On 04/26/2012 05:44 AM, Walter Bright wrote:
A subtle but nasty problem - are default arguments part of the type, or
part of the declaration?
See http://d.puremagic.com/issues/show_bug.cgi?id=3866
Currently, they are both,
That is how it should be.
which leads to the nasty behavior in the bug report.
It contributes, but it is not the main cause.
The problem centers around name mangling. If two types mangle the same,
then they are the same type.
Then they are equal types.
But default arguments are not part of the
mangled string. Hence the schizophrenic behavior.
The schizophrenic behavior occurs because the types cross-talk. Are
mangled names kept unique in the compiler or what is the implementation
issue exactly?
But if we make default arguments solely a part of the function
declaration, then function pointers (and delegates) cannot have default
arguments. (And maybe this isn't a bad thing?)
I think default arguments for delegates and function pointers are quite
a feat.
The proposal is to change the language in a backwards-incompatible way
based on implementation issues that shouldn't be that hard to resolve.
(Related: Template instantiation should strip off the default arguments
from delegate and function pointer types.)
