When/why are libstdc++ and libc++ symbols incompatible?

-1

Setup:

test.cpp

#include <set>

#include <string>



void common_config_file_iterator(const std::set<std::string>& allowed_options) {}

include.cpp

#include <set>

#include <string>



void common_config_file_iterator(const std::set<std::string>&) noexcept;



int main() {

    std::set<std::string> set;

    common_config_file_iterator(set);

    return 0;

}

test.sh

clang++-7 test.cpp -c -O3 -fno-rtti -fno-exceptions -o test.o

g++-8 test.o include.cpp -O3 -fno-rtti -fno-exceptions -o test

Output:

Undefined symbols for architecture x86_64:

  "common_config_file_iterator(std::set<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::less<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >, std::allocator<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > > const&)", referenced from:

      _main in ccWoGgrX.o

ld: symbol(s) not found for architecture x86_64

collect2: error: ld returned 1 exit status

So I did nm -g test.o:

0000000000000000 T __Z27common_config_file_iteratorRKNSt3__13setINS_12basic_stringIcNS_11char_traitsIcEENS_9allocatorIcEEEENS_4lessIS6_EENS4_IS6_EEEE

According to demangler.com, it means:

common_config_file_iterator(std::__1::set<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, std::__1::less<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > >, std::__1::allocator<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > > > const&)

Libc++ says:

[Features and Goals:] ABI compatibility with gcc's libstdc++ for some low-level features such as exception objects, rtti and memory allocation.

So, is the problem std::allocator<char>?

Note that I use the macOS assembler.

Curiosity caused by this issue and boost/program-options.

asked Nov 21 '18 at 15:37

MCCCS

4271828

Goal may mean that they don't agree at this stage?

– Matthieu Brucher
Nov 21 '18 at 15:47

noexcept is missing, it is part of the function signature.

– Hans Passant
Nov 21 '18 at 16:31

@Hans but is noexcept also part of the ABI?

– rubenvb
Nov 22 '18 at 8:43

@MatthieuBrucher no, it means "some low-level features such as exception objects, rtti and memory allocation" not std::set and std::string.

– Jonathan Wakely
Nov 23 '18 at 11:24

1

Did you maybe read the goal as "except for" instead of just "for"? You disable RTTI and exceptions and worry about std::allocator as if you think that exception objects, rtti and memory allocation are the things that are not compatible, when in fact they are the only things that are.

– Sebastian Redl
Nov 23 '18 at 11:29

|
show 1 more comment

-1

Setup:

test.cpp

#include <set>

#include <string>



void common_config_file_iterator(const std::set<std::string>& allowed_options) {}

include.cpp

#include <set>

#include <string>



void common_config_file_iterator(const std::set<std::string>&) noexcept;



int main() {

    std::set<std::string> set;

    common_config_file_iterator(set);

    return 0;

}

test.sh

clang++-7 test.cpp -c -O3 -fno-rtti -fno-exceptions -o test.o

g++-8 test.o include.cpp -O3 -fno-rtti -fno-exceptions -o test

Output:

Undefined symbols for architecture x86_64:

  "common_config_file_iterator(std::set<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::less<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >, std::allocator<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > > const&)", referenced from:

      _main in ccWoGgrX.o

ld: symbol(s) not found for architecture x86_64

collect2: error: ld returned 1 exit status

So I did nm -g test.o:

0000000000000000 T __Z27common_config_file_iteratorRKNSt3__13setINS_12basic_stringIcNS_11char_traitsIcEENS_9allocatorIcEEEENS_4lessIS6_EENS4_IS6_EEEE

According to demangler.com, it means:

common_config_file_iterator(std::__1::set<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, std::__1::less<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > >, std::__1::allocator<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > > > const&)

Libc++ says:

[Features and Goals:] ABI compatibility with gcc's libstdc++ for some low-level features such as exception objects, rtti and memory allocation.

So, is the problem std::allocator<char>?

Note that I use the macOS assembler.

Curiosity caused by this issue and boost/program-options.

asked Nov 21 '18 at 15:37

MCCCS

4271828

Goal may mean that they don't agree at this stage?

– Matthieu Brucher
Nov 21 '18 at 15:47

noexcept is missing, it is part of the function signature.

– Hans Passant
Nov 21 '18 at 16:31

@Hans but is noexcept also part of the ABI?

– rubenvb
Nov 22 '18 at 8:43

@MatthieuBrucher no, it means "some low-level features such as exception objects, rtti and memory allocation" not std::set and std::string.

– Jonathan Wakely
Nov 23 '18 at 11:24

1

Did you maybe read the goal as "except for" instead of just "for"? You disable RTTI and exceptions and worry about std::allocator as if you think that exception objects, rtti and memory allocation are the things that are not compatible, when in fact they are the only things that are.

– Sebastian Redl
Nov 23 '18 at 11:29

|
show 1 more comment

-1

Setup:

test.cpp

#include <set>

#include <string>



void common_config_file_iterator(const std::set<std::string>& allowed_options) {}

include.cpp

#include <set>

#include <string>



void common_config_file_iterator(const std::set<std::string>&) noexcept;



int main() {

    std::set<std::string> set;

    common_config_file_iterator(set);

    return 0;

}

test.sh

clang++-7 test.cpp -c -O3 -fno-rtti -fno-exceptions -o test.o

g++-8 test.o include.cpp -O3 -fno-rtti -fno-exceptions -o test

Output:

Undefined symbols for architecture x86_64:

  "common_config_file_iterator(std::set<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::less<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >, std::allocator<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > > const&)", referenced from:

      _main in ccWoGgrX.o

ld: symbol(s) not found for architecture x86_64

collect2: error: ld returned 1 exit status

So I did nm -g test.o:

0000000000000000 T __Z27common_config_file_iteratorRKNSt3__13setINS_12basic_stringIcNS_11char_traitsIcEENS_9allocatorIcEEEENS_4lessIS6_EENS4_IS6_EEEE

According to demangler.com, it means:

common_config_file_iterator(std::__1::set<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, std::__1::less<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > >, std::__1::allocator<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > > > const&)

Libc++ says:

[Features and Goals:] ABI compatibility with gcc's libstdc++ for some low-level features such as exception objects, rtti and memory allocation.

So, is the problem std::allocator<char>?

Note that I use the macOS assembler.

Curiosity caused by this issue and boost/program-options.

asked Nov 21 '18 at 15:37

MCCCS

4271828

Setup:

test.cpp

#include <set>

#include <string>



void common_config_file_iterator(const std::set<std::string>& allowed_options) {}

include.cpp

#include <set>

#include <string>



void common_config_file_iterator(const std::set<std::string>&) noexcept;



int main() {

    std::set<std::string> set;

    common_config_file_iterator(set);

    return 0;

}

test.sh

clang++-7 test.cpp -c -O3 -fno-rtti -fno-exceptions -o test.o

g++-8 test.o include.cpp -O3 -fno-rtti -fno-exceptions -o test

Output:

Undefined symbols for architecture x86_64:

  "common_config_file_iterator(std::set<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::less<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >, std::allocator<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > > const&)", referenced from:

      _main in ccWoGgrX.o

ld: symbol(s) not found for architecture x86_64

collect2: error: ld returned 1 exit status

So I did nm -g test.o:

0000000000000000 T __Z27common_config_file_iteratorRKNSt3__13setINS_12basic_stringIcNS_11char_traitsIcEENS_9allocatorIcEEEENS_4lessIS6_EENS4_IS6_EEEE

According to demangler.com, it means:

common_config_file_iterator(std::__1::set<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, std::__1::less<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > >, std::__1::allocator<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > > > const&)

Libc++ says:

[Features and Goals:] ABI compatibility with gcc's libstdc++ for some low-level features such as exception objects, rtti and memory allocation.

So, is the problem std::allocator<char>?

Note that I use the macOS assembler.

Curiosity caused by this issue and boost/program-options.

c++ libstdc++ abi libc++ object-files

asked Nov 21 '18 at 15:37

MCCCS

4271828

asked Nov 21 '18 at 15:37

MCCCS

4271828

asked Nov 21 '18 at 15:37

MCCCS

4271828

asked Nov 21 '18 at 15:37

MCCCS

4271828

asked Nov 21 '18 at 15:37

MCCCS

4271828

Goal may mean that they don't agree at this stage?

– Matthieu Brucher
Nov 21 '18 at 15:47

noexcept is missing, it is part of the function signature.

– Hans Passant
Nov 21 '18 at 16:31

@Hans but is noexcept also part of the ABI?

– rubenvb
Nov 22 '18 at 8:43

@MatthieuBrucher no, it means "some low-level features such as exception objects, rtti and memory allocation" not std::set and std::string.

– Jonathan Wakely
Nov 23 '18 at 11:24

1

Did you maybe read the goal as "except for" instead of just "for"? You disable RTTI and exceptions and worry about std::allocator as if you think that exception objects, rtti and memory allocation are the things that are not compatible, when in fact they are the only things that are.

– Sebastian Redl
Nov 23 '18 at 11:29

|
show 1 more comment

Goal may mean that they don't agree at this stage?

– Matthieu Brucher
Nov 21 '18 at 15:47

noexcept is missing, it is part of the function signature.

– Hans Passant
Nov 21 '18 at 16:31

@Hans but is noexcept also part of the ABI?

– rubenvb
Nov 22 '18 at 8:43

@MatthieuBrucher no, it means "some low-level features such as exception objects, rtti and memory allocation" not std::set and std::string.

– Jonathan Wakely
Nov 23 '18 at 11:24

1

Did you maybe read the goal as "except for" instead of just "for"? You disable RTTI and exceptions and worry about std::allocator as if you think that exception objects, rtti and memory allocation are the things that are not compatible, when in fact they are the only things that are.

– Sebastian Redl
Nov 23 '18 at 11:29

Goal may mean that they don't agree at this stage?

– Matthieu Brucher
Nov 21 '18 at 15:47

noexcept is missing, it is part of the function signature.

– Hans Passant
Nov 21 '18 at 16:31

@Hans but is noexcept also part of the ABI?

– rubenvb
Nov 22 '18 at 8:43

@MatthieuBrucher no, it means "some low-level features such as exception objects, rtti and memory allocation" not std::set and std::string.

– Jonathan Wakely
Nov 23 '18 at 11:24

Did you maybe read the goal as "except for" instead of just "for"? You disable RTTI and exceptions and worry about std::allocator as if you think that exception objects, rtti and memory allocation are the things that are not compatible, when in fact they are the only things that are.

– Sebastian Redl
Nov 23 '18 at 11:29

|
show 1 more comment

1 Answer
1

active

oldest

votes

So, is the problem std::allocator<char>?

What? No. It's everything in your example.

The doc you quoted clearly says the goal is compatibility for "low-level features such as exception objects, rtti and memory allocation".

std::set and std::string are not "low-level features such as exception objects, rtti and memory allocation". They are very definitely not compatible between libc++ and libstdc++, which are completely different libraries with completely different implementations.

The compatible pieces are things like std::type_info and std::exception (and the derived exception types in <stdexcept>) because those are part of the basic language runtime. Anything above that, such as containers, strings, algorithms, I/O, locales etc. is not compatible.

answered Nov 23 '18 at 11:23

Jonathan Wakely

131k16239408

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1 Answer
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1 Answer
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active

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So, is the problem std::allocator<char>?

What? No. It's everything in your example.

The doc you quoted clearly says the goal is compatibility for "low-level features such as exception objects, rtti and memory allocation".

answered Nov 23 '18 at 11:23

Jonathan Wakely

131k16239408

add a comment |

So, is the problem std::allocator<char>?

What? No. It's everything in your example.

The doc you quoted clearly says the goal is compatibility for "low-level features such as exception objects, rtti and memory allocation".

answered Nov 23 '18 at 11:23

Jonathan Wakely

131k16239408

add a comment |

So, is the problem std::allocator<char>?

What? No. It's everything in your example.

The doc you quoted clearly says the goal is compatibility for "low-level features such as exception objects, rtti and memory allocation".

answered Nov 23 '18 at 11:23

Jonathan Wakely

131k16239408

So, is the problem std::allocator<char>?

What? No. It's everything in your example.

The doc you quoted clearly says the goal is compatibility for "low-level features such as exception objects, rtti and memory allocation".

answered Nov 23 '18 at 11:23

Jonathan Wakely

131k16239408

answered Nov 23 '18 at 11:23

Jonathan Wakely

131k16239408

answered Nov 23 '18 at 11:23

Jonathan Wakely

131k16239408

answered Nov 23 '18 at 11:23

Jonathan Wakely

131k16239408

add a comment |

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