| commit | bf7caaf6db43f85e933dad843d4d84c99f1360dc | [log] [tgz] |
|---|---|---|
| author | Peter Kasting <pkasting@chromium.org> | Tue Aug 04 04:53:20 2020 +0000 |
| committer | Commit Bot <commit-bot@chromium.org> | Tue Aug 04 04:53:20 2020 +0000 |
| tree | 098e52632757556514ab8bc7adf6b3a58b7a698e | |
| parent | ba3b7ecf04099620c6087451156a1793dcc3607f [diff] |
Fix raw_logging.h to allow deterministic symbols, and regenerate .defs. __FILE__ is replaced by a string constant, whose type is const char[n], where 'n' is the length of the actual filename. Because ABSL_INTERNAL_LOG() passes __FILE__ to the templated function AtomicHook::operator()(Args&...), the value of 'n' is encoded into the mangled name of the generated operator. As a result, generated .def files containing an entry for this operator would result in "symbol not found" errors during link on machines which used a different-length filename for such a call. This was not previously a problem because for some reason this particular symbol was omitted from the generated .defs. As part of trying to fix the win32-archive-dbg builder, which failed due to not-found symbols after crrev.com/793680, I saw that no updates to these files had been applied during the last couple of Abseil rolls, suspected they might be out of date, and regenerated the files. This caused more builds to break rather than fewer since this symbol was now being included. It's possible this has something to do with absolute paths (see blog.llvm.org/2019/11/deterministic-builds-with-clang-and-lld.html ), but I don't think so; we should be using relative paths to compile. Plus, the failed builds were on configurations that did not enable is_official_build, and when that's not enabled, we should be setting strip_absolute_paths_from_debug_symbols as well. (That might be irrelevant; I'm overly ignorant of how object files encode info.) I am guessing the core problem is that if multiple files invoke ABSL_INTERNAL_LOG(), then even with relative file paths, the generated symbol effectively depends on which file ends up instantiating this first, or gets selected by the linker, or whatever. So this patch modifies the macro to explicitly cast __FILE__ to a pointer (the type that will be passed to the ultimate destination anyway), making the symbol name for the operator deterministic. If we think this patch is a good idea, we should try to upstream it. The .def files have been subsequently regenerated (and got one other symbol added, so maybe they did omit something important?), and I added a note to README.chromium about running this script, along with trying to update that file more generally. Bug: 1103706 Change-Id: I39ba72b4dd688340cacf0a814d6f461a96f891e6 Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2333649 Commit-Queue: Peter Kasting <pkasting@chromium.org> Reviewed-by: Nico Weber <thakis@chromium.org> Cr-Original-Commit-Position: refs/heads/master@{#794391} Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src Cr-Mirrored-Commit: 2a15c32108ed6c80bb75b529e027860c17219553
The repository contains the Abseil C++ library code. Abseil is an open-source collection of C++ code (compliant to C++11) designed to augment the C++ standard library.
Abseil is an open-source collection of C++ library code designed to augment the C++ standard library. The Abseil library code is collected from Google's own C++ code base, has been extensively tested and used in production, and is the same code we depend on in our daily coding lives.
In some cases, Abseil provides pieces missing from the C++ standard; in others, Abseil provides alternatives to the standard for special needs we've found through usage in the Google code base. We denote those cases clearly within the library code we provide you.
Abseil is not meant to be a competitor to the standard library; we've just found that many of these utilities serve a purpose within our code base, and we now want to provide those resources to the C++ community as a whole.
If you want to just get started, make sure you at least run through the Abseil Quickstart. The Quickstart contains information about setting up your development environment, downloading the Abseil code, running tests, and getting a simple binary working.
Bazel is the official build system for Abseil, which is supported on most major platforms (Linux, Windows, macOS, for example) and compilers. See the quickstart for more information on building Abseil using the Bazel build system.
If you require CMake support, please check the CMake build instructions.
Abseil contains the following C++ library components:
base Abseil Fundamentals base library contains initialization code and other code which all other Abseil code depends on. Code within base may not depend on any other code (other than the C++ standard library).algorithm algorithm library contains additions to the C++ <algorithm> library and container-based versions of such algorithms.container container library contains additional STL-style containers, including Abseil's unordered “Swiss table” containers.debugging debugging library contains code useful for enabling leak checks, and stacktrace and symbolization utilities.hash hash library contains the hashing framework and default hash functor implementations for hashable types in Abseil.memory memory library contains C++11-compatible versions of std::make_unique() and related memory management facilities.meta meta library contains C++11-compatible versions of type checks available within C++14 and C++17 versions of the C++ <type_traits> library.numeric numeric library contains C++11-compatible 128-bit integers.strings strings library contains a variety of strings routines and utilities, including a C++11-compatible version of the C++17 std::string_view type.synchronization synchronization library contains concurrency primitives (Abseil's absl::Mutex class, an alternative to std::mutex) and a variety of synchronization abstractions.time time library contains abstractions for computing with absolute points in time, durations of time, and formatting and parsing time within time zones.types types library contains non-container utility types, like a C++11-compatible version of the C++17 std::optional type.utility utility library contains utility and helper code.The Abseil C++ library is licensed under the terms of the Apache license. See LICENSE for more information.
For more information about Abseil: