How do I tell gcc to relax its restrictions on typecasting when calling a C function from C++?
- by Daryl Spitzer
I'm trying to use Cmockery to mock C functions called from C++ code. Because the SUT is in C++, my tests need to be in C++.
When I use the Cmockery expect_string() macro like this:
expect_string(mock_function, url, "Foo");
I get:
my_tests.cpp: In function ‘void test_some_stuff(void**)’:
my_tests.cpp:72: error: invalid conversion from ‘void*’ to ‘const char*’
my_tests.cpp:72: error: initializing argument 5 of ‘void _expect_string(const char*, const char*, const char*, int, const char*, int)’
I see in cmockery.h that expect_string is defined:
#define expect_string(function, parameter, string) \
expect_string_count(function, parameter, string, 1)
#define expect_string_count(function, parameter, string, count) \
_expect_string(#function, #parameter, __FILE__, __LINE__, (void*)string, \
count)
And here's the prototype for _expect_string (from cmockery.h):
void _expect_string(
const char* const function, const char* const parameter,
const char* const file, const int line, const char* string,
const int count);
I believe the problem is that I'm compiling C code as C++, so the C++ compiler is objecting to (void*)string in the expect_string_count macro being passed as the const char* string parameter to the _expect_string() function.
I've already used extern "C" around the cmockery.h include in my_tests.cpp like this:
extern "C" {
#include <cmockery.h>
}
...in order to get around name-mangling problems. (See "How do I compile and link C++ code with compiled C code?")
Is there a command-line option or some other means of telling g++ how to relax its restrictions on typecasting from my test's C++ code to the C function in cmockery.c?
This is the command I'm currently using to build my_tests.cpp:
g++ -m32 -I ../cmockery-0.1.2 -c my_tests.cpp -o $(obj_dir)/my_tests.o
