[cfe-dev] Strange dimension errors in a custom matrix class

[Tony Kelman]

> I'm seeing some strange runtime errors that don't occur when the same code 
> is built with g++. I've tried to cut down the class in question and reduce 
> the error to a small test case, and posted the result at 
> https://gist.github.com/8875125

Following up here. I've found and figured out how to use the absolutely 
amazing tool C-Reduce (http://embed.cs.utah.edu/creduce/) which I imagine 
this list is familiar with. The result is the following:



class A
{
public:
    A (const A &);
    ~A ();
};

A::A (const A &)
{
}

A & fn1 ()
{
}

A::~A ()
{
}

A a = fn1 ();
int
main ()
{
}



$ g++ -g -o dmtest-g++ dmtest.cxx && ./dmtest-g++
succeeds silently, while
$ clang++ -g -o dmtest-clang dmtest.cxx && ./dmtest-clang
gives a warning "control reaches end of non-void function" during 
compilation, and a runtime error "Illegal instruction (core dumped)". This 
comparison was on Ubuntu 13.10 as it was the easiest platform for me to get 
C-Reduce running on.

Is this difference in behavior between the two compilers expected and/or 
intended, or is this a bug in Clang? If the former, does anyone have any 
suggestions for how to translate this back into a workaround for the 
purposes of the real code that originally ran into this difference?

Thanks,
Tony