Unresolved external symbols when using ORTools with VS19

Diego Martino

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Mar 30, 2021, 3:03:24 PM3/30/21

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Hi

I'm trying to use ORTools within Visual Studio 2019 but I've been struggling many problems due to unresolved external symbols. I have already checked other issues and questions here in the group but I couldn't find how to fix it.

I've already tried two things:

- getting the code directly from GitHub and build using tools\make third_party and

- getting the compiled file available for VS19

But in both I have the same problem.

Some of the problems:

- LNK2001

- LNK2019

- LNK4049

Can anybody help me? Thanks

Mizux Seiha

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Mar 31, 2021, 2:52:01 AM3/31/21

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Don't get it...
1) Did you manage to run tests ?
```
make third_party

make cc

make test_cc
```

2) Which language are you using ? C++ ?

3) Did you try to integrate the OR-Tools C++ library in your project ?

4) If yes, how did you do that ? can we have a trace (detailed log) of the error ?

5) If you integrate libortools.lib did you also set all needed flags ?
e.g. https://github.com/google/or-tools/blob/fa84bc05e72641dddfbb98164d81b8bc9bef6ea5/tools/Makefile.cc.java.dotnet#L126-L132

Diego Martino

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Mar 31, 2021, 4:18:13 AM3/31/21

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Hi

Sorry for not providing enough details

1) When I run make third_party directly from the source code, I got the following error:

-- The CXX compiler identification is unknown

CMake Error at CMakeLists.txt:44 (project):

The CMAKE_CXX_COMPILER:

C:/Program Files (x86)/Microsoft Visual Studio/2019/Community/VC/Tools/MSVC/14.26.28801/bin/Hostx64/x64/cl.exe

is not a full path to an existing compiler tool.

2) Yes, C++ within VS2019

3, 4) Yes.

In C++ > General >Additional include directories: path to include

In Linker > General > Additional library directoires: path to lib

In Linker > General > Additional dependencies: ortools.lib

5) These flags are already in the Makefile for the binary version

The log file is attached to the discussion (sorry but my VS19 is in french)

Thanks

detailed_log.txt

Laurent Perron

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Mar 31, 2021, 4:29:01 AM3/31/21

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You should build in release mode in /MD

Laurent Perron | Operations Research | lpe...@google.com | (33) 1 42 68 53 00

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Diego Martino

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Mar 31, 2021, 4:33:41 AM3/31/21

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Building in release mode in \MD also gives me these problems (see attached log file)

detailed_log_MD_release.txt

Laurent Perron

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Mar 31, 2021, 4:42:51 AM3/31/21

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No, you are still compiling in /MT

Laurent Perron | Operations Research | lpe...@google.com | (33) 1 42 68 53 00

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Diego Martino

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Mar 31, 2021, 4:49:58 AM3/31/21

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Now I think I changed that

detailed_log_MD_release.txt

Laurent Perron

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Mar 31, 2021, 4:59:48 AM3/31/21

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are you compiling in c++17 ?

Laurent Perron | Operations Research | lpe...@google.com | (33) 1 42 68 53 00

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Diego Martino

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Mar 31, 2021, 5:18:04 AM3/31/21

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Yes

I changed it to 19 and it apparently worked for some example cpp files

However for the jobshop example (https://github.com/google/or-tools/blob/fa84bc05e72641dddfbb98164d81b8bc9bef6ea5/examples/cpp/jobshop_sat.cc#L34) I get some problems with the ABSL_FLAGS (log file attached). This problem is most related to C++ rather than ORTools?

absl_flags_problem.txt

Laurent Perron

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Mar 31, 2021, 5:40:24 AM3/31/21

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c++19 does not exist

Laurent Perron | Operations Research | lpe...@google.com | (33) 1 42 68 53 00

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Diego Martino

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Mar 31, 2021, 5:45:06 AM3/31/21

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I thought you were talking about VS17 v141 and VS19 v142

I'm using C++14 in default mode. Should I use C++17 ?

Laurent Perron

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Mar 31, 2021, 5:51:17 AM3/31/21

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yes

Laurent Perron | Operations Research | lpe...@google.com | (33) 1 42 68 53 00

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Diego Martino

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Mar 31, 2021, 6:14:42 AM3/31/21

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now it works correctly

Thank you!

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