LegacySupport messes up isnan with GCC (and isinfinity): error: 'isnan' was not declared in this scope; did you mean 'std::isnan'

[barracuda156]

In file included from /opt/local/include/ImageMagick-6/magick/MagickCore.h:78,
                 from /opt/local/include/ImageMagick-6/Magick++/Include.h:45,
                 from /opt/local/include/ImageMagick-6/Magick++.h:10,
                 from magick_types.h:3,
                 from RcppExports.cpp:4:
/opt/local/include/ImageMagick-6/magick/quantum.h: In function 'MagickCore::Quantum MagickCore::ClampToQuantum(MagickRealType)':
/opt/local/include/ImageMagick-6/magick/magick-type.h:220:20: error: 'isnan' was not declared in this scope; did you mean 'std::isnan'?
  220 | #  define IsNaN(a) isnan(a)
      |                    ^~~~~
/opt/local/include/ImageMagick-6/magick/magick-type.h:220:20: note: in definition of macro 'IsNaN'
  220 | #  define IsNaN(a) isnan(a)
      |                    ^~~~~
In file included from /opt/local/include/LegacySupport/cmath:54,
                 from /opt/local/Library/Frameworks/R.framework/Versions/4.2/Resources/library/Rcpp/include/Rcpp/platform/compiler.h:100,
                 from /opt/local/Library/Frameworks/R.framework/Versions/4.2/Resources/library/Rcpp/include/Rcpp/r/headers.h:62,
                 from /opt/local/Library/Frameworks/R.framework/Versions/4.2/Resources/library/Rcpp/include/RcppCommon.h:30,
                 from /opt/local/Library/Frameworks/R.framework/Versions/4.2/Resources/library/Rcpp/include/Rcpp.h:27,
                 from magick_types.h:2:
/opt/local/include/gcc12/c++/cmath:632:5: note: 'std::isnan' declared here
  632 |     isnan(_Tp __x)
      |     ^~~~~
make: *** [RcppExports.o] Error 1

I am not sure on which side is the error. I got this now trying to build R-magick, but apparently it merely passes ImageMagic headers. Issue with the package upstream: ​https://github.com/ropensci/magick/issues/369 This is the same error which got R-igraph broken on some configs: ​https://github.com/igraph/rigraph/issues/669

Any ideas what is going wrong and where?

[barracuda156]

Okay, I am pretty sure it is LegacySupport messing up something. See: ​https://stackoverflow.com/questions/39130040/cmath-hides-isnan-in-math-h-in-c14-c11 Also: ​https://sourceware.org/bugzilla/show_bug.cgi?id=19439

[kencu (Ken)]

As mentioned in the original ticket description, see:

​https://github.com/igraph/rigraph/issues/669

and this reproducer is mentioned:

​https://github.com/igraph/rigraph/issues/669#issuecomment-1426711903

and also this:

​https://developers.redhat.com/blog/2016/02/29/why-cstdlib-is-more-complicated-than-you-might-think

This could have something to do with the math modifications in legacysupport... they have been very complicated to sort out exactly correctly. A number of folks have had a stab at it, and there are still issues. There is an open PR to fix an issue with clang building against libstdc++ that is still not fully sorted out after some many weeks.