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From: Marek Polacek <mpolacek@gcc.gnu.org> To: gcc-cvs@gcc.gnu.org, libstdc++-cvs@gcc.gnu.org Subject: [gcc/trunk] c++: Reject ordered comparison of null pointers [PR99701] Date: Tue, 27 Jul 2021 15:39:46 +0000 (GMT) [thread overview] Message-ID: <20210727153946.C5E1B3851C39@sourceware.org> (raw) https://gcc.gnu.org/g:bee2f80b901d73f50275f2b44932067ffcf616ca commit bee2f80b901d73f50275f2b44932067ffcf616ca Author: Marek Polacek <polacek@redhat.com> Date: Fri Jul 16 15:58:01 2021 -0400 c++: Reject ordered comparison of null pointers [PR99701] When implementing DR 1512 in r11-467 I neglected to reject ordered comparison of two null pointers, like nullptr < nullptr. This patch fixes that omission. DR 1512 PR c++/99701 gcc/cp/ChangeLog: * cp-gimplify.c (cp_fold): Remove {LE,LT,GE,GT_EXPR} from a switch. * typeck.c (cp_build_binary_op): Reject ordered comparison of two null pointers. gcc/testsuite/ChangeLog: * g++.dg/cpp0x/nullptr11.C: Remove invalid tests. * g++.dg/cpp0x/nullptr46.C: Add dg-error. * g++.dg/cpp2a/spaceship-err7.C: New test. * g++.dg/expr/ptr-comp4.C: New test. libstdc++-v3/ChangeLog: * testsuite/20_util/tuple/comparison_operators/overloaded.cc: Move a line... * testsuite/20_util/tuple/comparison_operators/overloaded2.cc: ...here. New test. Diff: --- gcc/cp/cp-gimplify.c | 4 -- gcc/cp/typeck.c | 15 ++----- gcc/testsuite/g++.dg/cpp0x/nullptr11.C | 16 ------- gcc/testsuite/g++.dg/cpp0x/nullptr46.C | 3 +- gcc/testsuite/g++.dg/cpp2a/spaceship-err7.C | 14 ++++++ gcc/testsuite/g++.dg/expr/ptr-comp4.C | 21 +++++++++ .../tuple/comparison_operators/overloaded.cc | 1 - .../tuple/comparison_operators/overloaded2.cc | 52 ++++++++++++++++++++++ 8 files changed, 92 insertions(+), 34 deletions(-) diff --git a/gcc/cp/cp-gimplify.c b/gcc/cp/cp-gimplify.c index ff0bff771df..0520fa45b91 100644 --- a/gcc/cp/cp-gimplify.c +++ b/gcc/cp/cp-gimplify.c @@ -2433,13 +2433,9 @@ cp_fold (tree x) switch (code) { case EQ_EXPR: - case LE_EXPR: - case GE_EXPR: x = constant_boolean_node (true, TREE_TYPE (x)); break; case NE_EXPR: - case LT_EXPR: - case GT_EXPR: x = constant_boolean_node (false, TREE_TYPE (x)); break; default: diff --git a/gcc/cp/typeck.c b/gcc/cp/typeck.c index a483e1f988d..738e69a0440 100644 --- a/gcc/cp/typeck.c +++ b/gcc/cp/typeck.c @@ -5483,7 +5483,9 @@ cp_build_binary_op (const op_location_t &location, result_type = composite_pointer_type (location, type0, type1, op0, op1, CPO_COMPARISON, complain); - else if (code0 == POINTER_TYPE && null_ptr_cst_p (orig_op1)) + else if ((code0 == POINTER_TYPE && null_ptr_cst_p (orig_op1)) + || (code1 == POINTER_TYPE && null_ptr_cst_p (orig_op0)) + || (null_ptr_cst_p (orig_op0) && null_ptr_cst_p (orig_op1))) { /* Core Issue 1512 made this ill-formed. */ if (complain & tf_error) @@ -5491,17 +5493,6 @@ cp_build_binary_op (const op_location_t &location, "integer zero (%qT and %qT)", type0, type1); return error_mark_node; } - else if (code1 == POINTER_TYPE && null_ptr_cst_p (orig_op0)) - { - /* Core Issue 1512 made this ill-formed. */ - if (complain & tf_error) - error_at (location, "ordered comparison of pointer with " - "integer zero (%qT and %qT)", type0, type1); - return error_mark_node; - } - else if (null_ptr_cst_p (orig_op0) && null_ptr_cst_p (orig_op1)) - /* One of the operands must be of nullptr_t type. */ - result_type = TREE_TYPE (nullptr_node); else if (code0 == POINTER_TYPE && code1 == INTEGER_TYPE) { result_type = type0; diff --git a/gcc/testsuite/g++.dg/cpp0x/nullptr11.C b/gcc/testsuite/g++.dg/cpp0x/nullptr11.C index f81f0c3c1c8..b8bc682f2ea 100644 --- a/gcc/testsuite/g++.dg/cpp0x/nullptr11.C +++ b/gcc/testsuite/g++.dg/cpp0x/nullptr11.C @@ -9,31 +9,15 @@ void fun() { assert_true(nullptr == nullptr); assert_false(nullptr != nullptr); - assert_false(nullptr < nullptr); - assert_false(nullptr > nullptr); - assert_true(nullptr <= nullptr); - assert_true(nullptr >= nullptr); decltype(nullptr) mynull = 0; assert_true(mynull == nullptr); assert_false(mynull != nullptr); - assert_false(mynull < nullptr); - assert_false(mynull > nullptr); - assert_true(mynull <= nullptr); - assert_true(mynull >= nullptr); assert_true(nullptr == mynull); assert_false(nullptr != mynull); - assert_false(nullptr < mynull); - assert_false(nullptr > mynull); - assert_true(nullptr <= mynull); - assert_true(nullptr >= mynull); assert_true(mynull == mynull); assert_false(mynull != mynull); - assert_false(mynull < mynull); - assert_false(mynull > mynull); - assert_true(mynull <= mynull); - assert_true(mynull >= mynull); } diff --git a/gcc/testsuite/g++.dg/cpp0x/nullptr46.C b/gcc/testsuite/g++.dg/cpp0x/nullptr46.C index 1514cee3c3b..6c08eaa4d8f 100644 --- a/gcc/testsuite/g++.dg/cpp0x/nullptr46.C +++ b/gcc/testsuite/g++.dg/cpp0x/nullptr46.C @@ -7,5 +7,6 @@ decltype(nullptr) foo (); bool bar () { - return foo () > nullptr || foo () < nullptr; + return foo () > nullptr // { dg-error "ordered comparison" } + || foo () < nullptr; // { dg-error "ordered comparison" } } diff --git a/gcc/testsuite/g++.dg/cpp2a/spaceship-err7.C b/gcc/testsuite/g++.dg/cpp2a/spaceship-err7.C new file mode 100644 index 00000000000..bc309230239 --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp2a/spaceship-err7.C @@ -0,0 +1,14 @@ +// PR c++/99701 +// { dg-do compile { target c++20 } } + +#include <compare> + +decltype(nullptr) foo (); + +auto b0 = nullptr <=> nullptr; // { dg-error "ordered comparison" } +auto b1 = 0 <=> nullptr; // { dg-error "ordered comparison" } +auto b2 = nullptr <=> 0; // { dg-error "ordered comparison" } +auto b3 = foo () <=> 0; // { dg-error "ordered comparison" } +auto b4 = 0 <=> foo (); // { dg-error "ordered comparison" } +auto b5 = foo () <=> nullptr; // { dg-error "ordered comparison" } +auto b6 = nullptr <=> foo (); // { dg-error "ordered comparison" } diff --git a/gcc/testsuite/g++.dg/expr/ptr-comp4.C b/gcc/testsuite/g++.dg/expr/ptr-comp4.C new file mode 100644 index 00000000000..da4951806c1 --- /dev/null +++ b/gcc/testsuite/g++.dg/expr/ptr-comp4.C @@ -0,0 +1,21 @@ +// PR c++/99701 +// DR 1512 +// { dg-do compile { target c++11 } } + +/* Relational comparisons between null pointer constants and pointers are + ill-formed. */ + +decltype(nullptr) foo (); + +auto lt = nullptr < nullptr; // { dg-error "ordered comparison" } +auto gt = nullptr > nullptr; // { dg-error "ordered comparison" } +auto le = nullptr <= nullptr; // { dg-error "ordered comparison" } +auto ge = nullptr >= nullptr; // { dg-error "ordered comparison" } +auto eq = nullptr == nullptr; +auto ne = nullptr != nullptr; +auto a1 = nullptr > 0; // { dg-error "ordered comparison" } +auto a2 = 0 < nullptr; // { dg-error "ordered comparison" } +auto a3 = foo () > 0; // { dg-error "ordered comparison" } +auto a4 = 0 < foo (); // { dg-error "ordered comparison" } +auto a5 = 0 <= foo (); // { dg-error "ordered comparison" } +auto a6 = foo () >= 0; // { dg-error "ordered comparison" } diff --git a/libstdc++-v3/testsuite/20_util/tuple/comparison_operators/overloaded.cc b/libstdc++-v3/testsuite/20_util/tuple/comparison_operators/overloaded.cc index a25c374a932..ef90b6b5b73 100644 --- a/libstdc++-v3/testsuite/20_util/tuple/comparison_operators/overloaded.cc +++ b/libstdc++-v3/testsuite/20_util/tuple/comparison_operators/overloaded.cc @@ -48,4 +48,3 @@ TwistedLogic operator<(const Compares&, const Compares&) { return {false}; } auto a = std::make_tuple(nullptr, Compares{}, 2, 'U'); auto b = a == a; -auto c = a < a; diff --git a/libstdc++-v3/testsuite/20_util/tuple/comparison_operators/overloaded2.cc b/libstdc++-v3/testsuite/20_util/tuple/comparison_operators/overloaded2.cc new file mode 100644 index 00000000000..fc3118f85a8 --- /dev/null +++ b/libstdc++-v3/testsuite/20_util/tuple/comparison_operators/overloaded2.cc @@ -0,0 +1,52 @@ +// { dg-do compile { target c++11 } } + +// Copyright (C) 2014-2021 Free Software Foundation, Inc. +// +// This file is part of the GNU ISO C++ Library. This library is free +// software; you can redistribute it and/or modify it under the +// terms of the GNU General Public License as published by the +// Free Software Foundation; either version 3, or (at your option) +// any later version. + +// This library is distributed in the hope that it will be useful, +// but WITHOUT ANY WARRANTY; without even the implied warranty of +// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +// GNU General Public License for more details. + +// You should have received a copy of the GNU General Public License along +// with this library; see the file COPYING3. If not see +// <http://www.gnu.org/licenses/>. + +#include <tuple> + +// A type that is contextually convertible to bool but cannot be used with +// the usual logical operators, and/or/not. +struct TwistedLogic { + bool value; + + explicit operator bool() const noexcept { return value; } +}; + +template<typename T> +bool operator&&(const T&, TwistedLogic) = delete; + +template<typename T> +bool operator&&(TwistedLogic, const T&) = delete; + +template<typename T> +bool operator||(const T&, TwistedLogic) = delete; + +template<typename T> +bool operator||(TwistedLogic, const T&) = delete; + +bool operator!(TwistedLogic) noexcept = delete; + +struct Compares {}; + +TwistedLogic operator==(const Compares&, const Compares&) { return {true}; } +TwistedLogic operator<(const Compares&, const Compares&) { return {false}; } + +auto a = std::make_tuple(nullptr, Compares{}, 2, 'U'); +auto b = a < a; + +// { dg-error "ordered comparison" "" { target *-*-* } 0 }
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