Re: C++ PATCH for c++/78244 - narrowing conversion in template not detected, part 2

[Marek Polacek <polacek@redhat.com>]

On Wed, Jan 23, 2019 at 09:00:36AM -0500, Jason Merrill wrote:
> I was talking about digest_init, not reshape_init.  digest_init calls
> convert_for_initialization.

/facepalm

So yes, digest_init calls convert_for_initialization which will end up
calling perform_implicit_conversion_flags which could call convert_like_real
where the narrowing warnings are given, but it doesn't, we go to this case:

  else if (processing_template_decl && conv->kind != ck_identity)
    {
      /* In a template, we are only concerned about determining the
         type of non-dependent expressions, so we do not have to
         perform the actual conversion.  But for initializers, we
         need to be able to perform it at instantiation
         (or instantiate_non_dependent_expr) time.  */
      expr = build1 (IMPLICIT_CONV_EXPR, type, expr);

finish_decltype_type throws away the expression because it's not dependent, and
only uses its type.  So narrowing remains undetected.  Not sure if I should mess
with perform_implicit_conversion_flags.