Export of internal Abseil changes

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0f6565955231dc74ebad62ef32a18c457afa2dc7 by Abseil Team <absl-team@google.com>:

Document guarantee that we do not move from rvalue arguments if no insertion happens with absl::raw_hash_map::try_emplace, as done with std::unordered_map::try_emplace.

PiperOrigin-RevId: 264430409

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292e6b9e08fa689e8400d7f2db94cbcab29d5889 by CJ Johnson <johnsoncj@google.com>:

Removes use of aligned_storage in FixedArray and InlinedVector in favor of aligned char buffers.

PiperOrigin-RevId: 264385559

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aa0b19ad11ae5702022feee0e2e6434cfb28c9e9 by Derek Mauro <dmauro@google.com>:

Make the unit tests for absl::any, absl::optional, and absl::variant
no-ops when these types are just aliases for the corresponding std::
types. We have no way to fix standard library implementation bugs, so
don't bother working around them.

Also disable the corresponding exception-safety tests as well when
exceptions are not enabled.

Fixes https://github.com/abseil/abseil-cpp/pull/360

PiperOrigin-RevId: 264382050

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65896a911f36481b89b4712c83b91c90a76b64e8 by Abseil Team <absl-team@google.com>:

Improve documentation on erase

PiperOrigin-RevId: 264381266
GitOrigin-RevId: 0f6565955231dc74ebad62ef32a18c457afa2dc7
Change-Id: I74b9bd2ddf84526014104f17e87de70bd3fe65fa

1 files changed, 7 insertions, 6 deletions

diff --git a/absl/container/internal/raw_hash_set.h b/absl/container/internal/raw_hash_set.h
index 656e9806d899..2e6f4dd3e66e 100644
--- a/absl/container/internal/raw_hash_set.h
+++ b/absl/container/internal/raw_hash_set.h
@@ -1133,15 +1133,16 @@ class raw_hash_set {
   }
 
   // Erases the element pointed to by `it`.  Unlike `std::unordered_set::erase`,
-  // this method returns void to reduce algorithmic complexity to O(1).  In
-  // order to erase while iterating across a map, use the following idiom (which
-  // also works for standard containers):
+  // this method returns void to reduce algorithmic complexity to O(1).  The
+  // iterator is invalidated, so any increment should be done before calling
+  // erase.  In order to erase while iterating across a map, use the following
+  // idiom (which also works for standard containers):
   //
   // for (auto it = m.begin(), end = m.end(); it != end;) {
+  //   // `erase()` will invalidate `it`, so advance `it` first.
+  //   auto copy_it = it++;
   //   if (<pred>) {
-  //     m.erase(it++);
-  //   } else {
-  //     ++it;
+  //     m.erase(copy_it);
   //   }
   // }
   void erase(const_iterator cit) { erase(cit.inner_); }