diff -r 61fdd06833a6 -r d7e25df22e88 tools/dimacs-to-lgf.cc
--- a/tools/dimacs-to-lgf.cc	Mon Oct 15 23:22:18 2018 +0200
+++ b/tools/dimacs-to-lgf.cc	Mon Oct 15 23:39:22 2018 +0200
@@ -73,11 +73,13 @@
       if (!output) {
         throw IoError("Cannot open the file for writing", ap.files()[1]);
       }
+      // fall through
     case 1:
       input.open(ap.files()[0].c_str());
       if (!input) {
         throw IoError("File cannot be found", ap.files()[0]);
       }
+      // fall through
     case 0:
       break;
     default: