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From: Steven Watanabe (watanabesj_at_[hidden])
Date: 2008-07-12 23:56:49
AMDG
I've been trying to work out a way to cause
an explicit error if configuration macros are defined
differently in different translation units. I really wish
I could cause a link error, but the best I've been able
to come up with so far is a runtime error
// test_odr.hpp
#ifndef TEST_ODR_HPP_INCLUDED
#define TEST_ODR_HPP_INCLUDED
#include <iostream>
#include <cstdlib>
#ifndef SOME_MACRO
#define SOME_MACRO true
#endif
template<bool>
struct test_odr {
static bool value;
};
template<bool b>
bool test_odr<b>::value = SOME_MACRO;
namespace {
struct test_odr_impl_t {
test_odr_impl_t() {
if(test_odr<true>::value != SOME_MACRO) {
std::cerr << "Error: SOME_MACRO defined differently in
two translation units.\n";
std::abort();
}
}
};
test_odr_impl_t test_odr_impl;
}
#endif
// test_odr1.cpp
#include "test_odr.hpp"
int main() {}
// test_odr2.cpp
#define SOME_MACRO false
#include "test_odr.hpp"
Comments? Any better ideas?
In Christ,
Steven Watanabe
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