Build failure on Fedora 34

[richmattes]

Environment

• OS Version: Fedora 34 (pre-release)
• Source or binary build? Source - ignition-common-3.10.1

Description

When building ignition-common on Fedora 34 and higher, I am experiencing a build failure when compiling plugin.cc for the INTEGRATION_plugin test. The command line (see Output section) doesn't include the necessary -std=c++17, instead it includes -std=c++11.

There are a couple of conflicting C++ standards being set in different places:

• libignition_common3 has an INTERFACE target_compile_features set for cxx_std_17
• test/CMakeLists.txt appends std=c++11 to the CMAKE_CXX_FLAGS before building gtest targets and including test subdirectories.

Given that the build works as expected on Fedora 33 with CMake 3.18, my guess is something changed in CMake 3.19 where the CMAKE_CXX_FLAGS take precedence and isn't overridden by target properties.

The CMAKE_CXX_FLAGS in test/CMakeLists.txt should be removed in favor of target-specific standards version selection if needed for the gtest libraries.

• Expected behavior:
  Package builds as expected, including all tests

• Actual behavior:
  Building the INTEGRATION_plugin test fails with an error (C++17 required for string_view - see the Output section)

Steps to reproduce

1. Download CMake 3.19 or higher
2. Configure and build with the CMake 3.19 binary

Output

Successful, and failed logs are (here)[https://copr.fedorainfracloud.org/coprs/g/robotics-sig/gazebo-latest/build/2059613/] in the builder_live logs. Excerpt of a failure case is shown below

[ 56%] Building CXX object test/integration/CMakeFiles/INTEGRATION_plugin.dir/plugin.cc.o
cd /builddir/build/BUILD/ignition-common-3.10.1/aarch64-redhat-linux-gnu/test/integration && /usr/bin/g++  -I/builddir/build/BUILD/ignition-common-3.10.1/include -I/builddir/build/BUILD/ignition-common-3.10.1/aarch64-redhat-linux-gnu/include -I/builddir/build/BUILD/ignition-common-3.10.1/test/gtest/include -I/builddir/build/BUILD/ignition-common-3.10.1/test/gtest -I/builddir/build/BUILD/ignition-common-3.10.1/test -I/builddir/build/BUILD/ignition-common-3.10.1/aarch64-redhat-linux-gnu -I/builddir/build/BUILD/ignition-common-3.10.1 -I/builddir/build/BUILD/ignition-common-3.10.1/aarch64-redhat-linux-gnu/core/include -isystem /usr/include/uuid -O2 -flto=auto -ffat-lto-objects -fexceptions -g -grecord-gcc-switches -pipe -Wall -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2 -Wp,-D_GLIBCXX_ASSERTIONS -specs=/usr/lib/rpm/redhat/redhat-hardened-cc1 -fstack-protector-strong -specs=/usr/lib/rpm/redhat/redhat-annobin-cc1  -mbranch-protection=standard -fasynchronous-unwind-tables -fstack-clash-protection -std=c++11 -DNDEBUG  -Wall -Wextra -Wno-long-long -Wno-unused-value -Wfloat-equal -Wshadow -Winit-self -Wswitch-default -Wmissing-include-dirs -pedantic  -I/usr/include/uuid -o CMakeFiles/INTEGRATION_plugin.dir/plugin.cc.o -c /builddir/build/BUILD/ignition-common-3.10.1/test/integration/plugin.cc
In file included from /builddir/build/BUILD/ignition-common-3.10.1/include/ignition/common/Console.hh:25,
                 from /builddir/build/BUILD/ignition-common-3.10.1/test/integration/plugin.cc:28:
/builddir/build/BUILD/ignition-common-3.10.1/include/ignition/common/Util.hh:197:60: warning: 'visibility' attribute ignored [-Wattributes]
  197 |     constexpr uint64_t IGNITION_COMMON_VISIBLE hash64(std::string_view _key)
      |                                                            ^~~~~~~~~~~
/builddir/build/BUILD/ignition-common-3.10.1/include/ignition/common/Util.hh:197:60: error: 'string_view' is not a member of 'std'
/builddir/build/BUILD/ignition-common-3.10.1/include/ignition/common/Util.hh:197:60: note: 'std::string_view' is only available from C++17 onwards
gmake[2]: *** [test/integration/CMakeFiles/INTEGRATION_plugin.dir/build.make:85: test/integration/CMakeFiles/INTEGRATION_plugin.dir/plugin.cc.o] Error 1
gmake[2]: Leaving directory '/builddir/build/BUILD/ignition-common-3.10.1/aarch64-redhat-linux-gnu'
gmake[1]: *** [CMakeFiles/Makefile2:1984: test/integration/CMakeFiles/INTEGRATION_plugin.dir/all] Error 2
gmake[1]: *** Waiting for unfinished jobs....

[richmattes]

I've confirmed that changing c++11 to c++17, and removing the modification of CMAKE_CXX_FLAGS altogether in test/CMakeLists.txt both resolve the failure.

[chapulina]

Thanks for the ticket.

I've confirmed that changing c++11 to c++17, and removing the modification of CMAKE_CXX_FLAGS altogether in test/CMakeLists.txt both resolve the failure.

Would you mind opening a PR with the flags removal approach?

[mjcarroll]

@richmattes Can you check #214 for me?

[mjcarroll]

Closed by #214