MSVC 2017.5 deprecation warnings

[Neil Hodgson]

Just updated to the new (.5) release of Visual C++ 2017 (also called 15.5.0). There are new deprecation warnings due to derivation of regex support classes from std::iterator. While this produces many warnings, the core issue is a C++17 deprecation:

C:\Program Files (x86)\Microsoft Visual Studio\2017\Community\VC\Tools\MSVC\14.12.25827\include\xutility(620): warning C4996: 'std::iterator<std::bidirectional_iterator_tag,wchar_t,ptrdiff_t,_Ty *,_Ty &>::iterator_category': warning STL4015: The std::iterator class template (used as a base class to provide typedefs) is deprecated in C++17. (The <iterator> header is NOT deprecated.) The C++ Standard has never required user-defined iterators to derive from std::iterator. To fix this warning, stop deriving from std::iterator and start providing publicly accessible typedefs named iterator_category, value_type, difference_type, pointer, and reference. Note that value_type is required to be non-const, even for constant iterators. You can define _SILENCE_CXX17_ITERATOR_BASE_CLASS_DEPRECATION_WARNING or _SILENCE_ALL_CXX17_DEPRECATION_WARNINGS to acknowledge that you have received this warning.

Could someone on Windows interested in regex look into this and work out a patch, please?

Neil

[George Hummet]

   Could someone on Windows interested in regex look into this and work out a patch, please?

   Neil

Hey Neal, im not quite what you might call an expert in regexps but i will see what i can do.

enjoy, Thorsten

[George Hummet]

had a quick look,dont think its worth the effort, sorry.

[Greg Smith]

The fix is to remove use of the iterator and provide the 5 typedefs:

class ByteIterator : public std::iterator<std::bidirectional_iterator_tag, char> {
public:
 const Document *doc;



 becomes:

class ByteIterator {
public:
       typedef std::bidirectional_iterator_tag iterator_category;
       typedef char value_type;
       typedef ptrdiff_t difference_type;
       typedef char* pointer;
       typedef char& reference;
 const Document *doc;

And similarly for the other two cases with char replaced by wchar_t.

There never has been a requirement for iterators to derive from std::iterator, and this can be the source of perplexing parse errors due to two stage name lookup (especially as the Microsoft compiler used to get this wrong by allowing you to refer to dependent names declared in a base class).

 

[Neil Hodgson]

Greg Smith:

> The fix is to remove use of the iterator and provide the 5 typedefs:
>
> class ByteIterator : public std::iterator<std::bidirectional_iterator_tag, char> {
> public:
> const Document *doc;
>
>
> becomes:
> class ByteIterator {
> public:
> typedef std::bidirectional_iterator_tag iterator_category;
> typedef char value_type;
> typedef ptrdiff_t difference_type;
> typedef char* pointer;
> typedef char& reference;
> const Document *doc;
>
> And similarly for the other two cases with char replaced by wchar_t.

OK, committed:
https://sourceforge.net/p/scintilla/code/ci/fd2f856b8d582df2e3e60073721a84b9f464a72b/

Neil