qt,cpp: Consistently use nullptr and override

* lang/cpp/src/Makefile.am, lang/qt/src/Makefile.am (AM_CPPFLAGS):
Add suggest-override and zero-as-null-pointer-constant warnings.

* lang/cpp/src/*, lang/qt/src/*: Consistenly use nullptr and override.

--
This was especially important for the headers so that downstream
users of GpgME++ or QGpgME do not get flooded by warnings if
they have these warnings enabled.

It also improves compiler errors/warnings in case of accidental
mistakes.

1 files changed, 1 insertions, 1 deletions

diff --git a/lang/qt/src/qgpgmedecryptverifyjob.cpp b/lang/qt/src/qgpgmedecryptverifyjob.cpp
index 01cf2478..9b3f73db 100644
--- a/lang/qt/src/qgpgmedecryptverifyjob.cpp
+++ b/lang/qt/src/qgpgmedecryptverifyjob.cpp
@@ -108,7 +108,7 @@ static QGpgMEDecryptVerifyJob::result_type decrypt_verify_qba(Context *ctx, cons
     if (!buffer->open(QIODevice::ReadOnly)) {
         assert(!"This should never happen: QBuffer::open() failed");
     }
-    return decrypt_verify(ctx, 0, buffer, std::shared_ptr<QIODevice>());
+    return decrypt_verify(ctx, nullptr, buffer, std::shared_ptr<QIODevice>());
 }
 
 Error QGpgMEDecryptVerifyJob::start(const QByteArray &cipherText)