patch 8.0.0074
Problem:    Cannot make Vim fail on an internal error.
Solution:   Add IEMSG() and IEMSG2(). (Domenique Pelle)  Avoid reporting an
            internal error without mentioning where.
diff --git a/src/Makefile b/src/Makefile
index fd07946..fef53af 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -681,6 +681,10 @@
 #LEAK_CFLAGS = -DEXITFREE
 #LEAK_LIBS = -lccmalloc
 
+# Uncomment this line to have Vim call abort() when an internal error is
+# detected.  Useful when using a tool to find errors.
+#ABORT_CLFAGS = -DABORT_ON_INTERNAL_ERROR
+
 #####################################################
 ###  Specific systems, check if yours is listed!  ### {{{
 #####################################################
@@ -1409,7 +1413,7 @@
 PRE_DEFS = -Iproto $(DEFS) $(GUI_DEFS) $(GUI_IPATH) $(CPPFLAGS) $(EXTRA_IPATHS)
 POST_DEFS = $(X_CFLAGS) $(MZSCHEME_CFLAGS) $(EXTRA_DEFS)
 
-ALL_CFLAGS = $(PRE_DEFS) $(CFLAGS) $(PROFILE_CFLAGS) $(SANITIZER_CFLAGS) $(LEAK_CFLAGS) $(POST_DEFS)
+ALL_CFLAGS = $(PRE_DEFS) $(CFLAGS) $(PROFILE_CFLAGS) $(SANITIZER_CFLAGS) $(LEAK_CFLAGS) $(ABORT_CLFAGS) $(POST_DEFS)
 
 # Exclude $CFLAGS for osdef.sh, for Mac 10.4 some flags don't work together
 # with "-E".