Re: [PATCH 2/2] PR c++/64382 * cp/parser.c (parsing_default_capturing_generic_lambda_in_template): New function. * cp/cp-tree.h: Declare it. * cp/semantics.c (finish_id_expression): Resolve names within a default capturing generic lambda defined within a template prior to instantiation to allow for captures to be added to the closure type.

[Jakub Jelinek]

On Tue, Apr 14, 2015 at 09:16:32AM +0200, Marek Polacek wrote:
> On Fri, Apr 10, 2015 at 04:31:34AM +0100, Adam Butcher wrote:
> > +/* Return true iff our current scope is a default capturing generic lambda
> > +   defined within a template.  */
> > +
> > +bool
> > +parsing_default_capturing_generic_lambda_in_template (void)
> > +{
> > +  if (processing_template_decl && current_class_type)
> > +    if (tree lam = CLASSTYPE_LAMBDA_EXPR (current_class_type))
> > +      if (LAMBDA_EXPR_DEFAULT_CAPTURE_MODE (lam) != CPLD_NONE)
> > +   if (tree callop = lambda_function (lam))
> > +     if (DECL_TEMPLATE_INFO (callop)
> > +         && (DECL_TEMPLATE_RESULT (DECL_TI_TEMPLATE (callop))
> > +             == callop)
> > +         && ((current_nonlambda_class_type ()
> > +              && CLASSTYPE_TEMPLATE_INFO (current_nonlambda_class_type ()))
> > +             || ((current_nonlambda_function ()
> > +                  && DECL_TEMPLATE_INFO (current_nonlambda_function ())))))
> > +       return true;
> > +  return false;
> > +}
> > +
> 
> Eek, why not &&s rather than cascading ifs?

Perhaps because of the lam / callop declarations.
Even a large && is not that readable, I'd say best would be to just use
separate ifs with return false.

  if (!processing_template_decl || !current_class_type)
    return false;

  tree lam = CLASSTYPE_LAMBDA_EXPR (current_class_type);
  if (!lam || LAMBDA_EXPR_DEFAULT_CAPTURE_MODE (lam) == CPLD_NONE)
    return false;

  tree callop = lambda_function (lam);
  if (!callop)
    return false;

...

        Jakub