In a header file of your C/C++ application or extension that includes the Tcl library, add these lines
#include <tcl.h> ... #if (TCL_MAJOR_VERSION < 8) || (TCL_MAJOR_VERSION == 8) && (TCL_MINOR_VERSION < 6) #define Tcl_GetErrorLine(interp) (interp->errorLine) #endif
Why? This helps you deprecate direct access to interp->errorLine so you can upgrade your code written for pre-8.6 Tcl so it can be used with Tcl 8.6, yet still work with earlier Tcl releases.