Link D library with C ++ code

Question

I recently learned the beautiful D language, which is so flexible and helps you write stable fast programs. But it is not popular ... because little code is written in D and so on in C and C ++. Therefore, after I read the book by Andrei Aleksandrsku, where the author very superficially described the question of linking the D library with C ++ code, I tried to study it myself and wrote some D code, where a certain function that returns an instance of the CompleteAutomata class, which implements AutomataInterface, in C ++ code:

#ifndef AUTOMATAINTERFACE_H #define AUTOMATAINTERFACE_H class AutomataInterface { public: virtual ~AutomataInterface() {} virtual void next() = 0; virtual void save() = 0; virtual void restore() = 0; virtual void zerofile() = 0; virtual void invert(unsigned long x, unsigned long y) = 0; virtual int state(unsigned long x, unsigned long y) const = 0; virtual unsigned long x() const = 0; virtual unsigned long y() const = 0; }; AutomataInterface *createAutomata(unsigned long x, unsigned long y); #endif // AUTOMATAINTERFACE_H 

Corresponding D code:

 import agregator; // this is my own lib extern(C++) { interface AutomataInterface { void next(); void save(); void restore(); void zerofile(); void invert(size_t x, size_t y); int state(size_t x, size_t y) const; size_t x() const; size_t y() const; } AutomataInterface createAutomata(ulong x, ulong y) { return new CompleteAutomata(x, y); } } export class CompleteAutomata : AutomataInterface { // instance variables... this(size_t x, size_t y) { /* ... */ } extern(C++) { override void next() { // ... } // others overridden interface methods... } } 

After writing the code, I compile the D library with two different compilers ( dmd and gdc ) with the following flags:

 dmd -release -O -lib -odlib -ofliblife.h *.d 

or

 gdc -frelease -O2 -Wall -c *.d ar cq lib/liblife.a *.o 

When I try to link each of the resulting libraries with a Qt project, adding the dir ( -L ) library path and adding lib directly ( -L ). I got errors in both cases.

In the first case, dmd , I have an "undefined reference to` _d_newclass "and two other errors:

 g++ -Wl,-O1 -Wl,-z,relro -o automata main.o mainwindow.o renderarea.o button.o playbutton.o moc_mainwindow.o moc_renderarea.o moc_button.o moc_playbutton.o -L/home/newmen/projects/d/life/lib -llife -lQtGui -lQtCore -lpthread /home/newmen/projects/d/life/lib/liblife.a(complete_automata_1fe_5b0.o): In function `createAutomata(unsigned int, unsigned int)': complete_automata.d:(.text._Z14createAutomatajj+0x27): undefined reference to `_d_newclass' /home/newmen/projects/d/life/lib/liblife.a(complete_automata_1ff_675.o):(.data+0x0): undefined reference to `_D14TypeInfo_Class6__vtblZ' /home/newmen/projects/d/life/lib/liblife.a(complete_automata_1ff_675.o):(.data+0x50): undefined reference to `_D6Object7__ClassZ' /home/newmen/projects/d/life/lib/liblife.a(complete_automata_1ff_675.o):(.data+0xd0): undefined reference to `_D14TypeInfo_Class6__vtblZ' /home/newmen/projects/d/life/lib/liblife.a(complete_automata_1ff_675.o):(.data+0x120): undefined reference to `_D6Object7__ClassZ' /home/newmen/projects/d/life/lib/liblife.a(complete_automata_1ff_675.o):(.rodata+0x68): undefined reference to `_D6object6Object8toStringMFZAya' /home/newmen/projects/d/life/lib/liblife.a(complete_automata_1ff_675.o):(.rodata+0x70): undefined reference to `_D6object6Object6toHashMFNbNeZm' /home/newmen/projects/d/life/lib/liblife.a(complete_automata_1ff_675.o):(.rodata+0x78): undefined reference to `_D6object6Object5opCmpMFC6ObjectZi' /home/newmen/projects/d/life/lib/liblife.a(complete_automata_1ff_675.o):(.rodata+0x80): undefined reference to `_D6object6Object8opEqualsMFC6ObjectZb' /home/newmen/projects/d/life/lib/liblife.a(complete_automata_1ff_675.o):(.rodata+0xf8): undefined reference to `_D6object6Object8toStringMFZAya' /home/newmen/projects/d/life/lib/liblife.a(complete_automata_1ff_675.o):(.rodata+0x100): undefined reference to `_D6object6Object6toHashMFNbNeZm' /home/newmen/projects/d/life/lib/liblife.a(complete_automata_1ff_675.o):(.rodata+0x108): undefined reference to `_D6object6Object5opCmpMFC6ObjectZi' /home/newmen/projects/d/life/lib/liblife.a(complete_automata_1ff_675.o):(.rodata+0x110): undefined reference to `_D6object6Object8opEqualsMFC6ObjectZb' /home/newmen/projects/d/life/lib/liblife.a(complete_automata_1ff_675.o): In function `_D17complete_automata16CompleteAutomata6__ctorMFmmZC17complete_automata16CompleteAutomata': complete_automata.d:(.text._D17complete_automata16CompleteAutomata6__ctorMFmmZC17complete_automata16CompleteAutomata+0x1f): undefined reference to `_d_newclass' complete_automata.d:(.text._D17complete_automata16CompleteAutomata6__ctorMFmmZC17complete_automata16CompleteAutomata+0x46): undefined reference to `_d_newclass' /home/newmen/projects/d/life/lib/liblife.a(complete_automata_1ff_675.o): In function `CompleteAutomata::next()': complete_automata.d:(.text._ZN16CompleteAutomata4nextEv+0x2f): undefined reference to `_d_newclass' /home/newmen/projects/d/life/lib/liblife.a(complete_automata_1ff_675.o): In function `CompleteAutomata::save()': complete_automata.d:(.text._ZN16CompleteAutomata4saveEv+0x25): undefined reference to `_adDupT' /home/newmen/projects/d/life/lib/liblife.a(complete_automata_1ff_675.o): In function `CompleteAutomata::restore()': complete_automata.d:(.text._ZN16CompleteAutomata7restoreEv+0x33): undefined reference to `_d_newclass' /home/newmen/projects/d/life/lib/liblife.a(complete_automata_1ff_675.o): In function `CompleteAutomata::zerofile()': complete_automata.d:(.text._ZN16CompleteAutomata8zerofileEv+0x2f): undefined reference to `_d_newclass' /home/newmen/projects/d/life/lib/liblife.a(object_201_8b7.o): In function `no symbol': /usr/include/dmd/druntime/import/object.di:(.text+0x6): undefined reference to `_Dmodule_ref' /home/newmen/projects/d/life/lib/liblife.a(object_201_8b7.o):(.data._D12TypeInfo_Axi6__initZ+0x0): undefined reference to `_D14TypeInfo_Array6__vtblZ' /home/newmen/projects/d/life/lib/liblife.a(object_201_8b7.o): In function `_D46/usr/include/dmd/druntime/import/object.di.5137__arrayZ': /usr/include/dmd/druntime/import/object.di:(.text._D46/usr/include/dmd/druntime/import/object.di.5137__arrayZ+0x16): undefined reference to `_d_array_bounds' /home/newmen/projects/d/life/lib/liblife.a(object_201_8b7.o): In function `_D46/usr/include/dmd/druntime/import/object.di.5138__assertFiZv': /usr/include/dmd/druntime/import/object.di:(.text._D46/usr/include/dmd/druntime/import/object.di.5138__assertFiZv+0x16): undefined reference to `_d_assertm' /home/newmen/projects/d/life/lib/liblife.a(object_201_8b7.o): In function `_D46/usr/include/dmd/druntime/import/object.di.51315__unittest_failFiZv': /usr/include/dmd/druntime/import/object.di:(.text._D46/usr/include/dmd/druntime/import/object.di.51315__unittest_failFiZv+0x16): undefined reference to `_d_unittestm' /home/newmen/projects/d/life/lib/liblife.a(object_203_875.o): In function `no symbol': /usr/include/dmd/druntime/import/object.di:(.text+0x6): undefined reference to `_Dmodule_ref' /home/newmen/projects/d/life/lib/liblife.a(object_203_875.o):(.data._D11TypeInfo_xi6__initZ+0x0): undefined reference to `_D14TypeInfo_Const6__vtblZ' /home/newmen/projects/d/life/lib/liblife.a(object_203_875.o):(.data._D11TypeInfo_xi6__initZ+0x10): undefined reference to `_D10TypeInfo_i6__initZ' /home/newmen/projects/d/life/lib/liblife.a(object_203_875.o): In function `_D46/usr/include/dmd/druntime/import/object.di.5157__arrayZ': /usr/include/dmd/druntime/import/object.di:(.text._D46/usr/include/dmd/druntime/import/object.di.5157__arrayZ+0x16): undefined reference to `_d_array_bounds' /home/newmen/projects/d/life/lib/liblife.a(object_203_875.o): In function `_D46/usr/include/dmd/druntime/import/object.di.5158__assertFiZv': /usr/include/dmd/druntime/import/object.di:(.text._D46/usr/include/dmd/druntime/import/object.di.5158__assertFiZv+0x16): undefined reference to `_d_assertm' /home/newmen/projects/d/life/lib/liblife.a(object_203_875.o): In function `_D46/usr/include/dmd/druntime/import/object.di.51515__unittest_failFiZv': /usr/include/dmd/druntime/import/object.di:(.text._D46/usr/include/dmd/druntime/import/object.di.51515__unittest_failFiZv+0x16): undefined reference to `_d_unittestm' /home/newmen/projects/d/life/lib/liblife.a(agregator.o): In function `no symbol': agregator.d:(.text+0x6): undefined reference to `_Dmodule_ref' /home/newmen/projects/d/life/lib/liblife.a(agregator.o):(.data+0x10): undefined reference to `_D3std6random12__ModuleInfoZ' /home/newmen/projects/d/life/lib/liblife.a(agregator.o):(.rodata+0x20): undefined reference to `_D14TypeInfo_Class6__vtblZ' /home/newmen/projects/d/life/lib/liblife.a(agregator.o): In function `_D9agregator7__arrayZ': agregator.d:(.text._D9agregator7__arrayZ+0x16): undefined reference to `_d_array_bounds' /home/newmen/projects/d/life/lib/liblife.a(agregator.o): In function `_D9agregator8__assertFiZv': agregator.d:(.text._D9agregator8__assertFiZv+0x16): undefined reference to `_d_assertm' /home/newmen/projects/d/life/lib/liblife.a(agregator.o): In function `_D9agregator15__unittest_failFiZv': agregator.d:(.text._D9agregator15__unittest_failFiZv+0x16): undefined reference to `_d_unittestm' /home/newmen/projects/d/life/lib/liblife.a(agregator_2_5fd.o):(.data+0x0): undefined reference to `_D14TypeInfo_Class6__vtblZ' /home/newmen/projects/d/life/lib/liblife.a(agregator_2_5fd.o):(.data+0x50): undefined reference to `_D6Object7__ClassZ' /home/newmen/projects/d/life/lib/liblife.a(agregator_2_5fd.o):(.rodata+0x48): undefined reference to `_D6object6Object8toStringMFZAya' ... 

In the second case (when using gdc ) I get a "multiple definition" message:

 g++ -Wl,-O1 -Wl,-z,relro -o cellular_life main.o mainwindow.o renderarea.o button.o playbutton.o moc_mainwindow.o moc_renderarea.o moc_button.o moc_playbutton.o -L/home/newmen/projects/d/life/lib -llife -lQtGui -lQtCore -lpthread /home/newmen/projects/d/life/lib/liblife.a(complete_automata.o): In function `_D17complete_automata16CompleteAutomata7restoreMRZv14SliceAgregator9initValueMxFmmZi': complete_automata.d:(.text+0x0): multiple definition of `_D17complete_automata16CompleteAutomata7restoreMRZv14SliceAgregator9initValueMxFmmZi' /home/newmen/projects/d/life/lib/liblife.a(complete_automata_1ff_675.o):complete_automata.d:(.text._D17complete_automata16CompleteAutomata7restoreMRZv14SliceAgregator9initValueMxFmmZi+0x0): first defined here /home/newmen/projects/d/life/lib/liblife.a(complete_automata.o): In function `CompleteAutomata::invert(unsigned long long, unsigned long long)': complete_automata.d:(.text+0x40): multiple definition of `CompleteAutomata::invert(unsigned long long, unsigned long long)' /home/newmen/projects/d/life/lib/liblife.a(complete_automata_1ff_675.o):complete_automata.d:(.text._ZN16CompleteAutomata6invertEyy+0x0): first defined here /home/newmen/projects/d/life/lib/liblife.a(complete_automata.o): In function `CompleteAutomata::state(unsigned long long, unsigned long long) const': complete_automata.d:(.text+0x60): multiple definition of `CompleteAutomata::state(unsigned long long, unsigned long long) const' /home/newmen/projects/d/life/lib/liblife.a(complete_automata_1ff_675.o):complete_automata.d:(.text._ZNK16CompleteAutomata5stateEyy+0x0): first defined here /home/newmen/projects/d/life/lib/liblife.a(complete_automata.o): In function `CompleteAutomata::x() const': complete_automata.d:(.text+0x80): multiple definition of `CompleteAutomata::x() const' /home/newmen/projects/d/life/lib/liblife.a(complete_automata_1ff_675.o):complete_automata.d:(.text._ZNK16CompleteAutomata1xEv+0x0): first defined here /home/newmen/projects/d/life/lib/liblife.a(complete_automata.o): In function `CompleteAutomata::y() const': complete_automata.d:(.text+0xa0): multiple definition of `CompleteAutomata::y() const' /home/newmen/projects/d/life/lib/liblife.a(complete_automata_1ff_675.o):complete_automata.d:(.text._ZNK16CompleteAutomata1yEv+0x0): first defined here /home/newmen/projects/d/life/lib/liblife.a(complete_automata.o): In function `CompleteAutomata::next()': complete_automata.d:(.text+0x140): multiple definition of `CompleteAutomata::next()' /home/newmen/projects/d/life/lib/liblife.a(complete_automata_1ff_675.o):complete_automata.d:(.text._ZN16CompleteAutomata4nextEv+0x0): first defined here /home/newmen/projects/d/life/lib/liblife.a(complete_automata.o):(.tbss+0x10): multiple definition of `_D17complete_automata16CompleteAutomata4nextMRZv7changerC7changer7Changer' /home/newmen/projects/d/life/lib/liblife.a(complete_automata_1ff_675.o):(.tbss+0x0): first defined here /home/newmen/projects/d/life/lib/liblife.a(complete_automata.o): In function `CompleteAutomata::restore()': complete_automata.d:(.text+0x1b0): multiple definition of `CompleteAutomata::restore()' /home/newmen/projects/d/life/lib/liblife.a(complete_automata_1ff_675.o):complete_automata.d:(.text._ZN16CompleteAutomata7restoreEv+0x0): first defined here /home/newmen/projects/d/life/lib/liblife.a(complete_automata.o):(.tbss+0x8): multiple definition of `_D17complete_automata16CompleteAutomata7restoreMRZv9agregatorC9agregator9Agregator' /home/newmen/projects/d/life/lib/liblife.a(complete_automata_1ff_675.o):(.tbss+0x8): first defined here /home/newmen/projects/d/life/lib/liblife.a(complete_automata.o):(.data+0x180): multiple definition of `_D_ZN16CompleteAutomata7restoreEv14SliceAgregator7__ClassZ' /home/newmen/projects/d/life/lib/liblife.a(complete_automata_1ff_675.o):(.data+0x0): first defined here /home/newmen/projects/d/life/lib/liblife.a(complete_automata.o): In function `CompleteAutomata::zerofile()': complete_automata.d:(.text+0x220): multiple definition of `CompleteAutomata::zerofile()' /home/newmen/projects/d/life/lib/liblife.a(complete_automata_1ff_675.o):complete_automata.d:(.text._ZN16CompleteAutomata8zerofileEv+0x0): first defined here /home/newmen/projects/d/life/lib/liblife.a(complete_automata.o):(.tbss+0x0): multiple definition of `_D17complete_automata16CompleteAutomata8zerofileMRZv9agregatorC9agregator9Agregator' /home/newmen/projects/d/life/lib/liblife.a(complete_automata_1ff_675.o):(.tbss+0x10): first defined here /home/newmen/projects/d/life/lib/liblife.a(complete_automata.o): In function `CompleteAutomata::save()': complete_automata.d:(.text+0x290): multiple definition of `CompleteAutomata::save()' /home/newmen/projects/d/life/lib/liblife.a(complete_automata_1ff_675.o):complete_automata.d:(.text._ZN16CompleteAutomata4saveEv+0x0): first defined here /home/newmen/projects/d/life/lib/liblife.a(complete_automata.o):(.data+0x80): multiple definition of `_D17complete_automata16CompleteAutomata7__ClassZ' /home/newmen/projects/d/life/lib/liblife.a(complete_automata_1ff_675.o):(.data+0xd0): first defined here /home/newmen/projects/d/life/lib/liblife.a(complete_automata.o): In function `_D17complete_automata16CompleteAutomata6__ctorMFmmZC17complete_automata16CompleteAutomata': complete_automata.d:(.text+0x9b0): multiple definition of `_D17complete_automata16CompleteAutomata6__ctorMFmmZC17complete_automata16CompleteAutomata' /home/newmen/projects/d/life/lib/liblife.a(complete_automata_1ff_675.o):complete_automata.d:(.text._D17complete_automata16CompleteAutomata6__ctorMFmmZC17complete_automata16CompleteAutomata+0x0): first defined here /home/newmen/projects/d/life/lib/liblife.a(complete_automata.o):(.rodata+0x420): multiple definition of `_D17complete_automata16CompleteAutomata6__vtblZ' /home/newmen/projects/d/life/lib/liblife.a(complete_automata_1ff_675.o):(.rodata+0xf0): first defined here /usr/bin/ld: Warning: size of symbol `_D17complete_automata16CompleteAutomata6__vtblZ' changed from 104 in /home/newmen/projects/d/life/lib/liblife.a(complete_automata_1ff_675.o) to 112 in /home/newmen/projects/d/life/lib/liblife.a(complete_automata.o) /home/newmen/projects/d/life/lib/liblife.a(complete_automata.o):(.rodata+0x4a0): multiple definition of `_D17complete_automata16CompleteAutomata6__initZ' /home/newmen/projects/d/life/lib/liblife.a(complete_automata_1ff_675.o):(.rodata+0x90): first defined here /home/newmen/projects/d/life/lib/liblife.a(complete_automata.o):(.rodata+0x4e0): multiple definition of `_D_ZN16CompleteAutomata7restoreEv14SliceAgregator6__vtblZ' /home/newmen/projects/d/life/lib/liblife.a(complete_automata_1ff_675.o):(.rodata+0x60): first defined here /usr/bin/ld: Warning: size of symbol `_D_ZN16CompleteAutomata7restoreEv14SliceAgregator6__vtblZ' changed from 48 in /home/newmen/projects/d/life/lib/liblife.a(complete_automata_1ff_675.o) to 56 in /home/newmen/projects/d/life/lib/liblife.a(complete_automata.o) /home/newmen/projects/d/life/lib/liblife.a(complete_automata.o):(.rodata+0x520): multiple definition of `_D_ZN16CompleteAutomata7restoreEv14SliceAgregator6__initZ' /home/newmen/projects/d/life/lib/liblife.a(complete_automata_1ff_675.o):(.rodata+0x0): first defined here /home/newmen/projects/d/life/lib/liblife.a(agregator.o): In function `_D3std7complex14__T7ComplexTeZ7Complex8toStringMxFMDFAxaZvAyaZAya12__lambda1223MFNbNfAxaZv': agregator.d:(.text+0xaf): undefined reference to `_D11TypeInfo_Aa6__initZ' agregator.d:(.text+0xb7): undefined reference to `_d_arrayappendT' /home/newmen/projects/d/life/lib/liblife.a(agregator.o): In function `_D3std4conv16__T6toImplTiTxkZ6toImplFNaNfxkZi15__dgliteral1389MFNaNfZC6object9Throwable': agregator.d:(.text+0xc5): undefined reference to `_D3std4conv21ConvOverflowException7__ClassZ' agregator.d:(.text+0xca): undefined reference to `_d_newclass' agregator.d:(.text+0xed): undefined reference to `_D3std4conv21ConvOverflowException6__ctorMFAyaAyamZC3std4conv21ConvOverflowException' /home/newmen/projects/d/life/lib/liblife.a(agregator.o): In function `_D3std6format17__T9getNthIntTxeZ9getNthIntFNaNfkxeZi.part.6': agregator.d:(.text+0x105): undefined reference to `_D3std6format15FormatException7__ClassZ' agregator.d:(.text+0x10a): undefined reference to `_d_newclass' ... 

After two days of trying to do this ...

I recently tried adding Phobos (the standard D library) to bind a process. For the dmd -lphobos2 flag and for the gdc -lgphobos2 flag, match. But that does not help me ...

When using output

 g++ -Wl,-O1 -Wl,-z,relro -o cellular_life main.o mainwindow.o renderarea.o button.o playbutton.o moc_mainwindow.o moc_renderarea.o moc_button.o moc_playbutton.o -L/home/newmen/projects/d/life/lib -llife -lQtGui -lQtCore -lpthread -lphobos2 /usr/lib/gcc/x86_64-redhat-linux/4.7.2/../../../../lib64/libphobos2.so: undefined reference to ` curl_easy_duphandle@CURL _GNUTLS_3' /usr/lib/gcc/x86_64-redhat-linux/4.7.2/../../../../lib64/libphobos2.so: undefined reference to ` curl_easy_strerror@CURL _GNUTLS_3' /usr/lib/gcc/x86_64-redhat-linux/4.7.2/../../../../lib64/libphobos2.so: undefined reference to ` curl_slist_free_all@CURL _GNUTLS_3' /usr/lib/gcc/x86_64-redhat-linux/4.7.2/../../../../lib64/libphobos2.so: undefined reference to ` curl_global_init@CURL _GNUTLS_3' /usr/lib/gcc/x86_64-redhat-linux/4.7.2/../../../../lib64/libphobos2.so: undefined reference to ` curl_easy_perform@CURL _GNUTLS_3' /usr/lib/gcc/x86_64-redhat-linux/4.7.2/../../../../lib64/libphobos2.so: undefined reference to ` curl_easy_init@CURL _GNUTLS_3' /usr/lib/gcc/x86_64-redhat-linux/4.7.2/../../../../lib64/libphobos2.so: undefined reference to ` curl_easy_pause@CURL _GNUTLS_3' /usr/lib/gcc/x86_64-redhat-linux/4.7.2/../../../../lib64/libphobos2.so: undefined reference to `_Dmain' /usr/lib/gcc/x86_64-redhat-linux/4.7.2/../../../../lib64/libphobos2.so: undefined reference to ` curl_easy_setopt@CURL _GNUTLS_3' /usr/lib/gcc/x86_64-redhat-linux/4.7.2/../../../../lib64/libphobos2.so: undefined reference to ` curl_slist_append@CURL _GNUTLS_3' /usr/lib/gcc/x86_64-redhat-linux/4.7.2/../../../../lib64/libphobos2.so: undefined reference to ` curl_global_cleanup@CURL _GNUTLS_3' /usr/lib/gcc/x86_64-redhat-linux/4.7.2/../../../../lib64/libphobos2.so: undefined reference to ` curl_easy_cleanup@CURL _GNUTLS_3' collect2: error: ld returned 1 exit status make: *** [cellular_life] Error 1 

and I will try to replace libcurl-gnutls: ln -s /usr/lib64/libcurl.so.4 /usr/lib64/libcurl-gnutls.so.4 . Then the result of the binding is the same, but without reporting libcurl-gnutls.

When reusing the output of gdc linker talk about "multiple definition to":

 /home/newmen/gcc/bin/g++ -Wl,-O1 -Wl,-z,relro -o cellular_life main.o mainwindow.o renderarea.o button.o playbutton.o moc_mainwindow.o moc_renderarea.o moc_button.o moc_playbutton.o -L/home/newmen/gcc/lib64 -L/home/newmen/projects/d/life/lib -llife -lQtGui -lQtCore -lpthread -lgphobos2 /home/newmen/projects/d/life/lib/liblife.a(complete_automata.o): In function `_D17complete_automata16CompleteAutomata7restoreMRZv14SliceAgregator9initValueMxFmmZi': complete_automata.d:(.text+0x0): multiple definition of `_D17complete_automata16CompleteAutomata7restoreMRZv14SliceAgregator9initValueMxFmmZi' /home/newmen/projects/d/life/lib/liblife.a(complete_automata_1e3_675.o):complete_automata.d:(.text._D17complete_automata16CompleteAutomata7restoreMRZv14SliceAgregator9initValueMxFmmZi+0x0): first defined here /home/newmen/projects/d/life/lib/liblife.a(complete_automata.o): In function `CompleteAutomata::invert(unsigned long long, unsigned long long)': complete_automata.d:(.text+0x40): multiple definition of `CompleteAutomata::invert(unsigned long long, unsigned long long)' /home/newmen/projects/d/life/lib/liblife.a(complete_automata_1e3_675.o):complete_automata.d:(.text._ZN16CompleteAutomata6invertEyy+0x0): first defined here ... /home/newmen/gcc/lib64/libgphobos2.a(dmain2.o): In function `main': /home/newmen/projects/distrib/gcc-4.8.1/x86_64-unknown-linux-gnu/libphobos/libdruntime/../../.././libphobos/libdruntime/rt/dmain2.d:394: multiple definition of `main' main.o:/home/newmen/projects/d/life/qt_viewer/main.cpp:5: first defined here /usr/bin/ld: /home/newmen/gcc/lib64/libgphobos2.a(time.o): undefined reference to symbol ' clock_getres@ @GLIBC_2.2.5' /usr/bin/ld: note: ' clock_getres@ @GLIBC_2.2.5' is defined in DSO /lib64/librt.so.1 so try adding it to the linker command line /lib64/librt.so.1: could not read symbols: Invalid operation collect2: error: ld returned 1 exit status make: *** [cellular_life] Error 1 

with the librt.so.1 message at the end. I check / usr / lib 64 and see the library file there.

Dear magic, please tell me how to connect the D library to C ++ code.

Answer 1

It is generally easier to compile a D compiler:

  g++ -c yourfile.cpp dmd yourfile.o d_file.d 

You may need to add a curl to it, as before. To pass the linker argument via dmd (or gdmd, if you use gdc, should work the same way), pass -Larg

  dmd yourfile.o d_file.d -L-lstdc++ -L-lcurl -L-lQtGui # and so on 

It is generally easier to put main () in D (it can immediately call the C ++ function), because otherwise you will probably have to initialize the D working environment before using it from C ++.

But to finish the process that you started ... first, it looks like your liblife.a has the same file added twice. I would try to delete this file and recreate it, or just skip this step and transfer the .o files directly to the linker without first packing them into .a. This will simplify things a bit.

My other question is: why is he trying to pull out the main D? Is there a main () in your .d code? If yes, this is fine, but you will have to remove it from your C ++ code. (Perhaps rename it to cppmain, and then call it from main D:

D code:

 extern(C++) int cppmain(int argc, char** argv); int main() { import core.runtime; return cppmain(Runtime.cArgs.argc, Runtime.cArgs.argv); } 

And this will go to your main C ++. If you want to remove the main D (if there is one, if you don’t tell me, and I’ll try to think what else might cause this linker error), before using the D code in C ++, you will want to initialize D. So:

D code:

 extern(C++) void initD() { import core.runtime; Runtime.initialize(); } 

C ++ Code:

 extern "C++" void initD(); int main() { initD(); // the rest of your stuff } 

If you do not, calls to D functions can call segfault.

But to summarize, I'm sure that you have a duplicated .o file added to your archive, and the main part is defined in both D and C ++. Delete the duplicate in the archive and destroy one of the network duplicates, and you should have some success.