Merge bitcoin#19739: refactor: remove c-string interfaces for DecodeBase58{Check}

d3e8adf util: remove c-string interfaces for DecodeBase58{Check} (Sebastian Falbesoner)

Pull request description:

  This micro-PR gets rid of base58 function interfaces that are redundant in terms of c-string / std::string variants; the c-string interface for `DecodeBase58Check` is completely unused outside the base58 module, while the c-string interface for `DecodeBase58` is only used in unit tests, where an implicit conversion to std::string is not problematic.

ACKs for top commit:
  practicalswift:
    ACK d3e8adf -- patch looks correct
  laanwj:
    Code review ACK d3e8adf

Tree-SHA512: 006a4a1e23b11385f60820c188b8e6b1634a182ca36e29a6580f72150214c65a3fdb273ec439165f26ba88a42d2bf5bab1cf3666a9eaee222fb4e1c00aeba433

Author: laanwj

src/base58.cpp

@@ -35,7 +35,7 @@ static const int8_t mapBase58[256] = {
     -1,-1,-1,-1,-1,-1,-1,-1, -1,-1,-1,-1,-1,-1,-1,-1,
 };
 
-bool DecodeBase58(const char* psz, std::vector<unsigned char>& vch, int max_ret_len)
+NODISCARD static bool DecodeBase58(const char* psz, std::vector<unsigned char>& vch, int max_ret_len)
 {
     // Skip leading spaces.
     while (*psz && IsSpace(*psz))
@@ -141,7 +141,7 @@ std::string EncodeBase58Check(Span<const unsigned char> input)
     return EncodeBase58(vch);
 }
 
-bool DecodeBase58Check(const char* psz, std::vector<unsigned char>& vchRet, int max_ret_len)
+NODISCARD static bool DecodeBase58Check(const char* psz, std::vector<unsigned char>& vchRet, int max_ret_len)
 {
     if (!DecodeBase58(psz, vchRet, max_ret_len > std::numeric_limits<int>::max() - 4 ? std::numeric_limits<int>::max() : max_ret_len + 4) ||
         (vchRet.size() < 4)) {

src/base58.h

@@ -25,13 +25,6 @@
  */
 std::string EncodeBase58(Span<const unsigned char> input);
 
-/**
- * Decode a base58-encoded string (psz) into a byte vector (vchRet).
- * return true if decoding is successful.
- * psz cannot be nullptr.
- */
-NODISCARD bool DecodeBase58(const char* psz, std::vector<unsigned char>& vchRet, int max_ret_len);
-
 /**
  * Decode a base58-encoded string (str) into a byte vector (vchRet).
  * return true if decoding is successful.
@@ -43,12 +36,6 @@ NODISCARD bool DecodeBase58(const std::string& str, std::vector<unsigned char>&
  */
 std::string EncodeBase58Check(Span<const unsigned char> input);
 
-/**
- * Decode a base58-encoded string (psz) that includes a checksum into a byte
- * vector (vchRet), return true if decoding is successful
- */
-NODISCARD bool DecodeBase58Check(const char* psz, std::vector<unsigned char>& vchRet, int max_ret_len);
-
 /**
  * Decode a base58-encoded string (str) that includes a checksum into a byte
  * vector (vchRet), return true if decoding is successful