Export of internal Abseil changes

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cfd7ee2487ed9b5636d8f83d3850c02e3b4a5cb0 by Jorg Brown <jorg@google.com>:

Add union padding to AsTree, to avoid issues on 32-bit MSVC 2015 compilers

alignas() causes compiler errors as per https://godbolt.org/z/vaTKjn
This change uses explicit padding to achieve what we want: https://godbolt.org/z/Mfjhhj

PiperOrigin-RevId: 353211413

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b1ac7430ffdefe58c01b29e9acd182cda4630e1d by Jorg Brown <jorg@google.com>:

Make the casting functions flat() and ring() be static_cast, rather than reinterpret_cast.

PiperOrigin-RevId: 353149543

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c37a6761c31720317c8b0b7db62b693643a88586 by Abseil Team <absl-team@google.com>:

Integrate CordRepRing logic into cord (but do not enable it)

PiperOrigin-RevId: 353135656

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2007fd3045ed6285106795cf8f2e6d792922f5e8 by Abseil Team <absl-team@google.com>:

Fix a typo in the description of ::equal_range(). The correct return is actually a half-open range [first, last).

PiperOrigin-RevId: 353122213

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6683fa2ba7271dd1f575bd7742d97f47a034c9d2 by Abseil Team <absl-team@google.com>:

Integrate CordRepRing logic into cord (but do not enable it)

PiperOrigin-RevId: 353121763
GitOrigin-RevId: cfd7ee2487ed9b5636d8f83d3850c02e3b4a5cb0
Change-Id: I6635163cd634706f5462c4065aa278e6bf193a72

1 files changed, 11 insertions, 0 deletions

diff --git a/absl/strings/internal/cord_rep_ring.h b/absl/strings/internal/cord_rep_ring.h
index e6f6b59c..55cba8b4 100644
--- a/absl/strings/internal/cord_rep_ring.h
+++ b/absl/strings/internal/cord_rep_ring.h
@@ -563,6 +563,17 @@ inline CordRepRing::Position CordRepRing::FindTail(index_type head,
   return (offset == length) ? Position{tail_, 0} : FindTailSlow(head, offset);
 }
 
+// Now that CordRepRing is defined, we can define CordRep's helper casts:
+inline CordRepRing* CordRep::ring() {
+  assert(tag == RING);
+  return static_cast<CordRepRing*>(this);
+}
+
+inline const CordRepRing* CordRep::ring() const {
+  assert(tag == RING);
+  return static_cast<const CordRepRing*>(this);
+}
+
 std::ostream& operator<<(std::ostream& s, const CordRepRing& rep);
 
 #ifdef __clang__