On Wednesday 29 June 2005 19:40, "Peter Dimov" <pdimov@gmail.com> wrote:

Michael Stevens wrote:

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template<class V> void hard (V &data, const typename vector_range<V>::range_type &r) {} template<class V> void hard (vector_slice<V> &data, const typename vector_slice<V>::range_type &r) {}

[...]

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It thinks the functions 'hard' are ambiguous despite the fact that the first parameter is more specialised in the second version.

The functions do seem ambiguous to me. I see no partial ordering between them.

I'm being a little hard on the compiler here. In the single parameter case. Things are easy, the second template is more specialised. The difficultly is the second parameter. In the first case we have vector_range<V>::range_type in the second vector_slice<V>::range_type The crux of the problem is these two are actually the same type! I think VC is missing this when it performs 'argument deduction against the other function template' to determine if the templates are 'at least as specialized'. See 14.5.5.2 para 4. At least some other modern compilers (GCC4.0, Intel 8.0 CW-9.4) are with on this on this! VC has no problems if we help it by using 'vector_range<V>::range_type' in both cases. Thanks, Michael