On 1 April 2015 at 16:09, Jonathan Wakely <jwakely@xxxxxxxxxx> wrote: > On 01/04/15 15:16 +0100, Ian Malone wrote: >> >> Do you mind clarifying? I thought <string> should provide that >> http://www.cplusplus.com/reference/string/string/operator+/ or is that >> what fno-implicit-templates is turning off? > > > Of course string provides it, but it's a template, so it needs to be > instantiated. The GCC manual documents -fno-implicit-templates like > so: > > Never emit code for non-inline templates that are instantiated > implicitly (i.e. by use); only emit code for explicit > instantiations. > > The invalid program in the OP uses operator+(), which would normally > instantiate the function template implicitly. But if you use > -fno-implicit-templates you are promising the compiler you will > provide explicit instantiations. The program above does not provide > them, so it is broken. > Thanks. Hadn't occurred to me the + operator here was a template as I'd never had to deal with basic_string. Still a bit puzzled as cplusplus.com says string is an instantiation of basic_string while cppreference.com says it's a typedef (which I guess doesn't count as explicit instantiation). -- imalone http://ibmalone.blogspot.co.uk -- devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxxx https://admin.fedoraproject.org/mailman/listinfo/devel Fedora Code of Conduct: http://fedoraproject.org/code-of-conduct
