Compile and loadlibrary() issues.

I compile a simple function using this command in the command prompt...

mcc -v -B csharedlib:InputTest InputTest.m

Then, to try to test the library I try to load it in using the load library function...

loadlibrary('InputTest.dll','InputTest.h');

Then, I get a huge amount of errors. Theres thousands of lines of erros but here's an example...

Error using loadlibrary

Building InputTest_thunk_pcwin64 failed. Compiler output is:

C:\ProgramData\MATLAB\SupportPackages\R2021b\3P.instrset\mingw_w64.instrset\bin\gcc -I"C:\Program

Files\MATLAB\R2021b\extern\include" -fexceptions -fno-omit-frame-pointer

-I"C:\Users\User\Desktop\Testing Folder\Matlab dll" -I"C:\Users\User\Desktop\Testing

Folder\Matlab dll" "InputTest_thunk_pcwin64.c" -o "InputTest_thunk_pcwin64.dll" -shared

In file included from C:\Program Files\MATLAB\R2021b\extern\include/mclmcrrt.h:741:0,

from C:\Users\User\Desktop\Testing Folder\Matlab dll/InputTest.h:15,

from InputTest_thunk_pcwin64.c:27:

C:\Program Files\MATLAB\R2021b\extern\include/mclbase.h:23:0: warning: "DLL_EXPORT_SYM" redefined

#define DLL_EXPORT_SYM __attribute__ ((visibility("default")))

Does anybody understand whats going on here?

Answer 1

[Maneet Kaur Bagga]

Hi Xymbu,

As per my understanding of the question, the above command is being used to compile a MATLAB function file(InputTest.m) into a shared library named "InputTest" using the MATLAB compiler.

The "loadlibrary" function is being used to load the shared library and its associated header file("InputTest.h"). The command runs successfully depending on the availability of the header file "InputTest.dll" on the path and the correct association of the header file "InputTest.h" with the library.

The error message suggests that there was an issue while building the InputTest_thunk_pcwin64.dll library using the MinGW-w64 compiler. The error message also includes a warning related to the redefinition of DLL_EXPORT_SYM in the mclbase.h file.

Here are some of the troubleshooting steps you can follow to resolve the error:

1. Check that the paths provided for the input files (InputTest.dll and InputTest.h) are located in the specified directories and accessible.
2. If MATLAB function or the associated header file depends on external libraries, make sure that those libraries are correctly installed and accessible to the compiler.
3. Check if the MATLAB Compiler version being used is compatible with the MATLAB version installed on your system. To check the compatibility you may use the "ver" command in the Command Prompt to display the MATLAB version along with all the toolboxes including MATLAB Compiler with their version.

ver

-----------------------------------------------------------------------------------------------------
MATLAB Version: 9.14.0.2343484 (R2023a) Update 5
MATLAB License Number: 0
Operating System: Linux 5.4.233-0504233-generic #202302250651 SMP Sat Feb 25 12:26:27 UTC 2023 x86_64
Java Version: Java 1.8.0_292-b10 with AdoptOpenJDK OpenJDK 64-Bit Server VM mixed mode
-----------------------------------------------------------------------------------------------------
MATLAB                                                Version 9.14        (R2023a)
Simulink                                              Version 10.7        (R2023a)
5G Toolbox                                            Version 2.6         (R2023a)
Aerospace Blockset                                    Version 6.0         (R2023a)
Aerospace Toolbox                                     Version 4.4         (R2023a)
Antenna Toolbox                                       Version 5.4         (R2023a)
Audio Toolbox                                         Version 3.4         (R2023a)
Automated Driving Toolbox                             Version 3.7         (R2023a)
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Embedded Coder                                        Version 7.10        (R2023a)
Filter Design HDL Coder                               Version 3.1.13      (R2023a)
Financial Instruments Toolbox                         Version 3.6         (R2023a)
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Fixed-Point Designer                                  Version 7.6         (R2023a)
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MATLAB Compiler                                       Version 8.6         (R2023a)
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MATLAB Report Generator                               Version 5.14        (R2023a)
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Partial Differential Equation Toolbox                 Version 3.10        (R2023a)
Phased Array System Toolbox                           Version 5.0         (R2023a)
Powertrain Blockset                                   Version 2.0         (R2023a)
Predictive Maintenance Toolbox                        Version 2.7         (R2023a)
RF Blockset                                           Version 8.5         (R2023a)
RF Toolbox                                            Version 4.5         (R2023a)
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Risk Management Toolbox                               Version 2.2         (R2023a)
Robotics System Toolbox                               Version 4.2         (R2023a)
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Sensor Fusion and Tracking Toolbox                    Version 2.5         (R2023a)
SerDes Toolbox                                        Version 3.0         (R2023a)
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SimBiology                                            Version 6.4.1       (R2023a)
SimEvents                                             Version 5.14        (R2023a)
Simscape                                              Version 5.5         (R2023a)
Simscape Driveline                                    Version 3.7         (R2023a)
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Vision HDL Toolbox                                    Version 2.7         (R2023a)
WLAN Toolbox                                          Version 3.6         (R2023a)
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If none of the above steps work, then there might be more relevant information further down the error log. Review the complete error message to see if there are any additional details or specific errors that can help identify the problem.

Please refer to the following "loadlibrary" documentation for better understanding of the function.

https://www.mathworks.com/help/matlab/ref/loadlibrary.html

Hope this helps!

Thank You

Maneet Bagga