[cfe-dev] Additional instantiations of anonymous enum inside a template

[Pavel Morozkin]

Hello cfe-dev group,

Consider this template metaprogram:
template <unsigned N> struct fib { enum { value = fib<N-1>::value +
fib<N-2>::value}; };
template <> struct fib<1> { enum { value = 1 }; };
template <> struct fib<0> { enum { value = 0 }; };

During compilation of 'fib<2>::value' (after finally getting memoized
result of instantiation of struct fib<0>) Clang «instantiates the anonymous
enum inside fib<0> and fib<1>» 129 times in sum. In case, when we use
'constexpr static auto' instead of 'enum', no additional instantiations
occurs. Why Clang performs additional instantiations in the first case?

Thank you,
Pavel
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