qt6: Fix linking when configured with -DENABLE_WALLET=OFF #837

1. 
   hebasto commented at 5:38 pm on September 18, 2024: member

   Split from https://github.com/bitcoin/bitcoin/pull/30997.

   When building with Qt 6 in my dev branch, I encountered a linker error when configured with -DENABLE_WALLET=OFF:

    0$ cmake -B build -DENABLE_WALLET=OFF -DBUILD_GUI=ON
    1$ cmake --build build -t bitcoin-qt
    2<snip>
    3[100%] Linking CXX executable bitcoin-qt
    4/usr/bin/ld: libbitcoinqt.a(rpcconsole.cpp.o): in function `QtPrivate::MetaObjectForType<WalletModel const*, void>::metaObjectFunction(QtPrivate::QMetaTypeInterface const*)':
    5/usr/include/x86_64-linux-gnu/qt6/QtCore/qmetatype.h:903:(.text._ZN9QtPrivate17MetaObjectForTypeIPK11WalletModelvE18metaObjectFunctionEPKNS_18QMetaTypeInterfaceE[_ZN9QtPrivate17MetaObjectForTypeIPK11WalletModelvE18metaObjectFunctionEPKNS_18QMetaTypeInterfaceE]+0x2b): undefined reference to `WalletModel::staticMetaObject'
    6/usr/bin/ld: libbitcoinqt.a(rpcconsole.cpp.o): in function `QMetaTypeIdQObject<WalletModel const*, 8>::qt_metatype_id()':
    7/usr/include/x86_64-linux-gnu/qt6/QtCore/qmetatype.h:1313:(.text._ZZN9QtPrivate16QMetaTypeForTypeIPK11WalletModelE17getLegacyRegisterEvENUlvE_4_FUNEv[_ZZN9QtPrivate16QMetaTypeForTypeIPK11WalletModelE17getLegacyRegisterEvENUlvE_4_FUNEv]+0x53): undefined reference to `WalletModel::staticMetaObject'
    8collect2: error: ld returned 1 exit status
    9gmake[3]: *** [src/qt/CMakeFiles/bitcoin-qt.dir/build.make:154: src/qt/bitcoin-qt] Error 1
   10gmake[2]: *** [CMakeFiles/Makefile2:2107: src/qt/CMakeFiles/bitcoin-qt.dir/all] Error 2
   11gmake[1]: *** [CMakeFiles/Makefile2:2114: src/qt/CMakeFiles/bitcoin-qt.dir/rule] Error 2
   12gmake: *** [Makefile:998: bitcoin-qt] Error 2
   

   This PR resolves the issue.

2. qt: Fix linking when configured with `-DENABLE_WALLET=OFF`

   This change is required for Qt 6, but it is meaningful on its own.

   5be34bacf6
3. hebasto added the label Qt 6 on Sep 18, 2024
4. 
   DrahtBot commented at 5:38 pm on September 18, 2024: contributor

   The following sections might be updated with supplementary metadata relevant to reviewers and maintainers.

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   Type	Reviewers
   ACK	pablomartin4btc, promag

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   Conflicts

   Reviewers, this pull request conflicts with the following ones:

   • #692 (Debug Console implementation of generate method by hernanmarino)

   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.

5. 
   fanquake commented at 5:39 pm on September 18, 2024: member

   What is the error? Why does it only happen with Qt6?
6. 
   hebasto commented at 5:44 pm on September 18, 2024: member

   What is the error?

   I put it to the PR description.

   Why does it only happen with Qt6?

   Differences in Qt implementation between Qt 5 and Qt 6? (did not dig into the exact code change though)

7. in src/qt/rpcconsole.cpp:21 in 5be34bacf6

   15@@ -16,7 +16,9 @@
   16 #include <qt/guiutil.h>
   17 #include <qt/peertablesortproxy.h>
   18 #include <qt/platformstyle.h>
   19+#ifdef ENABLE_WALLET
   20 #include <qt/walletmodel.h>
   21+#endif // ENABLE_WALLET
   

   ---

   ---

   

   furszy commented at 1:51 am on September 19, 2024:

   How the RPCExecutor::request method compiles when this line doesn’t exist?

   ---

   

   pablomartin4btc commented at 11:35 pm on September 19, 2024:

   I think because the compiler only needs to know WalletModel, it doesn’t need the full definition unless you dereference the pointer (eg as in RPCConsole::RPCParseCommandLine -> wallet_model->getWalletName() - which is guarded).

   ---

   

   hebasto commented at 3:41 pm on October 3, 2024:

   Reworked.

   ---

   

   hebasto commented at 8:55 am on October 4, 2024:

   Reworked.

   Reverted back.

   How the RPCExecutor::request method compiles when this line doesn’t exist?

   Due to https://github.com/bitcoin-core/gui/blob/5be34bacf6d07fb73a0cedfb63a384968d538f3e/src/qt/rpcconsole.h#L24

8. pablomartin4btc approved
9. 
   pablomartin4btc commented at 11:16 pm on September 19, 2024: contributor

   tACK 5be34bacf6d07fb73a0cedfb63a384968d538f3e

   It builds correctly on Qt5 and qt runs fine, with both -DENABLE_WALLET=OFF & -DENABLE_WALLET=ON. When wallet support is off also tested the rpc console and several rpc commands.

10. hebasto renamed this:
    Fix linking when configured with `-DENABLE_WALLET=OFF` (Qt 6)
    qt6: Fix linking when configured with `-DENABLE_WALLET=OFF`
    on Oct 3, 2024
11. hebasto force-pushed on Oct 3, 2024
12. hebasto added the label Wallet on Oct 3, 2024
13. 
    pablomartin4btc commented at 5:16 pm on October 3, 2024: contributor

    utACK 33657e1c958146312e4c68765a92871920401396

    Guarded all WalletModel references (and overriding functions without it) in rpcconsole.

14. 
    promag commented at 6:41 pm on October 3, 2024: contributor

    I’ll try a different approach.
15. 
    promag commented at 8:29 am on October 4, 2024: contributor

    ACK 5be34bacf6d07fb73a0cedfb63a384968d538f3e, all other changes in 33657e1c958146312e4c68765a92871920401396 are not required, makes the code harder to read.
16. DrahtBot requested review from promag on Oct 4, 2024
17. hebasto force-pushed on Oct 4, 2024
18. hebasto merged this on Oct 4, 2024
19. hebasto closed this on Oct 4, 2024

    ---

20. hebasto deleted the branch on Oct 4, 2024
21. 
    furszy commented at 2:02 pm on October 4, 2024: member

    Arrived a bit late, but see #841. It drops WalletModel linkage and removes an extra #ifdef ENABLE_WALLET in the RPC executor class.

Contributors
hebasto DrahtBot fanquake furszy pablomartin4btc promag

Review Requested
promag

Labels
Wallet Qt 6