cmake: Add standalone build support for building and running unit tests

[nigels-com]

The CMakeLists.txt currently supports the "superproject" boost build,
but does not work stand alone.

This change adds support for a stand-alone build of boost::sort, using the cmake method of detecting an existing boost installation.

-DBUILD_TESTING=Y can be used for opting into the test coverage.

The default all target will not build anything, since sort is a header-only library.
The tests target can be used to build the unit tests.
The check target can be used to run the unit tests, building if necessary.

$ PATH=/opt/cmake-3.10.0-Linux-x86_64/bin:$PATH cmake .. -G Ninja -DCMAKE_BUILD_TYPE=Release -DCMAKE_CXX_COMPILER_LAUNCHER=ccache -DBUILD_TESTING=Y -DCMAKE_CXX_COMPILER=clang++-18 && ninja check
-- Using cmake version 3.10.0
-- Found Boost 1.89.0 at /opt/boost-1.89.0/lib/cmake/Boost-1.89.0
--   Requested configuration: QUIET REQUIRED COMPONENTS core;range;included_test_exec_monitor
-- BoostConfig: find_package(boost_headers 1.89.0 EXACT CONFIG REQUIRED QUIET HINTS /opt/boost-1.89.0/lib/cmake)
-- Found boost_headers 1.89.0 at /opt/boost-1.89.0/lib/cmake/boost_headers-1.89.0
-- BoostConfig: find_package(boost_core 1.89.0 EXACT CONFIG REQUIRED QUIET HINTS /opt/boost-1.89.0/lib/cmake)
-- Found boost_core 1.89.0 at /opt/boost-1.89.0/lib/cmake/boost_core-1.89.0
-- Found boost_assert 1.89.0 at /opt/boost-1.89.0/lib/cmake/boost_assert-1.89.0
-- Found boost_config 1.89.0 at /opt/boost-1.89.0/lib/cmake/boost_config-1.89.0
-- Found boost_static_assert 1.89.0 at /opt/boost-1.89.0/lib/cmake/boost_static_assert-1.89.0
-- Found boost_throw_exception 1.89.0 at /opt/boost-1.89.0/lib/cmake/boost_throw_exception-1.89.0
-- BoostConfig: find_package(boost_range 1.89.0 EXACT CONFIG REQUIRED QUIET HINTS /opt/boost-1.89.0/lib/cmake)
-- Found boost_range 1.89.0 at /opt/boost-1.89.0/lib/cmake/boost_range-1.89.0
-- Found boost_array 1.89.0 at /opt/boost-1.89.0/lib/cmake/boost_array-1.89.0
-- Found boost_concept_check 1.89.0 at /opt/boost-1.89.0/lib/cmake/boost_concept_check-1.89.0
-- Found boost_preprocessor 1.89.0 at /opt/boost-1.89.0/lib/cmake/boost_preprocessor-1.89.0
-- Found boost_type_traits 1.89.0 at /opt/boost-1.89.0/lib/cmake/boost_type_traits-1.89.0
-- Found boost_container_hash 1.89.0 at /opt/boost-1.89.0/lib/cmake/boost_container_hash-1.89.0
-- Found boost_describe 1.89.0 at /opt/boost-1.89.0/lib/cmake/boost_describe-1.89.0
-- Found boost_mp11 1.89.0 at /opt/boost-1.89.0/lib/cmake/boost_mp11-1.89.0
-- Found boost_conversion 1.89.0 at /opt/boost-1.89.0/lib/cmake/boost_conversion-1.89.0
-- Found boost_smart_ptr 1.89.0 at /opt/boost-1.89.0/lib/cmake/boost_smart_ptr-1.89.0
-- Found boost_detail 1.89.0 at /opt/boost-1.89.0/lib/cmake/boost_detail-1.89.0
-- Found boost_iterator 1.89.0 at /opt/boost-1.89.0/lib/cmake/boost_iterator-1.89.0
-- Found boost_fusion 1.89.0 at /opt/boost-1.89.0/lib/cmake/boost_fusion-1.89.0
-- Found boost_function_types 1.89.0 at /opt/boost-1.89.0/lib/cmake/boost_function_types-1.89.0
-- Found boost_mpl 1.89.0 at /opt/boost-1.89.0/lib/cmake/boost_mpl-1.89.0
-- Found boost_predef 1.89.0 at /opt/boost-1.89.0/lib/cmake/boost_predef-1.89.0
-- Found boost_utility 1.89.0 at /opt/boost-1.89.0/lib/cmake/boost_utility-1.89.0
-- Found boost_io 1.89.0 at /opt/boost-1.89.0/lib/cmake/boost_io-1.89.0
-- Found boost_tuple 1.89.0 at /opt/boost-1.89.0/lib/cmake/boost_tuple-1.89.0
-- Found boost_typeof 1.89.0 at /opt/boost-1.89.0/lib/cmake/boost_typeof-1.89.0
-- Found boost_functional 1.89.0 at /opt/boost-1.89.0/lib/cmake/boost_functional-1.89.0
-- Found boost_function 1.89.0 at /opt/boost-1.89.0/lib/cmake/boost_function-1.89.0
-- Found boost_bind 1.89.0 at /opt/boost-1.89.0/lib/cmake/boost_bind-1.89.0
-- Found boost_optional 1.89.0 at /opt/boost-1.89.0/lib/cmake/boost_optional-1.89.0
-- Found boost_regex 1.89.0 at /opt/boost-1.89.0/lib/cmake/boost_regex-1.89.0
-- BoostConfig: find_package(boost_included_test_exec_monitor 1.89.0 EXACT CONFIG REQUIRED QUIET HINTS /opt/boost-1.89.0/lib/cmake)
-- Found boost_included_test_exec_monitor 1.89.0 at /opt/boost-1.89.0/lib/cmake/boost_included_test_exec_monitor-1.89.0
-- Found boost_algorithm 1.89.0 at /opt/boost-1.89.0/lib/cmake/boost_algorithm-1.89.0
-- Found boost_exception 1.89.0 at /opt/boost-1.89.0/lib/cmake/boost_exception-1.89.0
-- Found boost_unordered 1.89.0 at /opt/boost-1.89.0/lib/cmake/boost_unordered-1.89.0
-- Found boost_numeric_conversion 1.89.0 at /opt/boost-1.89.0/lib/cmake/boost_numeric_conversion-1.89.0
-- Boost 1.85 found.
-- Found Boost components:
   core;range;included_test_exec_monitor
-- Configuring done
-- Generating done
-- Build files have been written to: /home/nigels/dev/boost/libs/sort/build
[1/1] cd /home/nigels/dev/boost/libs/sort/build && /opt/cmake-3.10.0-Linux-x86_64/bin/ctest --output-on-failure -C Release
Test project /home/nigels/dev/boost/libs/sort/build
      Start  1: boost_sort_float_sort_test
 1/11 Test  #1: boost_sort_float_sort_test .............   Passed    0.62 sec
      Start  2: boost_sort_integer_sort_test
 2/11 Test  #2: boost_sort_integer_sort_test ...........   Passed    0.03 sec
      Start  3: boost_sort_sort_detail_test
 3/11 Test  #3: boost_sort_sort_detail_test ............   Passed    0.00 sec
      Start  4: boost_sort_string_sort_test
 4/11 Test  #4: boost_sort_string_sort_test ............   Passed    0.08 sec
      Start  5: boost_sort_test_block_indirect_sort
 5/11 Test  #5: boost_sort_test_block_indirect_sort ....   Passed    0.89 sec
      Start  6: boost_sort_test_flat_stable_sort
 6/11 Test  #6: boost_sort_test_flat_stable_sort .......   Passed    0.21 sec
      Start  7: boost_sort_test_insert_sort
 7/11 Test  #7: boost_sort_test_insert_sort ............   Passed    0.02 sec
      Start  8: boost_sort_test_parallel_stable_sort
 8/11 Test  #8: boost_sort_test_parallel_stable_sort ...   Passed    0.97 sec
      Start  9: boost_sort_test_pdqsort
 9/11 Test  #9: boost_sort_test_pdqsort ................   Passed    0.14 sec
      Start 10: boost_sort_test_sample_sort
10/11 Test #10: boost_sort_test_sample_sort ............   Passed    0.90 sec
      Start 11: boost_sort_test_spinsort
11/11 Test #11: boost_sort_test_spinsort ...............   Passed    0.20 sec

100% tests passed, 0 tests failed out of 11

Total Test time (real) =   4.06 sec

[Flamefire]

Just had a quick look and pointed out enhancement from a the CMake perspective alone.

I'd recommend waiting for the maintainer to decide if this use case should be supported. The current file is auto-generated

[Flamefire]

You wrote

it's find_package(Boost) that seems problematic prior to cmake-3.10.

In which way? What is the issue?

[nigels-com]

$ PATH=/opt/cmake-3.9.0-Linux-x86_64/bin:$PATH cmake .. -G Ninja -DCMAKE_BUILD_TYPE=Release -DCMAKE_CXX_COMPILER_LAUNCHER=ccache -DBUILD_TESTING=Y -DCMAKE_CXX_COMPILER=clang++-18 && ninja check
-- Using cmake version 3.9.0
-- The CXX compiler identification is Clang 18.1.3
...
-- Found Boost 1.89.0 at /opt/boost-1.89.0/lib/cmake/Boost-1.89.0
--   Requested configuration: QUIET REQUIRED COMPONENTS core;range;included_test_exec_monitor
...
-- Found boost_numeric_conversion 1.89.0 at /opt/boost-1.89.0/lib/cmake/boost_numeric_conversion-1.89.0
Boost 1.85 found.
Found Boost components:
   core;range;included_test_exec_monitor
CMake Error in /opt/cmake-3.9.0-Linux-x86_64/share/cmake-3.9/Modules/FindBoost.cmake:
  cmake_policy PUSH without matching POP
Call Stack (most recent call first):
  CMakeLists.txt:22 (find_package)


-- Configuring incomplete, errors occurred!

[Flamefire]

I see, a bug introduced in CMake 3.9 and fixed in 3.9.1

[Flamefire]

This is for users to set, not projects and produces log spam for everyone

Suggested change

set(Boost_DEBUG ON)

[nigels-com]

I tend to prefer this much information about boost.
cmake doesn't always do what's expected in terms of the version it found, or honoring BOOST_ROOT.

[Flamefire]

Yes you prefer this information. So you can use -DBoost_DEBUG=ON in the invocation of CMake

With this you are forcing this on every user. And you/one usually only want this when something fails

[nigels-com]

More than that, I recommend it here in this mode. These tests pull in a surprisingly large subset of boost, which I think that is relevant information in this context.

Besides that find_package(Boost) is hit and miss in practice (maybe more-so for older boost and older cmake), it will log that it succeeded but doesn't actually make clear what version it's using, which can be an ODR concern. In that sense failure is not always obvious via cmake failure.

Perhaps log spam to you, but I'd very much prefer to see it in a bug report, than not.

Boost is big, let's not pretend it doesn't have a bunch of moving parts.

-- Found boost_numeric_conversion 1.89.0 at /opt/boost-1.89.0/lib/cmake/boost_numeric_conversion-1.89.0
-- Boost 1.85 found.

(Yeah thanks cmake for the misleading logging!)

[Flamefire]

I personally dislike such comments. if(BUILD_TESTING already provides this information so I see no added value.