Qt 5.11.3 works fine, but Qt 5.12.1 throws LINKER errors

m3g1dd

I double-checked to make sure nothing is missed:

Qt_5_12_0_MSVC2017_64bit-Debug links fine and application runs :)
Qt_5_12_0_MSVC2017_64bit-Release links fine and application runs :)
Qt_5_12_1_MSVC2017_64bit-Debug throws:

main.obj : error LNK2019: unresolved external symbol "__declspec(dllimport) void __cdecl NetLibrary::registerNetLibraryQML(void)" (_imp?registerNetLibraryQML@NetLibrary@@YAXXZ) referenced in function main

Qt_5_12_1_MSVC2017_64bit-Release throws:

main.obj : error LNK2019: unresolved external symbol "__declspec(dllimport) void __cdecl NetLibrary::registerNetLibraryQML(void)" (_imp?registerNetLibraryQML@NetLibrary@@YAXXZ) referenced in function main

Also, here is the dumpbin for netlib.lib on Qt_5_12_0_MSVC2017_64bit-Debug which links fine and works nice:

C:\Users\me\repos\build-application-Desktop_Qt_5_12_0_MSVC2017_64bit-Debug\netlib\debug>dumpbin /linkermember netlib.lib
Microsoft (R) COFF/PE Dumper Version 14.15.26730.0
Copyright (C) Microsoft Corporation.  All rights reserved.


Dump of file netlib.lib

File Type: LIBRARY

Archive member name at 8: /
FFFFFFFF time/date
         uid
         gid
       0 mode
     C3D size
correct header end

    69 public symbols

     190A __IMPORT_DESCRIPTOR_netlib
     1B30 __NULL_IMPORT_DESCRIPTOR
     1C66 netlib_NULL_THUNK_DATA
     2878 ?registerNetLibraryQML@NetLibrary@@YAXXZ
     2878 __imp_?registerNetLibraryQML@NetLibrary@@YAXXZ
     2E0C ?tr@Netlib@@SA?AVQString@@PEBD0H@Z
     2E0C __imp_?tr@Netlib@@SA?AVQString@@PEBD0H@Z
     2E8A ?trUtf8@Netlib@@SA?AVQString@@PEBD0H@Z
     2E8A __imp_?trUtf8@Netlib@@SA?AVQString@@PEBD0H@Z
     1DBE ??0Netlib@@QEAA@XZ
     1DBE __imp_??0Netlib@@QEAA@XZ
     1E2C ??1Netlib@@UEAA@XZ
     1E2C __imp_??1Netlib@@UEAA@XZ
     1F06 ?agentDiscover@Netlib@@QEAAXXZ
     1F06 __imp_?agentDiscover@Netlib@@QEAAXXZ
     1FFA ?agentSlice@Netlib@@QEAA_NAEBVQUrl@@AEBVQString@@V3@222@Z
     1FFA __imp_?agentSlice@Netlib@@QEAA_NAEBVQUrl@@AEBVQString@@V3@222@Z
     210E ?discoveryInProgress@Netlib@@QEBA_NXZ
     210E __imp_?discoveryInProgress@Netlib@@QEBA_NXZ
     28FC ?setDiscoveryInProgress@Netlib@@QEAAX_N@Z
     28FC __imp_?setDiscoveryInProgress@Netlib@@QEAAX_N@Z
     2C7E ?slicingInProgress@Netlib@@QEBA_NXZ
     2C7E __imp_?slicingInProgress@Netlib@@QEBA_NXZ
     2A82 ?setSlicingInProgress@Netlib@@QEAAX_N@Z
     2A82 __imp_?setSlicingInProgress@Netlib@@QEAAX_N@Z
     2530 ?layerID@Netlib@@QEBA?AVQString@@XZ
     2530 __imp_?layerID@Netlib@@QEBA?AVQString@@XZ
     2982 ?setLayerID@Netlib@@QEAAXVQString@@@Z
     2982 __imp_?setLayerID@Netlib@@QEAAXVQString@@@Z
     2B82 ?slicingDone@Netlib@@QEBA_NXZ
     2B82 __imp_?slicingDone@Netlib@@QEBA_NXZ
     2A04 ?setSlicingDone@Netlib@@QEAAX_N@Z
     2A04 __imp_?setSlicingDone@Netlib@@QEAAX_N@Z
     24BE ?init@Netlib@@AEAAXXZ
     24BE __imp_?init@Netlib@@AEAAXXZ
     22AA ?getOsName@Netlib@@AEAA?AVQString@@XZ
     22AA __imp_?getOsName@Netlib@@AEAA?AVQString@@XZ
     2090 ?discoveryFinished@Netlib@@AEAAXXZ
     2090 __imp_?discoveryFinished@Netlib@@AEAAXXZ
     2B06 ?slicerFinished@Netlib@@AEAAXXZ
     2B06 __imp_?slicerFinished@Netlib@@AEAAXXZ
     1F80 ?agentLogReady@Netlib@@AEAAXXZ
     1F80 __imp_?agentLogReady@Netlib@@AEAAXXZ
     2430 ?handleSlicingInProgressChanged@Netlib@@AEAAX_N@Z
     2430 __imp_?handleSlicingInProgressChanged@Netlib@@AEAAX_N@Z
     232C ?getSlicerProgress@Netlib@@AEAAXXZ
     232C __imp_?getSlicerProgress@Netlib@@AEAAXXZ
     23AA ?getSlicerProgressFinished@Netlib@@AEAAXXZ
     23AA __imp_?getSlicerProgressFinished@Netlib@@AEAAXXZ
     1E9A __imp_??_7Netlib@@6B@
     2636 ?metaObject@Netlib@@UEBAPEBUQMetaObject@@XZ
     2636 __imp_?metaObject@Netlib@@UEBAPEBUQMetaObject@@XZ
     2752 ?qt_metacast@Netlib@@UEAAPEAXPEBD@Z
     2752 __imp_?qt_metacast@Netlib@@UEAAPEAXPEBD@Z
     26BE ?qt_metacall@Netlib@@UEAAHW4Call@QMetaObject@@HPEAPEAX@Z
     26BE __imp_?qt_metacall@Netlib@@UEAAHW4Call@QMetaObject@@HPEAPEAX@Z
     27D2 ?qt_static_metacall@Netlib@@CAXPEAVQObject@@W4Call@QMetaObject@@HPEAPEAX@Z
     27D2 __imp_?qt_static_metacall@Netlib@@CAXPEAVQObject@@W4Call@QMetaObject@@HPEAPEAX@Z
     2190 ?discoveryInProgressChanged@Netlib@@QEAAX_N@Z
     2190 __imp_?discoveryInProgressChanged@Netlib@@QEAAX_N@Z
     221A ?discoveryResultChanged@Netlib@@QEAAXVQJsonArray@@@Z
     221A __imp_?discoveryResultChanged@Netlib@@QEAAXVQJsonArray@@@Z
     2CFE ?slicingInProgressChanged@Netlib@@QEAAX_N@Z
     2CFE __imp_?slicingInProgressChanged@Netlib@@QEAAX_N@Z
     25B0 ?layerIDChanged@Netlib@@QEAAXVQString@@@Z
     25B0 __imp_?layerIDChanged@Netlib@@QEAAXVQString@@@Z
     2BFC ?slicingDoneChanged@Netlib@@QEAAX_N@Z
     2BFC __imp_?slicingDoneChanged@Netlib@@QEAAX_N@Z
     2D86 __imp_?staticMetaObject@Netlib@@2UQMetaObject@@B

Archive member name at C82: /
FFFFFFFF time/date
         uid
         gid
       0 mode
     C4B size
correct header end

    37 offsets

        1     190A
        2     1B30
        3     1C66
        4     2878
        5     2E0C
        6     2E8A
        7     1DBE
        8     1E2C
        9     1F06
        A     1FFA
        B     210E
        C     28FC
        D     2C7E
        E     2A82
        F     2530
       10     2982
       11     2B82
       12     2A04
       13     24BE
       14     22AA
       15     2090
       16     2B06
       17     1F80
       18     2430
       19     232C
       1A     23AA
       1B     1E9A
       1C     2636
       1D     2752
       1E     26BE
       1F     27D2
       20     2190
       21     221A
       22     2CFE
       23     25B0
       24     2BFC
       25     2D86

    69 public symbols

        7 ??0Netlib@@QEAA@XZ
        8 ??1Netlib@@UEAA@XZ
        9 ?agentDiscover@Netlib@@QEAAXXZ
       17 ?agentLogReady@Netlib@@AEAAXXZ
        A ?agentSlice@Netlib@@QEAA_NAEBVQUrl@@AEBVQString@@V3@222@Z
       15 ?discoveryFinished@Netlib@@AEAAXXZ
        B ?discoveryInProgress@Netlib@@QEBA_NXZ
       20 ?discoveryInProgressChanged@Netlib@@QEAAX_N@Z
       21 ?discoveryResultChanged@Netlib@@QEAAXVQJsonArray@@@Z
       14 ?getOsName@Netlib@@AEAA?AVQString@@XZ
       19 ?getSlicerProgress@Netlib@@AEAAXXZ
       1A ?getSlicerProgressFinished@Netlib@@AEAAXXZ
       18 ?handleSlicingInProgressChanged@Netlib@@AEAAX_N@Z
       13 ?init@Netlib@@AEAAXXZ
        F ?layerID@Netlib@@QEBA?AVQString@@XZ
       23 ?layerIDChanged@Netlib@@QEAAXVQString@@@Z
       1C ?metaObject@Netlib@@UEBAPEBUQMetaObject@@XZ
       1E ?qt_metacall@Netlib@@UEAAHW4Call@QMetaObject@@HPEAPEAX@Z
       1D ?qt_metacast@Netlib@@UEAAPEAXPEBD@Z
       1F ?qt_static_metacall@Netlib@@CAXPEAVQObject@@W4Call@QMetaObject@@HPEAPEAX@Z
        4 ?registerNetLibraryQML@NetLibrary@@YAXXZ
        C ?setDiscoveryInProgress@Netlib@@QEAAX_N@Z
       10 ?setLayerID@Netlib@@QEAAXVQString@@@Z
       12 ?setSlicingDone@Netlib@@QEAAX_N@Z
        E ?setSlicingInProgress@Netlib@@QEAAX_N@Z
       16 ?slicerFinished@Netlib@@AEAAXXZ
       11 ?slicingDone@Netlib@@QEBA_NXZ
       24 ?slicingDoneChanged@Netlib@@QEAAX_N@Z
        D ?slicingInProgress@Netlib@@QEBA_NXZ
       22 ?slicingInProgressChanged@Netlib@@QEAAX_N@Z
        5 ?tr@Netlib@@SA?AVQString@@PEBD0H@Z
        6 ?trUtf8@Netlib@@SA?AVQString@@PEBD0H@Z
        1 __IMPORT_DESCRIPTOR_netlib
        2 __NULL_IMPORT_DESCRIPTOR
        7 __imp_??0Netlib@@QEAA@XZ
        8 __imp_??1Netlib@@UEAA@XZ
       1B __imp_??_7Netlib@@6B@
        9 __imp_?agentDiscover@Netlib@@QEAAXXZ
       17 __imp_?agentLogReady@Netlib@@AEAAXXZ
        A __imp_?agentSlice@Netlib@@QEAA_NAEBVQUrl@@AEBVQString@@V3@222@Z
       15 __imp_?discoveryFinished@Netlib@@AEAAXXZ
        B __imp_?discoveryInProgress@Netlib@@QEBA_NXZ
       20 __imp_?discoveryInProgressChanged@Netlib@@QEAAX_N@Z
       21 __imp_?discoveryResultChanged@Netlib@@QEAAXVQJsonArray@@@Z
       14 __imp_?getOsName@Netlib@@AEAA?AVQString@@XZ
       19 __imp_?getSlicerProgress@Netlib@@AEAAXXZ
       1A __imp_?getSlicerProgressFinished@Netlib@@AEAAXXZ
       18 __imp_?handleSlicingInProgressChanged@Netlib@@AEAAX_N@Z
       13 __imp_?init@Netlib@@AEAAXXZ
        F __imp_?layerID@Netlib@@QEBA?AVQString@@XZ
       23 __imp_?layerIDChanged@Netlib@@QEAAXVQString@@@Z
       1C __imp_?metaObject@Netlib@@UEBAPEBUQMetaObject@@XZ
       1E __imp_?qt_metacall@Netlib@@UEAAHW4Call@QMetaObject@@HPEAPEAX@Z
       1D __imp_?qt_metacast@Netlib@@UEAAPEAXPEBD@Z
       1F __imp_?qt_static_metacall@Netlib@@CAXPEAVQObject@@W4Call@QMetaObject@@HPEAPEAX@Z
        4 __imp_?registerNetLibraryQML@NetLibrary@@YAXXZ
        C __imp_?setDiscoveryInProgress@Netlib@@QEAAX_N@Z
       10 __imp_?setLayerID@Netlib@@QEAAXVQString@@@Z
       12 __imp_?setSlicingDone@Netlib@@QEAAX_N@Z
        E __imp_?setSlicingInProgress@Netlib@@QEAAX_N@Z
       16 __imp_?slicerFinished@Netlib@@AEAAXXZ
       11 __imp_?slicingDone@Netlib@@QEBA_NXZ
       24 __imp_?slicingDoneChanged@Netlib@@QEAAX_N@Z
        D __imp_?slicingInProgress@Netlib@@QEBA_NXZ
       22 __imp_?slicingInProgressChanged@Netlib@@QEAAX_N@Z
       25 __imp_?staticMetaObject@Netlib@@2UQMetaObject@@B
        5 __imp_?tr@Netlib@@SA?AVQString@@PEBD0H@Z
        6 __imp_?trUtf8@Netlib@@SA?AVQString@@PEBD0H@Z
        3 netlib_NULL_THUNK_DATA

  Summary

          C0 .debug$S
          14 .idata$2
          14 .idata$3
           8 .idata$4
           8 .idata$5
           C .idata$6

hskoglund

Hi, the dumpbin for 5.12.1 is identical to 5.12.0. Seems netlib.lib is the innocent guy here. So it must be the client program, i.e. your main.cpp, perhaps some kind of visibility problem. We're running out of options so I'm thinking you could try renaming your library to something less generic/vanilla (there are many other libraries called netlib.xxx out there, perhaps one of them has snuck into in 5.12.1)

So say instead of netlib you could call it m3gnetlib (prefixing with half of your username).
That would mean changing the .pro file, the .h and .cpp files and also the #define from NETLIBSHARED_EXPORT to M3GNETLIBSHARED_EXPORT.

I remember running into similar inexplicable issues in the past, and renaming the files helped (sometimes :-)

mchinand

In 5.12.1, default Windows library paths (e.g., Windows Kits) were added to the search path in qmake's makefile generator, but were added before the user-specified paths instead of after. There's already a commit to fix this and should be in 5.12.3. See this bugreport

hskoglund

Thanks @mchinand!

In Qt 5.12.1 @m3g1dd 's netlib.lib gets muscled out by the big wheels at Microsoft, when I do a dir of the Windows Kits on my C: indeed there's a netlib.lib there. And that's what the linker tries to link with.

So either as I mentioned above go do that renaming, or wait for 5.12.3.

m3g1dd

@hskoglund

Hi, Thanks! Problem got resolved by renaming the netlib library to netagentlib, and Qt 5.12.1 builds and runs the application without any issue.

These are all my code changes to rename the library:

On my netlib library project file i.e. netlib.pro file I changed:

-TARGET = netlib
+TARGET = netagentlib

Also, on my application executable project *.pro file I replaced these lines:

win32:CONFIG(release, debug|release): LIBS += -L$$OUT_PWD/../netlib/release/ -lnetlib
else:win32:CONFIG(debug, debug|release): LIBS += -L$$OUT_PWD/../netlib/debug/ -lnetlib
else:unix: LIBS += -L$$OUT_PWD/../netlib/ -lnetlib

with these lines:

win32:CONFIG(release, debug|release): LIBS += -L$$OUT_PWD/../netlib/release/ -lnetagentlib
else:win32:CONFIG(debug, debug|release): LIBS += -L$$OUT_PWD/../netlib/debug/ -lnetagentlib
else:unix: LIBS += -L$$OUT_PWD/../netlib/ -lnetagentlib