www/qt6-webengine: fix build with libc++ 17

Building www/qt6-webengine with libc++ 17 results in the following
compile errors:

  In file included from gen/base/base_jumbo_2.cc:7:
  In file included from ./../../../../../qtwebengine-everywhere-src-6.5.3/src/3rdparty/chromium/base/check.cc:17:
  In file included from ../../../../../qtwebengine-everywhere-src-6.5.3/src/3rdparty/chromium/base/debug/crash_logging.h:16:
  In file included from ../../../../../qtwebengine-everywhere-src-6.5.3/src/3rdparty/chromium/base/strings/string_number_conversions.h:15:
  In file included from ../../../../../qtwebengine-everywhere-src-6.5.3/src/3rdparty/chromium/base/containers/span.h:18:
  ../../../../../qtwebengine-everywhere-src-6.5.3/src/3rdparty/chromium/base/containers/checked_iterators.h:241:8: error: no template named '__is_cpp17_contiguous_iterator'; did you mean '__libcpp_is_contiguous_iterator'?
    241 | struct __is_cpp17_contiguous_iterator<::base::CheckedContiguousIterator<T>>
        |        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
        |        __libcpp_is_contiguous_iterator
  /usr/include/c++/v1/__iterator/iterator_traits.h:476:8: note: '__libcpp_is_contiguous_iterator' declared here
    476 | struct __libcpp_is_contiguous_iterator : _Or<
        |        ^

This is because the copy of chromium in qt6-webengine is missing an
upstream fix for recent libc++ changes, in particular:

  https://chromium.googlesource.com/chromium/src/+/9bfbbffdba73668fdb483e5a850911d2b64c35d7

and its dependency:

  https://chromium.googlesource.com/chromium/src/+/5b5551edd3961481e617e510276b9f015a35b861

Apply these patches to work around the compile error.

PR:		273753
MFH:		2023Q4

1 files changed, 75 insertions, 0 deletions

diff --git a/www/qt6-webengine/files/patch-src_3rdparty_chromium_base_containers_checked__iterators.h b/www/qt6-webengine/files/patch-src_3rdparty_chromium_base_containers_checked__iterators.h
new file mode 100644
index 000000000000..5a63712a10bb
--- /dev/null
+++ b/www/qt6-webengine/files/patch-src_3rdparty_chromium_base_containers_checked__iterators.h
@@ -0,0 +1,75 @@
+--- src/3rdparty/chromium/base/containers/checked_iterators.h.orig	2023-09-07 16:02:00 UTC
++++ src/3rdparty/chromium/base/containers/checked_iterators.h
+@@ -23,6 +23,9 @@ class CheckedContiguousIterator {
+   using pointer = T*;
+   using reference = T&;
+   using iterator_category = std::random_access_iterator_tag;
++#if __cplusplus >= 202002L
++  using iterator_concept = std::contiguous_iterator_tag;
++#endif
+ 
+   // Required for converting constructor below.
+   template <typename U>
+@@ -30,10 +33,8 @@ class CheckedContiguousIterator {
+ 
+   // Required for certain libc++ algorithm optimizations that are not available
+   // for NaCl.
+-#if defined(_LIBCPP_VERSION) && !BUILDFLAG(IS_NACL)
+   template <typename Ptr>
+   friend struct std::pointer_traits;
+-#endif
+ 
+   constexpr CheckedContiguousIterator() = default;
+ 
+@@ -217,7 +218,6 @@ using CheckedContiguousConstIterator = CheckedContiguo
+ 
+ }  // namespace base
+ 
+-#if defined(_LIBCPP_VERSION) && !BUILDFLAG(IS_NACL)
+ // Specialize both std::__is_cpp17_contiguous_iterator and std::pointer_traits
+ // for CCI in case we compile with libc++ outside of NaCl. The former is
+ // required to enable certain algorithm optimizations (e.g. std::copy can be a
+@@ -235,13 +235,35 @@ using CheckedContiguousConstIterator = CheckedContiguo
+ // [1] https://wg21.link/iterator.concept.contiguous
+ // [2] https://wg21.link/std.iterator.tags
+ // [3] https://wg21.link/pointer.traits.optmem
+-namespace std {
+ 
++#if defined(_LIBCPP_VERSION)
++
++// TODO(crbug.com/1284275): Remove when C++20 is on by default, as the use
++// of `iterator_concept` above should suffice.
++_LIBCPP_BEGIN_NAMESPACE_STD
++
++// TODO(crbug.com/1449299): https://reviews.llvm.org/D150801 renamed this from
++// `__is_cpp17_contiguous_iterator` to `__libcpp_is_contiguous_iterator`. Clean
++// up the old spelling after libc++ rolls.
+ template <typename T>
++struct __is_cpp17_contiguous_iterator;
++template <typename T>
+ struct __is_cpp17_contiguous_iterator<::base::CheckedContiguousIterator<T>>
+     : true_type {};
+ 
+ template <typename T>
++struct __libcpp_is_contiguous_iterator;
++template <typename T>
++struct __libcpp_is_contiguous_iterator<::base::CheckedContiguousIterator<T>>
++    : true_type {};
++
++_LIBCPP_END_NAMESPACE_STD
++
++#endif
++
++namespace std {
++
++template <typename T>
+ struct pointer_traits<::base::CheckedContiguousIterator<T>> {
+   using pointer = ::base::CheckedContiguousIterator<T>;
+   using element_type = T;
+@@ -260,6 +282,5 @@ struct pointer_traits<::base::CheckedContiguousIterato
+ };
+ 
+ }  // namespace std
+-#endif
+ 
+ #endif  // BASE_CONTAINERS_CHECKED_ITERATORS_H_