CODEWITHSUNDEEP
c++scons
Ariel Baron
Ariel Baron

Reputation: 351

difficulty linking c and c++ code in SCONS framework

I am trying to make a shared library in scons but it keeps telling me there is an error because there is an undefined reference to some functions I wrote. I include the .c file from which I am trying to make the shared library. For some reason it is recognizing the cpp file I am inputting but not the .c file.

Your help would be much appreciated`

import os

Import('env')

env = env.Clone()
env.Append(CPPPATH=['include'])
env.Append(LIBS=['serial'])

env.Append(LIBPATH=['/usr/local/lib'])
env.Append(LIBS=['boost_date_time','boost_system', 'boost_thread'])


lib = []
binaries = []

lib.extend(env.SharedLibrary('File1.c', 'File2.cpp']))
print "the error is here"
test_env = env.Clone()
test_env.Append(LIBS=['Program'], LIBPATH=['.'])
binaries.extend([
  test_env.Program('test_Program', Glob('test/test_Adafruit.cpp')),
])

Return('lib', 'binaries')

during the linking phase: I get the errors like:

LINK    build/test_Program
build/test_Program/libProgram.so:

undefined reference to function(int, sensor_xyz_s*)'

Upvotes: 0

Views: 544

Answers (1)

Dave Bacher
Dave Bacher

Reputation: 15972

C and C++ don't have the same calling conventions, so C++ does not recognize C functions from other objects. If you're trying to call a C function in File1.c from a C++ function in File2.cpp, you either need to (1) make sure to declare the C function with extern "C", (2) explicitly use the C++ compiler to create File1.o, or (3) rename File1 to File1.cpp (assuming that your C code is valid C++). The cleanest solution is probably option (1).

To set the C compiler in your SConscript, use:

env['CC'] = env['CXX']

To tell the C++ code that function is a C function, change the declaration of the C function to the following. Note that this is just the declaration of the function -- if the declaration is in a header used by both C and C++, you need to wrap the extern "C" so that it's hidden from the C compiler (which may not understand it). 

#ifdef __cplusplus
extern "C" {
#endif

    void function(int, sensor_xyz_s*);

#ifdef __cplusplus
}
#endif

Upvotes: 2

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