util: Allow std::byte and char Span serialization

src/serialize.h

@@ -188,6 +188,7 @@ template<typename X> const X& ReadWriteAsHelper(const X& x) { return x; }
     }                                                                               \
     FORMATTER_METHODS(cls, obj)
 
+// clang-format off
 #ifndef CHAR_EQUALS_INT8
 template <typename Stream> void Serialize(Stream&, char) = delete; // char serialization forbidden. Use uint8_t or int8_t
 #endif
@@ -201,8 +202,7 @@ template<typename Stream> inline void Serialize(Stream& s, int64_t a ) { ser_wri
 template<typename Stream> inline void Serialize(Stream& s, uint64_t a) { ser_writedata64(s, a); }
 template<typename Stream, int N> inline void Serialize(Stream& s, const char (&a)[N]) { s.write(MakeByteSpan(a)); }
 template<typename Stream, int N> inline void Serialize(Stream& s, const unsigned char (&a)[N]) { s.write(MakeByteSpan(a)); }
-template<typename Stream> inline void Serialize(Stream& s, const Span<const unsigned char>& span) { s.write(AsBytes(span)); }
-template<typename Stream> inline void Serialize(Stream& s, const Span<unsigned char>& span) { s.write(AsBytes(span)); }
+template <typename Stream, typename B> void Serialize(Stream& s, Span<B> span) { (void)/* force byte-type */UCharCast(span.data()); s.write(AsBytes(span)); }
 
 #ifndef CHAR_EQUALS_INT8
 template <typename Stream> void Unserialize(Stream&, char) = delete; // char serialization forbidden. Use uint8_t or int8_t
@@ -217,10 +217,11 @@ template<typename Stream> inline void Unserialize(Stream& s, int64_t& a ) { a =
 template<typename Stream> inline void Unserialize(Stream& s, uint64_t& a) { a = ser_readdata64(s); }
 template<typename Stream, int N> inline void Unserialize(Stream& s, char (&a)[N]) { s.read(MakeWritableByteSpan(a)); }
 template<typename Stream, int N> inline void Unserialize(Stream& s, unsigned char (&a)[N]) { s.read(MakeWritableByteSpan(a)); }
-template<typename Stream> inline void Unserialize(Stream& s, Span<unsigned char>& span) { s.read(AsWritableBytes(span)); }
+template <typename Stream, typename B> void Unserialize(Stream& s, Span<B> span) { (void)/* force byte-type */UCharCast(span.data()); s.read(AsWritableBytes(span)); }
 
 template <typename Stream> inline void Serialize(Stream& s, bool a) { uint8_t f = a; ser_writedata8(s, f); }
 template <typename Stream> inline void Unserialize(Stream& s, bool& a) { uint8_t f = ser_readdata8(s); a = f; }
+// clang-format on
 
 
 /**

src/test/serialize_tests.cpp

@@ -241,6 +241,15 @@ BOOST_AUTO_TEST_CASE(class_methods)
     ss2 << intval << boolval << stringval << charstrval << txval;
     ss2 >> methodtest3;
     BOOST_CHECK(methodtest3 == methodtest4);
+    {
+        DataStream ds;
+        const std::string in{"ab"};
+        ds << Span{in};
+        std::array<std::byte, 2> out;
+        ds >> Span{out};
+        BOOST_CHECK_EQUAL(out.at(0), std::byte{'a'});
+        BOOST_CHECK_EQUAL(out.at(1), std::byte{'b'});
+    }
 }
 
 BOOST_AUTO_TEST_SUITE_END()