MantisBT - CMake
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IDProjectCategoryView StatusDate SubmittedLast Update
0015359CMakeCMakepublic2015-01-19 16:392016-06-10 14:31
ReporterLaurent Demailly 
Assigned ToKitware Robot 
PrioritynormalSeverityfeatureReproducibilityalways
StatusclosedResolutionmoved 
PlatformApple MacOSOS XOS Version10.4.10
Product VersionCMake 3.1 
Target VersionFixed in Version 
Summary0015359: __attribute__((weak)) support/detection (weak symbols)
Descriptionit would be great if some built in recipe would set some variable depending on whether the
compiler/linker support __attribute__((weak))


this is done in autoconf the following way for instance:

AC_CACHE_CHECK(
  [for weak symbol support],
  [folly_cv_prog_cc_weak_symbols],
  [AC_LINK_IFELSE(
    [AC_LANG_SOURCE[
      extern "C" void configure_link_extern_weak_test()
__attribute__((weak));
      int main(int argc, char** argv) {
          return configure_link_extern_weak_test == nullptr;
      }]],
    [folly_cv_prog_cc_weak_symbols="yes"],
    [folly_cv_prog_cc_weak_symbols="no"])])

if test "$folly_cv_prog_cc_weak_symbols" = yes; then
  AC_DEFINE([HAVE_WEAK_SYMBOLS], [1],
            [Define to 1 if the linker supports weak symbols.])
fi


ps: sent similar request (more of a question on how to do it pending built in support by cmake base) to the cmake@cmake.org mailing list - hope it's ok to have some amount of duplicate
Steps To Reproduce
Additional Information
TagsNo tags attached.
Relationships
related to 0015361closed Kitware Robot CHECK_CXX_SOURCE_COMPILES doesn't use c++11 flags specified 
Attached Files
Issue History
Date ModifiedUsernameFieldChange
2015-01-19 16:39Laurent DemaillyNew Issue
2015-01-19 16:43Brad KingNote Added: 0037749
2015-01-19 18:30Laurent DemaillyNote Added: 0037752
2015-01-20 08:31Brad KingRelationship addedrelated to 0015361
2016-06-10 14:29Kitware RobotNote Added: 0042700
2016-06-10 14:29Kitware RobotStatusnew => resolved
2016-06-10 14:29Kitware RobotResolutionopen => moved
2016-06-10 14:29Kitware RobotAssigned To => Kitware Robot
2016-06-10 14:31Kitware RobotStatusresolved => closed

Notes
(0037749)
Brad King   
2015-01-19 16:43   
Link to mailing list thread mentioned in description:

 detecting __attribute__((weak)) support
 http://thread.gmane.org/gmane.comp.programming.tools.cmake.user/51503 [^]
(0037752)
Laurent Demailly   
2015-01-19 18:30   
so I tried to use
CHECK_CXX_SOURCE_COMPILES to do the above
and stepped on
http://public.kitware.com/Bug/view.php?id=15361 [^]

(2 different issues though - one would for cmake to know about weak symbol support and the other is how to test compile with the same flags as requested)
(0042700)
Kitware Robot   
2016-06-10 14:29   
Resolving issue as `moved`.

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