When a member template is redeclared as a friend, we enter the context of the member before looking it up, and then we check that the decls are compatible. However, when the member template references template types of the enclosing context, say an enclosing template class, the compare fails because the friend decl is already tsubsted, whereas the looked up name isn't.
The problem is that the enclosing context is taken from the friend declaration before tsubsting it, so we look up in the context of the generic template instead of that of the tsubsted one we're specializing. The solution is to tsubst the enclosing context when it's a non-namespace scope. Regstrapped on i686- and x86_64-linux-gnu. Ok to install? for gcc/cp/ChangeLog PR c++/86747 * pt.c (tsubst_friend_class): Enter tsubsted class context. for gcc/testsuite/ChangeLog PR c++/86747 * g++.dg/pr86747.C: New. --- gcc/cp/pt.c | 5 ++++- gcc/testsuite/g++.dg/pr86747.C | 8 ++++++++ 2 files changed, 12 insertions(+), 1 deletion(-) create mode 100644 gcc/testsuite/g++.dg/pr86747.C diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c index 83d0a74b209f..82c8019431b8 100644 --- a/gcc/cp/pt.c +++ b/gcc/cp/pt.c @@ -10568,7 +10568,10 @@ tsubst_friend_class (tree friend_tmpl, tree args) if (TREE_CODE (context) == NAMESPACE_DECL) push_nested_namespace (context); else - push_nested_class (context); + { + context = tsubst (context, args, tf_error, NULL_TREE); + push_nested_class (context); + } tmpl = lookup_name_real (DECL_NAME (friend_tmpl), /*prefer_type=*/false, /*non_class=*/false, /*block_p=*/false, diff --git a/gcc/testsuite/g++.dg/pr86747.C b/gcc/testsuite/g++.dg/pr86747.C new file mode 100644 index 000000000000..5b0a0bb95146 --- /dev/null +++ b/gcc/testsuite/g++.dg/pr86747.C @@ -0,0 +1,8 @@ +// { dg-do compile } + +template <typename T> class A { + template <void (A::*p)()> class C; // #1 + template <void (A::*q)()> friend class C; // #2 +}; + +A<double> a; -- Alexandre Oliva, freedom fighter https://FSFLA.org/blogs/lxo Be the change, be Free! FSF Latin America board member GNU Toolchain Engineer Free Software Evangelist Hay que enGNUrecerse, pero sin perder la terGNUra jamás-GNUChe