Jason Merrill wrote: > may_alias and target attributes are the problematic case. Most of these > just get added to the TYPE_ATTRIBUTES list, and > build_type_attribute_qual_variant creates a new TYPE_MAIN_VARIANT > without copying the fields, which is why things break. > > A simple solution might be to just have > build_type_attribute_qual_variant refuse to make a variant of > record/enum types. This will reject the may_alias cases that break, but > leave existing use of aligned/packed/unused/deprecated alone.
That seems reasonable to me. The transparent_union trick (copying the fields, along with making a new TYPE_MAIN_VARIANT) might work, but even there you have to worry about making sure you a different type_info object, how do you mangle the name, etc. You're also likely to get messages like "can't convert X to X" because one of them has an attribute. If we can mandate that all semantic type attributes apply only at the point of definition, then we can dodge all these issues; there will always be only one "class X", whatever attributes it might happen to have. So, I like that answer. -- Mark Mitchell CodeSourcery [EMAIL PROTECTED] (650) 331-3385 x713
