Merge #20499: Remove obsolete NODISCARD ifdef forest. Use [[nodiscard]] (C++17).

79bff8e Remove NODISCARD (practicalswift)
4848e71 scripted-diff: Use [[nodiscard]] (C++17) instead of NODISCARD (practicalswift)

Pull request description:

  Remove obsolete `NODISCARD` `ifdef` forest. Use `[[nodiscard]]` (C++17).

ACKs for top commit:
  theStack:
    ACK 79bff8e
  fanquake:
    ACK 79bff8e

Tree-SHA512: 56dbb8e50ed97ecfbce28cdc688a01146108acae49a943e338a8f983f7168914710d36e38632f6a7c200ba6c6ac35b2519e97d6c985e8e7eb23223f13bf985d6

Author: MarcoFalke

src/attributes.h

@@ -6,19 +6,6 @@
 #ifndef BITCOIN_ATTRIBUTES_H
 #define BITCOIN_ATTRIBUTES_H
 
-#if defined(__has_cpp_attribute)
-#  if __has_cpp_attribute(nodiscard)
-#    define NODISCARD [[nodiscard]]
-#  endif
-#endif
-#ifndef NODISCARD
-#  if defined(_MSC_VER) && _MSC_VER >= 1700
-#    define NODISCARD _Check_return_
-#  else
-#    define NODISCARD __attribute__((warn_unused_result))
-#  endif
-#endif
-
 #if defined(__clang__)
 #  if __has_attribute(lifetimebound)
 #    define LIFETIMEBOUND [[clang::lifetimebound]]

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,
 };
 
-NODISCARD static 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);
 }
 
-NODISCARD static 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

@@ -29,7 +29,7 @@ std::string EncodeBase58(Span<const unsigned char> input);
  * Decode a base58-encoded string (str) into a byte vector (vchRet).
  * return true if decoding is successful.
  */
-NODISCARD bool DecodeBase58(const std::string& str, std::vector<unsigned char>& vchRet, int max_ret_len);
+[[nodiscard]] bool DecodeBase58(const std::string& str, std::vector<unsigned char>& vchRet, int max_ret_len);
 
 /**
  * Encode a byte span into a base58-encoded string, including checksum
@@ -40,6 +40,6 @@ std::string EncodeBase58Check(Span<const unsigned char> input);
  * Decode a base58-encoded string (str) that includes a checksum into a byte
  * vector (vchRet), return true if decoding is successful
  */
-NODISCARD bool DecodeBase58Check(const std::string& str, std::vector<unsigned char>& vchRet, int max_ret_len);
+[[nodiscard]] bool DecodeBase58Check(const std::string& str, std::vector<unsigned char>& vchRet, int max_ret_len);
 
 #endif // BITCOIN_BASE58_H

src/core_io.h

@@ -22,8 +22,8 @@ class UniValue;
 // core_read.cpp
 CScript ParseScript(const std::string& s);
 std::string ScriptToAsmStr(const CScript& script, const bool fAttemptSighashDecode = false);
-NODISCARD bool DecodeHexTx(CMutableTransaction& tx, const std::string& hex_tx, bool try_no_witness = false, bool try_witness = true);
-NODISCARD bool DecodeHexBlk(CBlock&, const std::string& strHexBlk);
+[[nodiscard]] bool DecodeHexTx(CMutableTransaction& tx, const std::string& hex_tx, bool try_no_witness = false, bool try_witness = true);
+[[nodiscard]] bool DecodeHexBlk(CBlock&, const std::string& strHexBlk);
 bool DecodeHexBlockHeader(CBlockHeader&, const std::string& hex_header);
 
 /**

src/hash.h

@@ -197,7 +197,7 @@ uint256 SerializeHash(const T& obj, int nType=SER_GETHASH, int nVersion=PROTOCOL
 }
 
 /** Single-SHA256 a 32-byte input (represented as uint256). */
-NODISCARD uint256 SHA256Uint256(const uint256& input);
+[[nodiscard]] uint256 SHA256Uint256(const uint256& input);
 
 unsigned int MurmurHash3(unsigned int nHashSeed, Span<const unsigned char> vDataToHash);
 

src/init.cpp

@@ -113,7 +113,7 @@ static fs::path GetPidFile(const ArgsManager& args)
     return AbsPathForConfigVal(fs::path(args.GetArg("-pid", BITCOIN_PID_FILENAME)));
 }
 
-NODISCARD static bool CreatePidFile(const ArgsManager& args)
+[[nodiscard]] static bool CreatePidFile(const ArgsManager& args)
 {
     fsbridge::ofstream file{GetPidFile(args)};
     if (file) {

src/node/transaction.h

@@ -36,6 +36,6 @@ static const CFeeRate DEFAULT_MAX_RAW_TX_FEE_RATE{COIN / 10};
  * @param[in]  wait_callback wait until callbacks have been processed to avoid stale result due to a sequentially RPC.
  * return error
  */
-NODISCARD TransactionError BroadcastTransaction(NodeContext& node, CTransactionRef tx, std::string& err_string, const CAmount& max_tx_fee, bool relay, bool wait_callback);
+[[nodiscard]] TransactionError BroadcastTransaction(NodeContext& node, CTransactionRef tx, std::string& err_string, const CAmount& max_tx_fee, bool relay, bool wait_callback);
 
 #endif // BITCOIN_NODE_TRANSACTION_H

src/outputtype.h

@@ -22,7 +22,7 @@ enum class OutputType {
 
 extern const std::array<OutputType, 3> OUTPUT_TYPES;
 
-NODISCARD bool ParseOutputType(const std::string& str, OutputType& output_type);
+[[nodiscard]] bool ParseOutputType(const std::string& str, OutputType& output_type);
 const std::string& FormatOutputType(OutputType type);
 
 /**

src/psbt.h

@@ -398,7 +398,7 @@ struct PartiallySignedTransaction
 
     /** Merge psbt into this. The two psbts must have the same underlying CTransaction (i.e. the
       * same actual Bitcoin transaction.) Returns true if the merge succeeded, false otherwise. */
-    NODISCARD bool Merge(const PartiallySignedTransaction& psbt);
+    [[nodiscard]] bool Merge(const PartiallySignedTransaction& psbt);
     bool AddInput(const CTxIn& txin, PSBTInput& psbtin);
     bool AddOutput(const CTxOut& txout, const PSBTOutput& psbtout);
     PartiallySignedTransaction() {}
@@ -605,11 +605,11 @@ bool FinalizeAndExtractPSBT(PartiallySignedTransaction& psbtx, CMutableTransacti
  * @param[in]  psbtxs the PSBTs to combine
  * @return error (OK if we successfully combined the transactions, other error if they were not compatible)
  */
-NODISCARD TransactionError CombinePSBTs(PartiallySignedTransaction& out, const std::vector<PartiallySignedTransaction>& psbtxs);
+[[nodiscard]] TransactionError CombinePSBTs(PartiallySignedTransaction& out, const std::vector<PartiallySignedTransaction>& psbtxs);
 
 //! Decode a base64ed PSBT into a PartiallySignedTransaction
-NODISCARD bool DecodeBase64PSBT(PartiallySignedTransaction& decoded_psbt, const std::string& base64_psbt, std::string& error);
+[[nodiscard]] bool DecodeBase64PSBT(PartiallySignedTransaction& decoded_psbt, const std::string& base64_psbt, std::string& error);
 //! Decode a raw (binary blob) PSBT into a PartiallySignedTransaction
-NODISCARD bool DecodeRawPSBT(PartiallySignedTransaction& decoded_psbt, const std::string& raw_psbt, std::string& error);
+[[nodiscard]] bool DecodeRawPSBT(PartiallySignedTransaction& decoded_psbt, const std::string& raw_psbt, std::string& error);
 
 #endif // BITCOIN_PSBT_H

src/script/descriptor.cpp

@@ -731,7 +731,7 @@ enum class ParseScriptContext {
 };
 
 /** Parse a key path, being passed a split list of elements (the first element is ignored). */
-NODISCARD bool ParseKeyPath(const std::vector<Span<const char>>& split, KeyPath& out, std::string& error)
+[[nodiscard]] bool ParseKeyPath(const std::vector<Span<const char>>& split, KeyPath& out, std::string& error)
 {
     for (size_t i = 1; i < split.size(); ++i) {
         Span<const char> elem = split[i];