# How to correctly include header files for compilation of cxx SWIG wrapped files ?
**URL:** https://discourse.cmake.org/t/how-to-correctly-include-header-files-for-compilation-of-cxx-swig-wrapped-files/8533
**Category:** Usage
**Created:** [July 17, 2023, 10:33am UTC](https://discourse.cmake.org/t/how-to-correctly-include-header-files-for-compilation-of-cxx-swig-wrapped-files/8533 "2023-07-17T10:33:42Z")
**Posts on this page:** 8
**Page:** 1
### Author:  [@JSn](https://discourse.cmake.org/u/JSn)
#### Post date: [July 17, 2023, 10:33am UTC](https://discourse.cmake.org/t/how-to-correctly-include-header-files-for-compilation-of-cxx-swig-wrapped-files/8533/1 "2023-07-17T10:33:42Z")
Hi, I’m almost newbie in CMake and SWIG. Currently I’m using CMake 3.23.3 and SWIG 4.0.2. I’m trying to compile the .cxx file wrapped from a C++ project in order to create a Python package. Can you confirm me that the instruction `set_property` is still valid, or should I use `set_target_properties(myProject PROPERTIES SWIG_USE_TARGET_INCLUDE_DIRECTORIES TRUE)` instead ? Here is the current minimum version of my project ([GitHub - jsn-inrs/GravForcesProcessor: Python package wrapped from C++ code to implement features about Gravity Forces not available in OpenSim'sPython API](https://github.com/jsn-inrs/GravForcesProcessor)). Generation of the Python package with VS2019 fails because an included header file is not found ("Unable to find ‘spdlog\spdlog.h’ ") however the C++ dll and test executable are correctly processed. Would you please help in the jungle of CMake / SWIG ? Thanks in advance…
---
### Author:  [@ben.boeckel](https://discourse.cmake.org/u/ben.boeckel)
#### Post date: [July 18, 2023, 11:31pm UTC](https://discourse.cmake.org/t/how-to-correctly-include-header-files-for-compilation-of-cxx-swig-wrapped-files/8533/2 "2023-07-18T23:31:05Z")
Is SWIG generating the `spdlog.h` include? If not, whatever target has the header that does so should `PUBLIC` or `INTERFACE` depend on some target that provides `spdlog` headers or the variable if you’re not using a target.
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### Author:  [@JSn](https://discourse.cmake.org/u/JSn)
#### Post date: [July 21, 2023, 11:31am UTC](https://discourse.cmake.org/t/how-to-correctly-include-header-files-for-compilation-of-cxx-swig-wrapped-files/8533/3 "2023-07-21T11:31:32Z")
Thank you very much for the attention you gave to this topic. Unfortunately, I’m not sure to understand the answer correctly. Actually, the “spdlog.h” is not a part of my project, and it is not generated by swig. It’s an external project ([GitHub - gabime/spdlog: Fast C++ logging library.](https://github.com/gabime/spdlog)) used in my code.
My CMakeLists.txt files contains the following instructions (see [https://github.com/jsn-inrs/GravForcesProcessor/blob/main/CMakeLists.txt](https://github.com/jsn-inrs/GravForcesProcessor/blob/main/CMakeLists.txt) lines 102+):
```
set_target_properties(swigGravForcesProcessor PROPERTIES SWIG_USE_TARGET_INCLUDE_DIRECTORIES TRUE)
target_include_directories(swigGravForcesProcessor PUBLIC ${SPDLOG_INCLUDE_DIRS})
target_link_libraries(swigGravForcesProcessor ${SPDLOG_LIBRARIES})
target_compile_definitions(swigGravForcesProcessor PRIVATE ${SPDLOG_COMPILE_DEFINITIONS})
```
So I think what you’ve highlighted is accounted for, isn’t it ? Thanks in advance
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### Author:  [@ben.boeckel](https://discourse.cmake.org/u/ben.boeckel)
#### Post date: [July 21, 2023, 12:03pm UTC](https://discourse.cmake.org/t/how-to-correctly-include-header-files-for-compilation-of-cxx-swig-wrapped-files/8533/4 "2023-07-21T12:03:11Z")
Ah, sorry. By
> [@ben.boeckel](#):
>
> generating the `spdlog.h` include
I meant the `#include` line, not the file itself.
Yes, that looks fine to me. If you run a verbose build, do you see the include path for `spdlog.h` there? Does your target compile properly before SWIG tries to wrap it? Can you provide the full error that you get for better context?
---
### Author:  [@JSn](https://discourse.cmake.org/u/JSn)
#### Post date: [July 21, 2023, 2:15pm UTC](https://discourse.cmake.org/t/how-to-correctly-include-header-files-for-compilation-of-cxx-swig-wrapped-files/8533/5 "2023-07-21T14:15:33Z")
I’m not used to this forum (how to attach a file ?). Here after are the last trace lines in “detailed” verbose mode (otherwise it’s far too long for this post). By the way, I’ve jumped to CMake 3.27, I don’t think it matters a lot (same error):
```auto
2> Task "CustomBuild"
2> setlocal
2> "C:\Program Files\CMake\bin\cmake.exe" -E make_directory C:/Users/jonathan.savin/Documents/WIP/SwigGravityForcesProcessor/build/CMakeFiles/swigGravForcesProcessor.dir C:/Users/jonathan.savin/Documents/WIP/SwigGravityForcesProcessor/build C:/Users/jonathan.savin/Documents/WIP/SwigGravityForcesProcessor/wrapper
2> if %errorlevel% neq 0 goto :cmEnd
2> "C:\Program Files\CMake\bin\cmake.exe" -E env SWIG_LIB=C:/ProgramData/chocolatey/lib/swig/tools/install/swigwin-4.0.2/Lib C:/ProgramData/chocolatey/bin/swig.exe -python -includeall -outdir C:/Users/jonathan.savin/Documents/WIP/SwigGravityForcesProcessor/build -c++ -module GravForcesProcessor -interface _GravForcesProcessor -o C:/Users/jonathan.savin/Documents/WIP/SwigGravityForcesProcessor/wrapper/GravForcesProcessorPYTHON_wrap.cxx C:/Users/jonathan.savin/Documents/WIP/SwigGravityForcesProcessor/GravForcesProcessor.i
2> if %errorlevel% neq 0 goto :cmEnd
2> :cmEnd
2> endlocal & call :cmErrorLevel %errorlevel% & goto :cmDone
2> :cmErrorLevel
2> exit /b %1
2> :cmDone
2> if %errorlevel% neq 0 goto :VCEnd
2> Swig compile GravForcesProcessor.i for python
2> C:\Users\jonathan.savin\Documents\WIP\SwigGravityForcesProcessor\GravForcesProcessor.h(15): error : Unable to find 'spdlog\spdlog.h'
2> C:\Users\jonathan.savin\Documents\WIP\SwigGravityForcesProcessor\GravForcesProcessor.i(20): error : Unable to find 'spdlog\spdlog.h'
2> C:\Users\jonathan.savin\Documents\WIP\SwigGravityForcesProcessor\GravForcesProcessor.i(23): error : Unable to find 'spdlog\common.h'
2> C:\Users\jonathan.savin\Documents\WIP\SwigGravityForcesProcessor\GravForcesProcessor.i(24): error : Unable to find 'spdlog\logger.h'
2> C:\Users\jonathan.savin\Documents\WIP\SwigGravityForcesProcessor\GravForcesProcessor.i(25): error : Unable to find 'spdlog\sinks\stdout_color_sinks.h'
2> C:\Users\jonathan.savin\Documents\WIP\SwigGravityForcesProcessor\GravForcesProcessor.i(26): error : Unable to find 'spdlog\fmt\ostr.h'
2> C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\MSBuild\Microsoft\VC\v160\Microsoft.CppCommon.targets(241,5): error MSB8066: Custom build for 'C:\Users\jonathan.savin\Documents\WIP\SwigGravityForcesProcessor\GravForcesProcessor.i' exited with code 1.
2> The command exited with code 1.
2> Done executing task "CustomBuild" -- FAILED.
2>Done building target "CustomBuild" in project "swigGravForcesProcessor.vcxproj" -- FAILED.
2>
2>Done building project "swigGravForcesProcessor.vcxproj" -- FAILED.
2>
2>Build FAILED.
2>
2>C:\Users\jonathan.savin\Documents\WIP\SwigGravityForcesProcessor\GravForcesProcessor.h(15): error : Unable to find 'spdlog\spdlog.h'
2>C:\Users\jonathan.savin\Documents\WIP\SwigGravityForcesProcessor\GravForcesProcessor.i(20): error : Unable to find 'spdlog\spdlog.h'
2>C:\Users\jonathan.savin\Documents\WIP\SwigGravityForcesProcessor\GravForcesProcessor.i(23): error : Unable to find 'spdlog\common.h'
2>C:\Users\jonathan.savin\Documents\WIP\SwigGravityForcesProcessor\GravForcesProcessor.i(24): error : Unable to find 'spdlog\logger.h'
2>C:\Users\jonathan.savin\Documents\WIP\SwigGravityForcesProcessor\GravForcesProcessor.i(25): error : Unable to find 'spdlog\sinks\stdout_color_sinks.h'
2>C:\Users\jonathan.savin\Documents\WIP\SwigGravityForcesProcessor\GravForcesProcessor.i(26): error : Unable to find 'spdlog\fmt\ostr.h'
2>C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\MSBuild\Microsoft\VC\v160\Microsoft.CppCommon.targets(241,5): error MSB8066: Custom build for 'C:\Users\jonathan.savin\Documents\WIP\SwigGravityForcesProcessor\GravForcesProcessor.i' exited with code 1.
2> 0 Warning(s)
2> 7 Error(s)
2>
2>Time Elapsed 00:00:00.58
========== Build: 0 succeeded, 1 failed, 1 up-to-date, 0 skipped ==========
```
---
### Author:  [@ben.boeckel](https://discourse.cmake.org/u/ben.boeckel)
#### Post date: [July 21, 2023, 4:37pm UTC](https://discourse.cmake.org/t/how-to-correctly-include-header-files-for-compilation-of-cxx-swig-wrapped-files/8533/6 "2023-07-21T16:37:13Z")
Hmm, it seems that `swig` is not getting the `-I` flags at all… I wonder if using an `IMPORTED` target for `spdlog` would make this a lot smoother? Anyways, I see that _directory_ properties are used. Maybe:
```cmake
include_directories(${SPDLOG_INCLUDE_DIRS})
```
would work in the meantime?
---
### Author:  [@JSn](https://discourse.cmake.org/u/JSn)
#### Post date: [July 24, 2023, 8:10am UTC](https://discourse.cmake.org/t/how-to-correctly-include-header-files-for-compilation-of-cxx-swig-wrapped-files/8533/7 "2023-07-24T08:10:06Z")
thank you so much for persevering to help me. As a beginner in CMake and SWIG, I’ve tried to piece together snippets of CMake code I’ve found here and there, and I’m progressing a bit blindly. Actually, your advice is already implemented in my CMakeLists.txt, line 20:
```
include_directories(${SPDLOG_INCLUDE_DIR})
```
Obviously the final ‘S’ (\_DIR or \_DIRS) doesn’t matter, the building fails with the same error messages. I feel quite lost… Any idea, advice or explanation will be graetly appreciated ! Thanks in advance.
---
### Author:  [@ben.boeckel](https://discourse.cmake.org/u/ben.boeckel)
#### Post date: [July 24, 2023, 10:51am UTC](https://discourse.cmake.org/t/how-to-correctly-include-header-files-for-compilation-of-cxx-swig-wrapped-files/8533/8 "2023-07-24T10:51:34Z")
Hrm. This is outside of my SWIG/CMake knowledge at this point as that looks like it should work. Maybe someone else can help further though.
The next steps for investigating would be to trace how `FindSWIG` builds up `-I` flags for `swig` itself and find a place to add things to one of those sources (`--trace-expand` to the configure would be the tool I’d start with).