Warning GCC and Clang : Empty lines : %option '-L'

- Fixed [-Wmisleading-indentation] waning of clang(v10+) and gcc(v6+)
- Fixed a problem with a sequence of empty lines ('\n' sequence)
- Fixed a bugs with '-L' options (%top print a '#line')

flex/src/buf.c

@@ -95,8 +95,8 @@ struct Buf *buf_linedir (struct Buf *buf, const char* filename, int lineno)
     const char *src;
     size_t tsz;
 
-    if (gen_line_dirs)
-	return buf;
+    if (!gen_line_dirs)
+      return buf;
 
     tsz = strlen("#line \"\"\n")                +   /* constant parts */
                2 * strlen (filename)            +   /* filename with possibly all backslashes escaped */

flex/src/scan.c

@@ -2328,7 +2328,8 @@ YY_RULE_SETUP
 {
                 brace_start_line = linenum;
                 ++linenum;
-                buf_linedir( &top_buf, infilename?infilename:"<stdin>", linenum);
+                if(gen_line_dirs)
+                  buf_linedir(&top_buf, infilename ? infilename : "<stdin>", linenum);
                 brace_depth = 1;
                 yy_push_state(CODEBLOCK_MATCH_BRACE);
             }
@@ -4478,7 +4479,7 @@ static int yy_get_next_buffer (void)
 	yy_current_state = yy_nxt[yy_base[yy_current_state] + yy_c];
 	yy_is_jam = (yy_current_state == 1113);
 
-		return yy_is_jam ? 0 : yy_current_state;
+	return yy_is_jam ? 0 : yy_current_state;
 }
 
 #ifndef YY_NO_UNPUT

flex/src/skel.c

@@ -1651,8 +1651,8 @@ const char *skel[] = {
   "        /* Create the reject buffer large enough to save one state per allowed character. */",
   "        if ( ! YY_G(yy_state_buf) )",
   "            YY_G(yy_state_buf) = (yy_state_type *)yyalloc(YY_STATE_BUF_SIZE  M4_YY_CALL_LAST_ARG);",
-  "            if ( ! YY_G(yy_state_buf) )",
-  "                YY_FATAL_ERROR( \"out of dynamic memory in yylex()\" );",
+  "        if ( ! YY_G(yy_state_buf) )",
+  "            YY_FATAL_ERROR( \"out of dynamic memory in yylex()\" );",
   "]])",
   "",
   "		if ( ! YY_G(yy_start) )",
@@ -2181,7 +2181,7 @@ const char *skel[] = {
   "%% [17.0] code to find the next state, and perhaps do backing up, goes here",
   "",
   "	M4_YY_NOOP_GUTS_VAR();",
-  "	return yy_is_jam ? 0 : yy_current_state;",
+  "return yy_is_jam ? 0 : yy_current_state;",
   "}",
   "",
   "",