From 052b2df6f0ecd1e5b55056911b16bca8b31ef7df Mon Sep 17 00:00:00 2001 From: Patrick Palka Date: Thu, 7 Oct 2021 10:02:54 -0400 Subject: [PATCH] c++: variadic ttp constraint subsumption [PR99904] Here we're crashing when level-lowering the variadic constraint C on the template template parameter TT because tsubst_pack_expansion expects processing_template_decl to be set during a partial substitution. PR c++/99904 gcc/cp/ChangeLog: * pt.c (is_compatible_template_arg): Set processing_template_decl around tsubst_constraint_info. gcc/testsuite/ChangeLog: * g++.dg/cpp2a/concepts-ttp4.C: New test. (cherry picked from commit 2e6e0d86a06389056d0e7fecc99c547420ad787a) --- gcc/cp/pt.c | 2 ++ gcc/testsuite/g++.dg/cpp2a/concepts-ttp4.C | 9 +++++++++ 2 files changed, 11 insertions(+) create mode 100644 gcc/testsuite/g++.dg/cpp2a/concepts-ttp4.C diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c index 9e0266996202..5454bfca827a 100644 --- a/gcc/cp/pt.c +++ b/gcc/cp/pt.c @@ -8225,8 +8225,10 @@ is_compatible_template_arg (tree parm, tree arg) { tree aparms = DECL_INNERMOST_TEMPLATE_PARMS (arg); new_args = template_parms_level_to_args (aparms); + ++processing_template_decl; parm_cons = tsubst_constraint_info (parm_cons, new_args, tf_none, NULL_TREE); + --processing_template_decl; if (parm_cons == error_mark_node) return false; } diff --git a/gcc/testsuite/g++.dg/cpp2a/concepts-ttp4.C b/gcc/testsuite/g++.dg/cpp2a/concepts-ttp4.C new file mode 100644 index 000000000000..cf3e71ea974b --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp2a/concepts-ttp4.C @@ -0,0 +1,9 @@ +// PR c++/99904 +// { dg-do compile { target c++20 } } + +template concept C = (Ts::value && ...); +template requires C struct A; +template requires true struct B; +template requires C class TT> struct S; +using ty1 = S; +using ty2 = S; // { dg-error "constraint" } TT's constraints don't subsume B's -- 2.47.2