cmake: use upstream BoostConfig.cmake unconditionally

[lzaoral]

Fixes the following deprecation warning:

CMake Warning (dev) at src/CMakeLists.txt:38 (find_package):
  Policy CMP0167 is not set: The FindBoost module is removed.  Run "cmake
  --help-policy CMP0167" for policy details.  Use the cmake_policy command to
  set the policy and suppress this warning.

[kdudka]

@lzaoral Thanks for the update! Does it still make sense to compile with -Werror in the upstream CI?

OSH is now automatically triggered by Packit, so compiler warnings are processed in a more structured way.

[lzaoral]

Does it still make sense to compile with -Werror in the upstream CI?

Not with the latest GCC, I've disabled that explicitly.

[kdudka]

OK. I was thinking about dropping -Werror from the CI entirely but that can be done later if needed...

[lzaoral]

OK. I was thinking about dropping -Werror from the CI entirely but that can be done later if needed...

Older GCCs tend to have different warnings and AFAIK, OSH does not catch clang warnings at all (only clang analyzer), right?

[kdudka]

OSH catches both kinds of warnings if Clang is enabled. However, we have disabled the Clang Analyzer on both the OSH instances because it did not support the cleanup attribute as reported 16 years ago: https://bugs.llvm.org/show_bug.cgi?id=3888

[kdudka]

@lzaoral Bad news. I again forgot that we still build csdiff for RHEL-7 internally: https://copr.devel.redhat.com/coprs/g/osh/csdiff/builds/

This change caused the epel-7 build to fail with:

+ /usr/bin/cmake3 -S . -B x86_64-redhat-linux-gnu -DCMAKE_C_FLAGS_RELEASE:STRING=-DNDEBUG -DCMAKE_CXX_FLAGS_RELEASE:STRING=-DNDEBUG -DCMAKE_Fortran_FLAGS_RELEASE:STRING=-DNDEBUG -DCMAKE_VERBOSE_MAKEFILE:BOOL=ON -DCMAKE_INSTALL_PREFIX:PATH=/usr -DINCLUDE_INSTALL_DIR:PATH=/usr/include -DLIB_INSTALL_DIR:PATH=/usr/lib64 -DSYSCONF_INSTALL_DIR:PATH=/etc -DSHARE_INSTALL_PREFIX:PATH=/usr/share -DLIB_SUFFIX=64 -DBUILD_SHARED_LIBS:BOOL=ON -DCSGREP_STATIC= -DPYCSDIFF_PYTHON2=ON -DPYCSDIFF_PYTHON3=ON -DVERSION=csdiff-3.5.3.20250220.163025.gebea65c-1.el7_9
-- The CXX compiler identification is GNU 4.8.5
-- Check for working CXX compiler: /usr/bin/c++
-- Check for working CXX compiler: /usr/bin/c++ - works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- User-provided flags: -O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches   -m64 -mtune=generic
CMake Error at src/CMakeLists.txt:39 (find_package):
  Could not find a package configuration file provided by "Boost" with any of
  the following names:

    BoostConfig.cmake
    boost-config.cmake

  Add the installation prefix of "Boost" to CMAKE_PREFIX_PATH or set
  "Boost_DIR" to a directory containing one of the above files.  If "Boost"
  provides a separate development package or SDK, be sure it has been
  installed.


-- Configuring incomplete, errors occurred!

Any chance we could make the epel-7 builds work again please?

[lzaoral]

Can you test this patch on EL7, please?

diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 5d04096..5406858 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -34,9 +34,14 @@ if(SANITIZERS)
     set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fno-sanitize-recover=all")
 endif()

+# Disable deprecated internal FindBoost module if possible.
+if(POLICY CMP0167)
+    cmake_policy(SET CMP0167 NEW)
+endif()
+
 # find Boost
 set(Boost_VERBOSE TRUE)
-find_package(Boost CONFIG REQUIRED
+find_package(Boost REQUIRED
     COMPONENTS filesystem
                program_options
                regex
@@ -127,7 +132,7 @@ macro(build_pycsdiff version)

     # find boost_python${version}
     set(PYTHON_VERSION_SUFFIX "${version}${Python${version}_VERSION_MINOR}")
-    find_package(Boost CONFIG REQUIRED COMPONENTS python${PYTHON_VERSION_SUFFIX})
+    find_package(Boost REQUIRED COMPONENTS python${PYTHON_VERSION_SUFFIX})
     message(STATUS "Python ${version} binding enabled. "
         "The pycsdiff module will be built!")

This assumes that if CMake is new enough, Boost will be modern enough as well.

[kdudka]

@lzaoral Thanks! I have submitted the change on your behalf as #221.