In my latest attempt to finally build the gtk3 package with ghc-head 'ghc-master' (7.11.20151024) for a current project under windows x64 using the latest msys2-version and its supplied gtk3 libraries (mingw64/mingw-w64-x86_64-gtk3 3.18.2-1) I encountered this cryptical (linking) error. (See complete log for command './Setup build -v3' attached) I should add that I'm rather a beginner with regards to the Haskell language and its package distribution system cabal. Thus all thoughts, ideas and suggestions how to fix this problem are welcome. Best regards Burkhard complete building response in msys2-shell using the mingw64 script: $ ./Setup build -v3 Component build order: library creating dist\build creating dist\build\autogen Building glib-0.13.2.1... Environment: [("","C:=C:\\Windows\\System32"),("ACLOCAL_PATH","C:\\MSYS2\\mingw64\\share\\aclocal;C:\\MSYS2\\usr\\share\\aclocal"),("ALLUSERSPROFILE","C:\\ProgramData"),("APPDATA","C:\\Users\\PC-08\\AppData\\Roaming"),("CHECKDEF","C:\\Applications\\wingx\\bin"),("COMMONPROGRAMFILES","C:\\Program Files\\Common Files"),("COMMONPROGRAMFILES(X86)","C:\\Program Files (x86)\\Common Files"),("COMMONPROGRAMW6432","C:\\Program Files\\Common Files"),("COMPUTERNAME","PC-08"),("COMSPEC","C:\\Windows\\system32\\cmd.exe"),("FP_NO_HOST_CHECK","NO"),("HOME","C:\\MSYS2\\home\\Ms PC-08"),("HOMEDRIVE","C:"),("HOMEPATH","\\Users\\PC-08"),("HOSTNAME","PC-08"),("INFOPATH","C:\\MSYS2\\usr\\local\\info;C:\\MSYS2\\usr\\share\\info;C:\\MSYS2\\usr\\info;C:\\MSYS2\\share\\info"),("LANG","de_DE.UTF-8"),("LOCALAPPDATA","C:\\Users\\PC-08\\AppData\\Local"),("LOGONSERVER","\\\\PC-08"),("MANPATH","C:\\MSYS2\\mingw64\\share\\man;C:\\MSYS2\\usr\\local\\man;C:\\MSYS2\\usr\\share\\man;C:\\MSYS2\\usr\\man;C:\\MSYS2\\share\\man"),("MSYSCON","mintty.exe"),("MSYSTEM","MINGW64"),("NUMBER_OF_PROCESSORS","4"),("OLDPWD","C:/MSYS2/home/Ms PC-08/cabal"),("ORTEPDIR","C:\\Applications\\ortep3"),("OS","Windows_NT"),("PATH","C:\\Users\\PC-08\\AppData\\Roaming\\cabal\\bin;C:\\Haskell\\ghc-7.11.20151024\\bin;C:\\Haskell\\ghc-7.11.20151024\\mingw\\bin;C:\\MSYS2\\mingw64\\bin;C:\\MSYS2\\usr\\local\\bin;C:\\MSYS2\\usr\\bin;C:\\MSYS2\\usr\\bin;C:\\Program Files (x86)\\CambridgeSoft\\ChemOffice2015\\ChemScript\\Lib;C:\\Windows\\system32;C:\\Windows;C:\\Windows\\System32\\Wbem;C:\\Windows\\System32\\WindowsPowerShell\\v1.0;C:\\Program Files (x86)\\ATI Technologies\\ATI.ACE\\Core-Static;C:\\Program Files\\Intel\\WiFi\\bin;C:\\Program Files\\Common Files\\Intel\\WirelessCommon;C:\\Applications\\LinksPortable;C:\\Program Files\\Intel\\WiFi\\bin;C:\\Program Files\\Common Files\\Intel\\WirelessCommon;C:\\Program Files\\Miktex\\miktex\\bin\\x64;C:\\MSYS2\\usr\\bin\\site_perl;C:\\MSYS2\\usr\\bin\\vendor_perl;C:\\MSYS2\\usr\\bin\\core_perl;C:\\Users\\PC-08\\AppData\\Roaming\\cabal\\bin;C:\\Users\\PC-08\\AppData\\Roaming\\cabal\\bin"),("PATHEXT",".COM;.EXE;.BAT;.CMD;.VBS;.VBE;.JS;.JSE;.WSF;.WSH;.MSC"),("PGFONT","C:\\Applications\\wingx\\files\\grfont.dat"),("PKG_CONFIG_PATH","C:\\MSYS2\\mingw64\\lib\\pkgconfig;C:\\MSYS2\\mingw64\\share\\pkgconfig"),("PRINTER","Brother HL-5270DN"),("PROCESSOR_ARCHITECTURE","AMD64"),("PROCESSOR_IDENTIFIER","Intel64 Family 6 Model 69 Stepping 1, GenuineIntel"),("PROCESSOR_LEVEL","6"),("PROCESSOR_REVISION","4501"),("PROGRAMDATA","C:\\ProgramData"),("PROGRAMFILES","C:\\Program Files"),("PROGRAMFILES(X86)","C:\\Program Files (x86)"),("PROGRAMW6432","C:\\Program Files"),("PROMPT","$P$G"),("PS1","\\[\\e]0;\\w\\a\\]\\n\\[\\e[32m\\]\\u@\\h \\[\\e[35m\\]$MSYSTEM\\[\\e[0m\\] \\[\\e[33m\\]\\w\\[\\e[0m\\]\\n\\$ "),("PSMODULEPATH","C:\\Windows\\system32\\WindowsPowerShell\\v1.0\\Modules\\"),("PUBLIC","C:\\Users\\Public"),("PWD","C:/Haskell/gtk2hs-master/glib"),("PYTHONPATH","C:\\Program Files (x86)\\CambridgeSoft\\ChemOffice2015\\ChemScript\\Lib"),("RASMOLPATH","C:\\Program Files (x86)\\RasWin"),("SESSIONNAME","Console"),("SHELL","C:/MSYS2/usr/bin/bash"),("SHLVL","1"),("SYSTEMDRIVE","C:"),("SYSTEMROOT","C:\\Windows"),("TEMP","C:\\Users\\PC-08\\AppData\\Local\\Temp"),("TERM","xterm-256color"),("TMP","C:\\Users\\PC-08\\AppData\\Local\\Temp"),("UOIPME_REG_PATH","C:\\Program Files\\Intel Corporation\\USB over IP"),("USER","Ms PC-08"),("USERDOMAIN","PC-08"),("USERNAME","Ms PC-08"),("USERPROFILE","C:\\Users\\PC-08"),("VS110COMNTOOLS","C:\\Program Files (x86)\\Microsoft Visual Studio 11.0\\Common7\\Tools\\"),("VS120COMNTOOLS","C:\\Program Files (x86)\\Microsoft Visual Studio 12.0\\Common7\\Tools\\"),("WD","C:\\MSYS2\\usr\\bin\\"),("WINDIR","C:\\Windows"),("WINGXDIR","C:\\Applications\\wingx"),("XML_CATALOG_FILES","C:/MSYS2/etc/xml/docbook-xml /etc/xml/catalog"),("_","./Setup")] ("C:\\Haskell\\ghc-7.11.20151024\\bin\\ghc-pkg.exe",["init","dist\\package.conf.inplace","-v2"]) writing cache dist\package.conf.inplace\package.cache Preprocessing library glib-0.13.2.1... creating dist\build\System\Glib Environment: [("","C:=C:\\Windows\\System32"),("ACLOCAL_PATH","C:\\MSYS2\\mingw64\\share\\aclocal;C:\\MSYS2\\usr\\share\\aclocal"),("ALLUSERSPROFILE","C:\\ProgramData"),("APPDATA","C:\\Users\\PC-08\\AppData\\Roaming"),("CHECKDEF","C:\\Applications\\wingx\\bin"),("COMMONPROGRAMFILES","C:\\Program Files\\Common Files"),("COMMONPROGRAMFILES(X86)","C:\\Program Files (x86)\\Common Files"),("COMMONPROGRAMW6432","C:\\Program Files\\Common Files"),("COMPUTERNAME","PC-08"),("COMSPEC","C:\\Windows\\system32\\cmd.exe"),("FP_NO_HOST_CHECK","NO"),("HOME","C:\\MSYS2\\home\\Ms PC-08"),("HOMEDRIVE","C:"),("HOMEPATH","\\Users\\PC-08"),("HOSTNAME","PC-08"),("INFOPATH","C:\\MSYS2\\usr\\local\\info;C:\\MSYS2\\usr\\share\\info;C:\\MSYS2\\usr\\info;C:\\MSYS2\\share\\info"),("LANG","de_DE.UTF-8"),("LOCALAPPDATA","C:\\Users\\PC-08\\AppData\\Local"),("LOGONSERVER","\\\\PC-08"),("MANPATH","C:\\MSYS2\\mingw64\\share\\man;C:\\MSYS2\\usr\\local\\man;C:\\MSYS2\\usr\\share\\man;C:\\MSYS2\\usr\\man;C:\\MSYS2\\share\\man"),("MSYSCON","mintty.exe"),("MSYSTEM","MINGW64"),("NUMBER_OF_PROCESSORS","4"),("OLDPWD","C:/MSYS2/home/Ms PC-08/cabal"),("OS","Windows_NT"),("PATH","C:\\Users\\PC-08\\AppData\\Roaming\\cabal\\bin;C:\\Haskell\\ghc-7.11.20151024\\bin;C:\\Haskell\\ghc-7.11.20151024\\mingw\\bin;C:\\MSYS2\\mingw64\\bin;C:\\MSYS2\\usr\\local\\bin;C:\\MSYS2\\usr\\bin;C:\\MSYS2\\usr\\bin;C:\\Windows\\system32;C:\\Windows;C:\\Windows\\System32\\Wbem;C:\\Windows\\System32\\WindowsPowerShell\\v1.0;C:\\Program Files (x86)\\ATI Technologies\\ATI.ACE\\Core-Static;C:\\Program Files\\Intel\\WiFi\\bin;C:\\Program Files\\Common Files\\Intel\\WirelessCommon;C:\\Program Files\\Intel\\WiFi\\bin;C:\\Program Files\\Common Files\\Intel\\WirelessCommon;C:\\Program Files\\Miktex\\miktex\\bin\\x64;C:\\MSYS2\\usr\\bin\\site_perl;C:\\MSYS2\\usr\\bin\\vendor_perl;C:\\MSYS2\\usr\\bin\\core_perl;C:\\Users\\PC-08\\AppData\\Roaming\\cabal\\bin;C:\\Users\\PC-08\\AppData\\Roaming\\cabal\\bin"),("PATHEXT",".COM;.EXE;.BAT;.CMD;.VBS;.VBE;.JS;.JSE;.WSF;.WSH;.MSC"),("PGFONT","C:\\Applications\\wingx\\files\\grfont.dat"),("PKG_CONFIG_PATH","C:\\MSYS2\\mingw64\\lib\\pkgconfig;C:\\MSYS2\\mingw64\\share\\pkgconfig"),("PRINTER",""),("PROCESSOR_ARCHITECTURE","AMD64"),("PROCESSOR_IDENTIFIER","Intel64 Family 6 Model 69 Stepping 1, GenuineIntel"),("PROCESSOR_LEVEL","6"),("PROCESSOR_REVISION","4501"),("PROGRAMDATA","C:\\ProgramData"),("PROGRAMFILES","C:\\Program Files"),("PROGRAMFILES(X86)","C:\\Program Files (x86)"),("PROGRAMW6432","C:\\Program Files"),("PROMPT","$P$G"),("PS1","\\[\\e]0;\\w\\a\\]\\n\\[\\e[32m\\]\\u@\\h \\[\\e[35m\\]$MSYSTEM\\[\\e[0m\\] \\[\\e[33m\\]\\w\\[\\e[0m\\]\\n\\$ "),("PSMODULEPATH","C:\\Windows\\system32\\WindowsPowerShell\\v1.0\\Modules\\"),("PUBLIC","C:\\Users\\Public"),("PWD","C:/Haskell/gtk2hs-master/glib"),("PYTHONPATH","C:\\Program Files (x86)\\CambridgeSoft\\ChemOffice2015\\ChemScript\\Lib"),("RASMOLPATH","C:\\Program Files (x86)\\RasWin"),("SESSIONNAME","Console"),("SHELL","C:/MSYS2/usr/bin/bash"),("SHLVL","1"),("SYSTEMDRIVE","C:"),("SYSTEMROOT","C:\\Windows"),("TEMP","C:\\Users\\PC-08\\AppData\\Local\\Temp"),("TERM","xterm-256color"),("TMP","C:\\Users\\PC-08\\AppData\\Local\\Temp"),("UOIPME_REG_PATH","C:\\Program Files\\Intel Corporation\\USB over IP"),("USER","Ms PC-08"),("USERDOMAIN","PC-08"),("USERNAME","Ms PC-08"),("USERPROFILE","C:\\Users\\PC-08"),("VS110COMNTOOLS","C:\\Program Files (x86)\\Microsoft Visual Studio 11.0\\Common7\\Tools\\"),("VS120COMNTOOLS","C:\\Program Files (x86)\\Microsoft Visual Studio 12.0\\Common7\\Tools\\"),("WD","C:\\MSYS2\\usr\\bin\\"),("WINDIR","C:\\Windows"),("WINGXDIR","C:\\Applications\\wingx"),("XML_CATALOG_FILES","C:/MSYS2/etc/xml/docbook-xml /etc/xml/catalog"),("_","./Setup")] ("C:\\Haskell\\ghc-7.11.20151024\\bin\\hsc2hs.exe",["--cc=C:\\Haskell\\ghc-7.11.20151024\\mingw\\bin\\gcc.exe","--ld=C:\\Haskell\\ghc-7.11.20151024\\mingw\\bin\\gcc.exe","--cflag=-fno-stack-protector","--lflag=-fno-stack-protector","--cflag=-D__GLASGOW_HASKELL__=711","--cflag=-Dmingw32_BUILD_OS=1","--cflag=-Dx86_64_BUILD_ARCH=1","--cflag=-Dmingw32_HOST_OS=1","--cflag=-Dx86_64_HOST_ARCH=1","--cflag=-Idist\\build\\autogen","--cflag=-Idist\\build","--cflag=-ISystem/Glib","--cflag=-IC:/MSYS2/mingw64/include/glib-2.0","--cflag=-IC:/MSYS2/mingw64/lib/glib-2.0/include","--cflag=-mms-bitfields","--cflag=-U__BLOCKS__","--cflag=-D__attribute__(A)=","--cflag=-DUSE_GCLOSURE_SIGNALS_IMPL","--cflag=-Idist\\build\\autogen","--cflag=-include","--cflag=dist\\build\\autogen\\cabal_macros.h","--lflag=-LC:/MSYS2/mingw64/lib","--lflag=-lgobject-2.0","--lflag=-lglib-2.0","--lflag=-lintl","--cflag=-IC:\\Haskell\\ghc-7.11.20151024\\lib\\bytestring-0.10.6.0\\include","--cflag=-IC:\\Haskell\\ghc-7.11.20151024\\lib\\base-4.8.2.0\\include","--cflag=-IC:\\Haskell\\ghc-7.11.20151024\\lib\\integer-gmp-1.0.0.0\\include","--cflag=-IC:\\Haskell\\ghc-7.11.20151024\\lib/include","--lflag=-LC:\\Users\\PC-08\\AppData\\Roaming\\cabal\\x86_64-windows-ghc-7.11.20151024\\utf8s_LAIfwUZWplI3JK3b6W44Yv","--lflag=-LC:\\Users\\PC-08\\AppData\\Roaming\\cabal\\x86_64-windows-ghc-7.11.20151024\\text_IqwR9CiNGjxJyQdu3bLbNv","--lflag=-LC:\\Haskell\\ghc-7.11.20151024\\lib\\binary-0.7.5.0","--lflag=-LC:\\Haskell\\ghc-7.11.20151024\\lib\\containers-0.5.6.2","--lflag=-LC:\\Haskell\\ghc-7.11.20151024\\lib\\bytestring-0.10.6.0","--lflag=-LC:\\Haskell\\ghc-7.11.20151024\\lib\\deepseq-1.4.1.1","--lflag=-LC:\\Haskell\\ghc-7.11.20151024\\lib\\array-0.5.1.0","--lflag=-LC:\\Haskell\\ghc-7.11.20151024\\lib\\base-4.8.2.0","--lflag=-lwsock32","--lflag=-luser32","--lflag=-lshell32","--lflag=-LC:\\Haskell\\ghc-7.11.20151024\\lib\\integer-gmp-1.0.0.0","--lflag=-LC:\\Haskell\\ghc-7.11.20151024\\lib\\ghc-prim-0.4.0.0","--lflag=-LC:\\Haskell\\ghc-7.11.20151024\\lib/rts","--lflag=-lm","--lflag=-lwsock32","--lflag=-lgdi32","--lflag=-lwinmm","-o","dist\\build\\System\\Glib\\StoreValue.hs","System\\Glib\\StoreValue.hsc"]) dist\build\System\Glib\StoreValue_hsc_utils.o:StoreValue_hsc_utils.c:(.text+0x0): multiple definition of `__debugbreak' dist\build\System\Glib\StoreValue_hsc_make.o:StoreValue_hsc_make.c:(.text+0x0): first defined here collect2.exe: error: ld returned 1 exit status linking dist\build\System\Glib\StoreValue_hsc_make.o failed (exit code 1) command was: C:\Haskell\ghc-7.11.20151024\mingw\bin\gcc.exe dist\build\System\Glib\StoreValue_hsc_make.o dist\build\System\Glib\StoreValue_hsc_utils.o -o dist\build\System\Glib\StoreValue_hsc_make.exe -fno-stack-protector -LC:/MSYS2/mingw64/lib -lgobject-2.0 -lglib-2.0 -lintl -LC:\Users\PC-08\AppData\Roaming\cabal\x86_64-windows-ghc-7.11.20151024\utf8s_LAIfwUZWplI3JK3b6W44Yv -LC:\Users\PC-08\AppData\Roaming\cabal\x86_64-windows-ghc-7.11.20151024\text_IqwR9CiNGjxJyQdu3bLbNv -LC:\Haskell\ghc-7.11.20151024\lib\binary-0.7.5.0 -LC:\Haskell\ghc-7.11.20151024\lib\containers-0.5.6.2 -LC:\Haskell\ghc-7.11.20151024\lib\bytestring-0.10.6.0 -LC:\Haskell\ghc-7.11.20151024\lib\deepseq-1.4.1.1 -LC:\Haskell\ghc-7.11.20151024\lib\array-0.5.1.0 -LC:\Haskell\ghc-7.11.20151024\lib\base-4.8.2.0 -lwsock32 -luser32 -lshell32 -LC:\Haskell\ghc-7.11.20151024\lib\integer-gmp-1.0.0.0 -LC:\Haskell\ghc-7.11.20151024\lib\ghc-prim-0.4.0.0 -LC:\Haskell\ghc-7.11.20151024\lib/rts -lm -lwsock32 -lgdi32 -lwinmm C:\Haskell\ghc-7.11.20151024\bin\hsc2hs.exe returned ExitFailure 1