Error compiling with Intel 2017-2019 on Linux

[Zhen Wang]

Hi,

I'm having difficulty building Blaze on Linux. I pull latest source, include <blaze/Blaze.h> and compile an empty main with Intel Compiler 2017 (2018, or 2019) on CentOS 7.1. The icpc line is

icpc -std=c++11

The first few lines of the error message is

In file included from /home/zhewang/Tool/blaze-3.4-opt/include/blaze/util/constraints/FloatingPoint.h(43),
                 from /home/zhewang/Tool/blaze-3.4-opt/include/blaze/math/Accuracy.h(43),
                 from /home/zhewang/Tool/blaze-3.4-opt/include/blaze/Math.h(43),
                 from /home/zhewang/Tool/blaze-3.4-opt/include/blaze/Blaze.h(43),
                 from main.cpp(13):
/home/zhewang/Tool/blaze-3.4-opt/include/blaze/util/typetraits/IsFloatingPoint.h(95): error: "IsFloatingPoint_v" is not a function or static data member
  constexpr bool IsFloatingPoint_v = IsFloatingPoint<T>::value;
                 ^

In file included from /home/zhewang/Tool/blaze-3.4-opt/include/blaze/util/constraints/FloatingPoint.h(43),
                 from /home/zhewang/Tool/blaze-3.4-opt/include/blaze/math/Accuracy.h(43),
                 from /home/zhewang/Tool/blaze-3.4-opt/include/blaze/Math.h(43),
                 from /home/zhewang/Tool/blaze-3.4-opt/include/blaze/Blaze.h(43),
                 from main.cpp(13):
/home/zhewang/Tool/blaze-3.4-opt/include/blaze/util/typetraits/IsFloatingPoint.h(95): error: "constexpr" is not valid here
  constexpr bool IsFloatingPoint_v = IsFloatingPoint<T>::value;
  ^

In file included from /home/zhewang/Tool/blaze-3.4-opt/include/blaze/math/views/Forward.h(44),
                 from /home/zhewang/Tool/blaze-3.4-opt/include/blaze/math/typetraits/IsBand.h(43),
                 from /home/zhewang/Tool/blaze-3.4-opt/include/blaze/math/constraints/Band.h(43),
                 from /home/zhewang/Tool/blaze-3.4-opt/include/blaze/math/Band.h(44),
                 from /home/zhewang/Tool/blaze-3.4-opt/include/blaze/Math.h(46),
                 from /home/zhewang/Tool/blaze-3.4-opt/include/blaze/Blaze.h(43),
                 from main.cpp(13):
/home/zhewang/Tool/blaze-3.4-opt/include/blaze/math/expressions/Forward.h(190): error: expected an identifier
  decltype(auto) operator+( const DenseVector<VT1,TF>&, const DenseVector<VT2,TF>& );
  ^

It seems I did something wrong again.. Could you please help? Thanks.

[Klaus Iglberger]

Hi Zhen!

Thanks for creating this issue. Since Blaze 3.4 we no longer support the Intel compiler. The major reason is that it still does not provide full support of C++14, in particular variable templates. On the Blaze Bitbucket page you can still read the according announcement:

Please note that in Blaze 3.4 we make unrestricted use of variable templates. Unfortunately, compiler support for variable templates is not perfect yet and we have encountered various problems, especially with older compilers, which we supported up to Blaze 3.3. In order to being able to move forward and in order to benefit from variable templates, from as of today Blaze will no longer provide support for compilers without complete support for variable templates.

Hopefully Intel will resolve these issues of the Intel compiler soon, such we can provide support for Intel again.

Best regards,

Klaus!

[Zhen Wang]

Klaus,

Thanks for your response and pointing out variable templates. Intel does support variable templates stated here. GNU supports the same set of C++14 features. With -std=c++14 enabled for Intel, the errors become:

In file included from /home/zhewang/Tool/blaze-3.4-opt/include/blaze/math/expressions/DenseMatrix.h(43),
                 from /home/zhewang/Tool/blaze-3.4-opt/include/blaze/math/typetraits/IsDenseMatrix.h(43),
                 from /home/zhewang/Tool/blaze-3.4-opt/include/blaze/math/views/band/BaseTemplate.h(43),
                 from /home/zhewang/Tool/blaze-3.4-opt/include/blaze/math/views/Forward.h(45),
                 from /home/zhewang/Tool/blaze-3.4-opt/include/blaze/math/typetraits/IsBand.h(43),
                 from /home/zhewang/Tool/blaze-3.4-opt/include/blaze/math/constraints/Band.h(43),
                 from /home/zhewang/Tool/blaze-3.4-opt/include/blaze/math/Band.h(44),
                 from /home/zhewang/Tool/blaze-3.4-opt/include/blaze/Math.h(46),
                 from /home/zhewang/Tool/blaze-3.4-opt/include/blaze/Blaze.h(43),
                 from main.cpp(13):
/home/zhewang/Tool/blaze-3.4-opt/include/blaze/math/expressions/Matrix.h(107): error: cannot overload functions distinguished by return type alone
     BLAZE_ALWAYS_INLINE constexpr const MatrixType& operator~() const noexcept {
                                                     ^


In file included from /home/zhewang/Tool/blaze-3.4-opt/include/blaze/math/sparse/CompressedMatrix.h(57),
                 from /home/zhewang/Tool/blaze-3.4-opt/include/blaze/math/CompressedMatrix.h(45),
                 from /home/zhewang/Tool/blaze-3.4-opt/include/blaze/Math.h(48),
                 from /home/zhewang/Tool/blaze-3.4-opt/include/blaze/Blaze.h(43),
                 from main.cpp(13):
/home/zhewang/Tool/blaze-3.4-opt/include/blaze/math/sparse/ValueIndexPair.h(223): error: no instance of overloaded function "blaze::ValueIndexPair<Type>::operator=" matches the specified type
  inline constexpr auto ValueIndexPair<Type>::operator=( const Other& rhs )
                                              ^

Do you have any clue? Thanks.

[Klaus Iglberger]

Hi Zhen!

Your are correct, Intel states that they support variable templates and many other C++14 features. Unfortunately the implementation of many of these features is too buggy to be of any use. We have experienced so many bugs with variable templates, constexpr and decltype(auto) (just to name a few) that we have decided that it is not worth anymore to wait until these issues are fixed or to implement workarounds. The two errors you posted, for instance, are clear compiler bugs with constexpr and trailing return types. I hope this explanation helps to understand the decision.

Best regards,

Klaus!

[Zhen Wang]

Klaus,

I see. Thanks a lot for your explanation.

[Jannik Schürg]

Since you are using static asserts to check for the compiler in system/Compiler.h, could you add an error message? Like "We do not support this compiler any longer/at the moment."

[Klaus Iglberger]

Hi Jannik!

As you correctly state, "we don't support this compiler at the moment". Our hope, however, is that Intel will eventually catch up and that with a future release it will be possible to compile Blaze as cleanly as with all other compilers. Adding an error message would prevent this, since even in case a new release of the Intel compiler would compile cleanly you would get a compilation error. Thus we will not add any kind of compile time restriction. Still, thanks for the suggestion,

Best regards,

Klaus!

[Christoph Statz]

For reference: No luck with the 2020 release on macos as well (icpc 19.1.1.216). Just from including <blaze/Math.h>:

/usr/local/include/blaze/math/views/subvector/Dense.h(661): error: expected a ")"
IsSIMDCombinable_v< ElementType, ElementType_t<VT2> > );

‌

[Klaus Iglberger]

Hi Christoph!

Thanks for the heads up. We’ll investigate how many problems remain once we get access to this version ourselves. In case only a few problems remain we might be able to provide a couple of workarounds. Thanks again,

Best regards,

Klaus!

‌

[David Dixon]

I just tried with intel 20.0.1 and still no luck. However, if you use -qnextgen it will work but you are compiling with the llvm backend.

‌

Best,

David

‌

[Klaus Iglberger]

Hi David!

Thanks for testing this with Intel 20.0.1, that is valuable feedback.

Best regards,

Klaus!