http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49850
Summary: Implicit creation of a temporary object when a constant reference is passed as parameter and the actual and formal types are not identical Product: gcc Version: 4.4.5 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c++ AssignedTo: unassig...@gcc.gnu.org ReportedBy: gccb...@andreas-borchert.de The following has been tested with g++ (Debian 4.4.5-8) 4.4.5 for the amd64 architecture as shipped with stable Debian 6.0. I do not have it tested for newer releases as I do not have them conveniently available. Following code demonstrates the problem: ---- code start ---- #include <iostream> #include <sys/types.h> using namespace std; size_t si; void foo(const unsigned int& ui) { cout << "address of ui = " << (long long int) &ui << endl; } int main() { cout << "address of si = " << (long long int) &si << endl; foo(si); } ---- code end ---- The code generated for the invocation of foo() in main() shows the problem: movq si(%rip), %rax movl %eax, -20(%rbp) leaq -20(%rbp), %rax movq %rax, %rdi call _Z3fooRKj Instead of passing the address of the global si variable, a temporary object is created (at 20(%rbp)) whose address is passed. If you test this program, the output shows the effect: address of si = 6295456 address of ui = 140734739682956 The apparent problem is that "unsigned int" and "size_t" do not match, at least not on this platform (size and signedness are different). But then I would expect an error and not the implicit creation of a temporary object of the appropriate type.