fix building with tcl8.6 (#902561)

diff --git a/configure.ac b/configure.ac
index ff78d2bb1f72e83e8df3d49583d0b38699d99577..cd1afa31be76e452ca458d0209e4c046398d118e 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -96,6 +96,8 @@ else
     . ${ac_cv_c_tclconfig}/tclConfig.sh
     AC_SUBST([TCL_LIB_FLAG])
     WHIPTCLSO=whiptcl.so
+    # needed with tcl8.6
+    CPPFLAGS="$CPPFLAGS -DUSE_INTERP_RESULT"
   else
     AC_MSG_RESULT([NOT found])
   fi