When comparing two TEMPLATE_TYPE_PARM, we need to consider whether they are acting as placeholders for templates.
Tested x86_64-pc-linux-gnu, applying to trunk.
commit 10e5cb6bf4c605741ef59f17120304a3c261c06c Author: Jason Merrill <ja...@redhat.com> Date: Tue Jun 12 22:38:07 2018 -0400 PR c++/86098 - ICE with template placeholder for TTP. * typeck.c (structural_comptypes) [TEMPLATE_TYPE_PARM]: Check CLASS_PLACEHOLDER_TEMPLATE. diff --git a/gcc/cp/typeck.c b/gcc/cp/typeck.c index 9febdb908ae..b033afd9884 100644 --- a/gcc/cp/typeck.c +++ b/gcc/cp/typeck.c @@ -1375,6 +1375,11 @@ structural_comptypes (tree t1, tree t2, int strict) template parameters set, they can't be equal. */ if (!comp_template_parms_position (t1, t2)) return false; + /* If T1 and T2 don't represent the same class template deduction, + they aren't equal. */ + if (CLASS_PLACEHOLDER_TEMPLATE (t1) + != CLASS_PLACEHOLDER_TEMPLATE (t2)) + return false; /* Constrained 'auto's are distinct from parms that don't have the same constraints. */ if (!equivalent_placeholder_constraints (t1, t2)) diff --git a/gcc/testsuite/g++.dg/cpp1z/class-deduction58.C b/gcc/testsuite/g++.dg/cpp1z/class-deduction58.C new file mode 100644 index 00000000000..82c3f83710f --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp1z/class-deduction58.C @@ -0,0 +1,16 @@ +// PR c++/86098 +// { dg-additional-options -std=c++17 } + +template <class _Res> class future; +template <class T> T&& declval(); + +template<template <class...> class T> +struct construct_deduced { + template <class... AN> + using deduced_t = decltype(T{declval<AN>()...}); + template<class... AN> + deduced_t<AN...> operator()(AN&&... an) const; +}; + +template<class T> +future<T> future_from(T singleSender);