https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88947
--- Comment #4 from Tomalak Geret'kal <tom at kera dot name> --- To be honest I'd expect this in less trivial circumstances too. If, at a given stage of processing, the only possible paths towards a match all require a prefix that's already been ruled out, that should be an immediate return false. To the best of my knowledge this is commonly what happens in regex engines (though again libstdc++ is far from alone in the C++ world in not doing so!)
