Summary

This PR addresses compiler warnings reported in CI builds (GCC, Clang, MSVC) across multiple modules, improving code quality and C++ standards compliance.

80 files changed across Foundation, Net, Crypto, Data, JSON, MongoDB, Redis, XML, and Zip modules.

1. Stream Buffer Return Types

Changed readFromDevice() and writeToDevice() return types from int to std::streamsize to match the C++ standard library interface.

Affected files:

• Foundation/include/Poco/BufferedStreamBuf.h, BufferedBidirectionalStreamBuf.h
• Foundation/include/Poco/DeflatingStream.h, InflatingStream.h, DigestStream.h, FIFOBufferStream.h, FileStream_*.h, PipeStream.h, RandomStream.h
• Foundation/src/DeflatingStream.cpp, InflatingStream.cpp, DigestStream.cpp, FIFOBufferStream.cpp, FileStream_*.cpp, PipeStream.cpp, RandomStream.cpp, StreamConverter.cpp
• Net/include/Poco/Net/HTTPChunkedStream.h, HTTPFixedLengthStream.h, HTTPHeaderStream.h, HTTPStream.h, MultipartReader.h, SocketStream.h, HTTPReactorServerSession.h
• Net/src/HTTPChunkedStream.cpp, HTTPFixedLengthStream.cpp, HTTPHeaderStream.cpp, HTTPStream.cpp, MultipartReader.cpp, SocketStream.cpp, HTTPReactorServerSession.cpp
• Crypto/include/Poco/Crypto/CryptoStream.h, Crypto/src/CryptoStream.cpp
• Redis/include/Poco/Redis/RedisStream.h, Redis/src/RedisStream.cpp
• Zip/include/Poco/Zip/AutoDetectStream.h, PartialStream.h, ZipStream.h
• Zip/src/AutoDetectStream.cpp, PartialStream.cpp, ZipStream.cpp

2. Signed/Unsigned Comparison Warnings (C4244, C4245)

Added explicit static_cast<> to fix comparisons between signed and unsigned types.

3. Constructor Member Initializer Order

Fixed member initializer list order to match declaration order (GCC -Wreorder).

• Net/src/TCPReactorAcceptor.cpp
• Net/src/TCPReactorServer.cpp

4. Unused Result Warnings

Added [[maybe_unused]] for system call return values.

• Net/src/PollSet.cpp: read() and write() on eventfd

5. Unused Variable Warnings (C4189)

Added [[maybe_unused]] attribute or (void) cast for intentionally unused variables.

6. Missing Field Initializers (C4351)

Changed = {0} and = {nullptr} to = {} for proper aggregate initialization.

• Data/MySQL/src/Binder.cpp: MYSQL_TIME and MYSQL_BIND structs
• Data/MySQL/src/Extractor.cpp: MYSQL_TIME and MYSQL_BIND structs
• Data/PostgreSQL/src/StatementExecutor.cpp: RegularExpression::Match struct

7. Parameter/Variable Shadowing (C4456, C4457, C4458)

Renamed variables to avoid shadowing.

8. Other Fixes

Test plan

• CI builds pass on Linux (GCC/Clang)
• CI builds pass on Windows (MSVC)
• CI builds pass on macOS
• No new warnings introduced
• All existing tests pass