On Wed, 10 Feb 2016 17:38:08 +0100 Jakub Jelinek <ja...@redhat.com> wrote:
> On Wed, Feb 10, 2016 at 05:27:46PM +0100, Tomáš Smetana wrote: > > Hello, > > one of my packages (tvtime) failed to build during the mass rebuild. > > Not a big deal, I think there are several ways to fix it. The odd thing > > is that the build failed due to a rather unexpected change in C++ > > preprocessor (g++ -E or cpp). > > > > Let's assume I have a test.cpp file containing this: > > > > #define MYMACRO(a, b) ""a", "b"" > > MYMACRO(x,y) > > > > Now `cpp test.cpp' (or `g++ -E test.cpp') on rawhide produces: > > That is expected, and in F23 you get the same behavior if you use > -std=c++11 or -std=c++14. Yup. This part is obvious... :) > In C++11 and later the language has user defined literals, so if you just > want to concatenate strings, you need to put a whitespace in between them, > otherwise the preprocessor considers ""a as user defined literal, similarly > for ", "b and that is why it is not macro expanded. > Just use > #define MYMACRO(a, b) "" a ", " b "" OK. Thanks a lot for the explanation. Regards, -- Tomáš Smetana Platform Engineering, Red Hat -- devel mailing list devel@lists.fedoraproject.org http://lists.fedoraproject.org/admin/lists/devel@lists.fedoraproject.org
