From a8cef3cba6945730c69e15dcdad726e74b50fe58 Mon Sep 17 00:00:00 2001 From: Patrick Palka Date: Sat, 23 Jan 2021 00:24:17 -0500 Subject: [PATCH] c++: 'this' injection and static member functions [PR97399] In the testcase pr97399.C below, finish_qualified_id_expr at parse time adds an implicit 'this->' to the expression tmp::integral (because it's type-dependent, and also current_class_ptr is set at this point) within the trailing return type. Later when substituting into this trailing return type we crash because we can't resolve the 'this', since tsubst_function_type does inject_this_parm only for non-static member functions, which tmp::func is not. This patch fixes this issue by removing the type-dependence check in finish_qualified_id_expr added by r9-5972, and instead relaxes shared_member_p to handle dependent USING_DECLs: > I think I was wrong in my assertion around Alex's patch that > shared_member_p should abort on a dependent USING_DECL; it now seems > appropriate for it to return false if we don't know, we just need to > adjust the comment to say that. And when parsing a friend function declaration, we shouldn't be setting current_class_ptr at all, so this patch additionally suppresses inject_this_parm in this case. Finally, the self-contained change to cp_parser_init_declarator is so that we properly communicate static-ness to cp_parser_direct_declarator when parsing a member function template. This lets us reject the explicit use of 'this' in the testcase this2.C below. gcc/cp/ChangeLog: PR c++/97399 * cp-tree.h (shared_member_p): Adjust declaration. * parser.c (cp_parser_init_declarator): If the storage class specifier is sc_static, pass true for static_p to cp_parser_declarator. (cp_parser_direct_declarator): Don't do inject_this_parm when the declarator is a friend. * search.c (shared_member_p): Change return type to bool and adjust function body accordingly. Return false for a dependent USING_DECL instead of aborting. * semantics.c (finish_qualified_id_expr): Rely on shared_member_p even when type-dependent. gcc/testsuite/ChangeLog: PR c++/88548 PR c++/97399 * g++.dg/cpp0x/this2.C: New test. * g++.dg/template/pr97399.C: New test. --- gcc/cp/cp-tree.h | 2 +- gcc/cp/parser.c | 5 +++-- gcc/cp/search.c | 20 +++++++++++--------- gcc/cp/semantics.c | 3 +-- gcc/testsuite/g++.dg/cpp0x/this2.C | 8 ++++++++ gcc/testsuite/g++.dg/template/pr97399.C | 23 +++++++++++++++++++++++ 6 files changed, 47 insertions(+), 14 deletions(-) create mode 100644 gcc/testsuite/g++.dg/cpp0x/this2.C create mode 100644 gcc/testsuite/g++.dg/template/pr97399.C diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h index 51139f4a4be..3046c838630 100644 --- a/gcc/cp/cp-tree.h +++ b/gcc/cp/cp-tree.h @@ -7312,7 +7312,7 @@ extern tree adjust_result_of_qualified_name_lookup (tree, tree, tree); extern tree copied_binfo (tree, tree); extern tree original_binfo (tree, tree); -extern int shared_member_p (tree); +extern bool shared_member_p (tree); extern bool any_dependent_bases_p (tree = current_nonlambda_class_type ()); extern bool maybe_check_overriding_exception_spec (tree, tree); diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c index e0208d02bdc..e196db14113 100644 --- a/gcc/cp/parser.c +++ b/gcc/cp/parser.c @@ -21413,6 +21413,7 @@ cp_parser_init_declarator (cp_parser* parser, bool is_non_constant_init; int ctor_dtor_or_conv_p; bool friend_p = cp_parser_friend_p (decl_specifiers); + bool static_p = decl_specifiers->storage_class == sc_static; tree pushed_scope = NULL_TREE; bool range_for_decl_p = false; bool saved_default_arg_ok_p = parser->default_arg_ok_p; @@ -21446,7 +21447,7 @@ cp_parser_init_declarator (cp_parser* parser, = cp_parser_declarator (parser, CP_PARSER_DECLARATOR_NAMED, flags, &ctor_dtor_or_conv_p, /*parenthesized_p=*/NULL, - member_p, friend_p, /*static_p=*/false); + member_p, friend_p, static_p); /* Gather up the deferred checks. */ stop_deferring_access_checks (); @@ -22122,7 +22123,7 @@ cp_parser_direct_declarator (cp_parser* parser, tree save_ccp = current_class_ptr; tree save_ccr = current_class_ref; - if (memfn) + if (memfn && !friend_p) /* DR 1207: 'this' is in scope after the cv-quals. */ inject_this_parameter (current_class_type, cv_quals); diff --git a/gcc/cp/search.c b/gcc/cp/search.c index dd3773da4f7..81bdd45e40d 100644 --- a/gcc/cp/search.c +++ b/gcc/cp/search.c @@ -910,7 +910,7 @@ struct lookup_field_info { const char *errstr; }; -/* Nonzero for a class member means that it is shared between all objects +/* True for a class member means that it is shared between all objects of that class. [class.member.lookup]:If the resulting set of declarations are not all @@ -920,25 +920,27 @@ struct lookup_field_info { This function checks that T contains no non-static members. */ -int +bool shared_member_p (tree t) { - if (VAR_P (t) || TREE_CODE (t) == TYPE_DECL \ + if (VAR_P (t) || TREE_CODE (t) == TYPE_DECL || TREE_CODE (t) == CONST_DECL) - return 1; + return true; if (is_overloaded_fn (t)) { for (ovl_iterator iter (get_fns (t)); iter; ++iter) { tree decl = strip_using_decl (*iter); - /* We don't expect or support dependent decls. */ - gcc_assert (TREE_CODE (decl) != USING_DECL); + if (TREE_CODE (decl) == USING_DECL) + /* Conservatively assume a dependent using-declaration + might resolve to a non-static member. */ + return false; if (DECL_NONSTATIC_MEMBER_FUNCTION_P (decl)) - return 0; + return false; } - return 1; + return true; } - return 0; + return false; } /* Routine to see if the sub-object denoted by the binfo PARENT can be diff --git a/gcc/cp/semantics.c b/gcc/cp/semantics.c index 067095276af..51841dcf24a 100644 --- a/gcc/cp/semantics.c +++ b/gcc/cp/semantics.c @@ -2214,8 +2214,7 @@ finish_qualified_id_expr (tree qualifying_class, { /* See if any of the functions are non-static members. */ /* If so, the expression may be relative to 'this'. */ - if ((type_dependent_expression_p (expr) - || !shared_member_p (expr)) + if (!shared_member_p (expr) && current_class_ptr && DERIVED_FROM_P (qualifying_class, current_nonlambda_class_type ())) diff --git a/gcc/testsuite/g++.dg/cpp0x/this2.C b/gcc/testsuite/g++.dg/cpp0x/this2.C new file mode 100644 index 00000000000..ccc2608feb2 --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp0x/this2.C @@ -0,0 +1,8 @@ +// PR c++/88548 +// { dg-do compile { target c++11 } } + +struct S { + int a; + template static auto m1 () + -> decltype(this->a) { return 0; } // { dg-error "'this'" } +}; diff --git a/gcc/testsuite/g++.dg/template/pr97399.C b/gcc/testsuite/g++.dg/template/pr97399.C new file mode 100644 index 00000000000..4bb818908fd --- /dev/null +++ b/gcc/testsuite/g++.dg/template/pr97399.C @@ -0,0 +1,23 @@ +// PR c++/97399 +// { dg-do compile { target c++11 } } + +template struct enable_if_t {}; + +struct tmp { + template static constexpr bool is_integral(); + template static auto f() + -> enable_if_t()>; + template friend auto g(tmp, T) + -> enable_if_t()>; +}; + +template constexpr bool tmp::is_integral() { return true; } + +template auto tmp::f() + -> enable_if_t()> { return {}; } + +int main() +{ + tmp::f(); + g(tmp{}, 0); +} -- 2.30.2