More concretely utilize local modules in our CMake code. (#17022)

* Properly handle systemd.cmake as a module.

* Split CMake compiler flag handling functions to their own module.

* Add include guards to modules.

* Prefix module names with Netdata.

This ensures that we end up using our local modules instead of possibly
using a system module with the same name.

* Drop include guards.

And shift systemd detection code to a macro so it’s less dangerous to
import the module multiple times.

1 files changed, 4 insertions, 68 deletions

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 320a294e84..d6e9536bbc 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -56,6 +56,7 @@ project(netdata
         DESCRIPTION "Netdata real-time monitoring"
         HOMEPAGE_URL "https://www.netdata.cloud"
         LANGUAGES C CXX)
+list(APPEND CMAKE_MODULE_PATH "${PROJECT_SOURCE_DIR}/packaging/cmake/Modules")
 
 find_package(PkgConfig REQUIRED)
 
@@ -165,8 +166,7 @@ endif()
 # handling of extra compiler flags
 #
 
-include(CheckCCompilerFlag)
-include(CheckCXXCompilerFlag)
+include(NetdataCompilerFlags)
 
 # Disable hardening for debug builds by default.
 if(CMAKE_BUILD_TYPE STREQUAL "Debug")
@@ -175,71 +175,6 @@ else()
         option(DISABLE_HARDENING "disable adding extra compiler flags for hardening" FALSE)
 endif()
 
-# Construct a pre-processor safe name
-function(make_cpp_safe_name value target)
-        string(REPLACE "-" "_" tmp "${value}")
-        string(REPLACE "=" "_" tmp "${tmp}")
-        set(${target} "${tmp}" PARENT_SCOPE)
-endfunction()
-
-# Conditionally add an extra compiler flag to C and C++ flags.
-#
-# If the language flags already match the `match` argument, skip this flag.
-# Otherwise, check for support for `flag` and if support is found, add it to
-# the language-specific `target` flag group.
-function(add_simple_extra_compiler_flag match flag target)
-        set(CMAKE_REQUIRED_FLAGS "-Werror")
-
-        make_cpp_safe_name("${flag}" flag_name)
-
-        if(NOT ${CMAKE_C_FLAGS} MATCHES ${match})
-                check_c_compiler_flag("${flag}" HAVE_C_${flag_name})
-                if(HAVE_C_${flag_name})
-                        set(${target}_C_FLAGS "${${target}_C_FLAGS} ${flag}" PARENT_SCOPE)
-                endif()
-        endif()
-
-        if(NOT ${CMAKE_CXX_FLAGS} MATCHES ${match})
-                check_cxx_compiler_flag("${flag}" HAVE_CXX_${flag_name})
-                if(HAVE_CXX_${flag_name})
-                        set(${target}_CXX_FLAGS "${${target}_CXX_FLAGS} ${flag}" PARENT_SCOPE)
-                endif()
-        endif()
-endfunction()
-
-# Same as add_simple_extra_compiler_flag, but check for a second flag if the
-# first one is unsupported.
-function(add_double_extra_compiler_flag match flag1 flag2 target)
-        set(CMAKE_REQUIRED_FLAGS "-Werror")
-
-        make_cpp_safe_name("${flag1}" flag1_name)
-        make_cpp_safe_name("${flag2}" flag2_name)
-
-        if(NOT ${CMAKE_C_FLAGS} MATCHES ${match})
-                check_c_compiler_flag("${flag1}" HAVE_C_${flag1_name})
-                if(HAVE_C_${flag1_name})
-                        set(${target}_C_FLAGS "${${target}_C_FLAGS} ${flag1}" PARENT_SCOPE)
-                else()
-                        check_c_compiler_flag("${flag2}" HAVE_C_${flag2_name})
-                        if(HAVE_C_${flag2_name})
-                                set(${target}_C_FLAGS "${${target}_C_FLAGS} ${flag2}" PARENT_SCOPE)
-                        endif()
-                endif()
-        endif()
-
-        if(NOT ${CMAKE_CXX_FLAGS} MATCHES ${match})
-                check_cxx_compiler_flag("${flag1}" HAVE_CXX_${flag1_name})
-                if(HAVE_CXX_${flag1_name})
-                        set(${target}_CXX_FLAGS "${${target}_CXX_FLAGS} ${flag1}" PARENT_SCOPE)
-                else()
-                        check_cxx_compiler_flag("${flag2}" HAVE_CXX_${flag2_name})
-                        if(HAVE_CXX_${flag2_name})
-                                set(${target}_CXX_FLAGS "${${target}_CXX_FLAGS} ${flag2}" PARENT_SCOPE)
-                        endif()
-                endif()
-        endif()
-endfunction()
-
 set(EXTRA_HARDENING_C_FLAGS "")
 set(EXTRA_HARDENING_CXX_FLAGS "")
 
@@ -1524,7 +1459,8 @@ set_source_files_properties(JudyLTables.c PROPERTIES COMPILE_OPTIONS "-I${CMAKE_
 # build libnetdata
 #
 
-include(packaging/cmake/systemd.cmake)
+include(NetdataDetectSystemd)
+detect_systemd()
 
 add_library(libnetdata STATIC ${LIBNETDATA_FILES})