On Fri, Feb 16, 2018 at 4:33 PM, Martin Sebor <mse...@gmail.com> wrote: > On 02/16/2018 07:04 AM, Jason Merrill wrote: >> >> On Thu, Feb 15, 2018 at 6:36 PM, Martin Sebor <mse...@gmail.com> wrote: >>> >>> A failed template deduction in template member of a template >>> triggers an ICE with -std=c++17 due to what seems like >>> a missing handling of invalid input. Replacing >>> the gcc_unreachable() call that causes the ICE with a return >>> statement indicating the deduction failure eliminates the ICE >>> and restores sane diagnostics. >> >> >> Hmm, we really shouldn't have gotten there; that assert is checking >> that when we see a TEMPLATE_*_PARM node in the template signature, it >> corresponds to one of the actual parms of the template. Sounds like >> something is going wrong in build_deduction_guide. > > > Are you suggesting that build_deduction_guide should fail somehow > (it's not expected to fail right now) or that the guide it creates > is wrong?
The latter. Maybe we're handling T wrong somehow? We shouldn't be trying to deduce it. In fact, we probably shouldn't be trying to deduce arguments for 'b' until we instantiate A. Jason
