Bug#1143681: opm-common: FTBFS: /<<PKGBUILDDIR>>/opm/material/common/quad.hpp:282:13: error: redefinition of 'quad std::abs(quad)'

Control: reassign 1143684 src:opm-common
Control: tags -1 experimental
Control: forcemerge -1 1143684
Control: affects -1  src:opm-simulators libopm-common-dev
Control: retitle -1 opm-common FTBFS with GCC 16 on amd64

On Wed, Aug 05, 2026 at 11:24:41AM +0000, Santiago Vila wrote:
>...
> --------------------------------------------------------------------------------
> [...]
> [ 25%] Building CXX object CMakeFiles/opmcommon.dir/opm/material/densead/Evaluation.cpp.o
> /usr/bin/x86_64-linux-gnu-g++ -DEMBEDDED_PYTHON -DFMT_SHARED [too-long-redacted] material/densead/Evaluation.cpp
> In file included from /<<PKGBUILDDIR>>/opm/material/densead/Evaluation.cpp:28:
> /<<PKGBUILDDIR>>/opm/material/common/quad.hpp:282:13: error: redefinition of ‘quad std::abs(quad)’
>   282 | inline quad abs(quad val)
>       |             ^~~
> In file included from /usr/include/c++/16/cstdlib:87,
>                  from /usr/include/c++/16/ext/string_conversions.h:45,
>                  from /usr/include/c++/16/bits/basic_string.h:4499,
>                  from /usr/include/c++/16/string:58,
>                  from /usr/include/c++/16/stdexcept:41,
>                  from /<<PKGBUILDDIR>>/opm/material/densead/Evaluation.hpp:42,
>                  from /<<PKGBUILDDIR>>/opm/material/densead/Evaluation.cpp:25:
> /usr/include/c++/16/bits/std_abs.h:150:3: note: ‘constexpr __float128 std::abs(__float128)’ previously defined here
>   150 |   abs(__float128 __x)
>       |   ^~~
> make[3]: *** [CMakeFiles/opmcommon.dir/build.make:3840: CMakeFiles/opmcommon.dir/opm/material/densead/Evaluation.cpp.o] Error 1
> make[3]: *** Waiting for unfinished jobs....
> make[3]: Leaving directory '/<<PKGBUILDDIR>>/obj-x86_64-linux-gnu'
> make[2]: *** [CMakeFiles/Makefile2:871: CMakeFiles/opmcommon.dir/all] Error 2
> make[2]: Leaving directory '/<<PKGBUILDDIR>>/obj-x86_64-linux-gnu'
> make[1]: *** [Makefile:149: all] Error 2
> make[1]: Leaving directory '/<<PKGBUILDDIR>>/obj-x86_64-linux-gnu'
> dh_auto_build: error: cd obj-x86_64-linux-gnu && make -j2 INSTALL="install --strip-program=true" VERBOSE=1 returned exit code 2
> make: *** [debian/rules:17: binary] Error 25
> dpkg-buildpackage: error: debian/rules binary subprocess failed with exit status 2
> --------------------------------------------------------------------------------


Markus, the root cause is the following in the log that is already 
present with earlier GCC version:
  -- Performing Test QuadMath_HAS_MATH_OPS
  -- Performing Test QuadMath_HAS_MATH_OPS - Failed

When I edit cmake/Modules/FindQuadMath.cmake to have empty main() in 
the QuadMath_HAS_MATH_OPS check the build passes.


The test fails (also with older GCC versions) due to:

$ cat test.cc 
#include <cstdlib>
#include <cmath>
int main()
{
   __float128 b=10;
   __float128 c=std::atan(b);
}
$ g++ test.cc
test.cc: In function ‘int main()’:
test.cc:6:26: error: call of overloaded ‘atan(__float128&)’ is ambiguous
    6 |    __float128 c=std::atan(b);
      |                 ~~~~~~~~~^~~
  • there are 3 candidates
In file included from /usr/include/features.h:539,
                 from /usr/include/x86_64-linux-gnu/c++/16/bits/os_defines.h:39,
                 from /usr/include/x86_64-linux-gnu/c++/16/bits/c++config.h:733,
                 from /usr/include/c++/16/cstdlib:46,
                 from test.cc:1:
    • candidate 1: ‘double atan(double)’
      /usr/include/x86_64-linux-gnu/bits/mathcalls.h:57:1:
         57 | __MATHCALL_VEC (atan,, (_Mdouble_ __x));
            | ^~~~~~~~~~~~~~
In file included from test.cc:2:
    • candidate 2: ‘constexpr float std::atan(float)’
      /usr/include/c++/16/cmath:138:3:
        138 |   atan(float __x)
            |   ^~~~
    • candidate 3: ‘constexpr long double std::atan(long double)’
      /usr/include/c++/16/cmath:142:3:
        142 |   atan(long double __x)
            |   ^~~~
$


cu
Adrian