Error: This compiler appears to be too old to be supported by Eigen-CodePudding

I am trying to compile a project that includes the eigen library and I get this error:

In file included from /home/--/--/--/Eigen/Core:19,
             from /home/--/--/--/Eigen/Geometry:11,
             from /usr/include/rl-0.7.0/rl/math/Transform.h:34,
             from /home/--/--/--/example.cpp:2:
/home/--/--/--/Eigen/src/Core/util/Macros.h:674:2: error: #error This compiler appears to be too old to be supported by Eigen
674 | #error This compiler appears to be too old to be supported by Eigen
  |  ^~~~~

I am using:

Ubuntu 20.04
Cmake 3.16.3
VSCode Compiler GCC 10.3.1
Eigen 3.4.90

The problem seems to be related to these lines in Macros.h file:

// The macros EIGEN_HAS_CXX?? defines a rough estimate of available c   features
// but in practice we should not rely on them but rather on the availability of
// individual features as defined later.
// This is why there is no EIGEN_HAS_CXX17.
#if EIGEN_MAX_CPP_VER<14 || EIGEN_COMP_CXXVER<14 || (EIGEN_COMP_MSVC && EIGEN_COMP_MSVC < 1900) || \
   (EIGEN_COMP_ICC && EIGEN_COMP_ICC < 1500) || (EIGEN_COMP_NVCC && EIGEN_COMP_NVCC < 80000) ||     \
   (EIGEN_COMP_CLANG && ((EIGEN_COMP_CLANG<309) || (defined(__apple_build_version__) && (__apple_build_version__ < 9000000)))) || \
   (EIGEN_COMP_GNUC_STRICT && EIGEN_COMP_GNUC<51)
#error This compiler appears to be too old to be supported by Eigen
#endif

Do you know how to fix this error?

CodePudding user response：

As @Lala5th suggested, by changing the C standard the problem is solved.

I have modified the CMakeLists.txt:

From:

set(CMAKE_CXX_STANDARD 11)

To:

set(CMAKE_CXX_STANDARD 17)

(It also works with 14)

CodePudding user response：

As you've noted, Macros.h file tells us the problem is with compiler version.

VSCode compiler

GCC 10 definitely has support for c 17. It means that you should change it's starting flags. In settings.json file add this lines:

"code-runner.executorMap": {
    "cpp": "cd $dir && g   -std=c  17 $fileName -o $fileNameWithoutExt && $dir$fileNameWithoutExt",
},

according to this answer.

Standard Bash's g

Use g with -std=c 17 flag.