I have asked before about a possible bug in my code, it turns out the problem is quite puzzling. I am running Fenics 1.5, from the DMG.
A minimal running example is available here
Let's say I need to create a DirichletBC, I could do as follows:
bcs.push_back(new dolfin::DirichletBC(*V,
dolfin::Constant(0.0, 0.0),
edgedetect(dolfin::Point(0.0, 0.0), dolfin::Point(7.0, 0.0))));
bcs.push_back(new dolfin::DirichletBC(*V,
dolfin::Constant(1.0, 16.0),
edgedetect(dolfin::Point(0.0, 16.0), dolfin::Point(7.0, 16.0))));
These lines use an temporary variable, if I run this code, when calling dolfin::assemble_system I get an exception and the program dies.
But if I use a variable with automatic storage, then the assembly call works perfectly and everybody's happy:
dolfin::Constant clamped(0.0, 0.0);
bcs.push_back(new dolfin::DirichletBC(*V,
clamped,
edgedetect(dolfin::Point(0.0, 0.0), dolfin::Point(7.0, 0.0))));
bcs.push_back(new dolfin::DirichletBC(*V,
clamped,
edgedetect(dolfin::Point(0.0, 16.0), dolfin::Point(7.0, 16.0))));
The happiness continues if I use a shared pointer like std::make_shared<const dolfin::Constant>(0.0, 0.0) in lieu of clamped.
It seems that the constructor that is called with a temporary won't really use the temporary, making a copy if needed, but instead it will hold the pointer to the location, and of course, it goes FUBAR afterwards.
The source code I posted will compile to a single executable. If you call it without parameters then you will run the code with variables, if you execute it with some arguments it will run with temporaries.
Am I missing something here?
Thanks!
