[gentoo-dev] GCC / G++ 2.95.3 question

[Marc Chabrol]

Hi all, 

I submit the following problem to all readers of gentoo-dev, as I think it's 
an interesting issue. Sorry, it's a little long but it needs explanations.

A friend of mine installed Gentoo 1.2 this week end. After he finished his 
progression to stage 3, he started emerging kde. Qt 3.1 emerged fine but arts 
would not emerge (kde 3.0.4). After investigation we found that the configure 
was failing on checking QT, the conftest.cc file generated would be compiled 
with gcc instead of g++ and would fail on C++ symbols like cerr, cout, ... 
(see log at the end of mail).

We could track that the reason why gcc was used was the presence of the two 
following variables in /etc/env.d/05gcc:

CC=gcc
CXX=gcc

Because of this CXX, the configure would use gcc to compile C++ code. 

We checked on the Changelog of the gcc ebuild to see that this modification 
was recently (dec 3) made by azarah on the gcc-2.95.3-r7 ebuild (introduced 
in version 1.13 of the ebuild).

We tried to put these two variables in another working configuration with 
older gcc (same version 2.95.3-r7 but ebuild version 1.11) and it didn't 
cause the problem.

The gcc and g++ binaries (/usr/bin ones) are different between the newly built 
system and the old one, even if they were using the same ebuild (different 
sizes and md5sums).

So, was somebody able to emerge kde using gcc emerged with version 1.14 of the 
ebuild ? Is it a bug ? 

Anyway we workarounded by removing the two lines from /etc/env.d/05gcc and now 
it's working fine... I definitely had fun debugging this one ;) 


FYI, here is the snippet used by configure to check for QT, that would not 
compile using gcc and would using g++, followed by the bunch of errors while 
using gcc.

#include <qglobal.h>
#include <qapplication.h>
#include <qcursor.h>
#include <qstylefactory.h>
#include <private/qucomextra_p.h>
#if ! (QT_VERSION >= 302)
#error 1
#endif

int main() {
    (void)QStyleFactory::create(QString::null);
    QCursor c(Qt::WhatsThisCursor);
    return 0;
}

/tmp/ccMh8Cuu.o: In function 
`__malloc_alloc_template<0>::_S_oom_malloc(unsigned int)':
/tmp/ccMh8Cuu.o(.__malloc_alloc_template<0>::gnu.linkonce.t._S_oom_malloc(unsigned 
int)+0x1a): undefined reference to `endl(ostream &)'
/tmp/ccMh8Cuu.o(.__malloc_alloc_template<0>::gnu.linkonce.t._S_oom_malloc(unsigned 
int)+0x27): undefined reference to `cerr'
/tmp/ccMh8Cuu.o(.__malloc_alloc_template<0>::gnu.linkonce.t._S_oom_malloc(unsigned 
int)+0x2c): undefined reference to `ostream::operator<<(char const *)'
/tmp/ccMh8Cuu.o(.__malloc_alloc_template<0>::gnu.linkonce.t._S_oom_malloc(unsigned 
int)+0x37): undefined reference to `ostream::operator<<(ostream &(*)(ostream 
&))'
/tmp/ccMh8Cuu.o: In function `basic_string<char, string_char_traits<char>, 
__default_alloc_template<true, 0> >::Rep::copy(unsigned int, char const *, 
unsigned int)':
/tmp/ccMh8Cuu.o(.basic_string<char, string_char_traits<char>, 
__default_alloc_template<true, 0> >::Rep::gnu.linkonce.t.copy(unsigned int, 
char const *, unsigned int)+0x33): undefined reference to 
`string_char_traits<char>::copy(char *, char const *, unsigned int)'
/tmp/ccMh8Cuu.o: In function `basic_string<char, string_char_traits<char>, 
__default_alloc_template<true, 0> >::Rep::move(unsigned int, char const *, 
unsigned int)':
/tmp/ccMh8Cuu.o(.basic_string<char, string_char_traits<char>, 
__default_alloc_template<true, 0> >::Rep::gnu.linkonce.t.move(unsigned int, 
char const *, unsigned int)+0x33): undefined reference to 
`string_char_traits<char>::move(char *, char const *, unsigned int)'
/tmp/ccMh8Cuu.o: In function `basic_string<char, string_char_traits<char>, 
__default_alloc_template<true, 0> >::replace(unsigned int, unsigned int, char 
const *, unsigned int)':
/tmp/ccMh8Cuu.o(.basic_string<char, string_char_traits<char>, 
__default_alloc_template<true, 0> >::gnu.linkonce.t.replace(unsigned int, 
unsigned int, char const *, unsigned int)+0x31): undefined reference to 
`__out_of_range(char const *)'
/tmp/ccMh8Cuu.o(.basic_string<char, string_char_traits<char>, 
__default_alloc_template<true, 0> >::gnu.linkonce.t.replace(unsigned int, 
unsigned int, char const *, unsigned int)+0x8e): undefined reference to 
`__length_error(char const *)'
collect2: ld returned 1 exit status


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