[PATCH v2] c++: Reject ordered comparison of null pointers [PR99701]
Marek Polacek
polacek@redhat.com
Mon Jul 19 18:46:22 GMT 2021
On Sat, Jul 17, 2021 at 02:50:28PM -0700, Jason Merrill wrote:
> On 7/16/21 6:34 PM, Jakub Jelinek wrote:
> > On Fri, Jul 16, 2021 at 05:36:13PM -0400, Marek Polacek via Gcc-patches wrote:
> > > 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.
> > >
> > > Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
> > >
> > > 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/expr/ptr-comp4.C: New test.
> > >
> > > libstdc++-v3/ChangeLog:
> > >
> > > * testsuite/20_util/tuple/comparison_operators/overloaded.cc:
> > > Add dg-error.
> >
> > Maybe it would be useful to have also a g++.dg/cpp2a/ testcase with
> > nullptr <=> nullptr etc. (nullptr <=> 0, etc. what you test
> > in ptr-comp4.C after #include <compare>).
>
> Sounds good.
Done.
> > +++ b/libstdc++-v3/testsuite/20_util/tuple/comparison_operators/overloaded.cc
> > @@ -49,3 +49,5 @@ 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;
> > +
> > +// { dg-error "ordered comparison" "" { target *-*-* } 0 }
>
> If we can't test for the specific problematic line, let's split this
> testcase into separate well-formed and ill-formed tests.
Done, I don't know if there's a trick to check an error that comes
from tuple. Jon, are you OK with what I'm doing here? Since
overloaded.cc and overloaded2.cc are essentially the same I could
make the substance of the test into a separate file but since it's
just a test, I didn't bother.
Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
-- >8 --
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.
---
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(-)
create mode 100644 gcc/testsuite/g++.dg/cpp2a/spaceship-err7.C
create mode 100644 gcc/testsuite/g++.dg/expr/ptr-comp4.C
create mode 100644 libstdc++-v3/testsuite/20_util/tuple/comparison_operators/overloaded2.cc
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 }
base-commit: f007a638a86e4b59bef0a0d8efa5bb8c5e5b200a
--
2.31.1
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