[CMake] [cmake-developers] C++11/C++14 doesn't work in check_cxx_source_compiles

[Craig Scott]

You might also need to set CMAKE_CXX_EXTENSIONS
<https://cmake.org/cmake/help/latest/variable/CMAKE_CXX_EXTENSIONS.html> to
OFF (it's ON by default). This controls which c++ library is linked for
some compilers, with clang and gcc being two cases where it does this. You
may also find this article
<https://crascit.com/2015/03/28/enabling-cxx11-in-cmake/> about the related
CMake variables and commands to be of interest.

On Fri, Nov 25, 2016 at 5:43 AM, Roman Wüger <roman.wueger at gmx.at> wrote:

> It is working now, after I added -lc++ to CMAKE_REQUIRED_LIBRARIES before
> the check_cxx_source_compiles() call.
>
> Shouldn't this be done by CMAKE_CXX_STANDARD?
>
> Best Regards
> Roman
>
> Am 24.11.2016 um 19:08 schrieb Roman Wüger <roman.wueger at gmx.at>:
>
> Hello,
>
>
>
> If I use a small piece of code which uses <regex>, then it fails with
> check_cxx_source_compiles. If I copy the piece of code into a file and run
> the following on the command line, then it works:
>
>
>
> clang++ main.cpp -std=c++14 -stdlib=libc++
>
>
>
> Here is the piece of code:
>
>
>
> #include <regex>
>
> #include <string>
>
>
>
> int main() {
>
>     const std::string text = "Roses are #ff0000, other flowers have other
> colors.";
>
>     const std::regex pattern("#([a-f0-9]{2})");
>
>
>
>     std::smatch match;
>
>     std::regex_search(text, match, pattern);
>
>
>
>     return 0;
>
> }
>
>
>
> I use this code in CMake as a platform check as followed:
>
>
>
> # C++11 Regular Expression
>
> set(CMAKE_REQUIRED_FLAGS "${CMAKE_CXX_FLAGS}")
>
> check_cxx_source_compiles(
>
>   "#include <regex>
>
>    #include <string>
>
>
>
>    int main() {
>
>        const std::string text = \"Roses are #ff0000, other flowers have
> other colors.\";
>
>        const std::regex pattern(\"#([a-f0-9]{2})\");
>
>
>
>        std::smatch match;
>
>        std::regex_search(text, match, pattern);
>
>
>
>        return 0;
>
>    }"
>
>   HAVE_CXX11_REGULAR_EXPRESSIONS
>
> )
>
> set(CMAKE_REQUIRED_FLAGS "")
>
>
>
> CMakeFiles/CMakeError.log shows:
>
>
>
> Undefined symbols for architecture x86_64:
>
>   "std::__1::basic_string<char, std::__1::char_traits<char>,
> std::__1::allocator<char> >::compare(char const*) const", referenced from:
>
>       std::__1::basic_regex<char, std::__1::regex_traits<char>
> >::__start_matching_list(bool) in src.o
>
>   "std::__1::__vector_base_common<true>::__throw_length_error() const",
> referenced from:
>
>       std::__1::vector<std::__1::sub_match<char const*>,
> std::__1::allocator<std::__1::sub_match<char const*> > >::assign(unsigned
> long, std::__1::sub_match<char const*> const&) in src.o
>
>       std::__1::vector<std::__1::sub_match<char const*>,
> std::__1::allocator<std::__1::sub_match<char const*> >
> >::allocate(unsigned long) in src.o
>
>       void std::__1::vector<std::__1::__state<char>,
> std::__1::allocator<std::__1::__state<char> >
> >::__push_back_slow_path<std::__1::__state<char>
> >(std::__1::__state<char>&&) in src.o
>
>       std::__1::vector<std::__1::sub_match<char const*>,
> std::__1::allocator<std::__1::sub_match<char const*> >
> >::__append(unsigned long, std::__1::sub_match<char const*> const&) in src.o
>
>       std::__1::vector<std::__1::pair<unsigned long, char const*>,
> std::__1::allocator<std::__1::pair<unsigned long, char const*> >
> >::__append(unsigned long) in src.o
>
>       std::__1::vector<std::__1::pair<unsigned long, char const*>,
> std::__1::allocator<std::__1::pair<unsigned long, char const*> >
> >::allocate(unsigned long) in src.o
>
>       void std::__1::vector<char, std::__1::allocator<char>
> >::__push_back_slow_path<char>(char&&) in src.o
>
>       ...
>
>   "std::__1::__basic_string_common<true>::__throw_length_error() const",
> referenced from:
>
>       std::__1::enable_if<__is_forward_iterator<char*>::value,
> void>::type std::__1::basic_string<char, std::__1::char_traits<char>,
> std::__1::allocator<char> >::__init<char*>(char*, char*) in src.o
>
>       std::__1::enable_if<__is_forward_iterator<char const*>::value,
> void>::type std::__1::basic_string<char, std::__1::char_traits<char>,
> std::__1::allocator<char> >::__init<char const*>(char const*, char const*)
> in src.o
>
>       std::__1::enable_if<__is_forward_iterator<std::__1::__wrap_iter<char*>
> >::value, void>::type std::__1::basic_string<char,
> std::__1::char_traits<char>, std::__1::allocator<char>
> >::__init<std::__1::__wrap_iter<char*> >(std::__1::__wrap_iter<char*>,
> std::__1::__wrap_iter<char*>) in src.o
>
>   "std::__1::__match_any_but_newline<char>::__exec(std::__1::__state<char>&)
> const", referenced from:
>
>       vtable for std::__1::__match_any_but_newline<char> in src.o
>
>   "std::__1::locale::name() const", referenced from:
>
>       std::__1::basic_regex<char, std::__1::regex_traits<char>
> >::__start_matching_list(bool) in src.o
>
>   "std::__1::locale::use_facet(std::__1::locale::id&) const", referenced
> from:
>
>       std::__1::regex_traits<char>::__init() in src.o
>
>   "std::__1::regex_error::regex_error(std::__1::regex_constants::error_type)",
> referenced from:
>
>       char const* std::__1::basic_regex<char, std::__1::regex_traits<char>
> >::__parse<char const*>(char const*, char const*) in src.o
>
>       char const* std::__1::basic_regex<char, std::__1::regex_traits<char>
> >::__parse_basic_reg_exp<char const*>(char const*, char const*) in src.o
>
>       char const* std::__1::basic_regex<char, std::__1::regex_traits<char>
> >::__parse_extended_reg_exp<char const*>(char const*, char const*) in
> src.o
>
>       char const* std::__1::basic_regex<char, std::__1::regex_traits<char>
> >::__parse_assertion<char const*>(char const*, char const*) in src.o
>
>       char const* std::__1::basic_regex<char, std::__1::regex_traits<char>
> >::__parse_atom<char const*>(char const*, char const*) in src.o
>
>       char const* std::__1::basic_regex<char, std::__1::regex_traits<char>
> >::__parse_ERE_dupl_symbol<char const*>(char const*, char const*,
> std::__1::__owns_one_state<char>*, unsigned int, unsigned int) in src.o
>
>       bool std::__1::basic_regex<char, std::__1::regex_traits<char>
> >::__match_at_start_ecma<std::__1::allocator<std::__1::sub_match<char
> const*> > >(char const*, char const*, std::__1::match_results<char const*,
> std::__1::allocator<std::__1::sub_match<char const*> > >&,
> std::__1::regex_constants::match_flag_type, bool) const in src.o
>
>       ...
>
>   "std::__1::regex_error::~regex_error()", referenced from:
>
>       char const* std::__1::basic_regex<char, std::__1::regex_traits<char>
> >::__parse<char const*>(char const*, char const*) in src.o
>
>       char const* std::__1::basic_regex<char, std::__1::regex_traits<char>
> >::__parse_basic_reg_exp<char const*>(char const*, char const*) in src.o
>
>       char const* std::__1::basic_regex<char, std::__1::regex_traits<char>
> >::__parse_extended_reg_exp<char const*>(char const*, char const*) in
> src.o
>
>       char const* std::__1::basic_regex<char, std::__1::regex_traits<char>
> >::__parse_assertion<char const*>(char const*, char const*) in src.o
>
>       char const* std::__1::basic_regex<char, std::__1::regex_traits<char>
> >::__parse_atom<char const*>(char const*, char const*) in src.o
>
>       char const* std::__1::basic_regex<char, std::__1::regex_traits<char>
> >::__parse_ERE_dupl_symbol<char const*>(char const*, char const*,
> std::__1::__owns_one_state<char>*, unsigned int, unsigned int) in src.o
>
>       bool std::__1::basic_regex<char, std::__1::regex_traits<char>
> >::__match_at_start_ecma<std::__1::allocator<std::__1::sub_match<char
> const*> > >(char const*, char const*, std::__1::match_results<char const*,
> std::__1::allocator<std::__1::sub_match<char const*> > >&,
> std::__1::regex_constants::match_flag_type, bool) const in src.o
>
>       ...
>
>   "std::__1::basic_string<char, std::__1::char_traits<char>,
> std::__1::allocator<char> >::__init(char const*, unsigned long)",
> referenced from:
>
>       _main in src.o
>
>   "std::__1::basic_string<char, std::__1::char_traits<char>,
> std::__1::allocator<char> >::__init(unsigned long, char)", referenced from:
>
>       std::__1::__bracket_expression<char, std::__1::regex_traits<char>
> >::__exec(std::__1::__state<char>&) const in src.o
>
>   "std::__1::basic_string<char, std::__1::char_traits<char>,
> std::__1::allocator<char> >::reserve(unsigned long)", referenced from:
>
>       std::__1::basic_string<char, std::__1::char_traits<char>,
> std::__1::allocator<char> > std::__1::regex_traits<char>::
> __lookup_collatename<char*>(char*, char*, char) const in src.o
>
>       char const* std::__1::basic_regex<char, std::__1::regex_traits<char>
> >::__parse_collating_symbol<char const*>(char const*, char const*,
> std::__1::basic_string<char, std::__1::char_traits<char>,
> std::__1::allocator<char> >&) in src.o
>
>       std::__1::basic_string<char, std::__1::char_traits<char>,
> std::__1::allocator<char> > std::__1::regex_traits<char>::__lookup_collatename<char
> const*>(char const*, char const*, char) const in src.o
>
>   "std::__1::basic_string<char, std::__1::char_traits<char>,
> std::__1::allocator<char> >::basic_string(std::__1::basic_string<char,
> std::__1::char_traits<char>, std::__1::allocator<char> > const&)",
> referenced from:
>
>       char const* std::__1::basic_regex<char, std::__1::regex_traits<char>
> >::__parse_equivalence_class<char const*>(char const*, char const*,
> std::__1::__bracket_expression<char, std::__1::regex_traits<char> >*) in
> src.o
>
>       void std::__1::vector<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> > >
> >::__push_back_slow_path<std::__1::basic_string<char,
> std::__1::char_traits<char>, std::__1::allocator<char> >
> const&>(std::__1::basic_string<char, std::__1::char_traits<char>,
> std::__1::allocator<char> > const&&&) in src.o
>
>   "std::__1::basic_string<char, std::__1::char_traits<char>,
> std::__1::allocator<char> >::~basic_string()", referenced from:
>
>       _main in src.o
>
>       std::__1::basic_regex<char, std::__1::regex_traits<char>
> >::__start_matching_list(bool) in src.o
>
>       std::__1::__bracket_expression<char, std::__1::regex_traits<char>
> >::__exec(std::__1::__state<char>&) const in src.o
>
>       std::__1::__vector_base<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> > >
> >::~__vector_base() in src.o
>
>       std::__1::pair<std::__1::basic_string<char,
> std::__1::char_traits<char>, std::__1::allocator<char> >,
> std::__1::basic_string<char, std::__1::char_traits<char>,
> std::__1::allocator<char> > >::~pair() in src.o
>
>       std::__1::basic_string<char, std::__1::char_traits<char>,
> std::__1::allocator<char> > std::__1::regex_traits<char>::transform<char*>(char*,
> char*) const in src.o
>
>       std::__1::basic_string<char, std::__1::char_traits<char>,
> std::__1::allocator<char> > std::__1::regex_traits<char>::
> __lookup_collatename<char*>(char*, char*, char) const in src.o
>
>       ...
>
>   "std::__1::basic_string<char, std::__1::char_traits<char>,
> std::__1::allocator<char> >::operator=(std::__1::basic_string<char,
> std::__1::char_traits<char>, std::__1::allocator<char> > const&)",
> referenced from:
>
>       std::__1::basic_string<char, std::__1::char_traits<char>,
> std::__1::allocator<char> > std::__1::regex_traits<char>::
> __lookup_collatename<char*>(char*, char*, char) const in src.o
>
>       std::__1::basic_string<char, std::__1::char_traits<char>,
> std::__1::allocator<char> > std::__1::regex_traits<char>::__lookup_collatename<char
> const*>(char const*, char const*, char) const in src.o
>
>   "std::__1::basic_string<char, std::__1::char_traits<char>,
> std::__1::allocator<char> >::operator=(char)", referenced from:
>
>       char const* std::__1::basic_regex<char, std::__1::regex_traits<char>
> >::__parse_character_escape<char const*>(char const*, char const*,
> std::__1::basic_string<char, std::__1::char_traits<char>,
> std::__1::allocator<char> >*) in src.o
>
>       char const* std::__1::basic_regex<char, std::__1::regex_traits<char>
> >::__parse_expression_term<char const*>(char const*, char const*,
> std::__1::__bracket_expression<char, std::__1::regex_traits<char> >*) in
> src.o
>
>       char const* std::__1::basic_regex<char, std::__1::regex_traits<char>
> >::__parse_class_escape<char const*>(char const*, char const*,
> std::__1::basic_string<char, std::__1::char_traits<char>,
> std::__1::allocator<char> >&, std::__1::__bracket_expression<char,
> std::__1::regex_traits<char> >*) in src.o
>
>       char const* std::__1::basic_regex<char, std::__1::regex_traits<char>
> >::__parse_awk_escape<char const*>(char const*, char const*,
> std::__1::basic_string<char, std::__1::char_traits<char>,
> std::__1::allocator<char> >*) in src.o
>
>   "std::__1::__get_classname(char const*, bool)", referenced from:
>
>       unsigned int std::__1::regex_traits<char>::__lookup_classname<char
> const*>(char const*, char const*, bool, char) const in src.o
>
>   "std::__1::__shared_weak_count::__add_shared()", referenced from:
>
>       std::__1::basic_regex<char, std::__1::regex_traits<char>
> >::basic_regex(std::__1::basic_regex<char, std::__1::regex_traits<char> >
> const&) in src.o
>
>   "std::__1::__shared_weak_count::__release_shared()", referenced from:
>
>       std::__1::shared_ptr<std::__1::__empty_state<char> >::~shared_ptr()
> in src.o
>
>   "std::__1::__shared_weak_count::~__shared_weak_count()", referenced
> from:
>
>       std::__1::__shared_ptr_pointer<std::__1::__empty_state<char>*,
> std::__1::default_delete<std::__1::__empty_state<char> >,
> std::__1::allocator<std::__1::__empty_state<char> >
> >::~__shared_ptr_pointer() in src.o
>
>   "std::__1::__get_collation_name(char const*)", referenced from:
>
>       std::__1::basic_string<char, std::__1::char_traits<char>,
> std::__1::allocator<char> > std::__1::regex_traits<char>::
> __lookup_collatename<char*>(char*, char*, char) const in src.o
>
>       std::__1::basic_string<char, std::__1::char_traits<char>,
> std::__1::allocator<char> > std::__1::regex_traits<char>::__lookup_collatename<char
> const*>(char const*, char const*, char) const in src.o
>
>   "std::__1::ctype<char>::id", referenced from:
>
>       std::__1::regex_traits<char>::__init() in src.o
>
>   "std::__1::locale::locale(std::__1::locale const&)", referenced from:
>
>       std::__1::regex_traits<char>::regex_traits(std::__1::regex_traits<char>
> const&) in src.o
>
>       std::__1::basic_regex<char, std::__1::regex_traits<char>
> >::__start_matching_list(bool) in src.o
>
>   "std::__1::locale::locale()", referenced from:
>
>       std::__1::regex_traits<char>::regex_traits() in src.o
>
>  "std::__1::locale::~locale()", referenced from:
>
>       std::__1::regex_traits<char>::~regex_traits() in src.o
>
>       std::__1::regex_traits<char>::regex_traits() in src.o
>
>       std::__1::basic_regex<char, std::__1::regex_traits<char>
> >::__start_matching_list(bool) in src.o
>
>   "std::__1::collate<char>::id", referenced from:
>
>       std::__1::regex_traits<char>::__init() in src.o
>
>   "typeinfo for std::__1::regex_error", referenced from:
>
>       char const* std::__1::basic_regex<char, std::__1::regex_traits<char>
> >::__parse<char const*>(char const*, char const*) in src.o
>
>       char const* std::__1::basic_regex<char, std::__1::regex_traits<char>
> >::__parse_basic_reg_exp<char const*>(char const*, char const*) in src.o
>
>       char const* std::__1::basic_regex<char, std::__1::regex_traits<char>
> >::__parse_extended_reg_exp<char const*>(char const*, char const*) in
> src.o
>
>       char const* std::__1::basic_regex<char, std::__1::regex_traits<char>
> >::__parse_assertion<char const*>(char const*, char const*) in src.o
>
>       char const* std::__1::basic_regex<char, std::__1::regex_traits<char>
> >::__parse_atom<char const*>(char const*, char const*) in src.o
>
>       char const* std::__1::basic_regex<char, std::__1::regex_traits<char>
> >::__parse_ERE_dupl_symbol<char const*>(char const*, char const*,
> std::__1::__owns_one_state<char>*, unsigned int, unsigned int) in src.o
>
>       bool std::__1::basic_regex<char, std::__1::regex_traits<char>
> >::__match_at_start_ecma<std::__1::allocator<std::__1::sub_match<char
> const*> > >(char const*, char const*, std::__1::match_results<char const*,
> std::__1::allocator<std::__1::sub_match<char const*> > >&,
> std::__1::regex_constants::match_flag_type, bool) const in src.o
>
>       ...
>
>   "typeinfo for std::__1::__shared_weak_count", referenced from:
>
>       typeinfo for std::__1::__shared_ptr_pointer<std::__1::__empty_state<char>*,
> std::__1::default_delete<std::__1::__empty_state<char> >,
> std::__1::allocator<std::__1::__empty_state<char> > > in src.o
>
>   "vtable for std::__1::__shared_count", referenced from:
>
>       std::__1::shared_ptr<std::__1::__empty_state<char>
> >::shared_ptr<std::__1::__empty_state<char> >(std::__1::__empty_state<char>*,
> std::__1::enable_if<is_convertible<std::__1::__empty_state<char>*,
> std::__1::__empty_state<char>*>::value, std::__1::shared_ptr<std::__1::__empty_state<char>
> >::__nat>::type) in src.o
>
>   NOTE: a missing vtable usually means the first non-inline virtual member
> function has no definition.
>
>   "vtable for std::__1::__shared_weak_count", referenced from:
>
>       std::__1::shared_ptr<std::__1::__empty_state<char>
> >::shared_ptr<std::__1::__empty_state<char> >(std::__1::__empty_state<char>*,
> std::__1::enable_if<is_convertible<std::__1::__empty_state<char>*,
> std::__1::__empty_state<char>*>::value, std::__1::shared_ptr<std::__1::__empty_state<char>
> >::__nat>::type) in src.o
>
>   NOTE: a missing vtable usually means the first non-inline virtual member
> function has no definition.
>
> ld: symbol(s) not found for architecture x86_64
>
> clang: error: linker command failed with exit code 1 (use -v to see
> invocation)
>
>
>
> ** BUILD FAILED **
>
>
>
> Did I forget something?
>
>
>
> Thanks in advance
>
>
>
> Best Regards
>
> Roman
>
> --
>
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>
> Powered by www.kitware.com
>
> Please keep messages on-topic and check the CMake FAQ at:
> http://www.cmake.org/Wiki/CMake_FAQ
>
> Kitware offers various services to support the CMake community. For more
> information on each offering, please visit:
>
> CMake Support: http://cmake.org/cmake/help/support.html
> CMake Consulting: http://cmake.org/cmake/help/consulting.html
> CMake Training Courses: http://cmake.org/cmake/help/training.html
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-- 
Craig Scott
Melbourne, Australia
https://crascit.com
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