[PATCH][_GLIBCXX_DEBUG] Improve valid_range check

[Jonathan Wakely]

On 26/11/19 12:33 +0100, Stephan Bergmann wrote:
>On 22/11/2019 18:59, Jonathan Wakely wrote:
>>On 22/11/19 18:38 +0100, François Dumont wrote:
>>>    I noticed that we are not checking that iterators are not 
>>>singular in valid_range. Moreover __check_singular signature for 
>>>pointers is not intercepting all kind of pointers in terms of 
>>>qualification.
>>>
>>>    I'd like to commit it next week but considering we are in 
>>>stage 3 I need proper acceptance.
>>>
>>>    * include/debug/functions.h: Remove <bits/move.h> include.
>>>    (__check_singular_aux, __check_singular): Move...
>>>    * include/debug/helper_functions.h:
>>>    (__check_singular_aux, __check_singular): ...here.
>>>    (__valid_range_aux): Adapt to use latter.
>>>    * testsuite/25_algorithms/copy/debug/2_neg.cc: New.
>>>
>>>Tested under Linux x86_64 normal and debug modes.
>>
>>OK for trunk, thanks.
>
>The curly braces...
>
>>diff --git a/libstdc++-v3/include/debug/helper_functions.h b/libstdc++-v3/include/debug/helper_functions.h
>>index c3e7478f649..5a858754875 100644
>>--- a/libstdc++-v3/include/debug/helper_functions.h
>>+++ b/libstdc++-v3/include/debug/helper_functions.h
>[...]
>>@@ -138,14 +156,23 @@ namespace __gnu_debug
>>     inline bool
>>     __valid_range_aux(_InputIterator __first, _InputIterator __last,
>> 		      std::input_iterator_tag)
>>-    { return true; }
>>+    {
>>+      if (__first != __last)
>>+	return !__check_singular(__first) && !__check_singular(__last);
>>+
>>+      return true;
>>+    }
>>   template<typename _InputIterator>
>>     _GLIBCXX_CONSTEXPR
>>     inline bool
>>     __valid_range_aux(_InputIterator __first, _InputIterator __last,
>> 		      std::random_access_iterator_tag)
>>-    { return __first <= __last; }
>>+    {
>>+      return
>>+	__valid_range_aux(__first, __last, std::input_iterator_tag{})
>
>...^^^ here...
>
>>+	&& __first <= __last;
>>+    }
>>   /** We have iterators, so figure out what kind of iterators they are
>>    *  to see if we can check the range ahead of time.
>>@@ -167,6 +194,9 @@ namespace __gnu_debug
>> 		      typename _Distance_traits<_InputIterator>::__type& __dist,
>> 		      std::__false_type)
>>     {
>>+      if (!__valid_range_aux(__first, __last, std::input_iterator_tag{}))
>
>...and ^^^ here are not allowed pre C++11.  Replacing those with
>
>  std::input_iterator_tag()
>
>should fix it.

Indeed. We should also have tests that use "-std=gnu++98
-D_GLIBCXX_DEBUG" so they'd catch this.

François, can you take care of the fix please?