[PATCH][_GLIBCXX_DEBUG] Add basic_string::starts_with/ends_with checks

[PATCH][_GLIBCXX_DEBUG] Add basic_string::starts_with/ends_with checks

[François Dumont]

I think we can add those checks.

Note that I wonder if it was needed as in basic_string_view I see usages 
of __attribute__((__nonnull__)). But running the test I saw no impact 
even after I try to apply this attribute to the starts_with/ends_with 
methods themselves.

Also note that several checks like the ones I am adding here are XFAILS 
when using 'make check' because of the segfault rather than on a proper 
debug checks. Would you prefer to add dg-require-debug-mode to those ?

     libstdc++: [_GLIBCXX_DEBUG] Add basic_string::starts_with/ends_with 
checks

     Add simple checks on C string parameters which should not be null.

     Review null string checks to show:
     _String != nullptr

     rather than:
     _String != 0

     libstdc++-v3/ChangeLog:

             * include/bits/basic_string.h (starts_with, ends_with): Add 
__glibcxx_check_string.
             * include/bits/cow_string.h (starts_with, ends_with): Likewise.
             * include/debug/debug.h: Use nullptr rather than '0' in 
checks in C++11.
             * include/debug/string: Likewise.
             * 
testsuite/21_strings/basic_string/operations/ends_with/char.cc: Use 
__gnu_test::string.
             * 
testsuite/21_strings/basic_string/operations/ends_with/wchar_t.cc: Use 
__gnu_test::wstring.
             * 
testsuite/21_strings/basic_string/operations/starts_with/wchar_t.cc: Use 
__gnu_test::wstring.
             * 
testsuite/21_strings/basic_string/operations/starts_with/char.cc: Use 
__gnu_test::string.
             * 
testsuite/21_strings/basic_string/operations/ends_with/char_neg.cc: New 
test.
             * 
testsuite/21_strings/basic_string/operations/ends_with/wchar_t_neg.cc: 
New test.
             * 
testsuite/21_strings/basic_string/operations/starts_with/char_neg.cc: 
New test.
             * 
testsuite/21_strings/basic_string/operations/starts_with/wchar_t_neg.cc: 
New test.

Tested under linux normal and debug modes.

François

Re: [PATCH][_GLIBCXX_DEBUG] Add basic_string::starts_with/ends_with checks

[François Dumont]

[-- Attachment #1: Type: text/plain, Size: 2273 bytes --]

With the patch !

On 14/08/22 17:32, François Dumont wrote:
> I think we can add those checks.
>
> Note that I wonder if it was needed as in basic_string_view I see 
> usages of __attribute__((__nonnull__)). But running the test I saw no 
> impact even after I try to apply this attribute to the 
> starts_with/ends_with methods themselves.
>
> Also note that several checks like the ones I am adding here are 
> XFAILS when using 'make check' because of the segfault rather than on 
> a proper debug checks. Would you prefer to add dg-require-debug-mode 
> to those ?
>
>     libstdc++: [_GLIBCXX_DEBUG] Add 
> basic_string::starts_with/ends_with checks
>
>     Add simple checks on C string parameters which should not be null.
>
>     Review null string checks to show:
>     _String != nullptr
>
>     rather than:
>     _String != 0
>
>     libstdc++-v3/ChangeLog:
>
>             * include/bits/basic_string.h (starts_with, ends_with): 
> Add __glibcxx_check_string.
>             * include/bits/cow_string.h (starts_with, ends_with): 
> Likewise.
>             * include/debug/debug.h: Use nullptr rather than '0' in 
> checks in C++11.
>             * include/debug/string: Likewise.
>             * 
> testsuite/21_strings/basic_string/operations/ends_with/char.cc: Use 
> __gnu_test::string.
>             * 
> testsuite/21_strings/basic_string/operations/ends_with/wchar_t.cc: Use 
> __gnu_test::wstring.
>             * 
> testsuite/21_strings/basic_string/operations/starts_with/wchar_t.cc: 
> Use __gnu_test::wstring.
>             * 
> testsuite/21_strings/basic_string/operations/starts_with/char.cc: Use 
> __gnu_test::string.
>             * 
> testsuite/21_strings/basic_string/operations/ends_with/char_neg.cc: 
> New test.
>             * 
> testsuite/21_strings/basic_string/operations/ends_with/wchar_t_neg.cc: 
> New test.
>             * 
> testsuite/21_strings/basic_string/operations/starts_with/char_neg.cc: 
> New test.
>             * 
> testsuite/21_strings/basic_string/operations/starts_with/wchar_t_neg.cc: 
> New test.
>
> Tested under linux normal and debug modes.
>
> François
>
>

[-- Attachment #2: debug_string_starts_ends_with.patch --]
[-- Type: text/x-patch, Size: 14820 bytes --]

diff --git a/libstdc++-v3/include/bits/basic_string.h b/libstdc++-v3/include/bits/basic_string.h
index b04fba95678..d06330e6c48 100644
--- a/libstdc++-v3/include/bits/basic_string.h
+++ b/libstdc++-v3/include/bits/basic_string.h
@@ -3402,7 +3402,10 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11
 
       constexpr bool
       starts_with(const _CharT* __x) const noexcept
-      { return __sv_type(this->data(), this->size()).starts_with(__x); }
+      {
+	__glibcxx_requires_string(__x);
+	return __sv_type(this->data(), this->size()).starts_with(__x);
+      }
 
       constexpr bool
       ends_with(basic_string_view<_CharT, _Traits> __x) const noexcept
@@ -3414,7 +3417,10 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11
 
       constexpr bool
       ends_with(const _CharT* __x) const noexcept
-      { return __sv_type(this->data(), this->size()).ends_with(__x); }
+      {
+	__glibcxx_requires_string(__x);
+	return __sv_type(this->data(), this->size()).ends_with(__x);
+      }
 #endif // C++20
 
 #if __cplusplus > 202002L
diff --git a/libstdc++-v3/include/bits/cow_string.h b/libstdc++-v3/include/bits/cow_string.h
index f16e33ac1ef..59b36a1006a 100644
--- a/libstdc++-v3/include/bits/cow_string.h
+++ b/libstdc++-v3/include/bits/cow_string.h
@@ -3014,7 +3014,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
       bool
       starts_with(const _CharT* __x) const noexcept
-      { return __sv_type(this->data(), this->size()).starts_with(__x); }
+      {
+	__glibcxx_requires_string(__x);
+	return __sv_type(this->data(), this->size()).starts_with(__x);
+      }
 
       bool
       ends_with(basic_string_view<_CharT, _Traits> __x) const noexcept
@@ -3026,7 +3029,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
       bool
       ends_with(const _CharT* __x) const noexcept
-      { return __sv_type(this->data(), this->size()).ends_with(__x); }
+      {
+	__glibcxx_requires_string(__x);
+	return __sv_type(this->data(), this->size()).ends_with(__x);
+      }
 #endif // C++20
 
 #if __cplusplus > 202011L
diff --git a/libstdc++-v3/include/debug/debug.h b/libstdc++-v3/include/debug/debug.h
index 28e250f0c50..f4233760426 100644
--- a/libstdc++-v3/include/debug/debug.h
+++ b/libstdc++-v3/include/debug/debug.h
@@ -118,10 +118,17 @@ namespace __gnu_debug
   __glibcxx_check_heap(_First,_Last)
 # define __glibcxx_requires_heap_pred(_First,_Last,_Pred)	\
   __glibcxx_check_heap_pred(_First,_Last,_Pred)
-# define __glibcxx_requires_string(_String)	\
+# if __cplusplus < 201103L
+#  define __glibcxx_requires_string(_String)	\
   _GLIBCXX_DEBUG_PEDASSERT(_String != 0)
-# define __glibcxx_requires_string_len(_String,_Len)	\
+#  define __glibcxx_requires_string_len(_String,_Len)	\
   _GLIBCXX_DEBUG_PEDASSERT(_String != 0 || _Len == 0)
+# else
+#  define __glibcxx_requires_string(_String)	\
+  _GLIBCXX_DEBUG_PEDASSERT(_String != nullptr)
+#  define __glibcxx_requires_string_len(_String,_Len)	\
+  _GLIBCXX_DEBUG_PEDASSERT(_String != nullptr || _Len == 0)
+# endif
 # define __glibcxx_requires_irreflexive(_First,_Last)	\
   __glibcxx_check_irreflexive(_First,_Last)
 # define __glibcxx_requires_irreflexive2(_First,_Last)	\
diff --git a/libstdc++-v3/include/debug/string b/libstdc++-v3/include/debug/string
index c32eb41eacd..f02c74431ed 100644
--- a/libstdc++-v3/include/debug/string
+++ b/libstdc++-v3/include/debug/string
@@ -50,14 +50,25 @@
 #endif
 
 #ifdef _GLIBCXX_DEBUG_PEDANTIC
-# define __glibcxx_check_string(_String)				\
+# if __cplusplus < 201103L
+#  define __glibcxx_check_string(_String)			\
   _GLIBCXX_DEBUG_VERIFY_STR_COND_AT(_String != 0,		\
 				    __FILE__, __LINE__,		\
 				    __PRETTY_FUNCTION__);
-# define __glibcxx_check_string_len(_String,_Len)		\
+#  define __glibcxx_check_string_len(_String,_Len)		\
   _GLIBCXX_DEBUG_VERIFY_STR_COND_AT(_String != 0 || _Len == 0,	\
 				    __FILE__, __LINE__,		\
 				    __PRETTY_FUNCTION__);
+# else
+#  define __glibcxx_check_string(_String)			\
+  _GLIBCXX_DEBUG_VERIFY_STR_COND_AT(_String != nullptr,		\
+				    __FILE__, __LINE__,		\
+				    __PRETTY_FUNCTION__);
+#  define __glibcxx_check_string_len(_String,_Len)		\
+  _GLIBCXX_DEBUG_VERIFY_STR_COND_AT(_String != nullptr || _Len == 0,	\
+				    __FILE__, __LINE__,		\
+				    __PRETTY_FUNCTION__);
+# endif
 #else
 # define __glibcxx_check_string(_String)
 # define __glibcxx_check_string_len(_String,_Len)
@@ -75,8 +86,13 @@ namespace __gnu_debug
 		   const char* __function __attribute__((__unused__)))
     {
 #ifdef _GLIBCXX_DEBUG_PEDANTIC
+# if __cplusplus < 201103L
       _GLIBCXX_DEBUG_VERIFY_STR_COND_AT(__s != 0 || __n == 0,
 					__file, __line, __function);
+# else
+      _GLIBCXX_DEBUG_VERIFY_STR_COND_AT(__s != nullptr || __n == 0,
+					__file, __line, __function);
+# endif
 #endif
       return __s;
     }
@@ -90,8 +106,13 @@ namespace __gnu_debug
 		   const char* __function __attribute__((__unused__)))
     {
 #ifdef _GLIBCXX_DEBUG_PEDANTIC
+# if __cplusplus < 201103L
       _GLIBCXX_DEBUG_VERIFY_STR_COND_AT(__s != 0,
 					__file, __line, __function);
+# else
+      _GLIBCXX_DEBUG_VERIFY_STR_COND_AT(__s != nullptr,
+					__file, __line, __function);
+# endif
 #endif
       return __s;
     }
@@ -1033,6 +1054,26 @@ namespace __gnu_debug
 	return _Base::compare(__pos1, __n1, __s, __n2);
       }
 
+#if __cplusplus >= 202002L
+      using _Base::starts_with;
+
+      __attribute__((__nonnull__)) constexpr bool
+      starts_with(const _CharT* __x) const noexcept
+      {
+	__glibcxx_check_string(__x);
+	return _Base::starts_with(__x);
+      }
+
+      using _Base::ends_with;
+
+      constexpr bool
+      ends_with(const _CharT* __x) const noexcept
+      {
+	__glibcxx_check_string(__x);
+	return _Base::ends_with(__x);
+      }
+#endif
+
       _Base&
       _M_base() _GLIBCXX_NOEXCEPT		{ return *this; }
 
diff --git a/libstdc++-v3/testsuite/21_strings/basic_string/operations/ends_with/char.cc b/libstdc++-v3/testsuite/21_strings/basic_string/operations/ends_with/char.cc
index cfe18e0186c..3cf85121e36 100644
--- a/libstdc++-v3/testsuite/21_strings/basic_string/operations/ends_with/char.cc
+++ b/libstdc++-v3/testsuite/21_strings/basic_string/operations/ends_with/char.cc
@@ -20,7 +20,7 @@
 
 // basic_string ends_with
 
-#include <string>
+#include <testsuite_string.h>
 #include <testsuite_hooks.h>
 
 void
@@ -31,7 +31,7 @@ test01()
   const char cstr_suf2[] = ".rgb";
   const std::string_view sv_suf2(".rgb");
 
-  const std::string s_test("slugs/slimy.jpg");
+  const __gnu_test::string s_test("slugs/slimy.jpg");
 
   const auto cstr_in_slugs = s_test.ends_with(cstr_suf);
   VERIFY( cstr_in_slugs );
diff --git a/libstdc++-v3/testsuite/21_strings/basic_string/operations/ends_with/char_neg.cc b/libstdc++-v3/testsuite/21_strings/basic_string/operations/ends_with/char_neg.cc
new file mode 100644
index 00000000000..7a7b8dd077d
--- /dev/null
+++ b/libstdc++-v3/testsuite/21_strings/basic_string/operations/ends_with/char_neg.cc
@@ -0,0 +1,37 @@
+// Copyright (C) 2022 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++2a -O0" }
+// { dg-do run { target c++2a xfail *-*-* } }
+
+#define _GLIBCXX_DEBUG_PEDANTIC
+
+#include <testsuite_string.h>
+
+void
+test01()
+{
+  const __gnu_test::string s_test("slugs/slimy.jpg");
+  s_test.ends_with(nullptr);
+}
+
+int
+main()
+{
+  test01();
+  return 0;
+}
diff --git a/libstdc++-v3/testsuite/21_strings/basic_string/operations/ends_with/wchar_t.cc b/libstdc++-v3/testsuite/21_strings/basic_string/operations/ends_with/wchar_t.cc
index d27e8246fb8..70b522ff69e 100644
--- a/libstdc++-v3/testsuite/21_strings/basic_string/operations/ends_with/wchar_t.cc
+++ b/libstdc++-v3/testsuite/21_strings/basic_string/operations/ends_with/wchar_t.cc
@@ -20,7 +20,7 @@
 
 // basic_string ends_with
 
-#include <string>
+#include <testsuite_string.h>
 #include <testsuite_hooks.h>
 
 void
@@ -31,7 +31,7 @@ test01()
   const wchar_t cstr_suf2[] = L".rgb";
   const std::wstring_view sv_suf2(L".rgb");
 
-  const std::wstring s_test(L"slugs/slimy.jpg");
+  const __gnu_test::wstring s_test(L"slugs/slimy.jpg");
 
   const auto cstr_in_slugs = s_test.ends_with(cstr_suf);
   VERIFY( cstr_in_slugs );
diff --git a/libstdc++-v3/testsuite/21_strings/basic_string/operations/ends_with/wchar_t_neg.cc b/libstdc++-v3/testsuite/21_strings/basic_string/operations/ends_with/wchar_t_neg.cc
new file mode 100644
index 00000000000..a6881bf406b
--- /dev/null
+++ b/libstdc++-v3/testsuite/21_strings/basic_string/operations/ends_with/wchar_t_neg.cc
@@ -0,0 +1,37 @@
+// Copyright (C) 2022 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++2a -O0" }
+// { dg-do run { target c++2a xfail *-*-* } }
+
+#define _GLIBCXX_DEBUG_PEDANTIC
+
+#include <testsuite_string.h>
+
+void
+test01()
+{
+  const __gnu_test::wstring s_test(L"slugs/slimy.jpg");
+  s_test.ends_with(nullptr);
+}
+
+int
+main()
+{
+  test01();
+  return 0;
+}
diff --git a/libstdc++-v3/testsuite/21_strings/basic_string/operations/starts_with/char.cc b/libstdc++-v3/testsuite/21_strings/basic_string/operations/starts_with/char.cc
index 5c0b3afc0b6..dddf51cee16 100644
--- a/libstdc++-v3/testsuite/21_strings/basic_string/operations/starts_with/char.cc
+++ b/libstdc++-v3/testsuite/21_strings/basic_string/operations/starts_with/char.cc
@@ -20,7 +20,7 @@
 
 // basic_string begins_with
 
-#include <string>
+#include <testsuite_string.h>
 #include <testsuite_hooks.h>
 
 void
@@ -31,7 +31,7 @@ test01()
   const char cstr_dir2[] = "worms/";
   const std::string_view sv_dir2("worms/");
 
-  const std::string s_test("slugs/slimy.jpg");
+  const __gnu_test::string s_test("slugs/slimy.jpg");
 
   const auto cstr_in_slugs = s_test.starts_with(cstr_dir);
   VERIFY( cstr_in_slugs );
diff --git a/libstdc++-v3/testsuite/21_strings/basic_string/operations/starts_with/char_neg.cc b/libstdc++-v3/testsuite/21_strings/basic_string/operations/starts_with/char_neg.cc
new file mode 100644
index 00000000000..f357aef2289
--- /dev/null
+++ b/libstdc++-v3/testsuite/21_strings/basic_string/operations/starts_with/char_neg.cc
@@ -0,0 +1,37 @@
+// Copyright (C) 2022 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++2a -O0" }
+// { dg-do run { target c++2a xfail *-*-* } }
+
+#define _GLIBCXX_DEBUG_PEDANTIC
+
+#include <testsuite_string.h>
+
+void
+test01()
+{
+  const __gnu_test::string s_test("slugs/slimy.jpg");
+  s_test.starts_with(nullptr);
+}
+
+int
+main()
+{
+  test01();
+  return 0;
+}
diff --git a/libstdc++-v3/testsuite/21_strings/basic_string/operations/starts_with/wchar_t.cc b/libstdc++-v3/testsuite/21_strings/basic_string/operations/starts_with/wchar_t.cc
index eda73212ea0..747b23ae5c2 100644
--- a/libstdc++-v3/testsuite/21_strings/basic_string/operations/starts_with/wchar_t.cc
+++ b/libstdc++-v3/testsuite/21_strings/basic_string/operations/starts_with/wchar_t.cc
@@ -20,7 +20,7 @@
 
 // basic_string begins_with
 
-#include <string>
+#include <testsuite_string.h>
 #include <testsuite_hooks.h>
 
 void
@@ -31,7 +31,7 @@ test01()
   const wchar_t cstr_dir2[] = L"worms/";
   const std::wstring_view sv_dir2(L"worms/");
 
-  const std::wstring s_test(L"slugs/slimy.jpg");
+  const __gnu_test::wstring s_test(L"slugs/slimy.jpg");
 
   const auto cstr_in_slugs = s_test.starts_with(cstr_dir);
   VERIFY( cstr_in_slugs );
diff --git a/libstdc++-v3/testsuite/21_strings/basic_string/operations/starts_with/wchar_t_neg.cc b/libstdc++-v3/testsuite/21_strings/basic_string/operations/starts_with/wchar_t_neg.cc
new file mode 100644
index 00000000000..90065a459b6
--- /dev/null
+++ b/libstdc++-v3/testsuite/21_strings/basic_string/operations/starts_with/wchar_t_neg.cc
@@ -0,0 +1,37 @@
+// Copyright (C) 2022 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++2a -O0" }
+// { dg-do run { target c++2a xfail *-*-* } }
+
+#define _GLIBCXX_DEBUG_PEDANTIC
+
+#include <testsuite_string.h>
+
+void
+test01()
+{
+  const __gnu_test::wstring s_test(L"slugs/slimy.jpg");
+  s_test.starts_with(nullptr);
+}
+
+int
+main()
+{
+  test01();
+  return 0;
+}

Re: [PATCH][_GLIBCXX_DEBUG] Add basic_string::starts_with/ends_with checks

[Jonathan Wakely]

On Sun, 14 Aug 2022 at 16:34, François Dumont via Libstdc++
<libstdc++@gcc.gnu.org> wrote:
>
> I think we can add those checks.
>
> Note that I wonder if it was needed as in basic_string_view I see usages
> of __attribute__((__nonnull__)). But running the test I saw no impact
> even after I try to apply this attribute to the starts_with/ends_with
> methods themselves.

That should cause warnings, and does when I try it.

As you say, the relevant string_view constructor already has that anyway:

      __attribute__((__nonnull__)) constexpr
      basic_string_view(const _CharT* __str) noexcept

And so does string_view::find. The problem is that those only help if
the compiler inlines the calls to those functions and so can propagate
the null value all the way down to a function with the attribute.
Adding the attribute to the relevant starts_with, ends_with and
contains functions makes the diagnostics more likely to be emitted
without optimization.

>
> Also note that several checks like the ones I am adding here are XFAILS
> when using 'make check' because of the segfault rather than on a proper
> debug checks. Would you prefer to add dg-require-debug-mode to those ?
>
>      libstdc++: [_GLIBCXX_DEBUG] Add basic_string::starts_with/ends_with
> checks
>
>      Add simple checks on C string parameters which should not be null.
>
>      Review null string checks to show:
>      _String != nullptr
>
>      rather than:
>      _String != 0

I don't really like the extra complexity in the macros, but this does
seem like a nice improvement for what users see.

We could use __null for C++98, which is a compiler keyword that
expands to a null pointer constant, but I'm not sure if that would be
clear to all users or not. Maybe 0 is better.

Re: [PATCH][_GLIBCXX_DEBUG] Review null string assertions (was: Add basic_string::starts_with/ends_with checks)

[François Dumont]

[-- Attachment #1: Type: text/plain, Size: 3041 bytes --]

If I got your point correctly here is this patch again with just the 
change on '0' becoming 'nullptr' in assertions.

     libstdc++: [_GLIBCXX_DEBUG] Review nullptr assertion diagnostics

     Review null string checks to show:
     _String != nullptr

     rather than:
     _String != 0

     libstdc++-v3/ChangeLog:

             * include/debug/debug.h: Use nullptr rather than '0' in 
checks in post-C++11.
             * include/debug/string: Likewise.
             * 
testsuite/21_strings/basic_string/operations/ends_with/char.cc: Use 
__gnu_test::string.
             * 
testsuite/21_strings/basic_string/operations/ends_with/nonnull.cc: Likewise.
             * 
testsuite/21_strings/basic_string/operations/ends_with/wchar_t.cc: Likewise.
             * 
testsuite/21_strings/basic_string/operations/starts_with/wchar_t.cc: 
Likewise.
             * 
testsuite/21_strings/basic_string/operations/starts_with/nonnull.cc: 
Likewise.
             * 
testsuite/21_strings/basic_string/operations/starts_with/char.cc: Likewise..

Ok to commit ?

François

On 26/08/22 11:31, Jonathan Wakely wrote:
> On Sun, 14 Aug 2022 at 16:34, François Dumont via Libstdc++
> <libstdc++@gcc.gnu.org> wrote:
>> I think we can add those checks.
>>
>> Note that I wonder if it was needed as in basic_string_view I see usages
>> of __attribute__((__nonnull__)). But running the test I saw no impact
>> even after I try to apply this attribute to the starts_with/ends_with
>> methods themselves.
> That should cause warnings, and does when I try it.
>
> As you say, the relevant string_view constructor already has that anyway:
>
>        __attribute__((__nonnull__)) constexpr
>        basic_string_view(const _CharT* __str) noexcept
>
> And so does string_view::find. The problem is that those only help if
> the compiler inlines the calls to those functions and so can propagate
> the null value all the way down to a function with the attribute.
> Adding the attribute to the relevant starts_with, ends_with and
> contains functions makes the diagnostics more likely to be emitted
> without optimization.
>
>> Also note that several checks like the ones I am adding here are XFAILS
>> when using 'make check' because of the segfault rather than on a proper
>> debug checks. Would you prefer to add dg-require-debug-mode to those ?
>>
>>       libstdc++: [_GLIBCXX_DEBUG] Add basic_string::starts_with/ends_with
>> checks
>>
>>       Add simple checks on C string parameters which should not be null.
>>
>>       Review null string checks to show:
>>       _String != nullptr
>>
>>       rather than:
>>       _String != 0
> I don't really like the extra complexity in the macros, but this does
> seem like a nice improvement for what users see.
>
> We could use __null for C++98, which is a compiler keyword that
> expands to a null pointer constant, but I'm not sure if that would be
> clear to all users or not. Maybe 0 is better.
>
> .


[-- Attachment #2: debug_nullptr_string.patch --]
[-- Type: text/x-patch, Size: 7977 bytes --]

diff --git a/libstdc++-v3/include/debug/debug.h b/libstdc++-v3/include/debug/debug.h
index 28e250f0c50..f4233760426 100644
--- a/libstdc++-v3/include/debug/debug.h
+++ b/libstdc++-v3/include/debug/debug.h
@@ -118,10 +118,17 @@ namespace __gnu_debug
   __glibcxx_check_heap(_First,_Last)
 # define __glibcxx_requires_heap_pred(_First,_Last,_Pred)	\
   __glibcxx_check_heap_pred(_First,_Last,_Pred)
-# define __glibcxx_requires_string(_String)	\
+# if __cplusplus < 201103L
+#  define __glibcxx_requires_string(_String)	\
   _GLIBCXX_DEBUG_PEDASSERT(_String != 0)
-# define __glibcxx_requires_string_len(_String,_Len)	\
+#  define __glibcxx_requires_string_len(_String,_Len)	\
   _GLIBCXX_DEBUG_PEDASSERT(_String != 0 || _Len == 0)
+# else
+#  define __glibcxx_requires_string(_String)	\
+  _GLIBCXX_DEBUG_PEDASSERT(_String != nullptr)
+#  define __glibcxx_requires_string_len(_String,_Len)	\
+  _GLIBCXX_DEBUG_PEDASSERT(_String != nullptr || _Len == 0)
+# endif
 # define __glibcxx_requires_irreflexive(_First,_Last)	\
   __glibcxx_check_irreflexive(_First,_Last)
 # define __glibcxx_requires_irreflexive2(_First,_Last)	\
diff --git a/libstdc++-v3/include/debug/string b/libstdc++-v3/include/debug/string
index c32eb41eacd..574a78e3dac 100644
--- a/libstdc++-v3/include/debug/string
+++ b/libstdc++-v3/include/debug/string
@@ -50,14 +50,25 @@
 #endif
 
 #ifdef _GLIBCXX_DEBUG_PEDANTIC
-# define __glibcxx_check_string(_String)				\
+# if __cplusplus < 201103L
+#  define __glibcxx_check_string(_String)			\
   _GLIBCXX_DEBUG_VERIFY_STR_COND_AT(_String != 0,		\
 				    __FILE__, __LINE__,		\
 				    __PRETTY_FUNCTION__);
-# define __glibcxx_check_string_len(_String,_Len)		\
+#  define __glibcxx_check_string_len(_String,_Len)		\
   _GLIBCXX_DEBUG_VERIFY_STR_COND_AT(_String != 0 || _Len == 0,	\
 				    __FILE__, __LINE__,		\
 				    __PRETTY_FUNCTION__);
+# else
+#  define __glibcxx_check_string(_String)			\
+  _GLIBCXX_DEBUG_VERIFY_STR_COND_AT(_String != nullptr,		\
+				    __FILE__, __LINE__,		\
+				    __PRETTY_FUNCTION__);
+#  define __glibcxx_check_string_len(_String,_Len)		\
+  _GLIBCXX_DEBUG_VERIFY_STR_COND_AT(_String != nullptr || _Len == 0,	\
+				    __FILE__, __LINE__,		\
+				    __PRETTY_FUNCTION__);
+# endif
 #else
 # define __glibcxx_check_string(_String)
 # define __glibcxx_check_string_len(_String,_Len)
@@ -75,8 +86,13 @@ namespace __gnu_debug
 		   const char* __function __attribute__((__unused__)))
     {
 #ifdef _GLIBCXX_DEBUG_PEDANTIC
+# if __cplusplus < 201103L
       _GLIBCXX_DEBUG_VERIFY_STR_COND_AT(__s != 0 || __n == 0,
 					__file, __line, __function);
+# else
+      _GLIBCXX_DEBUG_VERIFY_STR_COND_AT(__s != nullptr || __n == 0,
+					__file, __line, __function);
+# endif
 #endif
       return __s;
     }
@@ -90,8 +106,13 @@ namespace __gnu_debug
 		   const char* __function __attribute__((__unused__)))
     {
 #ifdef _GLIBCXX_DEBUG_PEDANTIC
+# if __cplusplus < 201103L
       _GLIBCXX_DEBUG_VERIFY_STR_COND_AT(__s != 0,
 					__file, __line, __function);
+# else
+      _GLIBCXX_DEBUG_VERIFY_STR_COND_AT(__s != nullptr,
+					__file, __line, __function);
+# endif
 #endif
       return __s;
     }
diff --git a/libstdc++-v3/testsuite/21_strings/basic_string/operations/ends_with/char.cc b/libstdc++-v3/testsuite/21_strings/basic_string/operations/ends_with/char.cc
index cfe18e0186c..3cf85121e36 100644
--- a/libstdc++-v3/testsuite/21_strings/basic_string/operations/ends_with/char.cc
+++ b/libstdc++-v3/testsuite/21_strings/basic_string/operations/ends_with/char.cc
@@ -20,7 +20,7 @@
 
 // basic_string ends_with
 
-#include <string>
+#include <testsuite_string.h>
 #include <testsuite_hooks.h>
 
 void
@@ -31,7 +31,7 @@ test01()
   const char cstr_suf2[] = ".rgb";
   const std::string_view sv_suf2(".rgb");
 
-  const std::string s_test("slugs/slimy.jpg");
+  const __gnu_test::string s_test("slugs/slimy.jpg");
 
   const auto cstr_in_slugs = s_test.ends_with(cstr_suf);
   VERIFY( cstr_in_slugs );
diff --git a/libstdc++-v3/testsuite/21_strings/basic_string/operations/ends_with/nonnull.cc b/libstdc++-v3/testsuite/21_strings/basic_string/operations/ends_with/nonnull.cc
index 1f2a156bace..70ab867fa4e 100644
--- a/libstdc++-v3/testsuite/21_strings/basic_string/operations/ends_with/nonnull.cc
+++ b/libstdc++-v3/testsuite/21_strings/basic_string/operations/ends_with/nonnull.cc
@@ -1,10 +1,10 @@
 // { dg-options "-std=gnu++20 -Wnonnull -O0" }
 // { dg-do compile { target c++20 } }
 
-#include <string>
+#include <testsuite_string.h>
 
 void
-test01(const std::string& s)
+test01(const __gnu_test::string& s)
 {
   s.ends_with((const char*)nullptr);  // { dg-warning "\\\[-Wnonnull" }
   s.ends_with((char*)nullptr);	      // { dg-warning "\\\[-Wnonnull" }
diff --git a/libstdc++-v3/testsuite/21_strings/basic_string/operations/ends_with/wchar_t.cc b/libstdc++-v3/testsuite/21_strings/basic_string/operations/ends_with/wchar_t.cc
index d27e8246fb8..70b522ff69e 100644
--- a/libstdc++-v3/testsuite/21_strings/basic_string/operations/ends_with/wchar_t.cc
+++ b/libstdc++-v3/testsuite/21_strings/basic_string/operations/ends_with/wchar_t.cc
@@ -20,7 +20,7 @@
 
 // basic_string ends_with
 
-#include <string>
+#include <testsuite_string.h>
 #include <testsuite_hooks.h>
 
 void
@@ -31,7 +31,7 @@ test01()
   const wchar_t cstr_suf2[] = L".rgb";
   const std::wstring_view sv_suf2(L".rgb");
 
-  const std::wstring s_test(L"slugs/slimy.jpg");
+  const __gnu_test::wstring s_test(L"slugs/slimy.jpg");
 
   const auto cstr_in_slugs = s_test.ends_with(cstr_suf);
   VERIFY( cstr_in_slugs );
diff --git a/libstdc++-v3/testsuite/21_strings/basic_string/operations/starts_with/char.cc b/libstdc++-v3/testsuite/21_strings/basic_string/operations/starts_with/char.cc
index 5c0b3afc0b6..dddf51cee16 100644
--- a/libstdc++-v3/testsuite/21_strings/basic_string/operations/starts_with/char.cc
+++ b/libstdc++-v3/testsuite/21_strings/basic_string/operations/starts_with/char.cc
@@ -20,7 +20,7 @@
 
 // basic_string begins_with
 
-#include <string>
+#include <testsuite_string.h>
 #include <testsuite_hooks.h>
 
 void
@@ -31,7 +31,7 @@ test01()
   const char cstr_dir2[] = "worms/";
   const std::string_view sv_dir2("worms/");
 
-  const std::string s_test("slugs/slimy.jpg");
+  const __gnu_test::string s_test("slugs/slimy.jpg");
 
   const auto cstr_in_slugs = s_test.starts_with(cstr_dir);
   VERIFY( cstr_in_slugs );
diff --git a/libstdc++-v3/testsuite/21_strings/basic_string/operations/starts_with/nonnull.cc b/libstdc++-v3/testsuite/21_strings/basic_string/operations/starts_with/nonnull.cc
index 8514359c877..34614be0ab6 100644
--- a/libstdc++-v3/testsuite/21_strings/basic_string/operations/starts_with/nonnull.cc
+++ b/libstdc++-v3/testsuite/21_strings/basic_string/operations/starts_with/nonnull.cc
@@ -1,10 +1,10 @@
 // { dg-options "-std=gnu++20 -Wnonnull -O0" }
 // { dg-do compile { target c++20 } }
 
-#include <string>
+#include <testsuite_string.h>
 
 void
-test01(const std::string& s)
+test01(const __gnu_test::string& s)
 {
   s.starts_with((const char*)nullptr);  // { dg-warning "\\\[-Wnonnull" }
   s.starts_with((char*)nullptr);	// { dg-warning "\\\[-Wnonnull" }
diff --git a/libstdc++-v3/testsuite/21_strings/basic_string/operations/starts_with/wchar_t.cc b/libstdc++-v3/testsuite/21_strings/basic_string/operations/starts_with/wchar_t.cc
index eda73212ea0..747b23ae5c2 100644
--- a/libstdc++-v3/testsuite/21_strings/basic_string/operations/starts_with/wchar_t.cc
+++ b/libstdc++-v3/testsuite/21_strings/basic_string/operations/starts_with/wchar_t.cc
@@ -20,7 +20,7 @@
 
 // basic_string begins_with
 
-#include <string>
+#include <testsuite_string.h>
 #include <testsuite_hooks.h>
 
 void
@@ -31,7 +31,7 @@ test01()
   const wchar_t cstr_dir2[] = L"worms/";
   const std::wstring_view sv_dir2(L"worms/");
 
-  const std::wstring s_test(L"slugs/slimy.jpg");
+  const __gnu_test::wstring s_test(L"slugs/slimy.jpg");
 
   const auto cstr_in_slugs = s_test.starts_with(cstr_dir);
   VERIFY( cstr_in_slugs );

Re: [PATCH][_GLIBCXX_DEBUG] Review null string assertions (was: Add basic_string::starts_with/ends_with checks)

[Jonathan Wakely]

On Wed, 31 Aug 2022 at 05:38, François Dumont <frs.dumont@gmail.com> wrote:
>
> If I got your point correctly here is this patch again with just the
> change on '0' becoming 'nullptr' in assertions.
>
>      libstdc++: [_GLIBCXX_DEBUG] Review nullptr assertion diagnostics
>
>      Review null string checks to show:
>      _String != nullptr
>
>      rather than:
>      _String != 0
>
>      libstdc++-v3/ChangeLog:
>
>              * include/debug/debug.h: Use nullptr rather than '0' in
> checks in post-C++11.
>              * include/debug/string: Likewise.
>              *
> testsuite/21_strings/basic_string/operations/ends_with/char.cc: Use
> __gnu_test::string.
>              *
> testsuite/21_strings/basic_string/operations/ends_with/nonnull.cc: Likewise.
>              *
> testsuite/21_strings/basic_string/operations/ends_with/wchar_t.cc: Likewise.
>              *
> testsuite/21_strings/basic_string/operations/starts_with/wchar_t.cc:
> Likewise.
>              *
> testsuite/21_strings/basic_string/operations/starts_with/nonnull.cc:
> Likewise.
>              *
> testsuite/21_strings/basic_string/operations/starts_with/char.cc: Likewise..
>
> Ok to commit ?

The testsuite changes seem unrelated to the actual code change, so I'd
have done a separate patch. But OK for trunk.