On Wed, 6 Nov 2013, Jakub Jelinek wrote: > On Wed, Nov 06, 2013 at 12:31:00PM +0100, Richard Biener wrote: > > > Maybe we need to revisit it? As one of those who were not in favour of > > > the C++ move, can I ask you guys to step back for a moment and think > > > about - what do all of these changes buy us, exactly? Imagine the state > > > at the end, where everything is converted and supposedly the temporary > > > ugliness is gone, what have we gained over the code as it is now? > > > > as_a gains us less runtime checking and more static type checking > > which is good. > > But that really affects --enable-checking=yes builds (and only cases where > things aren't inlined). If the price for that is uglier and less readable > code, then the price is just too high.
I see static type checking as being about preventing certain sorts of bugs getting in the compiler at all, rather than about saving time on runtime checks for --enable-checking=yes. I don't have advice on the gimple case. But certainly trees and RTL could both do with more static typing. There, I'm thinking of different types of objects (types, expressions, ...) logically being completely separate static types, not inheriting from a common "tree" base class at all. But if inheritance and as_a can be used as intermediate steps to allow an incremental transition to completely separate static types, where otherwise the whole source tree would need converting at once, that seems reasonable to me. (I have no comments about what things should look like in cases where completely separate static types don't make sense but there is still some sort of inheritance structure.) -- Joseph S. Myers jos...@codesourcery.com
