std.xml should just go

[Walter Bright]

so wrote:
> You changed the function and the new function is not working, just what 
> you expect.
> It is not silently is it? Unlike you use "A a" instead of "const A a". 
> this const alone would give you all the guaranties you need.

What would you do in the case of pointers to functions, virtual functions, 
functions implemented with inline assembly, and functions for which the source 
is not available?