On 04/07/2011 05:41 PM, Jason Merrill wrote:
> PR 48450 has to do with SFINAE bugs, but one of them turns out to be a
> different sort of bug: we were failing to convert from a non-constant
> value of scoped enum type to bool, because that conversion was doing a
> != 0, which requires an implicit conversion to int. So now we explicitly
> convert to the underlying integral type first, and prevent c-common from
> helpfully removing it again.

...except that if the underlying type is bool, this leads to infinite 
recursion.  So use build_nop instead of convert.

Tested x86_64-pc-linux-gnu, applying to trunk and 4.6.