From: Jonathan Wakely <jwakely@redhat.com>
To: gcc-patches@gcc.gnu.org, libstdc++@gcc.gnu.org
Cc: Marek Polacek <polacek@redhat.com>, Jason Merrill <jason@redhat.com>
Subject: [PATCH] c++: Make __is_{,nothrow_}convertible SFINAE on access [PR107049]
Date: Tue, 27 Sep 2022 11:35:10 +0100 [thread overview]
Message-ID: <20220927103510.2321453-1-jwakely@redhat.com> (raw)
Tested powerpc64le-linux. OK for trunk?
-- >8 --
The is_convertible built-ins should return false if the conversion fails
an access check, not report an error.
PR c++/107049
gcc/cp/ChangeLog:
* method.cc (is_convertible_helper): Use access check sentinel.
gcc/testsuite/ChangeLog:
* g++.dg/ext/is_convertible4.C: New test.
* g++.dg/ext/is_nothrow_convertible4.C: New test.
libstdc++-v3/ChangeLog:
* testsuite/20_util/is_convertible/requirements/access.cc: New
test.
---
gcc/cp/method.cc | 1 +
gcc/testsuite/g++.dg/ext/is_convertible4.C | 33 +++++++++++++++++++
.../g++.dg/ext/is_nothrow_convertible4.C | 33 +++++++++++++++++++
.../is_convertible/requirements/access.cc | 18 ++++++++++
4 files changed, 85 insertions(+)
create mode 100644 gcc/testsuite/g++.dg/ext/is_convertible4.C
create mode 100644 gcc/testsuite/g++.dg/ext/is_nothrow_convertible4.C
create mode 100644 libstdc++-v3/testsuite/20_util/is_convertible/requirements/access.cc
diff --git a/gcc/cp/method.cc b/gcc/cp/method.cc
index 9f917f13134..55af5c43c18 100644
--- a/gcc/cp/method.cc
+++ b/gcc/cp/method.cc
@@ -2246,6 +2246,7 @@ is_convertible_helper (tree from, tree to)
return integer_one_node;
cp_unevaluated u;
tree expr = build_stub_object (from);
+ deferring_access_check_sentinel acs (dk_no_deferred);
return perform_implicit_conversion (to, expr, tf_none);
}
diff --git a/gcc/testsuite/g++.dg/ext/is_convertible4.C b/gcc/testsuite/g++.dg/ext/is_convertible4.C
new file mode 100644
index 00000000000..8a7724c5852
--- /dev/null
+++ b/gcc/testsuite/g++.dg/ext/is_convertible4.C
@@ -0,0 +1,33 @@
+// PR c++/107049
+// { dg-do compile { target c++11 } }
+// Failed access check should be a substitution failure, not an error.
+
+template<bool B>
+struct bool_constant { static constexpr bool value = B; };
+
+template<typename From, typename To>
+struct is_convertible
+: public bool_constant<__is_convertible(From, To)>
+{ };
+
+#if __cpp_variable_templates
+template<typename From, typename To>
+constexpr bool is_convertible_v = __is_convertible(From, To);
+#endif
+
+class Private
+{
+ operator int() const
+ {
+ static_assert( not is_convertible<Private, int>::value, "" );
+#if __cpp_variable_templates
+ static_assert( not is_convertible_v<Private, int>, "" );
+#endif
+ return 0;
+ }
+};
+
+static_assert( not is_convertible<Private, int>::value, "" );
+#if __cpp_variable_templates
+static_assert( not is_convertible_v<Private, int>, "" );
+#endif
diff --git a/gcc/testsuite/g++.dg/ext/is_nothrow_convertible4.C b/gcc/testsuite/g++.dg/ext/is_nothrow_convertible4.C
new file mode 100644
index 00000000000..f81b5944ca2
--- /dev/null
+++ b/gcc/testsuite/g++.dg/ext/is_nothrow_convertible4.C
@@ -0,0 +1,33 @@
+// PR c++/107049
+// { dg-do compile { target c++11 } }
+// Failed access check should be a substitution failure, not an error.
+
+template<bool B>
+struct bool_constant { static constexpr bool value = B; };
+
+template<typename From, typename To>
+struct is_nt_convertible
+: public bool_constant<__is_nothrow_convertible(From, To)>
+{ };
+
+#if __cpp_variable_templates
+template<typename From, typename To>
+constexpr bool is_nt_convertible_v = __is_nothrow_convertible(From, To);
+#endif
+
+class Private
+{
+ operator int() const
+ {
+ static_assert( not is_nt_convertible<Private, int>::value, "" );
+#if __cpp_variable_templates
+ static_assert( not is_nt_convertible_v<Private, int>, "" );
+#endif
+ return 0;
+ }
+};
+
+static_assert( not is_nt_convertible<Private, int>::value, "" );
+#if __cpp_variable_templates
+static_assert( not is_nt_convertible_v<Private, int>, "" );
+#endif
diff --git a/libstdc++-v3/testsuite/20_util/is_convertible/requirements/access.cc b/libstdc++-v3/testsuite/20_util/is_convertible/requirements/access.cc
new file mode 100644
index 00000000000..04a8c525961
--- /dev/null
+++ b/libstdc++-v3/testsuite/20_util/is_convertible/requirements/access.cc
@@ -0,0 +1,18 @@
+// { dg-do compile { target c++11 } }
+// PR c++/107049
+
+#include <type_traits>
+
+class Private
+{
+ operator int() const
+ {
+ static_assert( not std::is_convertible<Private, int>::value, "" );
+#if __cpp_lib_type_trait_variable_templates
+ static_assert( not std::is_convertible_v<Private, int>, "" );
+#endif
+ return 0;
+ }
+};
+
+static_assert( not std::is_convertible<Private, int>::value, "" );
--
2.37.3
next reply other threads:[~2022-09-27 10:35 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-27 10:35 Jonathan Wakely [this message]
2022-09-27 12:18 ` Marek Polacek
2022-09-27 12:53 ` Jason Merrill
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