On 8/30/24 3:40 PM, Marek Polacek wrote:
Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?-- >8 -- Redeclaration such as void f(void); consteval void f(void); is invalid. In a namespace scope, we detect the collision in validate_constexpr_redeclaration, but not when one declaration is at block scope. When we have void f(void); void g() { consteval void f(void); } we call pushdecl on the second f and call push_local_extern_decl_alias. It finds the namespace-scope f: for (ovl_iterator iter (binding); iter; ++iter) if (decls_match (decl, *iter, /*record_versions*/false)) { alias = *iter; break; } but decls_match says they match so we just set DECL_LOCAL_DECL_ALIAS (and do not call another pushdecl leading to duplicate_decls which would detect mismatching return types, for example). I don't think we want to change decls_match, so a simple fix is to detect the problem in push_local_extern_decl_alias. PR c++/116239 gcc/cp/ChangeLog: * cp-tree.h (validate_constexpr_redeclaration): Declare. * decl.cc (validate_constexpr_redeclaration): No longer static. * name-lookup.cc (push_local_extern_decl_alias): Call validate_constexpr_redeclaration. gcc/testsuite/ChangeLog: * g++.dg/diagnostic/redeclaration-6.C: New test. --- gcc/cp/cp-tree.h | 1 + gcc/cp/decl.cc | 2 +- gcc/cp/name-lookup.cc | 3 ++ .../g++.dg/diagnostic/redeclaration-6.C | 34 +++++++++++++++++++ 4 files changed, 39 insertions(+), 1 deletion(-) create mode 100644 gcc/testsuite/g++.dg/diagnostic/redeclaration-6.C diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h index 2eeb5e3e8b1..1a763b683de 100644 --- a/gcc/cp/cp-tree.h +++ b/gcc/cp/cp-tree.h @@ -6992,6 +6992,7 @@ extern bool member_like_constrained_friend_p (tree); extern bool fns_correspond (tree, tree); extern int decls_match (tree, tree, bool = true); extern bool maybe_version_functions (tree, tree, bool); +extern bool validate_constexpr_redeclaration (tree, tree); extern bool merge_default_template_args (tree, tree, bool); extern tree duplicate_decls (tree, tree, bool hiding = false, diff --git a/gcc/cp/decl.cc b/gcc/cp/decl.cc index 6458e96bded..4ad68d609d7 100644 --- a/gcc/cp/decl.cc +++ b/gcc/cp/decl.cc @@ -1412,7 +1412,7 @@ check_redeclaration_exception_specification (tree new_decl, /* Return true if OLD_DECL and NEW_DECL agree on constexprness. Otherwise issue diagnostics. */-static bool+bool validate_constexpr_redeclaration (tree old_decl, tree new_decl) { old_decl = STRIP_TEMPLATE (old_decl); diff --git a/gcc/cp/name-lookup.cc b/gcc/cp/name-lookup.cc index 70ad4cbf3b5..6777d97ac2e 100644 --- a/gcc/cp/name-lookup.cc +++ b/gcc/cp/name-lookup.cc @@ -3708,6 +3708,9 @@ push_local_extern_decl_alias (tree decl) } }+ if (!validate_constexpr_redeclaration (alias, decl))+ return; + retrofit_lang_decl (decl); DECL_LOCAL_DECL_ALIAS (decl) = alias; }
I don't think we need this in the case that we built a new alias and pushed it; in that case alias is built from decl, and should certainly match already. So let's put this call before we decide to build a new alias, either in the loop or just after it.
Jason
