From b083a14dfe1f53446722f488885078e419238d24 Mon Sep 17 00:00:00 2001 From: Patrick Palka Date: Thu, 22 Oct 2020 07:27:55 -0400 Subject: [PATCH] c++: Check DECL_TEMPLATE_PARM_P in duplicate_decls [PR97511] This makes duplicate_decls differentiate a TYPE_DECL for an alias template from a TYPE_DECL for one of its template parameters. The recently added assert in template_parm_to_arg revealed this latent issue because merging of the two TYPE_DECLs cleared the DECL_TEMPLATE_PARM_P flag. With this patch, we now also correctly diagnose the name shadowing in the below testcase (as required by [temp.local]/6). gcc/cp/ChangeLog: PR c++/97511 * decl.c (duplicate_decls): Return NULL_TREE if DECL_TEMPLATE_PARM_P differ. gcc/testsuite/ChangeLog: PR c++/97511 * g++.dg/template/shadow3.C: New test. --- gcc/cp/decl.c | 3 +++ gcc/testsuite/g++.dg/template/shadow3.C | 4 ++++ 2 files changed, 7 insertions(+) create mode 100644 gcc/testsuite/g++.dg/template/shadow3.C diff --git a/gcc/cp/decl.c b/gcc/cp/decl.c index 5f370e60b4e..2de4e1657fb 100644 --- a/gcc/cp/decl.c +++ b/gcc/cp/decl.c @@ -2002,6 +2002,9 @@ duplicate_decls (tree newdecl, tree olddecl, bool hiding, bool was_hidden) || DECL_IMPLICIT_TYPEDEF_P (newdecl))) return NULL_TREE; + if (DECL_TEMPLATE_PARM_P (olddecl) != DECL_TEMPLATE_PARM_P (newdecl)) + return NULL_TREE; + if (!validate_constexpr_redeclaration (olddecl, newdecl)) return error_mark_node; diff --git a/gcc/testsuite/g++.dg/template/shadow3.C b/gcc/testsuite/g++.dg/template/shadow3.C new file mode 100644 index 00000000000..a5f256384ac --- /dev/null +++ b/gcc/testsuite/g++.dg/template/shadow3.C @@ -0,0 +1,4 @@ +// PR c++/97511 +// { dg-do compile { target c++11 } } + +template using Z = Z; // { dg-error "shadow|declaration" } -- 2.30.2