libstdc++: Add a __nonnnull__ attribute to std::string's _CharT* constructor

Message ID CAFk2RUZQtZt=3i+bZQKb7+i=MKzgYacDj1KuHzEst6d7Q6ivqA@mail.gmail.com
State New
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  • libstdc++: Add a __nonnnull__ attribute to std::string's _CharT* constructor
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Commit Message

Peter Bergner via Gcc-patches June 28, 2020, 10:56 a.m.
2020-06-28  Ville Voutilainen  <ville.voutilainen@gmail.com>

    Add a __nonnnull__ attribute to std::string's _CharT* constructor
    * include/bits/basic_string.h (string(_CharT*, const _Alloc&)):
    Add a __nonnull__ attribute.
    * testsuite/21_strings/basic_string/cons/char/nonnull.cc: New.
    * testsuite/21_strings/basic_string/cons/wchar_t/nonnull.cc: Likewise.

Comments

Peter Bergner via Gcc-patches June 28, 2020, 11:01 a.m. | #1
On Sun, 28 Jun 2020 at 13:56, Ville Voutilainen
<ville.voutilainen@gmail.com> wrote:
>

> 2020-06-28  Ville Voutilainen  <ville.voutilainen@gmail.com>

>

>     Add a __nonnnull__ attribute to std::string's _CharT* constructor

>     * include/bits/basic_string.h (string(_CharT*, const _Alloc&)):

>     Add a __nonnull__ attribute.

>     * testsuite/21_strings/basic_string/cons/char/nonnull.cc: New.

>     * testsuite/21_strings/basic_string/cons/wchar_t/nonnull.cc: Likewise.



Hmm, let's use dg-additional-options here too, and axe the pointless
-std=gnu++11.
diff --git a/libstdc++-v3/include/bits/basic_string.h b/libstdc++-v3/include/bits/basic_string.h
index bc0c256b65e..d5e5eb06e1b 100644
--- a/libstdc++-v3/include/bits/basic_string.h
+++ b/libstdc++-v3/include/bits/basic_string.h
@@ -522,6 +522,7 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11
       // 3076. basic_string CTAD ambiguity
       template<typename = _RequireAllocator<_Alloc>>
 #endif
+      __attribute__((__nonnull__))
       basic_string(const _CharT* __s, const _Alloc& __a = _Alloc())
       : _M_dataplus(_M_local_data(), __a)
       { _M_construct(__s, __s ? __s + traits_type::length(__s) : __s+npos); }
diff --git a/libstdc++-v3/testsuite/21_strings/basic_string/cons/char/nonnull.cc b/libstdc++-v3/testsuite/21_strings/basic_string/cons/char/nonnull.cc
new file mode 100644
index 00000000000..1c09a1d2207
--- /dev/null
+++ b/libstdc++-v3/testsuite/21_strings/basic_string/cons/char/nonnull.cc
@@ -0,0 +1,29 @@
+// Copyright (C) 2020 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-additional-options "-Wnonnull" }
+// { dg-do compile { target c++11 } }
+
+#include <string>
+
+void
+test01()
+{
+  std::string s((const char*)nullptr); // { dg-warning "null arg" }
+  std::string t((char*)nullptr);       // { dg-warning "null arg" }
+  std::string u(nullptr);	       // { dg-warning "null arg" }
+}
diff --git a/libstdc++-v3/testsuite/21_strings/basic_string/cons/wchar_t/nonnull.cc b/libstdc++-v3/testsuite/21_strings/basic_string/cons/wchar_t/nonnull.cc
new file mode 100644
index 00000000000..456efed6c8c
--- /dev/null
+++ b/libstdc++-v3/testsuite/21_strings/basic_string/cons/wchar_t/nonnull.cc
@@ -0,0 +1,29 @@
+// Copyright (C) 2020 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-additional-options "-Wnonnull" }
+// { dg-do compile { target c++11 } }
+
+#include <string>
+
+void
+test01()
+{
+  std::wstring s((const wchar_t*)nullptr); // { dg-warning "null arg" }
+  std::wstring t((wchar_t*)nullptr);	   // { dg-warning "null arg" }
+  std::wstring u(nullptr);		   // { dg-warning "null arg" }
+}
Peter Bergner via Gcc-patches June 28, 2020, 9:16 p.m. | #2
On 28/06/20 14:01 +0300, Ville Voutilainen via Libstdc++ wrote:
>On Sun, 28 Jun 2020 at 13:56, Ville Voutilainen

><ville.voutilainen@gmail.com> wrote:

>>

>> 2020-06-28  Ville Voutilainen  <ville.voutilainen@gmail.com>

>>

>>     Add a __nonnnull__ attribute to std::string's _CharT* constructor

>>     * include/bits/basic_string.h (string(_CharT*, const _Alloc&)):

>>     Add a __nonnull__ attribute.

>>     * testsuite/21_strings/basic_string/cons/char/nonnull.cc: New.

>>     * testsuite/21_strings/basic_string/cons/wchar_t/nonnull.cc: Likewise.

>

>

>Hmm, let's use dg-additional-options here too, and axe the pointless

>-std=gnu++11.


I agree the -std=gnu++11 isn't needed, but thre doesn't seem to be any
advantage to dg-additional-options here. The reason I suggested it for
th other tests was that it can take a target selector, so it can be
used to add options for some targets only (in the case of the variant
tests, only if the dialect is c++17 or later).

Here you want the -Wnonnull added unconditionally, with no target
selector, so dg-options works fine.

No big deal though, they work equivalently for this case.

OK for master, thanks.
Peter Bergner via Gcc-patches June 28, 2020, 9:27 p.m. | #3
On Mon, 29 Jun 2020 at 00:16, Jonathan Wakely <jwakely@redhat.com> wrote:
> >Hmm, let's use dg-additional-options here too, and axe the pointless

> >-std=gnu++11.

>

> I agree the -std=gnu++11 isn't needed, but thre doesn't seem to be any

> advantage to dg-additional-options here. The reason I suggested it for

> th other tests was that it can take a target selector, so it can be

> used to add options for some targets only (in the case of the variant

> tests, only if the dialect is c++17 or later).

>

> Here you want the -Wnonnull added unconditionally, with no target

> selector, so dg-options works fine.


Right, I somehow managed to think that dg-additional-options amends options
and dg-options overrides them. Here my intent is certainly the former.

Patch

diff --git a/libstdc++-v3/include/bits/basic_string.h b/libstdc++-v3/include/bits/basic_string.h
index bc0c256b65e..d5e5eb06e1b 100644
--- a/libstdc++-v3/include/bits/basic_string.h
+++ b/libstdc++-v3/include/bits/basic_string.h
@@ -522,6 +522,7 @@  _GLIBCXX_BEGIN_NAMESPACE_CXX11
       // 3076. basic_string CTAD ambiguity
       template<typename = _RequireAllocator<_Alloc>>
 #endif
+      __attribute__((__nonnull__))
       basic_string(const _CharT* __s, const _Alloc& __a = _Alloc())
       : _M_dataplus(_M_local_data(), __a)
       { _M_construct(__s, __s ? __s + traits_type::length(__s) : __s+npos); }
diff --git a/libstdc++-v3/testsuite/21_strings/basic_string/cons/char/nonnull.cc b/libstdc++-v3/testsuite/21_strings/basic_string/cons/char/nonnull.cc
new file mode 100644
index 00000000000..b56bdc78b51
--- /dev/null
+++ b/libstdc++-v3/testsuite/21_strings/basic_string/cons/char/nonnull.cc
@@ -0,0 +1,29 @@ 
+// Copyright (C) 2020 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++11 -Wnonnull" }
+// { dg-do compile { target c++11 } }
+
+#include <string>
+
+void
+test01()
+{
+  std::string s((const char*)nullptr); // { dg-warning "null arg" }
+  std::string t((char*)nullptr);       // { dg-warning "null arg" }
+  std::string u(nullptr);	       // { dg-warning "null arg" }
+}
diff --git a/libstdc++-v3/testsuite/21_strings/basic_string/cons/wchar_t/nonnull.cc b/libstdc++-v3/testsuite/21_strings/basic_string/cons/wchar_t/nonnull.cc
new file mode 100644
index 00000000000..8196821f163
--- /dev/null
+++ b/libstdc++-v3/testsuite/21_strings/basic_string/cons/wchar_t/nonnull.cc
@@ -0,0 +1,29 @@ 
+// Copyright (C) 2020 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++11 -Wnonnull" }
+// { dg-do compile { target c++11 } }
+
+#include <string>
+
+void
+test01()
+{
+  std::wstring s((const wchar_t*)nullptr); // { dg-warning "null arg" }
+  std::wstring t((wchar_t*)nullptr);	   // { dg-warning "null arg" }
+  std::wstring u(nullptr);		   // { dg-warning "null arg" }
+}