Export of internal Abseil changes

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b1fc72630aaa81c8395c3b22ba267d938fe29a2e by Derek Mauro <dmauro@google.com>:

Fix -Wdeprecated-copy warnings from Clang 13.

Example:
error: definition of implicit copy assignment operator for 'UDT' is deprecated because it has a user-declared copy constructor [-Werror,-Wdeprecated-copy]
PiperOrigin-RevId: 380058303

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0422744812b1a2010d9eea5b17fbe89f3441b66b by Evan Brown <ezb@google.com>:

Change the "full table!" asserts in raw_hash_set to use `<= capacity` instead of `< capacity`.

If we add support for non-power-of-two-minus-one capacities, this is the correct thing to assert. For example, consider: Group::kWidth = 8, capacity_ = 8, ctrl_ = {kEmpty, 1, 2, 3, 4, 5, 6, 7, kSentinel, kEmpty, 1, 2, 3, 4, 5, 6}. In this case, if we do an unsuccessful lookup with H2 mapping to slot 1, then the first Group will contain {1, 2, 3, 4, 5, 6, 7, kSentinel} so we need to continue to the second Group (at which point seq.index() == 8 == capacity_) to find a kEmpty.

Note: this is a no-op change for now since we never have `capacity % Group::kWidth == 0`.
PiperOrigin-RevId: 380033480

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40628c34d540356de65fabb16c1439c0ec7a0764 by Abseil Team <absl-team@google.com>:

Drop out-of-date documentation about `absl::FixedArray`'s allocator support

PiperOrigin-RevId: 379811653

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e7ad047863ae55c9b7aec0753cfc527a4ea614bc by Evan Brown <ezb@google.com>:

Fix a bug in ConvertDeletedToEmptyAndFullToDeleted in which we were copying 1 more cloned control byte than actually exists.

When alignof(slot_type)>1, this wouldn't cause a problem because the extra byte is padding.

Also change loop bounds to not rely on the fact that capacity_+1 is a multiple of Group::kWidth.

PiperOrigin-RevId: 379311830

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1a3ba500fb2c33205854eb9258cd6e0fb1061bca by Martijn Vels <mvels@google.com>:

Change Ring, EXTERNAL and FLAT tag values to be consecutive values

The purpose of this change is to have FLAT = EXTERNAL + 1. Especially in the ring and btree alternative code, there is a common check if a node is a 'plain' edge (EXTERNAL or FLAT), or 'something else'. This change can make that check a single branch, i.e., instead of 'tag == EXTERNAL || tag >= FLAT', we can simply check for 'tag >= EXTERNAL'. Likewise we have some cases where we check for RING, EXTERNAL or FLAT, so we align RING + 1 with EXTERNAL.

PiperOrigin-RevId: 379291576

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0c78e65ca4d85244b106c3f8e24cf268e09e72a3 by Benjamin Barenblat <bbaren@google.com>:

Round a double multiplication before casting it to integer

The code

    static_cast<int>(x * y)

(for double x and y) performs a double multiplication into a temporary
that, by standard, may have excess precision. The subsequent cast to int
discards the excess precision. However, the cast may examine the excess
precision during conversion, producing surprising results like

    static_cast<int>(1.7 * 10) == 16

on certain systems. Correct this case by explicitly rounding 1.7 * 10
before casting it.

PiperOrigin-RevId: 378922064
GitOrigin-RevId: b1fc72630aaa81c8395c3b22ba267d938fe29a2e
Change-Id: Ica708a006921118673e78d5fd2d61fe0fb0894d1

1 files changed, 13 insertions, 3 deletions

diff --git a/absl/strings/internal/cord_internal.h b/absl/strings/internal/cord_internal.h
index 813b3f35..1e2436ba 100644
--- a/absl/strings/internal/cord_internal.h
+++ b/absl/strings/internal/cord_internal.h
@@ -154,9 +154,9 @@ class CordRepRing;
 // Various representations that we allow
 enum CordRepKind {
   CONCAT = 0,
-  EXTERNAL = 1,
-  SUBSTRING = 2,
-  RING = 3,
+  SUBSTRING = 1,
+  RING = 2,
+  EXTERNAL = 3,
 
   // We have different tags for different sized flat arrays,
   // starting with FLAT, and limited to MAX_FLAT_TAG. The 224 value is based on
@@ -168,6 +168,16 @@ enum CordRepKind {
   MAX_FLAT_TAG = 224
 };
 
+// There are various locations where we want to check if some rep is a 'plain'
+// data edge, i.e. an external or flat rep. By having FLAT == EXTERNAL + 1, we
+// can perform this check in a single branch as 'tag >= EXTERNAL'
+// Likewise, we have some locations where we check for 'ring or external/flat',
+// so likewise align RING to EXTERNAL.
+// Note that we can leave this optimization to the compiler. The compiler will
+// DTRT when it sees a condition like `tag == EXTERNAL || tag >= FLAT`.
+static_assert(EXTERNAL == RING + 1, "RING and EXTERNAL values not consecutive");
+static_assert(FLAT == EXTERNAL + 1, "EXTERNAL and FLAT values not consecutive");
+
 struct CordRep {
   CordRep() = default;
   constexpr CordRep(Refcount::Immortal immortal, size_t l)