README.chromium

Name: Abseil
Short Name: absl
URL: https://github.com/abseil/abseil-cpp
License: Apache-2.0
License File: LICENSE
Version: N/A
Revision: 5b1e199db4bc8f83f3d2dc1ced3dee7576ceedc2
Update Mechanism: Manual
Security Critical: yes
Shipped: yes

Description:
This directory contains the source code of Abseil for C++. This can be used by
Chromium, subject to the guidance at
https://chromium.googlesource.com/chromium/src/+/main/styleguide/c++/c++-features.md;
it can be used without restriction by Chromium's dependencies, except that
objects compiled into Chromium itself cannot use anything relying on
absl::base_internal::FastTypeId (see https://crbug.com/1096380).

How to update Abseil:

1. From your source root run third_party/abseil-cpp/roll_abseil.py to download the code from the Abseil git repository and apply chromium specific patches.

2. Update BUILD.gn files to match changes in BUILD.bazel

If there is a new test, add dependcy on it from absl_tests in the
third_party/abseil-cpp/BUILD.gn target

3. From your source root run third_party/abseil-cpp/generate_def_files.py to
   regenerate Windows symbol definition files.

4. If abseil adds new features, update styleguide/c++/c++-features.md and add headers for that feature into exclude list in root DEPS

5. Verify your roll no-ops upon `third_party/abseil-cpp/roll_abseil.py --no-branch --no-pull --no-upload --revision <Revision>`

How to review a roll:

1. `git cl patch <CL number>`, then verify that `third_party/abseil-cpp/roll_abseil.py --no-branch --no-pull --no-upload --revision <Revision>`
   no-ops.
2. Check that changes to the .def files exist, or whether there is a comment in the CL description calling out they don't change.
3. Check that every change in BUILD.bazel is matched by a counterpart in BUILD.gn.


Local Modifications:

* absl/copts.bzl has been translated to //third_party/absl-cpp/BUILD.gn. Both
  files contain lists of compiler flags in order to reduce duplication.

* All the BUILD.bazel files have been translated to BUILD.gn files.

* Patches from //third_party/abseil-cpp/patches have been applied.

* Increment this number to silence presubmits about modifying files in
  third_party when regenerating absl .def files: 3