From 0bc2a1dc327af9817163cc8df78b9f9be2ad0f90 Mon Sep 17 00:00:00 2001 From: Jason Merrill Date: Tue, 14 Mar 2023 15:16:46 -0400 Subject: [PATCH] c++: fix TTP level reduction cache We try to cache the result of reduce_template_parm_level so that when we reduce the same parm multiple times we get the same result, but this wasn't working for template template parms because in that case TYPE is a TEMPLATE_TEMPLATE_PARM, and so same_type_p was false because of the same level mismatch that we're trying to adjust for. So in that case compare the template parms of the template template parms instead. The result can be seen in nontype12.C, where we previously gave three duplicate errors on line 7 and now give only one because subsequent substitutions use the cache. gcc/cp/ChangeLog: * pt.cc (reduce_template_parm_level): Fix comparison of template template parm to cached version. gcc/testsuite/ChangeLog: * g++.dg/template/nontype12.C: Check for duplicate error. --- gcc/cp/pt.cc | 7 ++++++- gcc/testsuite/g++.dg/template/nontype12.C | 3 ++- 2 files changed, 8 insertions(+), 2 deletions(-) diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc index 471fc20bc5b9..5446b5058b75 100644 --- a/gcc/cp/pt.cc +++ b/gcc/cp/pt.cc @@ -4550,7 +4550,12 @@ reduce_template_parm_level (tree index, tree type, int levels, tree args, if (TEMPLATE_PARM_DESCENDANTS (index) == NULL_TREE || (TEMPLATE_PARM_LEVEL (TEMPLATE_PARM_DESCENDANTS (index)) != TEMPLATE_PARM_LEVEL (index) - levels) - || !same_type_p (type, TREE_TYPE (TEMPLATE_PARM_DESCENDANTS (index)))) + || !(TREE_CODE (type) == TEMPLATE_TEMPLATE_PARM + ? (comp_template_parms + (DECL_TEMPLATE_PARMS (TYPE_NAME (type)), + DECL_TEMPLATE_PARMS (TEMPLATE_PARM_DECL + (TEMPLATE_PARM_DESCENDANTS (index))))) + : same_type_p (type, TREE_TYPE (TEMPLATE_PARM_DESCENDANTS (index))))) { tree orig_decl = TEMPLATE_PARM_DECL (index); diff --git a/gcc/testsuite/g++.dg/template/nontype12.C b/gcc/testsuite/g++.dg/template/nontype12.C index e37cf8f7646f..6642ffd0a135 100644 --- a/gcc/testsuite/g++.dg/template/nontype12.C +++ b/gcc/testsuite/g++.dg/template/nontype12.C @@ -4,7 +4,8 @@ template struct A { template int foo(); // { dg-error "double" "" { target c++17_down } } - template class> int bar(); // { dg-error "double" "" { target c++17_down } } + template class> int bar(); // { dg-bogus {double.*C:7:[^\n]*double} } + // { dg-error "double" "" { target c++17_down } .-1 } template struct X; // { dg-error "double" "" { target c++17_down } } }; -- 2.47.2