Merge bitcoin/bitcoin#23438: refactor: Use spans of std::byte in serialize

fa5d2e678c809c26bd40d7e7c171529d3ffb5903 Remove unused char serialize (MarcoFalke)
fa24493d6394b3a477535f480664c9596f18e3c5 Use spans of std::byte in serialize (MarcoFalke)
fa65bbf217b725ada35107b4ad646d250228355c span: Add BytePtr helper (MarcoFalke)

Pull request description:

  This changes the serialize code (`.read()` and `.write()` functions) to take a `Span` instead of a pointer and size. This is a breaking change for the serialize interface, so at no additional cost we can also switch to `std::byte` (instead of using `char`).

  The benefits of using `Span`:
  * Less verbose and less fragile code when passing an already existing `Span`(-like) object to or from serialization

  The benefits of using `std::byte`:
  * `std::byte` can't accidentally be mistaken for an integer

  The goal here is to only change serialize to use spans of `std::byte`. If needed, `AsBytes`,  `MakeUCharSpan`, ... can be used (temporarily) to pass spans of the right type.

  Other changes that are included here:

  * [#22167](https://github.com/bitcoin/bitcoin/pull/22167) (refactor: Remove char serialize by MarcoFalke)
  * [#21906](https://github.com/bitcoin/bitcoin/pull/21906) (Preserve const in cast on CTransactionSignatureSerializer by promag)

ACKs for top commit:
  laanwj:
    Concept and code review ACK fa5d2e678c809c26bd40d7e7c171529d3ffb5903
  sipa:
    re-utACK fa5d2e678c809c26bd40d7e7c171529d3ffb5903

Tree-SHA512: 08ee9eced5fb777cedae593b11e33660bed9a3e1711a7451a87b835089a96c99ce0632918bb4666a4e859c4d020f88fb50f2dd734216b0c3d1a9a704967ece6f

5 files changed, 10 insertions, 17 deletions

diff --git a/src/test/fuzz/autofile.cpp b/src/test/fuzz/autofile.cpp
index 0cc2d12d29..3b410930ed 100644
--- a/src/test/fuzz/autofile.cpp
+++ b/src/test/fuzz/autofile.cpp
@@ -23,16 +23,16 @@ FUZZ_TARGET(autofile)
         CallOneOf(
             fuzzed_data_provider,
             [&] {
-                std::array<uint8_t, 4096> arr{};
+                std::array<std::byte, 4096> arr{};
                 try {
-                    auto_file.read((char*)arr.data(), fuzzed_data_provider.ConsumeIntegralInRange<size_t>(0, 4096));
+                    auto_file.read({arr.data(), fuzzed_data_provider.ConsumeIntegralInRange<size_t>(0, 4096)});
                 } catch (const std::ios_base::failure&) {
                 }
             },
             [&] {
-                const std::array<uint8_t, 4096> arr{};
+                const std::array<std::byte, 4096> arr{};
                 try {
-                    auto_file.write((const char*)arr.data(), fuzzed_data_provider.ConsumeIntegralInRange<size_t>(0, 4096));
+                    auto_file.write({arr.data(), fuzzed_data_provider.ConsumeIntegralInRange<size_t>(0, 4096)});
                 } catch (const std::ios_base::failure&) {
                 }
             },
diff --git a/src/test/fuzz/buffered_file.cpp b/src/test/fuzz/buffered_file.cpp
index c3c2e4050f..a8c3318629 100644
--- a/src/test/fuzz/buffered_file.cpp
+++ b/src/test/fuzz/buffered_file.cpp
@@ -33,9 +33,9 @@ FUZZ_TARGET(buffered_file)
             CallOneOf(
                 fuzzed_data_provider,
                 [&] {
-                    std::array<uint8_t, 4096> arr{};
+                    std::array<std::byte, 4096> arr{};
                     try {
-                        opt_buffered_file->read((char*)arr.data(), fuzzed_data_provider.ConsumeIntegralInRange<size_t>(0, 4096));
+                        opt_buffered_file->read({arr.data(), fuzzed_data_provider.ConsumeIntegralInRange<size_t>(0, 4096)});
                     } catch (const std::ios_base::failure&) {
                     }
                 },
@@ -53,7 +53,7 @@ FUZZ_TARGET(buffered_file)
                         return;
                     }
                     try {
-                        opt_buffered_file->FindByte(fuzzed_data_provider.ConsumeIntegral<char>());
+                        opt_buffered_file->FindByte(fuzzed_data_provider.ConsumeIntegral<uint8_t>());
                     } catch (const std::ios_base::failure&) {
                     }
                 },
diff --git a/src/test/fuzz/integer.cpp b/src/test/fuzz/integer.cpp
index 3087f11771..72574612a2 100644
--- a/src/test/fuzz/integer.cpp
+++ b/src/test/fuzz/integer.cpp
@@ -206,11 +206,6 @@ FUZZ_TARGET_INIT(integer, initialize_integer)
         stream >> deserialized_i8;
         assert(i8 == deserialized_i8 && stream.empty());
 
-        char deserialized_ch;
-        stream << ch;
-        stream >> deserialized_ch;
-        assert(ch == deserialized_ch && stream.empty());
-
         bool deserialized_b;
         stream << b;
         stream >> deserialized_b;
diff --git a/src/test/fuzz/rpc.cpp b/src/test/fuzz/rpc.cpp
index b6ecf1c492..73bfb7ff55 100644
--- a/src/test/fuzz/rpc.cpp
+++ b/src/test/fuzz/rpc.cpp
@@ -271,7 +271,7 @@ std::string ConsumeScalarRPCArgument(FuzzedDataProvider& fuzzed_data_provider)
             }
             CDataStream data_stream{SER_NETWORK, PROTOCOL_VERSION};
             data_stream << *opt_psbt;
-            r = EncodeBase64({data_stream.begin(), data_stream.end()});
+            r = EncodeBase64(data_stream);
         },
         [&] {
             // base58 encoded key
diff --git a/src/test/fuzz/util.h b/src/test/fuzz/util.h
index fd7f40c01d..3bc62878bd 100644
--- a/src/test/fuzz/util.h
+++ b/src/test/fuzz/util.h
@@ -328,7 +328,6 @@ void WriteToStream(FuzzedDataProvider& fuzzed_data_provider, Stream& stream) noe
             CallOneOf(
                 fuzzed_data_provider,
                 WRITE_TO_STREAM_CASE(bool, fuzzed_data_provider.ConsumeBool()),
-                WRITE_TO_STREAM_CASE(char, fuzzed_data_provider.ConsumeIntegral<char>()),
                 WRITE_TO_STREAM_CASE(int8_t, fuzzed_data_provider.ConsumeIntegral<int8_t>()),
                 WRITE_TO_STREAM_CASE(uint8_t, fuzzed_data_provider.ConsumeIntegral<uint8_t>()),
                 WRITE_TO_STREAM_CASE(int16_t, fuzzed_data_provider.ConsumeIntegral<int16_t>()),
@@ -338,7 +337,7 @@ void WriteToStream(FuzzedDataProvider& fuzzed_data_provider, Stream& stream) noe
                 WRITE_TO_STREAM_CASE(int64_t, fuzzed_data_provider.ConsumeIntegral<int64_t>()),
                 WRITE_TO_STREAM_CASE(uint64_t, fuzzed_data_provider.ConsumeIntegral<uint64_t>()),
                 WRITE_TO_STREAM_CASE(std::string, fuzzed_data_provider.ConsumeRandomLengthString(32)),
-                WRITE_TO_STREAM_CASE(std::vector<char>, ConsumeRandomLengthIntegralVector<char>(fuzzed_data_provider)));
+                WRITE_TO_STREAM_CASE(std::vector<uint8_t>, ConsumeRandomLengthIntegralVector<uint8_t>(fuzzed_data_provider)));
         } catch (const std::ios_base::failure&) {
             break;
         }
@@ -358,7 +357,6 @@ void ReadFromStream(FuzzedDataProvider& fuzzed_data_provider, Stream& stream) no
             CallOneOf(
                 fuzzed_data_provider,
                 READ_FROM_STREAM_CASE(bool),
-                READ_FROM_STREAM_CASE(char),
                 READ_FROM_STREAM_CASE(int8_t),
                 READ_FROM_STREAM_CASE(uint8_t),
                 READ_FROM_STREAM_CASE(int16_t),
@@ -368,7 +366,7 @@ void ReadFromStream(FuzzedDataProvider& fuzzed_data_provider, Stream& stream) no
                 READ_FROM_STREAM_CASE(int64_t),
                 READ_FROM_STREAM_CASE(uint64_t),
                 READ_FROM_STREAM_CASE(std::string),
-                READ_FROM_STREAM_CASE(std::vector<char>));
+                READ_FROM_STREAM_CASE(std::vector<uint8_t>));
         } catch (const std::ios_base::failure&) {
             break;
         }