On 17 September 2011 14:23, Jeffrey Walton wrote: > /usr//include/cryptopp/cryptlib.h:99: error: template with C linkage ... > I've tried adding '-x c++' to force c++ in the files. That's obviously not going to help. If the compiler complains about a template, it's not compiling C, because there's no such thing in C. Ditto for C linkage; everything in C has C linkage, so there's no concept of any other kind of language linkage, so no reason a C compiler would ever mention "C linkage". So the compiler was already treating the files as containing C++ (just apparently assuming that everything in a system directory gets an implicit extern "C" around it.) Contrary to what some people seem to believe, extern "C" does NOT mean the compiler is compiling "in C mode" or treating the source code as C code, it means it's compiling C++ code with C language linkage i.e. the symbols will be named such that they can be easily called from C programs because the symbols names will not be mangled.
