qt, refactor: Drop unneeded Q_DECLARE_METATYPE #19108

For typedefs, which is CAmount, qRegisterMetaType(const char*) only is required.

I think you could also drop

--- a/src/qt/overviewpage.cpp
+++ b/src/qt/overviewpage.cpp
@@ -23,8 +23,6 @@
 #define DECORATION_SIZE 54
 #define NUM_ITEMS 5

-Q_DECLARE_METATYPE(interfaces::WalletBalances)
-
 class TxViewDelegate : public QAbstractItemDelegate
 {
     Q_OBJECT

cc @ryanofsky

@promag

I think you could also drop

--- a/src/qt/overviewpage.cpp
+++ b/src/qt/overviewpage.cpp
@@ -23,8 +23,6 @@
 #define DECORATION_SIZE 54
 #define NUM_ITEMS 5

-Q_DECLARE_METATYPE(interfaces::WalletBalances)
-
 class TxViewDelegate : public QAbstractItemDelegate
 {
     Q_OBJECT

cc @ryanofsky

https://github.com/bitcoin/bitcoin/blob/76e64525ff38eaedccf8c2b847eccfffb69be27f/src/qt/walletmodel.h#L193-L195

That doesn't matter with Qt5 connection style. We also don't use QVariant::fromValue with interfaces::WalletBalances. FWIW I've tested without and it worked with QT_FATAL_WARNINGS=1. Maybe I missed something?

That doesn't matter with Qt5 connection style. We also don't use QVariant::fromValue with interfaces::WalletBalances. FWIW I've tested without and it worked with QT_FATAL_WARNINGS=1. Maybe I missed something?

I'm totally agree with you. I mentioned balanceChanged() signal with idea: if it would use Qt::QueuedConnection it will require qRegisterMetaType() and Q_DECLARE_METATYPE().

The alone Q_DECLARE_METATYPE() (without paired qRegisterMetaType()) only matters for usage with QVariant.

if it would use Qt::QueuedConnection it will require qRegisterMetaType() and Q_DECLARE_METATYPE().

Are you sure about this?

@promag

if it would use Qt::QueuedConnection it will require qRegisterMetaType() and Q_DECLARE_METATYPE().

Are you sure about this?

https://doc.qt.io/qt-5/qt.html#ConnectionType-enum:

With queued connections, the parameters must be of types that are known to Qt's meta-object system, because Qt needs to copy the arguments to store them in an event behind the scenes.

Call qRegisterMetaType() to register the data type before you establish the connection.

https://doc.qt.io/qt-5/qmetatype.html#qRegisterMetaType-1:

Call this function to register the type T. T must be declared with Q_DECLARE_METATYPE().

To use the type T in QVariant, using Q_DECLARE_METATYPE() is sufficient. To use the type T in queued signal and slot connections, qRegisterMetaType<T>() must be called before the first connection is established.

Is not needing it for typedefs considered defined behaviour?

Is not needing it for typedefs considered defined behaviour?

Sorry, mind re-wording your question to be clear for me, please?

ACK ad113aeb29c7db6df94cebd784c0c6b668bfd9a5.

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Conflicts

Reviewers, this pull request conflicts with the following ones:

• #19471 (util: Make default arg values more specific by hebasto)

If you consider this pull request important, please also help to review the conflicting pull requests. Ideally, start with the one that should be merged first.

@laanwj or @jonasschnelli can you weigh in here?

Given there's been no follow up for > a month. Can you move this to the GUI repo.

Moved to https://github.com/bitcoin-core/gui/pull/61.