Doug Gregor wrote: [LLVM-ers: I CC this message since I explicity mention the LLVM project]
From: David Abrahams [mailto:dave@boost-consulting.com] Stefan has recently been trying to get compile-time constants from sizeof() into the parser. As he knows, this is going to mean handling such things as template instantiation and overload resolution. This is a great opportunity to learn more about how C++ works and to create a compiler platform that's actually usable by C++ programmers ...... I should mention that the design of the C++ parser allows to manipulate the generated parse tree in-memory and write it out into a file again in a non-lossy way, i.e. it could indeed be used as a source-to-source compiler.
That's an excellent goal, and you have me interested. It's a huge task, requiring a great deal of expertise (collectively, we have that) and will require a lot of time.
However, if we have a C++ parser, then we should be able to hook it with LLVM compiler infrastructure (http://llvm.cs.uiuc.edu/) and have a complete C++ compiler. LLVM already has intermediate program representation and an impressive set of optimizations, as well as code generators for x86, PPC and Spart, and also JIT support. They use modified gcc as C++ frontend, but I know some of the developers are interested in a new frontend. Maybe I'm dreaming, but the goal is interesting.
I think it would be wise to attempt to isolate some of the interesting-but-disjoint problems early, so we can put out a "request for libraries" of some sort. Things that come to mind quickly: a unification algorithm (for template instantiation/partial ordering), a tree manipulation/rewriting library (for AST transformations), and a flexible symbol table library.
And overload resulution, too. Maybe, we should put up a page somewhere (Boost Wiki?), with the list of tasks, and one it's finished put the "request for libraries", as you put it? - Volodya