Merge bitcoin/bitcoin#24402: refactor: Avoid implicit-integer-sign-change in bech32.cpp

aaaa4dbab4ec06d69645de919810ccd0da836a0e Avoid implicit-integer-sign-change in bech32.cpp (MarcoFalke)
fae6b26758fff0dd52a9f4f37bb8325907a48589 test: Remove no longer needed suppressions (MarcoFalke)

Pull request description:

  Clarifies sign conversion and allows to remove a file-wide suppression.

  Also, includes an unrelated commit to remove unused suppressions.

ACKs for top commit:
  fanquake:
    ACK aaaa4dbab4ec06d69645de919810ccd0da836a0e

Tree-SHA512: f06181494ea8a2890b510b0e840679635633146d27568adaa0f0216a52637068d32a880316e1608e08314e032565f67b6b980cc9143f420d5c15e51ef760e7e0

1 files changed, 3 insertions, 2 deletions

diff --git a/src/bech32.cpp b/src/bech32.cpp
index 3cda1dfff5..dce9b2e4cc 100644
--- a/src/bech32.cpp
+++ b/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);