Avoid implicit-integer-sign-change in bech32.cpp

Author: MarcoFalke

src/bech32.cpp

@@ -284,10 +284,11 @@ inline unsigned char LowerCase(unsigned char c)
 }
 
 /** Return indices of invalid characters in a Bech32 string. */
-bool CheckCharacters(const std::string& str, std::vector<int>& errors) {
+bool CheckCharacters(const std::string& str, std::vector<int>& errors)
+{
     bool lower = false, upper = false;
     for (size_t i = 0; i < str.size(); ++i) {
-        unsigned char c = str[i];
+        unsigned char c{(unsigned char)(str[i])};
         if (c >= 'a' && c <= 'z') {
             if (upper) {
                 errors.push_back(i);

test/sanitizer_suppressions/ubsan

@@ -53,7 +53,6 @@ unsigned-integer-overflow:policy/fees.cpp
 unsigned-integer-overflow:prevector.h
 unsigned-integer-overflow:script/interpreter.cpp
 unsigned-integer-overflow:txmempool.cpp
-implicit-integer-sign-change:bech32.cpp
 implicit-integer-sign-change:compat/stdin.cpp
 implicit-integer-sign-change:compressor.h
 implicit-integer-sign-change:crypto/