The C++ committee has confirmed that passing a null pointer to the
unary basic_string_view constructor is undefined. This removes the check
from our implementation, and adds the nonnull attribute to warn when the
compiler can detect undefined input.
Any objections to this change?
commit 05d33d556eaabb3c81f4db15b9818c465b359c15
Author: Jonathan Wakely <jwak...@redhat.com>
Date: Wed Jun 13 16:54:47 2018 +0100
Decorate string_view members with nonnull attribute
The C++ committee has confirmed that passing a null pointer to the
unary basic_string_view constructor is undefined. This removes the check
from our implementation, and adds the nonnull attribute to warn when the
compiler can detect undefined input.
* include/std/string_view (basic_string_view(const CharT*)): Remove
check for null pointer and add nonnull attribute.
(compare(const CharT*), compare(size_type, size_type, const CharT*))
(find(const CharT*, size_type), rfind(const CharT*, size_type))
(find_first_of(const CharT*, size_type))
(find_last_of(const CharT*, size_type))
(find_first_not_of(const CharT*, size_type))
(find_last_not_of(const CharT*, size_type)): Add nonnull attribute.
* testsuite/21_strings/basic_string_view/cons/char/nonnull.cc: New.
* testsuite/21_strings/basic_string_view/operations/compare/char/
nonnull.cc: New.
* testsuite/21_strings/basic_string_view/operations/find/char/
nonnull.cc: New.
* testsuite/21_strings/basic_string_view/operations/rfind/char/
nonnull.cc: New.
diff --git a/libstdc++-v3/include/std/string_view
b/libstdc++-v3/include/std/string_view
index 9f39df853e8..4de484a96ba 100644
--- a/libstdc++-v3/include/std/string_view
+++ b/libstdc++-v3/include/std/string_view
@@ -96,8 +96,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
constexpr basic_string_view(const basic_string_view&) noexcept = default;
- constexpr basic_string_view(const _CharT* __str) noexcept
- : _M_len{__str == nullptr ? 0 : traits_type::length(__str)},
+ [[gnu::nonnull]] constexpr
+ basic_string_view(const _CharT* __str) noexcept
+ : _M_len{traits_type::length(__str)},
_M_str{__str}
{ }
@@ -270,11 +271,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
return this->substr(__pos1, __n1).compare(__str.substr(__pos2, __n2));
}
- constexpr int
+ [[gnu::nonnull]] constexpr int
compare(const _CharT* __str) const noexcept
{ return this->compare(basic_string_view{__str}); }
- constexpr int
+ [[gnu::nonnull]] constexpr int
compare(size_type __pos1, size_type __n1, const _CharT* __str) const
{ return this->substr(__pos1, __n1).compare(basic_string_view{__str}); }
@@ -296,7 +297,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
constexpr size_type
find(const _CharT* __str, size_type __pos, size_type __n) const noexcept;
- constexpr size_type
+ [[gnu::nonnull]] constexpr size_type
find(const _CharT* __str, size_type __pos = 0) const noexcept
{ return this->find(__str, __pos, traits_type::length(__str)); }
@@ -310,7 +311,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
constexpr size_type
rfind(const _CharT* __str, size_type __pos, size_type __n) const
noexcept;
- constexpr size_type
+ [[gnu::nonnull]] constexpr size_type
rfind(const _CharT* __str, size_type __pos = npos) const noexcept
{ return this->rfind(__str, __pos, traits_type::length(__str)); }
@@ -323,9 +324,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
{ return this->find(__c, __pos); }
constexpr size_type
- find_first_of(const _CharT* __str, size_type __pos, size_type __n) const
noexcept;
+ find_first_of(const _CharT* __str, size_type __pos,
+ size_type __n) const noexcept;
- constexpr size_type
+ [[gnu::nonnull]] constexpr size_type
find_first_of(const _CharT* __str, size_type __pos = 0) const noexcept
{ return this->find_first_of(__str, __pos, traits_type::length(__str)); }
@@ -342,7 +344,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
find_last_of(const _CharT* __str, size_type __pos,
size_type __n) const noexcept;
- constexpr size_type
+ [[gnu::nonnull]] constexpr size_type
find_last_of(const _CharT* __str, size_type __pos = npos) const noexcept
{ return this->find_last_of(__str, __pos, traits_type::length(__str)); }
@@ -358,7 +360,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
find_first_not_of(const _CharT* __str,
size_type __pos, size_type __n) const noexcept;
- constexpr size_type
+ [[gnu::nonnull]] constexpr size_type
find_first_not_of(const _CharT* __str, size_type __pos = 0) const
noexcept
{
return this->find_first_not_of(__str, __pos,
@@ -377,7 +379,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
find_last_not_of(const _CharT* __str,
size_type __pos, size_type __n) const noexcept;
- constexpr size_type
+ [[gnu::nonnull]] constexpr size_type
find_last_not_of(const _CharT* __str,
size_type __pos = npos) const noexcept
{
diff --git
a/libstdc++-v3/testsuite/21_strings/basic_string_view/cons/char/nonnull.cc
b/libstdc++-v3/testsuite/21_strings/basic_string_view/cons/char/nonnull.cc
new file mode 100644
index 00000000000..463ece718bd
--- /dev/null
+++ b/libstdc++-v3/testsuite/21_strings/basic_string_view/cons/char/nonnull.cc
@@ -0,0 +1,29 @@
+// Copyright (C) 2018 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/>.
+
+// { dg-options "-std=gnu++17 -Wnonnull" }
+// { dg-do compile { target c++17 } }
+
+#include <string_view>
+
+void
+test01()
+{
+ std::string_view s((const char*)nullptr); // { dg-warning "null arg" }
+ std::string_view t((char*)nullptr); // { dg-warning "null arg" }
+ std::string_view u(nullptr); // { dg-warning "null arg" }
+}
diff --git
a/libstdc++-v3/testsuite/21_strings/basic_string_view/cons/wchar_t/nonnull.cc
b/libstdc++-v3/testsuite/21_strings/basic_string_view/cons/wchar_t/nonnull.cc
new file mode 100644
index 00000000000..8df61427a49
--- /dev/null
+++
b/libstdc++-v3/testsuite/21_strings/basic_string_view/cons/wchar_t/nonnull.cc
@@ -0,0 +1,29 @@
+// Copyright (C) 2018 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/>.
+
+// { dg-options "-std=gnu++17 -Wnonnull" }
+// { dg-do compile { target c++17 } }
+
+#include <string_view>
+
+void
+test01()
+{
+ std::wstring_view s((const wchar_t*)nullptr); // { dg-warning "null
arg" }
+ std::wstring_view t((wchar_t*)nullptr); // { dg-warning "null arg" }
+ std::wstring_view u(nullptr); // { dg-warning "null
arg" }
+}
diff --git
a/libstdc++-v3/testsuite/21_strings/basic_string_view/operations/compare/char/nonnull.cc
b/libstdc++-v3/testsuite/21_strings/basic_string_view/operations/compare/char/nonnull.cc
new file mode 100644
index 00000000000..1d12b700d88
--- /dev/null
+++
b/libstdc++-v3/testsuite/21_strings/basic_string_view/operations/compare/char/nonnull.cc
@@ -0,0 +1,29 @@
+// Copyright (C) 2018 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/>.
+
+// { dg-options "-std=gnu++17 -Wnonnull" }
+// { dg-do compile { target c++17 } }
+
+#include <string_view>
+
+int
+test01()
+{
+ std::string_view s = "abcd";
+ return s.compare((const char*)nullptr); // { dg-warning "null arg" }
+ return s.compare(0, 2, (const char*)nullptr); // { dg-warning "null
arg" }
+}
diff --git
a/libstdc++-v3/testsuite/21_strings/basic_string_view/operations/find/char/nonnull.cc
b/libstdc++-v3/testsuite/21_strings/basic_string_view/operations/find/char/nonnull.cc
new file mode 100644
index 00000000000..69f1850d9dc
--- /dev/null
+++
b/libstdc++-v3/testsuite/21_strings/basic_string_view/operations/find/char/nonnull.cc
@@ -0,0 +1,33 @@
+// Copyright (C) 2018 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/>.
+
+// { dg-options "-std=gnu++17 -Wnonnull" }
+// { dg-do compile { target c++17 } }
+
+#include <string_view>
+
+int
+test01()
+{
+ std::string_view s = "abcd";
+ return s.find((const char*)nullptr); // { dg-warning "null arg" }
+ return s.find((const char*)nullptr, 1); // { dg-warning "null arg" }
+ return s.find_first_of((const char*)nullptr); // { dg-warning "null
arg" }
+ return s.find_first_of((const char*)nullptr, 1); // { dg-warning "null arg" }
+ return s.find_first_not_of((const char*)nullptr); // { dg-warning "null arg"
}
+ return s.find_first_not_of((const char*)nullptr, 1); // { dg-warning "null
arg" }
+}
diff --git
a/libstdc++-v3/testsuite/21_strings/basic_string_view/operations/rfind/char/nonnull.cc
b/libstdc++-v3/testsuite/21_strings/basic_string_view/operations/rfind/char/nonnull.cc
new file mode 100644
index 00000000000..ca8527afa58
--- /dev/null
+++
b/libstdc++-v3/testsuite/21_strings/basic_string_view/operations/rfind/char/nonnull.cc
@@ -0,0 +1,29 @@
+// Copyright (C) 2018 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/>.
+
+// { dg-options "-std=gnu++17 -Wnonnull" }
+// { dg-do compile { target c++17 } }
+
+#include <string_view>
+
+int
+test01()
+{
+ std::string_view s = "abcd";
+ return s.rfind((const char*)nullptr); // { dg-warning "null
arg" }
+ return s.rfind((const char*)nullptr, 1); // { dg-warning "null arg" }
+}
