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* [Bug c++/50028] New: Ternary operator and static const member variable
@ 2011-08-09 13:54 protocolocon at gmail dot com
  2011-08-09 13:55 ` [Bug c++/50028] " protocolocon at gmail dot com
                   ` (4 more replies)
  0 siblings, 5 replies; 6+ messages in thread
From: protocolocon at gmail dot com @ 2011-08-09 13:54 UTC (permalink / raw)
  To: gcc-bugs

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50028

           Summary: Ternary operator and static const member variable
           Product: gcc
           Version: 4.6.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: protocolocon@gmail.com


Created attachment 24960
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=24960
Preprocessor intermediate file

Problem:

The following code:

#include <stdlib.h>
#include <stdio.h>

class test
{
public:
    static const unsigned char OPT1=27;
    static const unsigned char OPT2=72;
};

int main()
{
    unsigned cond=rand();
    unsigned value1, value2;
    if(cond) value1=test::OPT1; else value1=test::OPT2;
    value2=cond?test::OPT1:test::OPT2;
    printf("%d %d\n", value1, value2);
    return 0;
}

Compiles w/o warnings with:

$ g++ -Wall -Wextra -o testO2 -g -O2 test.cc

But fails to compile/link with:

$ g++ -Wall -Wextra -o testO2 -g -O0 test.cc
/tmp/ccwLVGVv.o: In function `main':
/home/asier/desarrollo/tmp/gcc_poc/test.cc:16: undefined reference to
`test::OPT1'
/home/asier/desarrollo/tmp/gcc_poc/test.cc:16: undefined reference to
`test::OPT2'
collect2: ld returned 1 exit status


Analysis:

The problem only happens in the ternary operator, but not in the if statement
that precedes it. Compiler is not substituting class constants in conditional
operator so that compilation unit gets a reference to a test::OPT1 and
test::OPT2 in the .rodata section (that actually does not exist).


See attacked preprocesor output and intermediate assembly code.







Compilers tested:

GCC 4.3

Using built-in specs.
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Debian 4.3.5-4'
--with-bugurl=file:///usr/share/doc/gcc-4.3/README.Bugs
--enable-languages=c,c++,fortran,objc,obj-c++ --prefix=/usr --enable-shared
--enable-multiarch --enable-linker-build-id --with-system-zlib
--libexecdir=/usr/lib --without-included-gettext --enable-threads=posix
--enable-nls --with-gxx-include-dir=/usr/include/c++/4.3 --program-suffix=-4.3
--enable-clocale=gnu --enable-libstdcxx-debug --enable-objc-gc --enable-mpfr
--with-tune=generic --enable-checking=release --build=x86_64-linux-gnu
--host=x86_64-linux-gnu --target=x86_64-linux-gnu
Thread model: posix
gcc version 4.3.5 (Debian 4.3.5-4) 

GCC 4.4

Using built-in specs.
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Debian 4.4.5-8'
--with-bugurl=file:///usr/share/doc/gcc-4.4/README.Bugs
--enable-languages=c,c++,fortran,objc,obj-c++ --prefix=/usr
--program-suffix=-4.4 --enable-shared --enable-multiarch
--enable-linker-build-id --with-system-zlib --libexecdir=/usr/lib
--without-included-gettext --enable-threads=posix
--with-gxx-include-dir=/usr/include/c++/4.4 --libdir=/usr/lib --enable-nls
--enable-clocale=gnu --enable-libstdcxx-debug --enable-objc-gc
--with-arch-32=i586 --with-tune=generic --enable-checking=release
--build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu
Thread model: posix
gcc version 4.4.5 (Debian 4.4.5-8) 

GCC 4.6

Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/lib/x86_64-linux-gnu/gcc/x86_64-linux-gnu/4.6.1/lto-wrapper
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Debian 4.6.1-4'
--with-bugurl=file:///usr/share/doc/gcc-4.6/README.Bugs
--enable-languages=c,c++,fortran,objc,obj-c++,go --prefix=/usr
--program-suffix=-4.6 --enable-shared --enable-multiarch
--with-multiarch-defaults=x86_64-linux-gnu --enable-linker-build-id
--with-system-zlib --libexecdir=/usr/lib/x86_64-linux-gnu
--without-included-gettext --enable-threads=posix
--with-gxx-include-dir=/usr/include/c++/4.6 --libdir=/usr/lib/x86_64-linux-gnu
--enable-nls --enable-clocale=gnu --enable-libstdcxx-debug
--enable-libstdcxx-time=yes --enable-plugin --enable-objc-gc
--with-arch-32=i586 --with-tune=generic --enable-checking=release
--build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu
Thread model: posix
gcc version 4.6.1 (Debian 4.6.1-4) 


System info:
Linux frito 2.6.32-5-amd64 #1 SMP Mon Mar 7 21:35:22 UTC 2011 x86_64 GNU/Linux


^ permalink raw reply	[flat|nested] 6+ messages in thread
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-- links below jump to the message on this page --
2011-08-09 13:54 [Bug c++/50028] New: Ternary operator and static const member variable protocolocon at gmail dot com
2011-08-09 13:55 ` [Bug c++/50028] " protocolocon at gmail dot com
2011-08-09 14:08 ` redi at gcc dot gnu.org
2011-08-09 14:16 ` redi at gcc dot gnu.org
2011-08-09 14:32 ` protocolocon at gmail dot com
2011-08-09 14:40 ` redi at gcc dot gnu.org

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