cmake: GUI build broken with -stdlib=libc++ #32331

1. 
   fanquake commented at 1:41 pm on April 23, 2025: member

    0master @ 9a4c92eb9ac29204df3d826f5ae526ab16b8ad65
    1clang version 20.1.2 (Fedora 20.1.2-3.fc42)
    2cmake -B build -DBUILD_GUI=ON -DAPPEND_CXXFLAGS="-stdlib=libc++" -DAPPEND_LDFLAGS="-stdlib=libc++"
    3cmake --build build
    4<snip>
    5cmake --build build -j17 --target bitcoin-qt
    6[  0%] Generating bitcoin-build-info.h
    7[  0%] Built target secp256k1_precomputed
    8[  0%] Built target crc32c
    9[  1%] Built target bitcoin_consensus
   10[  3%] Built target bitcoin_cli
   11[  4%] Built target univalue
   12[  7%] Built target minisketch
   13[  7%] Built target secp256k1
   14[ 12%] Built target bitcoin_crypto
   15[ 20%] Built target leveldb
   16[ 20%] Built target generate_build_info
   17[ 20%] Built target bitcoin_clientversion
   18[ 32%] Built target bitcoin_util
   19[ 32%] Built target bitcoin_wallet
   20[ 32%] Built target bitcoinqt_autogen_timestamp_deps
   21[ 43%] Built target bitcoin_common
   22[ 44%] Built target bitcoinqt_autogen
   23[ 63%] Built target bitcoin_node
   24[100%] Built target bitcoinqt
   25[100%] Built target bitcoin-qt_autogen_timestamp_deps
   26[100%] Built target bitcoin-qt_autogen
   27[100%] Linking CXX executable ../../bin/bitcoin-qt
   28/usr/bin/ld: CMakeFiles/bitcoin-qt.dir/main.cpp.o: in function `std::__1::__function::__func<$_0, std::__1::allocator<$_0>, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > (char const*)>::operator()(char const*&&)':
   29/usr/include/x86_64-linux-gnu/qt6/QtCore/qstring.h:1477:(.text+0x18f): undefined reference to `QByteArray::toStdString() const'
   30/usr/bin/ld: ../../lib/libbitcoinqt.a(bitcoin.cpp.o): in function `QString::toStdString() const':
   31/usr/include/x86_64-linux-gnu/qt6/QtCore/qstring.h:1477:(.text+0x3b): undefined reference to `QByteArray::toStdString() const'
   32/usr/bin/ld: /usr/include/x86_64-linux-gnu/qt6/QtCore/qstring.h:1477:(.text+0xe0): undefined reference to `QByteArray::toStdString() const'
   33/usr/bin/ld: ../../lib/libbitcoinqt.a(bitcoin.cpp.o): in function `BitcoinApplication::createOptionsModel(bool)':
   34/usr/include/x86_64-linux-gnu/qt6/QtCore/qstring.h:1477:(.text+0xc86): undefined reference to `QByteArray::toStdString() const'
   35/usr/bin/ld: ../../lib/libbitcoinqt.a(bitcoin.cpp.o): in function `initTranslations(QTranslator&, QTranslator&, QTranslator&, QTranslator&)':
   36/usr/include/x86_64-linux-gnu/qt6/QtCore/qstring.h:1477:(.text+0x5ab2): undefined reference to `QByteArray::toStdString() const'
   37/usr/bin/ld: ../../lib/libbitcoinqt.a(bitcoingui.cpp.o):/usr/include/x86_64-linux-gnu/qt6/QtCore/qstring.h:1477: more undefined references to `QByteArray::toStdString() const' follow
   38clang++: error: linker command failed with exit code 1 (use -v to see invocation)
   

2. 
   hebasto commented at 1:56 pm on April 23, 2025: member

   Is it supposed to work without using depends built with -stdlib=libc++?
3. maflcko added the label Build system on Apr 23, 2025
4. maflcko added the label GUI on Apr 23, 2025
5. maflcko added the label Upstream on Apr 23, 2025
6. 
   maflcko commented at 2:58 pm on April 23, 2025: member

   IIRC it used to work with qt5, but it is unclear if that was intentional or by accident. I guess in any case this is an upstream issue that would need to be fixed in the distro or in qt6, if it is an issue at all?

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fanquake hebasto maflcko

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