[BUG] the code can not build with C++ complier, reboot error

[freertos]

[BUG] the code can not build with C++ complier, reboot error

[muneebahmed10]

Hi @orkfire,

If you are using C code, then unless it's already compatible with C++, it will need to be compiled as C. Your compiler is likely treating the C input as C++, so you may have to specify the language for your input files. For example, simple programs compiled with g++ can have language specified with -x:

g++ *.cpp -x c *.c

Or, you could compile your C and C++ code separately and then use a C++ linker, e.g.

gcc -c *.c
g++ -c *.cpp
g++ *.o

Additionally, the C code will need extern "C" {} guards to avoid the C++ compiler mangling names when calling C functions from C++. The FreeRTOS kernel header files already include this, but some library files may not, so you should use the format

extern "C" {
    #include "some_c_header.h"
}

when including C header files that don't already have those guards.

[orkfire]

Hi @orkfire,

If you are using C code, then unless it's already compatible with C++, it will need to be compiled as C. Your compiler is likely treating the C input as C++, so you may have to specify the language for your input files. For example, simple programs compiled with g++ can have language specified with -x:

g++ *.cpp -x c *.c

Or, you could compile your C and C++ code separately and then use a C++ linker, e.g.

gcc -c *.c
g++ -c *.cpp
g++ *.o

Additionally, the C code will need extern "C" {} guards to avoid the C++ compiler mangling names when calling C functions from C++. The FreeRTOS kernel header files already include this, but some library files may not, so you should use the format

extern "C" {
    #include "some_c_header.h"
}

when including C header files that don't already have those guards.

I tried using the extern "c" method, but it doesn't help, now I have a method to deal with it, First I using IAR build a static library using the c compiler, and then link it using c++ complier, it can work. but I don't think it is a good method when building a large project.

[muneebahmed10]

Hi @orkfire,

Adding extern "C" doesn't automatically tell a compiler to compile specific code as C, it only tells a C++ compiler to not mangle certain C functions in C++ code so that compiled C code can be properly linked. You will still have to tell your compiler to compile C code with a C compiler and C++ with a C++ compiler. In the screenshot you posted, have you tried using the language setting "Auto (extension-based)"?

Additionally, have you taken a look at IAR's notes on mixing C and C++? One recommendation there is

If you want to use C code from your C++ application, consider building the C code in a separate (library) project. You can place the C (library) project in the same workspace as your C++ project for fast access.

[orkfire]

Hi @orkfire,

Adding extern "C" doesn't automatically tell a compiler to compile specific code as C, it only tells a C++ compiler to not mangle certain C functions in C++ code so that compiled C code can be properly linked. You will still have to tell your compiler to compile C code with a C compiler and C++ with a C++ compiler. In the screenshot you posted, have you tried using the language setting "Auto (extension-based)"?

Additionally, have you taken a look at IAR's notes on mixing C and C++? One recommendation there is

If you want to use C code from your C++ application, consider building the C code in a separate (library) project. You can place the C (library) project in the same workspace as your C++ project for fast access.

I tried the auto option, it doesn't work, if I using cmake or makefile, it may be very easy to organize the c and c++ file with a different compiler, but the IDE(IAR) is not that flexible. Maybe I should try using none IDE method to organize my project, os it will be very convenient.

[muneebahmed10]

Hi @orkfire,

Do you have any further questions on this, or can we close this issue?

Thanks