diff -ur libsmi-0.5.0/lib/scanner-smi.h libsmi-0.5.0.new/lib/scanner-smi.h

--- libsmi-0.5.0/lib/scanner-smi.h	2019-01-07 11:17:38.000000000 +0300

+++ libsmi-0.5.0.new/lib/scanner-smi.h	2019-08-28 23:43:43.536880810 +0300

@@ -21,7 +21,7 @@

 #define YY_NO_UNPUT

 extern char *yytext;

-#if 0

+#ifndef yyleng

 extern int yyleng;

 #endif

diff -ur libsmi-0.5.0/lib/scanner-sming.h libsmi-0.5.0.new/lib/scanner-sming.h

--- libsmi-0.5.0/lib/scanner-sming.h	2019-01-07 11:17:38.000000000 +0300

+++ libsmi-0.5.0.new/lib/scanner-sming.h	2019-08-28 23:44:09.944050865 +0300

@@ -21,7 +21,9 @@

 #define YY_NO_UNPUT

 extern char *yytext;

+#ifndef yyleng

 extern int yyleng;

+#endif

 extern int smingEnterLexRecursion(FILE *file);

 extern void smingLeaveLexRecursion();

diff -ur libsmi-0.5.0/lib/scanner-yang.h libsmi-0.5.0.new/lib/scanner-yang.h

--- libsmi-0.5.0/lib/scanner-yang.h	2019-01-07 11:17:38.000000000 +0300

+++ libsmi-0.5.0.new/lib/scanner-yang.h	2019-08-28 23:44:33.840204000 +0300

@@ -21,8 +21,7 @@

 #define YY_NO_UNPUT

 extern char *yytext;

-#if 0

-/* this does not seem to be needed with flex 2.5.35 and in fact conflicts */

+#ifndef yyleng

 extern int yyleng;

 #endif