From ee0ebdae4a9e789b92f5abbe8573ddeeaead4864 Mon Sep 17 00:00:00 2001 From: Eric Barndollar Date: Thu, 29 Jul 2021 21:33:51 -0400 Subject: CMake: option to use cxx_std_11 (minimum) that propagates. (#986) See https://github.com/abseil/abseil-cpp/issues/259 for context. This change introduces the ABSL_PROPAGATE_CXX_STD option (default to OFF for now, though it prints a warning in CMake 2.8+ builds that a future Abseil release will default to ON). When enabled, all Abseil CMake targets will set the cxx_std_11 target meta feature (which will then propagate to targets that depend upon Abseil) rather than setting the target-level CXX_STANDARD property to CMAKE_CXX_STANDARD (which is the default value anyway), which doesn't propagate. Updates README documentation to clarify behavior and with a different example recommendation for library projects (which should generally leave CMAKE_CXX_STANDARD to the root application project). See https://crascit.com/2015/03/28/enabling-cxx11-in-cmake/ for a useful overview of these different CMake features surrounding C++ standard version configuration. --- FAQ.md | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) (limited to 'FAQ.md') diff --git a/FAQ.md b/FAQ.md index 78028fc0..fbd92ce9 100644 --- a/FAQ.md +++ b/FAQ.md @@ -27,7 +27,10 @@ compiler, there several ways to do this: file](https://docs.bazel.build/versions/master/guide.html#bazelrc) If you are using CMake as the build system, you'll need to add a line like -`set(CMAKE_CXX_STANDARD 17)` to your top level `CMakeLists.txt` file. See the +`set(CMAKE_CXX_STANDARD 17)` to your top level `CMakeLists.txt` file. If you +are developing a library designed to be used by other clients, you should +instead leave `CMAKE_CXX_STANDARD` unset and configure the minimum C++ standard +required by each of your library targets via `target_compile_features`. See the [CMake build instructions](https://github.com/abseil/abseil-cpp/blob/master/CMake/README.md) for more information. -- cgit v1.2.3