From 29853c653245c37ed31b6abcc9799b534372e938 Mon Sep 17 00:00:00 2001 From: Patrick Palka Date: Tue, 19 Jan 2021 16:20:00 -0500 Subject: [PATCH] c++: Always check access during late-parsing of members [PR58993] This patch removes a vestigial use of dk_no_check from cp_parser_late_parsing_for_member, which ideally should have been removed as part of the PR41437 patch that improved access checking inside templates. This allows us to correctly reject f1 and f2 in the testcase access34.C below (whereas before we'd only reject f3). Additional testing revealed a new access issue when late-parsing a hidden friend within a class template. In the testcase friend68.C below, we're tripping over the checking assert from friend_accessible_p(f, S::j, S, S) during lookup of j in x.j (for which type_dependent_object_expression_p returns false, which is why we're doing the lookup at parse time). The reason for the assert failure is that DECL_FRIENDLIST(S) contains f but DECL_BEFRIENDING_CLASSES(f) is empty, and so friend_accessible_p (which looks at DECL_BEFRIENDING_CLASSES) wants to return false, but is_friend (which looks at DECL_FRIENDLIST) returns true. For sake of symmetry one would expect that DECL_BEFRIENDING_CLASSES(f) contains S, but add_friend avoids updating DECL_BEFRIENDING_CLASSES when the class type (S in this case) is dependent, for some reason. This patch works around this issue by making friend_accessible_p consider the DECL_FRIEND_CONTEXT of the access scope. Thus we sidestep the DECL_BEFRIENDING_CLASSES / DECL_FRIENDLIST asymmetry issue while correctly validating the x.j access at parse time. A earlier version of this patch checked friend_accessible_p instead of protected_accessible_p in the DECL_FRIEND_CONTEXT hunk below, but this had the side effect of making us accept the ill-formed testcase friend69.C below (ill-formed because the hidden friend g is not actually a member of A, so g doesn't have access to B's members despite B befriending A). gcc/cp/ChangeLog: PR c++/41437 PR c++/58993 * search.c (friend_accessible_p): If scope is a hidden friend defined inside a dependent class, consider access from the class. * parser.c (cp_parser_late_parsing_for_member): Don't push a dk_no_check access state. gcc/testsuite/ChangeLog: PR c++/41437 PR c++/58993 * g++.dg/opt/pr87974.C: Adjust. * g++.dg/template/access34.C: New test. * g++.dg/template/friend68.C: New test. * g++.dg/template/friend69.C: New test. --- gcc/cp/parser.c | 7 ------ gcc/cp/search.c | 8 +++++++ gcc/testsuite/g++.dg/opt/pr87974.C | 1 + gcc/testsuite/g++.dg/template/access34.C | 29 ++++++++++++++++++++++++ gcc/testsuite/g++.dg/template/friend68.C | 13 +++++++++++ gcc/testsuite/g++.dg/template/friend69.C | 18 +++++++++++++++ 6 files changed, 69 insertions(+), 7 deletions(-) create mode 100644 gcc/testsuite/g++.dg/template/access34.C create mode 100644 gcc/testsuite/g++.dg/template/friend68.C create mode 100644 gcc/testsuite/g++.dg/template/friend69.C diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c index 5651cfacd3c..eeffc2e7ae3 100644 --- a/gcc/cp/parser.c +++ b/gcc/cp/parser.c @@ -30823,10 +30823,6 @@ cp_parser_late_parsing_for_member (cp_parser* parser, tree member_function) start_preparsed_function (member_function, NULL_TREE, SF_PRE_PARSED | SF_INCLASS_INLINE); - /* Don't do access checking if it is a templated function. */ - if (processing_template_decl) - push_deferring_access_checks (dk_no_check); - /* #pragma omp declare reduction needs special parsing. */ if (DECL_OMP_DECLARE_REDUCTION_P (member_function)) { @@ -30840,9 +30836,6 @@ cp_parser_late_parsing_for_member (cp_parser* parser, tree member_function) cp_parser_function_definition_after_declarator (parser, /*inline_p=*/true); - if (processing_template_decl) - pop_deferring_access_checks (); - /* Leave the scope of the containing function. */ if (function_scope) pop_function_context (); diff --git a/gcc/cp/search.c b/gcc/cp/search.c index 1a9dba451c7..dd3773da4f7 100644 --- a/gcc/cp/search.c +++ b/gcc/cp/search.c @@ -698,6 +698,14 @@ friend_accessible_p (tree scope, tree decl, tree type, tree otype) if (DECL_CLASS_SCOPE_P (scope) && friend_accessible_p (DECL_CONTEXT (scope), decl, type, otype)) return 1; + /* Perhaps SCOPE is a friend function defined inside a class from which + DECL is accessible. Checking this is necessary only when the class + is dependent, for otherwise add_friend will already have added the + class to SCOPE's DECL_BEFRIENDING_CLASSES. */ + if (tree fctx = DECL_FRIEND_CONTEXT (scope)) + if (dependent_type_p (fctx) + && protected_accessible_p (decl, fctx, type, otype)) + return 1; } /* Maybe scope's template is a friend. */ diff --git a/gcc/testsuite/g++.dg/opt/pr87974.C b/gcc/testsuite/g++.dg/opt/pr87974.C index 4b070d2a6f8..7d8357a025c 100644 --- a/gcc/testsuite/g++.dg/opt/pr87974.C +++ b/gcc/testsuite/g++.dg/opt/pr87974.C @@ -8,6 +8,7 @@ class i { struct j { using c = int *; }; +public: using as = j::c; }; template class k { diff --git a/gcc/testsuite/g++.dg/template/access34.C b/gcc/testsuite/g++.dg/template/access34.C new file mode 100644 index 00000000000..ec79f87e624 --- /dev/null +++ b/gcc/testsuite/g++.dg/template/access34.C @@ -0,0 +1,29 @@ +// PR c++/58993 +// { dg-do compile } + +class base { void foo(); }; + +template +struct bar : public base { + void f1() { + &base::foo; // { dg-error "private" } + } + + template + void f2() { + &base::foo; // { dg-error "private" } + } + + void f3(); +}; + +template +void bar::f3() { + (void) &base::foo; // { dg-error "private" } +} + +int main() { + bar().f1(); + bar().f2(); + bar().f3(); +} diff --git a/gcc/testsuite/g++.dg/template/friend68.C b/gcc/testsuite/g++.dg/template/friend68.C new file mode 100644 index 00000000000..fa34d2c30d5 --- /dev/null +++ b/gcc/testsuite/g++.dg/template/friend68.C @@ -0,0 +1,13 @@ +// { dg-do compile } + +template +struct S { + S(); + friend int f(S x) { return x.i + x.j; } + template + friend int g(S x, T) { return x.i + x.j; } +private: + int i; +protected: + int j; +}; diff --git a/gcc/testsuite/g++.dg/template/friend69.C b/gcc/testsuite/g++.dg/template/friend69.C new file mode 100644 index 00000000000..f3086a9f980 --- /dev/null +++ b/gcc/testsuite/g++.dg/template/friend69.C @@ -0,0 +1,18 @@ +// { dg-do compile } + +struct A; + +struct B { + friend struct A; +private: + static void f(); +protected: + static void g(); +}; + +struct A { + friend void g(A) { + B::f(); // { dg-error "private" } + B::g(); // { dg-error "protected" } + } +}; -- 2.30.2