`MaybeRemoveEmptyCrcNode()`. Otherwise appending a `CordBuffer` an empty Cord
with a CRC node crashes (`RemoveCrcNode()` which increases the refcount of a
nullptr child).

Cosmetics: in `Cord::InlineRep::AppendArray()`, return early for empty `src`
before removing the empty CRC node.
PiperOrigin-RevId: 619107278
Change-Id: I4f1bc6b75c662f4678c61e3ef310e8597d62e2e1

PiperOrigin-RevId: 618970135
Change-Id: Ifb9d0b425904d5cb37d80ec28ab7845957209313

This can identify situations where flat_hash_* is suboptimal for large
elements.

PiperOrigin-RevId: 618937993
Change-Id: I2bde069bc3526b14ad1718ba6f50467002aeed16

PiperOrigin-RevId: 618872032
Change-Id: I9fdfadff906494eb64cee976c02a1fff57923c79

PiperOrigin-RevId: 618650101
Change-Id: I6cff17a9db0dc45ad3b1f833df6ea3d7d04a7449

Imported from GitHub PR https://github.com/abseil/abseil-cpp/pull/1644

Starting with Linux 6.6 [1], RDCYCLE is a privileged instruction on RISC-V and can't be used directly from userland. There is a sysctl option to change that as a transition period, but it will eventually disappear.

The RDTIME instruction is another less accurate alternative, however its frequency varies from board to board, and there is currently now way to get its frequency from userland [2].

Therefore this patch just removes the code for unscaledcycleclock on RISC-V. Without processor specific implementation, abseil relies on std::chrono::steady_clock::now().time_since_epoch() which is basically a wrapper around clock_gettime (CLOCK_MONOTONIC), which in turns use __vdso_clock_gettime(). On RISC-V this VDSO is just a wrapper around RDTIME correctly scaled to use nanoseconds units.

This fixes the testsuite on riscv64, tested on a VisionFive 2 board.

[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=cc4c07c89aada16229084eeb93895c95b7eabaa3
[2] https://github.com/abseil/abseil-cpp/pull/1631
Merge 43356a2548cfde76e164d446cb69004b488c6a71 into 76f8011b

Merging this change closes #1644

COPYBARA_INTEGRATE_REVIEW=https://github.com/abseil/abseil-cpp/pull/1644 from aurel32:rv64-no-unscaledcycleclock 43356a2548cfde76e164d446cb69004b488c6a71
PiperOrigin-RevId: 618286262
Change-Id: Ie4120a727e7d0bb185df6e06ea145c780ebe6652

Having DLOG(FATAL) be [[noreturn]] in debug builds makes dead-code
warnings impossible to satisfy between the release and debug build.

PiperOrigin-RevId: 618257732
Change-Id: Ib1c2cb6a026401fbaa0a6e0770adfc166b964ece

PiperOrigin-RevId: 617920100
Change-Id: I0717560a88d32c067ce26b463b14d0db458b28b6

PiperOrigin-RevId: 617877687
Change-Id: I29c52f9288f099255c4adb7c1f9fa8831ac55b05

Code below those comments does use ElementType.

PiperOrigin-RevId: 617854731
Change-Id: I7996b8cbaa2fb65855a801f634a57d821408b1f3

PiperOrigin-RevId: 617613544
Change-Id: I526b5bc087edf54046c77795dddf5412478ac6a8

PiperOrigin-RevId: 617573381
Change-Id: I0ddab2ab7cf68651424b3cf385b484d27106dd59

Consistent with std::aligned_storage_t, it is deprecated in C++23.

https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2021/p1413r3.pdf
has a suggested replacement

PiperOrigin-RevId: 617367005
Change-Id: I009533c5609c8ffd77e406e1fc88e51a3ce99f9f

PiperOrigin-RevId: 617266753
Change-Id: I6cac7b4616001c8d435fb1786da81b746f2d14cb

Fixes #1636 (GCC -Wmaybe-uninitialized warning)

PiperOrigin-RevId: 617253727
Change-Id: I246cd21d8123d4dfa7780b1c4cac8ea1558a4067

When sampling triggers, we skip SOO and allocate a backing array. We must do this because the HashtablezInfoHandle is part of the heap allocation (along with the control bytes and slots). By default, we sample 1 in ~1024 hashtables when sampling is enabled. This will impact performance because (a) we won't benefit from SOO so we would have worse data locality (more cache/TLB misses), and (b) the backing array capacity will be 3 instead of 1 so (b.1) we skip the rehash after the second insertion and (b.2) we potentially waste up to two slots worth of memory.

We also add an soo_capacity field to HashtablezInfo to allow for distinguishing which sampled tables may otherwise have been SOO - this will allow us to know approximately what fraction of tables are in SOO mode.

PiperOrigin-RevId: 617252334
Change-Id: Ib48b7a4870bd74ea3ba923ed8f350a3b75dbb7d3

Add explicit #include directives for <tuple>, "absl/base/config.h", and "absl/strings/string_view.h".

PiperOrigin-RevId: 617232899
Change-Id: I5e6c0bd4545d7f7ad9c5c494017269e247f620a3

PiperOrigin-RevId: 617186944
Change-Id: Id540fb42b02f24ad92b8f3898231f01ac004e191

PiperOrigin-RevId: 616951235
Change-Id: I2d6e95a432285c3f79ef8484848e88e06973f51f

Without this keyword, we can sometimes get cryptic compilation failures such as "error: expected ';' after alias declaration".

PiperOrigin-RevId: 616933517
Change-Id: I2209f3899a4ac03c031217cec67de25bd376d355

Imported from GitHub PR https://github.com/abseil/abseil-cpp/pull/1643

Addressing comments at https://github.com/abseil/abseil-cpp/pull/1604/#pullrequestreview-1937008657
Add a xcprivacy subspec and have all other subspecs depend on it (option 1)

Didn't going with option 3 because there are several levels of subspecs in abseil podspec, it's difficult to track whether all of them directly or indirectly depends on abseil/base/config or ensure they will continue to depend on it.

Example of generated podsped: https://gist.github.com/HannahShiSFB/15d8fb6aa637f2781b7be4218d080f11
Merge 4405cdfe71129bebb13c02a6d8ee18be7e813f73 into 4539c540

Merging this change closes #1643

COPYBARA_INTEGRATE_REVIEW=https://github.com/abseil/abseil-cpp/pull/1643 from HannahShiSFB:privacy-manifests 4405cdfe71129bebb13c02a6d8ee18be7e813f73
PiperOrigin-RevId: 616914674
Change-Id: If56d5a4f1a7cc6f9fac7a2d8e95b55d140e645fc

The sampling rate may change over time, so this allows us to weight samples by
the value observed when we made the sampling decision.

PiperOrigin-RevId: 616900100
Change-Id: I9b1affdba93f5f48367cb7503916296b2d84709a

PiperOrigin-RevId: 616895950
Change-Id: I9dc9099e779df4b692496aa5ee5573ef0e7fd826

PiperOrigin-RevId: 616818246
Change-Id: I1ee813dd1b4da2d25d6b1b9cdba9e8f70d6a6d90

Add a feature to container_internal::Layout that lets you specify some array sizes at compile-time as template parameters. This can make offset and size calculations faster.

In particular, it seems to always improve the performance of AllocSize(), and it sometimes improves the performance of other functions, e.g. when the Layout object outlives the function that created it.

PiperOrigin-RevId: 616817169
Change-Id: Id1d318d7d2af68783f9f59090d89c642be6ae558

The workaround was added for a bug in GCC < 6.1., which had since been fixed. Abseil only [supports](https://github.com/google/oss-policies-info/blob/9a9bfe8a4a12be20757497074fc2f0ecb77438ad/foundational-cxx-support-matrix.md) GCC > 7.3.1.

However, removing the workaround still trips even more recent GCC, such as 13.1. When `SizeSeq` is empty, `p` is not actually used.
Marking it as `ABSL_ATTRIBUTE_UNUSED` silences the GCC warning for that case too.

We could disable `Slices` altogether when `SizeSeq` is empty, but that would be a breaking change (even though this API is internal), and possibly hurt generic programming use (they'd have to check if their parameter packs are empty).

PiperOrigin-RevId: 616245873
Change-Id: I77f7b0b921dfd63fb01c5223851ad1d8a7da233b

`layout`: Use auto return type for functions that explicitly instantiate std::tuple in return statements

This improves readability by avoiding spelling the same type twice, the first time with even more boilerplate (e.g. `typename`).
Return type deduction is a C++14 feature, and Abseil [currently supports](https://github.com/google/oss-policies-info/blob/9a9bfe8a4a12be20757497074fc2f0ecb77438ad/foundational-cxx-support-matrix.md) C++ >= 14.

PiperOrigin-RevId: 616218396
Change-Id: I82aeec878dd69001d2cf822db6512f5a62baec02

PiperOrigin-RevId: 616083064
Change-Id: I3d69303d32431227c197247682f8dcb70f9a239d

No longer include vlog_is_on.h from log.h.  This is a breaking change.
To use VLOG_IS_ON(), absl/log/vlog_is_on.h must be included, not log.h.

PiperOrigin-RevId: 616045708
Change-Id: I59261eb5c28846557b43b040e187ec3ef36e4132

This change mainly affects 32-bit platforms. Similar to
4618865c, check for size_t overflow
in all places where string result sizes are precomputed before allocation.

PiperOrigin-RevId: 615792028
Change-Id: I71c774c5ef2c2978bd812c70e9bab36d266b7c90

This will allow us to give visibility to other Google-internal libraries. The
change is necessary since //visibility:private cannot be combined with other
specifications.

PiperOrigin-RevId: 615779561
Change-Id: I82b1edfa4e1ca280e429cf2a5e4003a1cc316a60

Imported from GitHub PR https://github.com/abseil/abseil-cpp/pull/1603

Merge e324303b1f2aaee8e4418cffb838f150a2d4f4e7 into d8027081

Merging this change closes #1603

COPYBARA_INTEGRATE_REVIEW=https://github.com/abseil/abseil-cpp/pull/1603 from adgajda:master e324303b1f2aaee8e4418cffb838f150a2d4f4e7
PiperOrigin-RevId: 615522811
Change-Id: I46a388ac62ffd42ce175dbfa04e414dd498855f8

PiperOrigin-RevId: 615504707
Change-Id: Ia0e8211bd3c3d28fd0715c8f296ec50f6a700757

Roll back extern template instatiations in swisstable due to binary size increases in shared libraries.

PiperOrigin-RevId: 615497725
Change-Id: Ic29db8923ea4ea7cd0b01b396896fa9fff8c74b0

PiperOrigin-RevId: 615473765
Change-Id: I03c3c16a0e178fce8a572ce272b7e1fd806a38a7

PiperOrigin-RevId: 615380243
Change-Id: I5400b40a6bc5ac52ece5d4fa6da7df9e4ff50855

Motivation: mitigate linker input size increase from swisstable optimizations.

Note: the changes in raw_hash_set.h are fixing build errors that happened when adding the explicit instantiations. The change in unchecked_deref is because set iterators have const reference access whereas map iterators have mutable reference access and the function is never actually called for sets (it's used in raw_hash_map) so it wasn't needed before. I'm not sure why the soo_slot/soo_iterator problems didn't cause compile errors earlier.
PiperOrigin-RevId: 615174043
Change-Id: Iac5eb2332a76e9b70021156fbb2b8def47a5391d

PiperOrigin-RevId: 615160537
Change-Id: I29070c898104c55e6563eed0eef7397441bef1d7

PiperOrigin-RevId: 615131303
Change-Id: I68fcbdd943594983c67f8e07810b05d5fa9a6f2e

PiperOrigin-RevId: 615090942
Change-Id: I7cc20a0129dcfbbddedd9e6d816bb6234bff14b3