Non-compliant (as far as I can tell) ValueMap allocator when using boehm

[copumpkin]

Right now, we have

typedef std::map<Symbol, Value *, std::less<Symbol>, gc_allocator<Value *> > ValueMap;

According to the official requirements, this is how it should look:

template<
    class Key,
    class T,
    class Compare = std::less<Key>,
    class Allocator = std::allocator<std::pair<const Key, T> >
> class map

Note that the allocator needs to be for a std::pair rather than just the value type. I think it should be a fairly simple fix, but it currently breaks with clang + libc++ 4, which are more strict about this sort of thing than they've been in the past.

cc @edolstra @shlevy @LnL7

[shlevy]

Does it work if you do the gc_allocator for the std::pair instead?

[copumpkin]

I haven't tried yet but I think @LnL7 is in a good position to try patching on the fly. Unfortunately it's behind a major LLVM+clang rebuild so it'll take me a while to get there 😄

[LnL7]

I tried with std::map<Symbol, Value *, std::less<Symbol>, gc_allocator<std::pair<const Symbol, Value *> > >, but that didn't seem to help. This is the build log https://gist.github.com/LnL7/26cc66bf15e2aeddb6729819ffa3aad4

[shlevy]

Are you sure the change was picked up? That error clearly shows a gc_allocator<Value *> somewhere...

[LnL7]

You are right, it's in a different file for 1.11. Looks good. 😄

LnL7/nixpkgs@d179233

[shlevy]

@LnL7 Can you submit a PR to 1.11-maintenance and master?