nixpkgs/pkgs/development/libraries/mimetic/narrowing.patch

diff -ru a/mimetic/codec/base64.cxx b/mimetic/codec/base64.cxx
--- a/mimetic/codec/base64.cxx	2014-06-17 10:12:00.000000000 +0200
+++ b/mimetic/codec/base64.cxx	2020-07-30 20:54:10.212742011 +0200
@@ -14,19 +14,19 @@
     "0123456789+/=";
 
 const char Base64::sDecTable[] = {
-        -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
-        -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
-        -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
-        -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
-        -1,-1,-1,62,-1,-1,-1,63,52,53,
-        54,55,56,57,58,59,60,61,-1,-1,
-        -1, eq_sign, -1,-1,-1, 0, 1, 2, 3, 4, 
+        255,255,255,255,255,255,255,255,255,255,
+        255,255,255,255,255,255,255,255,255,255,
+        255,255,255,255,255,255,255,255,255,255,
+        255,255,255,255,255,255,255,255,255,255,
+        255,255,255,62,255,255,255,63,52,53,
+        54,55,56,57,58,59,60,61,255,255,
+        255, eq_sign, 255,255,255, 0, 1, 2, 3, 4, 
          5, 6, 7, 8, 9,10,11,12,13,14,
         15,16,17,18,19,20,21,22,23,24,
-        25,-1,-1,-1,-1,-1,-1,26,27,28,
+        25,255,255,255,255,255,255,26,27,28,
         29,30,31,32,33,34,35,36,37,38,
         39,40,41,42,43,44,45,46,47,48,
-        49,50,51,-1
+        49,50,51,255
 };
 
 const int Base64::sDecTableSz = sizeof(Base64::sDecTable) / sizeof(char);