Use of auto_ptr causes dirty compile under Cygwin with -std=c++11

[weidai11]

Use of auto_ptr causes dirty compile under Cygwin with -std=c++11

[denisbider]

It seems challenging to simultaneously compile with no warnings both on C++11 platforms that deprecate auto_ptr, and C++03 platforms that don't have unique_ptr. Is there a way to disable the warning?

[noloader]

Cleared through a few different commits. Some are listed below.

The general strategy was to identify C++11, identify ancient C++11 standard libraries, and then swap-in unique_ptr for auto_ptr if available. The identification and swap-in occurred in smartptr.h:

// Hack ahead. Apple's standard library does not have C++'s unique_ptr in C++11. We can't
//   test for unique_ptr directly because some of the non-Apple Clangs on OS X fail the same
//   way. However, modern standard libraries have <forward_list>, so we test for it instead.
//   Thanks to Jonathan Wakely for devising the clever test for modern/ancient versions.
// Visual Studio did not add template aliases until VS 2015 (v19.00). Compile failed under
//   Visual Studio 2010 (v16.00) and Visual Studio 2012 (v17.00).
#if (__cplusplus >= 201103L) || (_MSC_VER >= 1900)
#  if defined(__clang__)
#    if (__has_include(<forward_list>))
#      define CRYPTOPP_HAVE_UNIQUE_PTR 1
#    endif
#  else
#    define CRYPTOPP_HAVE_UNIQUE_PTR 1
#  endif
#endif

// The result of below is a CryptoPP::auto_ptr in both cases
#ifdef CRYPTOPP_HAVE_UNIQUE_PTR
  template<typename T>
   using auto_ptr = std::unique_ptr<T>;
#else
  using std::auto_ptr;
#endif

Then, in the source code:

PK_Verifier::VerifyMessage(const byte*, size_t, const byte*, size_t) const
{
    using CryptoPP::auto_ptr;
    auto_ptr<PK_MessageAccumulator> m(NewVerificationAccumulator());
    ...
}

For testing on BSDs, Linux, OS X and Unix, you would build in one of four configurations to ensure correctness:

# c++ -DNDEBUG -g2 -O3 ...
export CXXFLAGS=""
make

# c++ -std=c++11 -DNDEBUG -g2 -O3 ...
export CXXFLAGS="-std=c++11"
make

# c++ -stdlib=libc++ -DNDEBUG -g2 -O3 ...
export CXXFLAGS="-stdlib=libc++"
make

# c++ -std=c++11 -stdlib=libc++ -DNDEBUG -g2 -O3 ...
export CXXFLAGS="-std=c++11 -stdlib=libc++"
make

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• 52b7fbb
• 17fd66f
• 7ad12ab
• 4d8ac2d
• 8c63032
• 6029112

[noloader]

It seems challenging to simultaneously compile with no warnings both on C++11 platforms that deprecate auto_ptr, and C++03 platforms that don't have unique_ptr...

This observation was insightful. I found we were able to sidestep most of the warnings by switching to Crypto++'s member_ptr. It provides the same basic functionality we needed, and it has both reset and release. It does not require the [sometimes] convoluted logic to determine when C++11 is really available, and does not require template declaration support.

We have one place we could not cleanly cut over, and that was in validat1.cpp (around line 575). So warnings went from "a lot" to "just one".