Issue
Trying to learn C/C++.
Why does this work when use g++ and not clang? But it works when I convert the same program to plain C and use gcc and clang...
The code:
#include <iostream>
#ifndef ARCH
#define ARCH "Undefined"
#endif
using namespace std;
int main() {
char str[] = "Hello C++";
cout << "Value of str is : " << str << endl;
cout << "Value of str is : " << ARCH << endl;
exit(0);
}
Using g++ I run g++ "-DARCH=\"`uname -m`\"" hello.cpp and it works just fine.
Using clang I run clang "-DARCH=\"`uname -m`\"" hello.cpp and it fails.
Undefined symbols for architecture x86_64:
"std::__1::locale::use_facet(std::__1::locale::id&) const", referenced from:
std::__1::ctype<char> const& std::__1::use_facet<std::__1::ctype<char> >(std::__1::locale const&) in hello-7c7087.o
"std::__1::ios_base::getloc() const", referenced from:
std::__1::basic_ios<char, std::__1::char_traits<char> >::widen(char) const in hello-7c7087.o
"std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >::__init(unsigned long, char)", referenced from:
std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >::basic_string(unsigned long, char) in hello-7c7087.o
"std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >::~basic_string()", referenced from:
std::__1::ostreambuf_iterator<char, std::__1::char_traits<char> > std::__1::__pad_and_output<char, std::__1::char_traits<char> >(std::__1::ostreambuf_iterator<char, std::__1::char_traits<char> >, char const*, char const*, char const*, std::__1::ios_base&, char) in hello-7c7087.o
"std::__1::basic_ostream<char, std::__1::char_traits<char> >::put(char)", referenced from:
std::__1::basic_ostream<char, std::__1::char_traits<char> >& std::__1::endl<char, std::__1::char_traits<char> >(std::__1::basic_ostream<char, std::__1::char_traits<char> >&) in hello-7c7087.o
"std::__1::basic_ostream<char, std::__1::char_traits<char> >::flush()", referenced from:
std::__1::basic_ostream<char, std::__1::char_traits<char> >& std::__1::endl<char, std::__1::char_traits<char> >(std::__1::basic_ostream<char, std::__1::char_traits<char> >&) in hello-7c7087.o
"std::__1::basic_ostream<char, std::__1::char_traits<char> >::sentry::sentry(std::__1::basic_ostream<char, std::__1::char_traits<char> >&)", referenced from:
std::__1::basic_ostream<char, std::__1::char_traits<char> >& std::__1::__put_character_sequence<char, std::__1::char_traits<char> >(std::__1::basic_ostream<char, std::__1::char_traits<char> >&, char const*, unsigned long) in hello-7c7087.o
"std::__1::basic_ostream<char, std::__1::char_traits<char> >::sentry::~sentry()", referenced from:
std::__1::basic_ostream<char, std::__1::char_traits<char> >& std::__1::__put_character_sequence<char, std::__1::char_traits<char> >(std::__1::basic_ostream<char, std::__1::char_traits<char> >&, char const*, unsigned long) in hello-7c7087.o
"std::__1::cout", referenced from:
_main in hello-7c7087.o
"std::__1::ctype<char>::id", referenced from:
std::__1::ctype<char> const& std::__1::use_facet<std::__1::ctype<char> >(std::__1::locale const&) in hello-7c7087.o
"std::__1::locale::~locale()", referenced from:
std::__1::basic_ios<char, std::__1::char_traits<char> >::widen(char) const in hello-7c7087.o
"std::__1::ios_base::__set_badbit_and_consider_rethrow()", referenced from:
std::__1::basic_ostream<char, std::__1::char_traits<char> >& std::__1::__put_character_sequence<char, std::__1::char_traits<char> >(std::__1::basic_ostream<char, std::__1::char_traits<char> >&, char const*, unsigned long) in hello-7c7087.o
"std::__1::ios_base::clear(unsigned int)", referenced from:
std::__1::ios_base::setstate(unsigned int) in hello-7c7087.o
"std::terminate()", referenced from:
___clang_call_terminate in hello-7c7087.o
"___cxa_begin_catch", referenced from:
std::__1::basic_ostream<char, std::__1::char_traits<char> >& std::__1::__put_character_sequence<char, std::__1::char_traits<char> >(std::__1::basic_ostream<char, std::__1::char_traits<char> >&, char const*, unsigned long) in hello-7c7087.o
___clang_call_terminate in hello-7c7087.o
"___cxa_call_unexpected", referenced from:
std::__1::ostreambuf_iterator<char, std::__1::char_traits<char> >::ostreambuf_iterator(std::__1::basic_ostream<char, std::__1::char_traits<char> >&) in hello-7c7087.o
"___cxa_end_catch", referenced from:
std::__1::basic_ostream<char, std::__1::char_traits<char> >& std::__1::__put_character_sequence<char, std::__1::char_traits<char> >(std::__1::basic_ostream<char, std::__1::char_traits<char> >&, char const*, unsigned long) in hello-7c7087.o
"___gxx_personality_v0", referenced from:
std::__1::basic_ostream<char, std::__1::char_traits<char> >& std::__1::__put_character_sequence<char, std::__1::char_traits<char> >(std::__1::basic_ostream<char, std::__1::char_traits<char> >&, char const*, unsigned long) in hello-7c7087.o
std::__1::ostreambuf_iterator<char, std::__1::char_traits<char> > std::__1::__pad_and_output<char, std::__1::char_traits<char> >(std::__1::ostreambuf_iterator<char, std::__1::char_traits<char> >, char const*, char const*, char const*, std::__1::ios_base&, char) in hello-7c7087.o
std::__1::ostreambuf_iterator<char, std::__1::char_traits<char> >::ostreambuf_iterator(std::__1::basic_ostream<char, std::__1::char_traits<char> >&) in hello-7c7087.o
std::__1::basic_ios<char, std::__1::char_traits<char> >::widen(char) const in hello-7c7087.o
Dwarf Exception Unwind Info (__eh_frame) in hello-7c7087.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
What really doesn't make sense to me is that it works both ways if I convert the code to C.
Thanks in advance!
Solution
It appears you're using clang to compile the C++ code. You should be using clang++ to compile it
Also you may want to use -Wall and possibly -Werror to catch many thing that might be an error in other languages (ex: not returning anything in a function with an int return type).
I personally compile with the below. I'm not sure if sanitize works on windows. no-exceptions and no-rtti is common but not what most people do. You'll have some errors with dynamic_cast and exceptions if you use these.
clang++ -g -fsanitize=undefined -fno-exceptions -fno-rtti -Wall -Wpedantic -Wextra myfile.cpp
Answered By - Eric Stotch
