[LLVMdev] DenseMap iterator constness fix

[Jeffrey Yasskin]

+template <bool, typename True, typename False>
+struct If { typedef True Result; };
+
+template <typename True, typename False>
+struct If<false, True, False> { typedef False Result; };

These should probably go into include/llvm/Support/type_traits.h. In
C++0x, this is named "conditional" (section 20.6.7), so I think you
should use the same name, despite the standard committee's bad taste.

+  DenseMapIterator(const DenseMapIterator<KeyT, ValueT,
+                                          KeyInfoT, ValueInfoT, false>& I)

This looks like it will make it impossible to copy const_iterators. I
guess it doesn't because the copy-constructor is auto-generated, but
please comment that and add tests for it and for the non-const->const
conversion to unittests/ADT/DenseMapTest.cpp.

Otherwise, the patches just change iterator to const_iterator, which looks fine.

On Tue, Nov 3, 2009 at 3:09 AM, Victor Zverovich
<victor.zverovich at googlemail.com> wrote:
> Dear all,
> The first of the proposed patches (DenseMapIterator.patch) forbids implicit
> conversion of DenseMap::const_iterator to DenseMap::iterator which was
> possible because DenseMapIterator inherited (publicly) from
> DenseMapConstIterator. Conversion the other way around is now allowed as one
> may expect.
> The template DenseMapConstIterator is removed and the template
> parameter IsConst which specifies whether the iterator is constant is added
> to DenseMapIterator.
> Actually IsConst parameter is not necessary since the constness can be
> determined from KeyT but this is not relevant to the fix and can be
> addressed later.
> The second patch (DenseMapIterator-clang.patch) corrects clang's usage of
> DenseMap iterators.
> Best regards,
> Victor
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>
>