Abseil LTS branch, Jan 2023, Patch 1

Abseil LTS 20230125.1

What's New:

• The Abseil logging library has been released. This library provides facilities for writing short text messages about the status of a program to stderr, disk files, or other sinks (via an extension API). See the logging library documentation for more information.
• An extension point, AbslStringify(), allows user-defined types to seamlessly work with Abseil's string formatting functions like absl::StrCat() and absl::StrFormat().
• A library for computing CRC32C checksums has been added.
• Floating-point parsing now uses the Eisel-Lemire algorithm, which provides a significant speed improvement.
• The flags library now provides suggestions for the closest flag(s) in the case of misspelled flags.
• Using CMake to install Abseil now makes the installed artifacts (in particular absl/base/options.h) reflect the compiled ABI.

Breaking Changes:

• Abseil now requires at least C++14 and follows Google's Foundational C++ Support Policy. See this table for a list of currently supported versions compilers, platforms, and build tools.
• The legacy spellings of the thread annotation macros/functions (e.g. GUARDED_BY()) have been removed by default in favor of the ABSL_ prefixed versions (e.g. ABSL_GUARDED_BY()) due to clashes with other libraries. The compatibility macro ABSL_LEGACY_THREAD_ANNOTATIONS can be defined on the compile command-line to temporarily restore these spellings, but this compatibility macro will be removed in the future.

Known Issues:

• The Abseil logging library in this release is not a feature-complete replacement for glog yet. VLOG and DFATAL are examples of features that have not yet been released.