#3 Failed to build: `invalid use of incomplete type ‘Address’`

When I try to build mario-dns, the following error message appears:

$ make
g++ -c -pipe -O2 -std=gnu++11 -Wall -Wextra -D_REENTRANT -fPIC -DQT_DEPRECATED_WARNINGS -DQT_NO_DEBUG -DQT_NETWORK_LIB -DQT_CORE_LIB -I. -I/usr/include/x86_64-linux-gnu/qt5 -I/usr/include/x86_64-linux-gnu/qt5/QtNetwork -I/usr/include/x86_64-linux-gnu/qt5/QtCore -I. -I/usr/lib/x86_64-linux-gnu/qt5/mkspecs/linux-g++ -o resolver.o resolver.cpp
resolver.cpp: In member function ‘void Resolver::convertStrToRaw(const QString&, Address&)’:
resolver.cpp:114:46: error: invalid use of incomplete type ‘Address’ {aka ‘struct std::array<unsigned char, 16>’}
  114 |     inet_pton(AF_INET6, str.toUtf8(), (void*)array.data());
      |                                              ^~~~~
In file included from /usr/include/c++/12/functional:54,
                 from /usr/include/x86_64-linux-gnu/qt5/QtCore/qhashfunctions.h:48,
                 from /usr/include/x86_64-linux-gnu/qt5/QtCore/qlist.h:47,
                 from /usr/include/x86_64-linux-gnu/qt5/QtCore/qhash.h:46,
                 from /usr/include/x86_64-linux-gnu/qt5/QtCore/qshareddata.h:46,
                 from /usr/include/x86_64-linux-gnu/qt5/QtCore/qjsonvalue.h:45,
                 from /usr/include/x86_64-linux-gnu/qt5/QtCore/qjsonobject.h:43,
                 from /usr/include/x86_64-linux-gnu/qt5/QtCore/QJsonObject:1,
                 from jsonanswer.h:5,
                 from resolver.h:4,
                 from resolver.cpp:2:
/usr/include/c++/12/tuple:1595:45: note: declaration of ‘Address’ {aka ‘struct std::array<unsigned char, 16>’}
 1595 |   template<typename _Tp, size_t _Nm> struct array;
      |                                             ^~~~~
resolver.cpp: In member function ‘QString Resolver::getBase32(const Address&)’:
resolver.cpp:119:45: error: invalid use of incomplete type ‘const Address’ {aka ‘const struct std::array<unsigned char, 16>’}
  119 |     return cppcodec::base32_rfc4648::encode(rawAddr.data(), ADDRIPV6_SIZE).c_str();
      |                                             ^~~~~~~
/usr/include/c++/12/tuple:1595:45: note: declaration of ‘Address’ {aka ‘struct std::array<unsigned char, 16>’}
 1595 |   template<typename _Tp, size_t _Nm> struct array;
      |                                             ^~~~~
resolver.cpp: In member function ‘QString Resolver::decodeMeshToIP(const QString&)’:
resolver.cpp:134:13: error: aggregate ‘Address rawAddr’ has incomplete type and cannot be defined
  134 |     Address rawAddr;
      |             ^~~~~~~
resolver.cpp: In member function ‘QString Resolver::getAddress(const Address&)’:
resolver.cpp:161:25: error: invalid use of incomplete type ‘const Address’ {aka ‘const struct std::array<unsigned char, 16>’}
  161 |     inet_ntop(AF_INET6, rawAddr.data(), ipStrBuf, 46);
      |                         ^~~~~~~
/usr/include/c++/12/tuple:1595:45: note: declaration of ‘Address’ {aka ‘struct std::array<unsigned char, 16>’}
 1595 |   template<typename _Tp, size_t _Nm> struct array;
      |                                             ^~~~~
resolver.cpp: In member function ‘void Resolver::toMeship(const QString&, QSharedPointer<QTextStream>, bool)’:
resolver.cpp:281:13: error: aggregate ‘Address rawAddr’ has incomplete type and cannot be defined
  281 |     Address rawAddr;
      |             ^~~~~~~
make: *** [Makefile:410: resolver.o] Error 1

Hi.

A couple years later I opened a project in Qt Creator with Qt6 and built it with no problems, despite the fact that the project was written under Qt5.

In the root of the directory, building Qt projects usually looks like qmake && make or qmake6 && make (If Qt6). Which tool did you use before make?

Since Qt5 was in the README, I executed the "normal" qmake. The error appears under both Debian and Arch Linux.

┌─[marek@ciel]─[~]
└──╼ $cd git
┌─[marek@ciel]─[~/git]
└──╼ $git clone git@notabug.org:acetone/mario-dns.git
Cloning into 'mario-dns'...
remote: Counting objects: 78, done.
remote: Compressing objects: 100% (3/3), done.
remote: Total 78 (delta 0), reused 0 (delta 0)
Receiving objects: 100% (78/78), 59.96 KiB | 739.00 KiB/s, done.
Resolving deltas: 100% (34/34), done.
┌─[marek@ciel]─[~/git]
└──╼ $cd mario-dns/
┌─[marek@ciel]─[~/git/mario-dns]─(master|0 0 0)
└──╼ $qmake
Info: creating stash file /home/marek/git/mario-dns/.qmake.stash
┌─[marek@ciel]─[~/git/mario-dns]─(master|0 0 0)
└──╼ $make
g++ -c -pipe -O2 -std=gnu++11 -flto -fno-fat-lto-objects -Wall -Wextra -D_REENTRANT -fPIC -DQT_DEPRECATED_WARNINGS -DQT_NO_DEBUG -DQT_NETWORK_LIB -DQT_CORE_LIB -I. -I/usr/include/qt -I/usr/include/qt/QtNetwork -I/usr/include/qt/QtCore -I. -I/usr/lib/qt/mkspecs/linux-g++ -o funcs.o funcs.cpp
g++ -c -pipe -O2 -std=gnu++11 -flto -fno-fat-lto-objects -Wall -Wextra -D_REENTRANT -fPIC -DQT_DEPRECATED_WARNINGS -DQT_NO_DEBUG -DQT_NETWORK_LIB -DQT_CORE_LIB -I. -I/usr/include/qt -I/usr/include/qt/QtNetwork -I/usr/include/qt/QtCore -I. -I/usr/lib/qt/mkspecs/linux-g++ -o jsonanswer.o jsonanswer.cpp
g++ -c -pipe -O2 -std=gnu++11 -flto -fno-fat-lto-objects -Wall -Wextra -D_REENTRANT -fPIC -DQT_DEPRECATED_WARNINGS -DQT_NO_DEBUG -DQT_NETWORK_LIB -DQT_CORE_LIB -I. -I/usr/include/qt -I/usr/include/qt/QtNetwork -I/usr/include/qt/QtCore -I. -I/usr/lib/qt/mkspecs/linux-g++ -o main.o main.cpp
g++ -c -pipe -O2 -std=gnu++11 -flto -fno-fat-lto-objects -Wall -Wextra -D_REENTRANT -fPIC -DQT_DEPRECATED_WARNINGS -DQT_NO_DEBUG -DQT_NETWORK_LIB -DQT_CORE_LIB -I. -I/usr/include/qt -I/usr/include/qt/QtNetwork -I/usr/include/qt/QtCore -I. -I/usr/lib/qt/mkspecs/linux-g++ -o resolver.o resolver.cpp
resolver.cpp: In member function ‘void Resolver::convertStrToRaw(const QString&, Address&)’:
resolver.cpp:114:46: error: invalid use of incomplete type ‘Address’ {aka ‘struct std::array<unsigned char, 16>’}
  114 |     inet_pton(AF_INET6, str.toUtf8(), (void*)array.data());
      |                                              ^~~~~
In file included from /usr/include/c++/13.2.1/functional:53,
                 from /usr/include/qt/QtCore/qhashfunctions.h:48,
                 from /usr/include/qt/QtCore/qlist.h:47,
                 from /usr/include/qt/QtCore/qhash.h:46,
                 from /usr/include/qt/QtCore/qshareddata.h:46,
                 from /usr/include/qt/QtCore/qjsonvalue.h:45,
                 from /usr/include/qt/QtCore/qjsonobject.h:43,
                 from /usr/include/qt/QtCore/QJsonObject:1,
                 from jsonanswer.h:5,
                 from resolver.h:4,
                 from resolver.cpp:2:
/usr/include/c++/13.2.1/tuple:2005:45: note: declaration of ‘Address’ {aka ‘struct std::array<unsigned char, 16>’}
 2005 |   template<typename _Tp, size_t _Nm> struct array;
      |                                             ^~~~~
resolver.cpp: In member function ‘QString Resolver::getBase32(const Address&)’:
resolver.cpp:119:45: error: invalid use of incomplete type ‘const Address’ {aka ‘const struct std::array<unsigned char, 16>’}
  119 |     return cppcodec::base32_rfc4648::encode(rawAddr.data(), ADDRIPV6_SIZE).c_str();
      |                                             ^~~~~~~
/usr/include/c++/13.2.1/tuple:2005:45: note: declaration of ‘Address’ {aka ‘struct std::array<unsigned char, 16>’}
 2005 |   template<typename _Tp, size_t _Nm> struct array;
      |                                             ^~~~~
resolver.cpp: In member function ‘QString Resolver::decodeMeshToIP(const QString&)’:
resolver.cpp:134:13: error: aggregate ‘Address rawAddr’ has incomplete type and cannot be defined
  134 |     Address rawAddr;
      |             ^~~~~~~
resolver.cpp: In member function ‘QString Resolver::getAddress(const Address&)’:
resolver.cpp:161:25: error: invalid use of incomplete type ‘const Address’ {aka ‘const struct std::array<unsigned char, 16>’}
  161 |     inet_ntop(AF_INET6, rawAddr.data(), ipStrBuf, 46);
      |                         ^~~~~~~
/usr/include/c++/13.2.1/tuple:2005:45: note: declaration of ‘Address’ {aka ‘struct std::array<unsigned char, 16>’}
 2005 |   template<typename _Tp, size_t _Nm> struct array;
      |                                             ^~~~~
resolver.cpp: In member function ‘void Resolver::toMeship(const QString&, QSharedPointer<QTextStream>, bool)’:
resolver.cpp:281:13: error: aggregate ‘Address rawAddr’ has incomplete type and cannot be defined
  281 |     Address rawAddr;
      |             ^~~~~~~
make: *** [Makefile:794: resolver.o] Error 1
┌─[✗]─[marek@ciel]─[~/git/mario-dns]─(master|0 0 0)
└──╼ $qmake --version
QMake version 3.1
Using Qt version 5.15.12 in /usr/lib

Compiling with qmake6 also failes (but with another error):

┌─[marek@ciel]─[~/git/mario-dns]─(master|0 0 0)
└──╼ $qmake6
┌─[marek@ciel]─[~/git/mario-dns]─(master|0 0 0)
└──╼ $make
g++ -c -pipe -O2 -Wall -Wextra -mno-direct-extern-access -D_REENTRANT -DQT_DEPRECATED_WARNINGS -DQT_NO_DEBUG -DQT_NETWORK_LIB -DQT_CORE_LIB -I. -I/usr/include/qt6 -I/usr/include/qt6/QtNetwork -I/usr/include/qt6/QtCore -I. -I/usr/lib/qt6/mkspecs/linux-g++ -o resolver.o resolver.cpp
g++ -pipe -O2 -Wall -Wextra -dM -E -o moc_predefs.h /usr/lib/qt6/mkspecs/features/data/dummy.cpp
/usr/lib/qt6/moc -DQT_DEPRECATED_WARNINGS -DQT_NO_DEBUG -DQT_NETWORK_LIB -DQT_CORE_LIB --include /home/marek/git/mario-dns/moc_predefs.h -I/usr/lib/qt6/mkspecs/linux-g++ -I/home/marek/git/mario-dns -I/usr/include/qt6 -I/usr/include/qt6/QtNetwork -I/usr/include/qt6/QtCore -I/usr/include/c++/13.2.1 -I/usr/include/c++/13.2.1/x86_64-pc-linux-gnu -I/usr/include/c++/13.2.1/backward -I/usr/lib/gcc/x86_64-pc-linux-gnu/13.2.1/include -I/usr/local/include -I/usr/lib/gcc/x86_64-pc-linux-gnu/13.2.1/include-fixed -I/usr/include resolver.h -o moc_resolver.cpp
g++ -c -pipe -O2 -Wall -Wextra -mno-direct-extern-access -D_REENTRANT -DQT_DEPRECATED_WARNINGS -DQT_NO_DEBUG -DQT_NETWORK_LIB -DQT_CORE_LIB -I. -I/usr/include/qt6 -I/usr/include/qt6/QtNetwork -I/usr/include/qt6/QtCore -I. -I/usr/lib/qt6/mkspecs/linux-g++ -o moc_resolver.o moc_resolver.cpp
g++ -Wl,-O1 -Wl,-rpath,/usr/lib -o mario-dns-tool  funcs.o jsonanswer.o main.o resolver.o moc_resolver.o   /usr/lib/libQt6Network.so /usr/lib/libQt6Core.so -lpthread   
/usr/bin/ld: /tmp/ccMwHZlU.ltrans0.ltrans.o: in function `operator+(char const*, QString const&)':
<artificial>:(.text+0x112): undefined reference to `QString::fromUtf8_helper(char const*, int)'
/usr/bin/ld: /tmp/ccMwHZlU.ltrans0.ltrans.o: in function `operator+(QString const&, char const*) [clone .isra.0]':
<artificial>:(.text+0x18f): undefined reference to `QString::fromUtf8_helper(char const*, int)'
/usr/bin/ld: <artificial>:(.text+0x1de): undefined reference to `QArrayData::deallocate(QArrayData*, unsigned long, unsigned long)'
/usr/bin/ld: /tmp/ccMwHZlU.ltrans0.ltrans.o: in function `QDebug::operator<<(char const*) [clone .isra.0]':
<artificial>:(.text+0x2b7): undefined reference to `QString::fromUtf8_helper(char const*, int)'
/usr/bin/ld: <artificial>:(.text+0x313): undefined reference to `QArrayData::deallocate(QArrayData*, unsigned long, unsigned long)'
/usr/bin/ld: /tmp/ccMwHZlU.ltrans0.ltrans.o: in function `QString::QString(char const*)':
<artificial>:(.text+0x454): undefined reference to `QString::fromAscii_helper(char const*, int)'
/usr/bin/ld: /tmp/ccMwHZlU.ltrans0.ltrans.o: in function `funcs::getValue(QString const&, QString const&)':
<artificial>:(.text+0x49c): undefined reference to `QArrayData::shared_null'
/usr/bin/ld: <artificial>:(.text+0x4fb): undefined reference to `QString::fromUtf8_helper(char const*, int)'
/usr/bin/ld: <artificial>:(.text+0x540): undefined reference to `QString::indexOf(QString const&, int, Qt::CaseSensitivity) const'
/usr/bin/ld: <artificial>:(.text+0x554): undefined reference to `QArrayData::shared_null'
/usr/bin/ld: <artificial>:(.text+0x58b): undefined reference to `QArrayData::deallocate(QArrayData*, unsigned long, unsigned long)'
/usr/bin/ld: <artificial>:(.text+0x5af): undefined reference to `QString::indexOf(QChar, int, Qt::CaseSensitivity) const'
/usr/bin/ld: <artificial>:(.text+0x694): undefined reference to `QString::fromAscii_helper(char const*, int)'
/usr/bin/ld: <artificial>:(.text+0x6c3): undefined reference to `QArrayData::deallocate(QArrayData*, unsigned long, unsigned long)'
/usr/bin/ld: <artificial>:(.text+0x6eb): undefined reference to `QArrayData::deallocate(QArrayData*, unsigned long, unsigned long)'
/usr/bin/ld: /tmp/ccMwHZlU.ltrans0.ltrans.o: in function `JsonAnswer::result() const':
<artificial>:(.text+0x7fa): undefined reference to `QString::fromUtf8_helper(char const*, int)'
/usr/bin/ld: <artificial>:(.text+0x831): undefined reference to `QString::fromUtf8_helper(char const*, int)'
/usr/bin/ld: <artificial>:(.text+0x898): undefined reference to `QArrayData::shared_null'
/usr/bin/ld: <artificial>:(.text+0x9f6): undefined reference to `QString::fromUtf8_helper(char const*, int)'
/usr/bin/ld: <artificial>:(.text+0xa0b): undefined reference to `QArrayData::deallocate(QArrayData*, unsigned long, unsigned long)'
/usr/bin/ld: <artificial>:(.text+0xa23): undefined reference to `QArrayData::deallocate(QArrayData*, unsigned long, unsigned long)'
/usr/bin/ld: <artificial>:(.text+0xa41): undefined reference to `QArrayData::deallocate(QArrayData*, unsigned long, unsigned long)'
/usr/bin/ld: <artificial>:(.text+0xa5f): undefined reference to `QArrayData::deallocate(QArrayData*, unsigned long, unsigned long)'
/usr/bin/ld: <artificial>:(.text+0xa7b): undefined reference to `QArrayData::deallocate(QArrayData*, unsigned long, unsigned long)'
/usr/bin/ld: /tmp/ccMwHZlU.ltrans0.ltrans.o:<artificial>:(.text+0xa93): more undefined references to `QArrayData::deallocate(QArrayData*, unsigned long, unsigned long)' follow
/usr/bin/ld: /tmp/ccMwHZlU.ltrans0.ltrans.o: in function `JsonAnswer::result() const':
<artificial>:(.text+0xaf4): undefined reference to `QString::fromUtf8_helper(char const*, int)'
/usr/bin/ld: /tmp/ccMwHZlU.ltrans0.ltrans.o: in function `QString::~QString()':
<artificial>:(.text+0x29): undefined reference to `QArrayData::deallocate(QArrayData*, unsigned long, unsigned long)'
/usr/bin/ld: /tmp/ccMwHZlU.ltrans0.ltrans.o: in function `QByteArray::~QByteArray()':
<artificial>:(.text.unlikely+0x17): undefined reference to `QArrayData::deallocate(QArrayData*, unsigned long, unsigned long)'
/usr/bin/ld: /tmp/ccMwHZlU.ltrans0.ltrans.o: in function `_sub_I_65535_0.0':
<artificial>:(.text.startup+0x1e6): undefined reference to `QArrayData::shared_null'
/usr/bin/ld: /tmp/ccMwHZlU.ltrans0.ltrans.o: in function `main':
<artificial>:(.text.startup+0x3a6): undefined reference to `QString::toInt(bool*, int) const'
collect2: error: ld returned 1 exit status
make: *** [Makefile:260: mario-dns-tool] Error 1
┌─[✗]─[marek@ciel]─[~/git/mario-dns]─(master|1 0 0)
└──╼ $qmake6 --version
QMake version 3.1
Using Qt version 6.6.1 in /usr/lib

let you check

Works!