ref parameters: there is no escape

[Michel Fortin]

On 2011-08-14 16:55:08 +0000, dsimcha <dsimcha at yahoo.com> said:

> Right, but they can be proven safe if they pass locals by ref **to 
> @safe functions**.  I don't think there's any disagreement that @safe 
> functions shouldn't be allowed to take the address of locals or 
> parameters.

Actually, no, that's not safe by itself. Consider this:

	ref int foo(ref int a) @safe
	{
		return a;
	}

	ref int bar() @safe
	{
		int a;
		return foo(a);
	}

And now 'bar' returns its local variable 'a' by ref, thanks to the 
complicity of 'foo'. All this unsafety is perfectly @safe.

I think a @safe function shouldn't be allowed to return by ref one of 
its parameter.


-- 
Michel Fortin
michel.fortin at michelf.com
http://michelf.com/