I'm not sure if it's standard c/c++ but there are the #line directives (https://gcc.gnu.org/onlinedocs/cpp/Line-Control.html https://gcc.gnu.org/onlinedocs/cpp/

I'm not sure if it's standard c/c++ but there are the #line directives (https://gcc.gnu.org/onlinedocs/cpp/Line-Control.html https://gcc.gnu.org/onlinedocs/cpp/Line-Control.html), bison and flex use them to good effect and I've used them when piping code into gcc. It'll give compiler errors in the right places and make gdb behave when stepping through code, not sure if it runs into limitations or not. According to the oldest docs I could quickly find (https://gcc.gnu.org/onlinedocs/gcc-4.0.4/cpp/Line-Control.html https://gcc.gnu.org/onlinedocs/gcc-4.0.4/cpp/Line-Control.ht...) it goes back to at least gcc 2.95 in 1999, but I wouldn't be surprised if it predated javascript and css themselves.