Export of internal Abseil changes

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8726480d631a3736347f542dab5628d5e2ace3c1 by Mark Barolak <mbar@google.com>:

Import of CCTZ from GitHub.

PiperOrigin-RevId: 323414814

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abc4a382a29fb857432e0e13a8c21ebe808f9828 by Abseil Team <absl-team@google.com>:

Fix buffer overflow when the result of demangling doesn't fit.

PiperOrigin-RevId: 323392968

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7ed3e514519a971322d0a3333c7e85ed1f2a5f71 by Gennadiy Rozental <rogeeff@google.com>:

Move ABSL_DEPRECATED and ABSL_FALLTHROUGH_INTENDED from base.h into attribute.h.

PiperOrigin-RevId: 323137526

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fc0afdb0792d565065d25feb9680972218355f90 by Xiaoyi Zhang <zhangxy@google.com>:

Add documentation for `absl::StatusCode`.

PiperOrigin-RevId: 323065623
GitOrigin-RevId: 8726480d631a3736347f542dab5628d5e2ace3c1
Change-Id: I9d39650e49ff265cd2dafee302013694e97c813f

1 files changed, 113 insertions, 0 deletions

diff --git a/absl/status/status.h b/absl/status/status.h
index 967e6064..42530621 100644
--- a/absl/status/status.h
+++ b/absl/status/status.h
@@ -24,24 +24,137 @@
 namespace absl {
 ABSL_NAMESPACE_BEGIN
 
+// Sometimes multiple error codes may apply.  Services should return
+// the most specific error code that applies.  For example, prefer
+// `kOutOfRange` over `kFailedPrecondition` if both codes apply.
+// Similarly prefer `kNotFound` or `kAlreadyExists` over `kFailedPrecondition`.
 enum class StatusCode : int {
+  // Not an error; returned on success
   kOk = 0,
+
+  // The operation was cancelled, typically by the caller.
   kCancelled = 1,
+
+  // Unknown error. For example, errors raised by APIs that do not return
+  // enough error information may be converted to this error.
   kUnknown = 2,
+
+  // The client specified an invalid argument. Note that this differs
+  // from `kFailedPrecondition`. `kInvalidArgument` indicates arguments
+  // that are problematic regardless of the state of the system
+  // (such as a malformed file name).
   kInvalidArgument = 3,
+
+  // The deadline expired before the operation could complete. For operations
+  // that change the state of the system, this error may be returned
+  // even if the operation has completed successfully. For example, a
+  // successful response from a server could have been delayed long
+  // enough for the deadline to expire.
   kDeadlineExceeded = 4,
+
+  // Some requested entity (such as file or directory) was not found.
+  //
+  // Note to server developers: if a request is denied for an entire class
+  // of users, such as gradual feature rollout or undocumented whitelist,
+  // `kNotFound` may be used. If a request is denied for some users within
+  // a class of users, such as user-based access control, `kPermissionDenied`
+  // must be used.
   kNotFound = 5,
+
+  // The entity that a client attempted to create (such as file or directory)
+  // already exists.
   kAlreadyExists = 6,
+
+  // The caller does not have permission to execute the specified
+  // operation. `kPermissionDenied` must not be used for rejections
+  // caused by exhausting some resource (use `kResourceExhausted`
+  // instead for those errors). `kPermissionDenied` must not be
+  // used if the caller can not be identified (use `kUnauthenticated`
+  // instead for those errors). This error code does not imply the
+  // request is valid or the requested entity exists or satisfies
+  // other pre-conditions.
   kPermissionDenied = 7,
+
+  // Some resource has been exhausted, perhaps a per-user quota, or
+  // perhaps the entire file system is out of space.
   kResourceExhausted = 8,
+
+  // The operation was rejected because the system is not in a state
+  // required for the operation's execution. For example, the directory
+  // to be deleted is non-empty, an rmdir operation is applied to
+  // a non-directory, etc.
+  //
+  // A litmus test that may help a service implementer in deciding
+  // between `kFailedPrecondition`, `kAborted`, and `kUnavailable`:
+  //  (a) Use `kUnavailable` if the client can retry just the failing call.
+  //  (b) Use `kAborted` if the client should retry at a higher-level
+  //      (such as when a client-specified test-and-set fails, indicating the
+  //      client should restart a read-modify-write sequence).
+  //  (c) Use `kFailedPrecondition` if the client should not retry until
+  //      the system state has been explicitly fixed. For example, if an "rmdir"
+  //      fails because the directory is non-empty, `kFailedPrecondition`
+  //      should be returned since the client should not retry unless
+  //      the files are deleted from the directory.
   kFailedPrecondition = 9,
+
+  // The operation was aborted, typically due to a concurrency issue such as
+  // a sequencer check failure or transaction abort.
+  //
+  // See litmus test above for deciding between `kFailedPrecondition`,
+  // `kAborted`, and `kUnavailable`.
   kAborted = 10,
+
+  // The operation was attempted past the valid range, such as seeking or
+  // reading past end-of-file.
+  //
+  // Unlike `kInvalidArgument`, this error indicates a problem that may
+  // be fixed if the system state changes. For example, a 32-bit file
+  // system will generate `kInvalidArgument` if asked to read at an
+  // offset that is not in the range [0,2^32-1], but it will generate
+  // `kOutOfRange` if asked to read from an offset past the current
+  // file size.
+  //
+  // There is a fair bit of overlap between `kFailedPrecondition` and
+  // `kOutOfRange`.  We recommend using `kOutOfRange` (the more specific
+  // error) when it applies so that callers who are iterating through
+  // a space can easily look for an `kOutOfRange` error to detect when
+  // they are done.
   kOutOfRange = 11,
+
+  // The operation is not implemented or is not supported/enabled in this
+  // service.
   kUnimplemented = 12,
+
+  // Internal errors. This means that some invariants expected by the
+  // underlying system have been broken. This error code is reserved
+  // for serious errors.
   kInternal = 13,
+
+  // The service is currently unavailable. This is most likely a
+  // transient condition, which can be corrected by retrying with
+  // a backoff. Note that it is not always safe to retry
+  // non-idempotent operations.
+  //
+  // See litmus test above for deciding between `kFailedPrecondition`,
+  // `kAborted`, and `kUnavailable`.
   kUnavailable = 14,
+
+  // Unrecoverable data loss or corruption.
   kDataLoss = 15,
+
+  // The request does not have valid authentication credentials for the
+  // operation.
   kUnauthenticated = 16,
+
+  // An extra enum entry to prevent people from writing code that
+  // fails to compile when a new code is added.
+  //
+  // Nobody should ever reference this enumeration entry. In particular,
+  // if you write C++ code that switches on this enumeration, add a default:
+  // case instead of a case that mentions this enumeration entry.
+  //
+  // Nobody should rely on the value (currently 20) listed here.  It
+  // may change in the future.
   kDoNotUseReservedForFutureExpansionUseDefaultInSwitchInstead_ = 20
 };