O_NOCTTY) = -1 ENOENT (No such file or directory)
5469  
open("/LFS2011/bin/../lib/gcc/i586-pc-linux/4.5.2/include-fixed/limits.h", 
O_RDONLY|O_NOCTTY) = 4

*****************************************************

strace -f -e open -o logs gcc -I/tmp test.c

grep limits.h logs
5460  open("limits.h", O_RDONLY|O_NOCTTY) = -1 ENOENT (No such file or 
directory)
5460  open("/tmp/limits.h", O_RDONLY|O_NOCTTY) = -1 ENOENT (No such 
file or directory)
5460  
open("/LFS2011/bin/../lib/gcc/i586-pc-linux/4.5.2/include/limits.h", 
O_RDONLY|O_NOCTTY) = -1 ENOENT (No such file or directory)
5460  
open("/LFS2011/bin/../lib/gcc/i586-pc-linux/4.5.2/include-fixed/limits.h", 
O_RDONLY|O_NOCTTY) = 4

*******************************************************

The options to build gcc (from LFS script) :

*********************************************
    --prefix=/LFS2011 \
    --with-local-prefix=/LFS2011 --enable-clocale=gnu \
    --enable-shared --enable-threads=posix \
    --enable-__cxa_atexit --enable-languages=c,c++ \
    --disable-libstdcxx-pch --disable-multilib \
    --disable-bootstrap --disable-libgomp \
    --with-gmp=/LFS2011 --with-mpfr=/LFS2011 --with-mpc=/LFS2011 \
    --without-ppl --without-cloog --target=$LFS_TGT --host=$LFS_TGT 
--build=$LFS_TGT

Re: Question about include path

[Ian Lance Taylor]

<yann@linuxconsole.org> writes:

> I build gcc (4.5.2) from scratch, and i have a question with include
> path.
>
> when i want to include "limits.h" (the good one is at
> /LFS2011/include/limits.h), gcc uses
> /LFS2011/bin/../lib/gcc/i686-pc-linux-gnu/4.5.1/include-fixed/limits.h
>
> When i add "-I/LFS2011/include" it does not look for
> /LFS2011/include/limits.h (bad ?) but when I add "-I/tmp", it looks
> for /tmp/limits.h (good)
>
> What is wrong, where can i look into gcc source code to debug it ?

The code in question is in the libcpp directory and in gcc/cppdefault.c.
However, this seems like an unlikely scenario.  Are you sure that the
directory /LFS2011/include exists?  Also, use the -v option to see the
exact search path that gcc will use.

Ian

Re: Question about include path

[yann]

into gcc/incpath.c  :

into remove_duplicates :

/LFS2011/include is removed because "it is a non-system directory that
duplicates a system directory"

Then the search order is :

 /LFS2011/bin/../lib/gcc/i586-pc-linux/4.5.2/include
 /LFS2011/bin/../lib/gcc/i586-pc-linux/4.5.2/include-fixed
 /LFS2011/include
 /usr/include

the problem is that a "limits.h" is into 
/LFS2011/bin/../lib/gcc/i586-pc-linux/4.5.2/include-fixed/

The "-I" option should not overwrite search order (and put
/LFS2011/include as first directory) ?

Thanks very much

Yann Le Doaré.


On Tue, 01 Feb 2011 11:47:01 -0800, Ian Lance Taylor <iant@google.com>
wrote:
> <yann@linuxconsole.org> writes:
> 
>> I build gcc (4.5.2) from scratch, and i have a question with include
>> path.
>>
>> when i want to include "limits.h" (the good one is at
>> /LFS2011/include/limits.h), gcc uses
>> /LFS2011/bin/../lib/gcc/i686-pc-linux-gnu/4.5.1/include-fixed/limits.h
>>
>> When i add "-I/LFS2011/include" it does not look for
>> /LFS2011/include/limits.h (bad ?) but when I add "-I/tmp", it looks
>> for /tmp/limits.h (good)
>>
>> What is wrong, where can i look into gcc source code to debug it ?
> 
> The code in question is in the libcpp directory and in gcc/cppdefault.c.
> However, this seems like an unlikely scenario.  Are you sure that the
> directory /LFS2011/include exists?  Also, use the -v option to see the
> exact search path that gcc will use.
> 
> Ian

Re: Question about include path

[Jonathan Wakely]

On 3 February 2011 14:31,  <yann@linuxconsole.org> wrote:
> into gcc/incpath.c  :
>
> into remove_duplicates :
>
> /LFS2011/include is removed because "it is a non-system directory that
> duplicates a system directory"
>
> Then the search order is :
>
>  /LFS2011/bin/../lib/gcc/i586-pc-linux/4.5.2/include
>  /LFS2011/bin/../lib/gcc/i586-pc-linux/4.5.2/include-fixed
>  /LFS2011/include
>  /usr/include
>
> the problem is that a "limits.h" is into
> /LFS2011/bin/../lib/gcc/i586-pc-linux/4.5.2/include-fixed/
>
> The "-I" option should not overwrite search order (and put
> /LFS2011/include as first directory) ?

No, see the manual entry for -I to see how standard system include
directories are handled:
http://gcc.gnu.org/onlinedocs/gcc/Directory-Options.html

As documented you can use -isystem if needed.

Re: Question about include path

[yann]

Thank you, 

to fix my problem, I just added 

#ifndef _LIBC_LIMITS_H_
#include "/LFS2011/include/limits.h"
#endif

on top of /LFS2011/lib/gcc/i586-pc-linux/4.5.2/include-fixed/limits.h

I tried to understand why (GCC) limits.h is into include-fixed, without
success.

I found Ian message here :
http://gcc.gnu.org/ml/gcc/2007-12/msg00095.html but my glibc is not
buildt with "-nostdinc" option.


On Thu, 3 Feb 2011 18:23:29 +0000, Jonathan Wakely
<jwakely.gcc@gmail.com> wrote:
> On 3 February 2011 14:31,  <yann@linuxconsole.org> wrote:
>> into gcc/incpath.c  :
>>
>> into remove_duplicates :
>>
>> /LFS2011/include is removed because "it is a non-system directory that
>> duplicates a system directory"
>>
>> Then the search order is :
>>
>>  /LFS2011/bin/../lib/gcc/i586-pc-linux/4.5.2/include
>>  /LFS2011/bin/../lib/gcc/i586-pc-linux/4.5.2/include-fixed
>>  /LFS2011/include
>>  /usr/include
>>
>> the problem is that a "limits.h" is into
>> /LFS2011/bin/../lib/gcc/i586-pc-linux/4.5.2/include-fixed/
>>
>> The "-I" option should not overwrite search order (and put
>> /LFS2011/include as first directory) ?
> 
> No, see the manual entry for -I to see how standard system include
> directories are handled:
> http://gcc.gnu.org/onlinedocs/gcc/Directory-Options.html
> 
> As documented you can use -isystem if needed.