Link external library with MSCV compiler

JonB · 22 Aug 2018, 15:28

@elsa
That page would imply it's all MSVC anyway there's no mention of MinGW?
So change your Qt project to link against MSVC .lib files?

elsa · 22 Aug 2018, 15:36

@JonB how do I do this? The code mentioned in my question was used for MinGW and doesn't work for MSCV, so how can I modify it? (I think these two lines link the .dll files, which are compatible with MinGW afaik, and for MSCV we need to explicitly tell it to choose the .lib files) You traditionally do not write the endings of the file name, so how can i specify it?
(and sorry for not replying right away, I can only post every 600s -.-)

JonB · 23 Aug 2018, 07:12

@elsa
I'm going to have to bow out, because I haven't used MinGW, I don't use Qt Creator/cmake/C++, someone else may know better than I.

I will say, I'm confused, because if the libraries are from that page it only talks about MSVC, so I don't even know how MinGW came into it.

I think you should:

Establish what/where your library files, and whether they are MSVC or MinGW.
Make sure however you configure your project to generate linker lines it's using the right linker and command-line options for whatever the correct files for it are. When you changed over from MinGW to MSVC you must have had to re-configure the makes from scratch I imagine, telling it which compiler/linker you're using, I imagine. I don't know, but those link library lines you show still look a bit gcc rather than msvc/link to me, but I could be mistaken.
Make sure your "unresolved"s are not because you are actually trying to call any functions which are not documented as exported from the third-party libraries.
Maybe find a couple of "typical" examples of the "unresolved external symbol errors" you are getting and show them here. It may give us an idea of just what sort of thing it's trying to find.

mrjj · 23 Aug 2018, 06:59

Hi
From page
http://arma.sourceforge.net/download.html
seems they used VS 2012.

Did you compile a new version with the new visual studio ( i assume you didn't use 2012) and new VS cannot load old VS dlls.

what version of VS did u use ?

JonB · 23 Aug 2018, 06:56

In https://forum.qt.io/topic/75458/compatibility-libraries-generated-by-msvc-and-mingw/3 @SGaist also wrote

Thus if any of your dependencies needs a particular version of VS, you have to stay with it.

@elsa Please do show some examples of the error messages.

elsa · 23 Aug 2018, 07:01

@JonB see my edit.

elsa · M mrjj 22 Aug 2018, 18:19

@mrjj hi, I have VS17 and VS15 installed, but yeah, good point. Microsoft has a redistributable for VS12. I will try using it and update you.

JonB · E elsa 23 Aug 2018, 06:56

@elsa
OK, at least that confirms the unresolveds are indeed from your libraries and not from, say, remaining references somewhere to MinGW functions. FWIW, those are "mangled" names which come from references to C++ functions.

I think you should work through the points I suggested. In particular it's now unclear how come MinGW ever came into it/worked, since the third-party link you provided talked only about MSVC....

elsa · 23 Aug 2018, 07:27

@JonB said in Link external library with MSCV compiler:

Make sure however you configure your project to generate linker lines it's using the right linker and command-line options for whatever the correct files for it are. When you changed over from MinGW to MSVC you must have had to re-configure the makes from scratch I imagine, telling it which compiler/linker you're using, I imagine. I don't know, but those link library lines you show still look a bit gcc rather than msvc/link to me, but I could be mistaken.

how does MSCV linking look like? and by "reconfigure" you mean choosing the new kit/compiler and running qmake or is there something else?

JonB · 23 Aug 2018, 08:01

@elsa
I'm not sure about the MSVC command-line. I was thinking it would use LINK and have something like /LIB and/or mention of blas_win32_MT.LIB, I'm niggled by the suspicion it's still trying to link with MinGW libraries, but I'm not sure. You could look at/show the actual linker line that's being executed?

Yes, you needed to pick new compiler/linker kit and re-run qmake, or similar. It's very important that you cleaned everything out --- perferably restarted in a clean folder --- as you don't want any artefacts left over from old compiler/configuration. If it were me, at this point I'd be tempted to set up a brand new project in a new directory which just makes a couple of calls to those libraries and get it all working with MSVC from scratch.

P.S.
blas_win32_MT, lapack_win32_MT: Apart from the fact that you need to check you're compiling & linking your code with /MT, those must be 32-bit libraries. You are compiling your code for 32-bit too, right?

elsa · 23 Aug 2018, 08:06

@JonB said in Link external library with MSCV compiler:

@elsa
I'm not sure about the MSVC command-line. I was thinking it would use LINK and have something like /LIB and/or mention of blas_win32_MT.LIB, I'm niggled by the suspicion it's still trying to link with MinGW libraries, but I'm not sure. You could look at/show the actual linker line that's being executed?

I thought this is just the line from the .pro file that I linked in the question. Is linking also defined somewhere else?

P.S.
blas_win32_MT, lapack_win32_MT: Apart from the fact that you need to check you're compiling & linking your code with /MT, those must be 32-bit libraries. You are compiling your code for 32-bit too, right?

Okay maybe this is the problem!
BIG UPDATE: The above mentioned errors get produced using the 64bit compiler, which -now that you say it- maybe explains why it doesn't work..
The weird thing is, however, when running the 32 bit compiler I get the following error:

error: LNK1112: module machine type 'x86' conflicts with target machine type 'x64'

so I am confused now. Is 32bit or 64bit correct?

JonB · 23 Aug 2018, 08:20

@elsa

I thought this is just the line from the .pro file that I linked in the question. Is linking also defined somewhere else?

All you have shown is a LIBS += ... line in a .pro file. When you compile (link) it must also show the actual command-line it has constructed and is executing using these, presumably in whatever "compiler output window" it has.

error: LNK1112: module machine type 'x86' conflicts with target machine type 'x64'

so I am confused now. Is 32bit or 64bit correct?

x86 means 32-bit, x64 means 64-bit. Assuming from the names that those libraries you have are compiled 32-bit, you must compile everything else 32-bit (or get/compile 64-bit version of the libraries). The fact that you have a message target machine type 'x64' must indicate that somewhere you have told Qt Creator (the .pro file?) that your target is 64-bit, and that does not look good....

elsa · 23 Aug 2018, 08:34

@JonB

All you have shown is a LIBS += ... line in a .pro file. When you compile (link) it must also show the actual command-line it has constructed and is executing using these, presumably in whatever "compiler output window" it has.

link /NOLOGO /DYNAMICBASE /NXCOMPAT /DEBUG /SUBSYSTEM:WINDOWS "/MANIFESTDEPENDENCY:type='win32' name='Microsoft.Windows.Common-Controls' version='6.0.0.0' publicKeyToken='6595b64144ccf1df' language='*' processorArchitecture='*'" /MANIFEST:embed /OUT:debug\DecaRangeRTLS.exe @C:\Users\FRHMELSA\AppData\Local\Temp\DecaRangeRTLS.exe.10468.50531.jom

x86 means 32-bit, x64 means 64-bit. Assuming from the names that those libraries you have are compiled 32-bit, you must compile everything else 32-bit (or get/compile 64-bit version of the libraries). The fact that you have a message target machine type 'x64' must indicate that somewhere you have told Qt Creator (the .pro file?) that your target is 64-bit, and that does not look good....

yes I have reached that assumption as well, but then how do I change the target machine type? :/

JonB · E elsa 23 Aug 2018, 08:20

@elsa
I don't know in Qt Creator, but it can hardly be difficult, presumably you specify it at some point when you set up your project. Google for it.

Unless the error is from one of your libraries already being compiled 64-bit. Check whether those libraries with win32 in them are indeed 32-bit, not 64-bit.

Come on, you can do this, I can't answer!

jsulm · E elsa 23 Aug 2018, 08:20

@elsa said in Link external library with MSCV compiler:

but then how do I change the target machine type?

Use Qt for that target machine type

elsa · 23 Aug 2018, 11:53

@JonB @jsulm @mrjj I will try to start doing all the steps from scratch, because I am getting frustrated and cannot get on with the project because of this linker problem..
I am running Qt5.11.1. So what I read is that it only supports up to VS15, so I installed VS15. Qt, however, did not auto-detect the VS 14.0 compiler, so I had to add it manually. I found the path of the compiler .dll file but Qt also wants a make path (where is it?). This is where I am stuck now. Which make executable do I need for the compiler? and what else am I missing? I am sorry if my questions are to confusing or too easy. I am just trying to understand, because I never dealt with compilers and linkers in detail before and this problem came very unexpected.

jsulm · 23 Aug 2018, 12:18

@elsa said in Link external library with MSCV compiler:

So what I read is that it only supports up to VS15

This is wrong - it supports VS17. But since VS15 and VS17 C++ compiler are compatible this does not matter. If you use Qt online installer you will see what compiler Qt 5.11.1 supports.

"but Qt also wants a make path" - can you please tell us exactly what it asks (screen-shot)?

If my understanding is correct the lib you want to use is built for x86, right? Official Qt build for Windows/VS are all x86_64. You will need a x86_64 build of that lib or build it by yourself.

elsa · 23 Aug 2018, 12:20

@jsulm

This is a screenshot of the kit I am using now. This warning made me think that qt only supports VS15, but if it doesn't make a difference, then it's ok. This is now using the autodetected compiler (VS17), so I don't need to set up the path manually.
And yes the library is x86.

jsulm · 23 Aug 2018, 12:23

@elsa OK, you have 32bit Qt, compiler and lib - does it work now?

elsa · 23 Aug 2018, 12:27

@jsulm it produces this error:

f:\dd\vctools\crt\vcstartup\src\gs\gs_report.c:220: error: Debugger encountered an exception: Exception at 0xca9b99, code: 0xc0000409: , flags=0x1 (execution cannot be continued)
f:\dd\vctools\crt\vcstartup\src\gs\gs_report.c:220: error: Debugger encountered an exception: Exception at 0xca9b99, code: 0xc0000409: , flags=0x1 (execution cannot be continued)