[Bug c++/67155] New: Linking of complex constexpr static class member failing across files

[Bug c++/67155] New: Linking of complex constexpr static class member failing across files

[JamesMikeDuPont at googlemail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67155

            Bug ID: 67155
           Summary: Linking of complex constexpr static class member
                    failing across files
           Product: gcc
           Version: 5.2.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: JamesMikeDuPont at googlemail dot com
  Target Milestone: ---

Created attachment 36148
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=36148&action=edit
test case

I encountered a strange behavior when creating a class that wraps a constexpr
string.

It seems that the static constant string field wrapped in a class is only
accessible in the same header file and not available in a separate compilation
unit. 

The workaround is to move the usage of the static fields into the header.

If you prefer git you can find the test case here as well :
https://github.com/h4ck3rm1k3/gcc-plugin-cpp-template/tree/constexpr/testcase

[Bug c++/67155] Linking of complex constexpr static class member failing across files

[JamesMikeDuPont at googlemail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67155

--- Comment #1 from James Michael DuPont <JamesMikeDuPont at googlemail dot com> ---
The compiler output :

g++ -std=gnu++11 test.cpp test.hpp
/tmp/cceBFmJM.o: In function `S::S()':
test.cpp:(.text+0x35): undefined reference to `S::u'
collect2: error: ld returned 1 exit status
Makefile:2: recipe for target 'test' failed
make: *** [test] Error 1

[Bug c++/67155] Linking of complex constexpr static class member failing across files

[JamesMikeDuPont at googlemail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67155

--- Comment #2 from James Michael DuPont <JamesMikeDuPont at googlemail dot com> ---
adding this seems to solve the linker error:

constexpr CU S::u;

[Bug c++/67155] Linking of complex constexpr static class member failing across files

[JamesMikeDuPont at googlemail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67155

James Michael DuPont <JamesMikeDuPont at googlemail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|---                         |FIXED

--- Comment #3 from James Michael DuPont <JamesMikeDuPont at googlemail dot com> ---
got feedback on so
http://stackoverflow.com/questions/31889247/c-static-constexpr-class-member-with-complex-class-linking-issues/31889510#31889510

[Bug c++/67155] Linking of complex constexpr static class member failing across files

[trippels at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67155

Markus Trippelsdorf <trippels at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |trippels at gcc dot gnu.org
         Resolution|FIXED                       |INVALID

[Bug c++/67155] Linking of complex constexpr static class member failing across files

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67155

--- Comment #4 from Jonathan Wakely <redi at gcc dot gnu.org> ---
https://gcc.gnu.org/wiki/VerboseDiagnostics#missing_static_const_definition