error: C++ requires a type specifier for all declaration

[muschellij2]

Not a bug (the fix is update rcpp to the github one for now), but if you run into this error:

In file included from /Library/Frameworks/R.framework/Versions/3.6/Resources/library/ITKR/libs/include/ITK-5.1/itkImageFileReader.h:173:
In file included from /Library/Frameworks/R.framework/Versions/3.6/Resources/library/ITKR/libs/include/ITK-5.1/itkImageFileReader.hxx:29:
In file included from /Library/Frameworks/R.framework/Versions/3.6/Resources/library/ITKR/libs/include/ITK-5.1/itksys/SystemTools.hxx:18:
In file included from /Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/unistd.h:658:
/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/gethostuuid.h:39:17: error: C++ requires a type specifier for all declarations
int gethostuuid(uuid_t, const struct timespec *) __OSX_AVAILABLE_STARTING(__MAC_10_5, __IPHONE_NA);

See thread at
RcppCore/Rcpp#1046

[muschellij2]

Solution:

remotes::install_github("RcppCore/Rcpp")