cmake: cleanup

* make re2 mandatory
* rework check_deps and system_deps

Author: Mizux

CMakeLists.txt

@@ -85,20 +85,18 @@ message(STATUS "Build abseil-cpp: ${BUILD_absl}")
 option(BUILD_Protobuf "Build the Protobuf dependency Library" ON)
 message(STATUS "Build protobuf: ${BUILD_Protobuf}")
 
-if(BUILD_TESTING)
-  option(BUILD_re2 "Build the re2 dependency Library" ON)
-  message(STATUS "Build re2: ${BUILD_re2}")
+option(BUILD_re2 "Build the re2 dependency Library" ON)
+message(STATUS "Build re2: ${BUILD_re2}")
 
+if(BUILD_TESTING)
   option(BUILD_googletest "Build googletest" ON)
-  message(STATUS "Build googletest: ${BUILD_googletest}")
-
   option(BUILD_benchmark "Build benchmark" ON)
-  message(STATUS "Build benchmark: ${BUILD_benchmark}")
 else()
-  set(BUILD_re2 OFF)
   set(BUILD_googletest OFF)
   set(BUILD_benchmark OFF)
 endif()
+message(STATUS "Build googletest: ${BUILD_googletest}")
+message(STATUS "Build benchmark: ${BUILD_benchmark}")
 
 # Find system deps
 include(system_deps)

cmake/check_deps.cmake

@@ -45,13 +45,16 @@ if(NOT TARGET protobuf::libprotobuf)
   message(FATAL_ERROR "Target protobuf::libprotobuf not available.")
 endif()
 
+if(NOT TARGET re2::re2)
+  message(FATAL_ERROR "Target re2::re2 not available.")
+endif()
+
 # CXX Test
 if(BUILD_TESTING)
-  if(NOT TARGET re2::re2)
-    message(FATAL_ERROR "Target re2::re2 not available.")
-  endif()
-
   if(NOT TARGET GTest::gtest_main)
     message(FATAL_ERROR "Target GTest::gtest_main not available.")
   endif()
+  if(NOT TARGET benchmark::benchmark)
+    message(FATAL_ERROR "Target benchmark::benchmark not available.")
+  endif()
 endif()

cmake/system_deps.cmake

@@ -9,25 +9,29 @@ find_package(Threads REQUIRED)
 set(CMAKE_FIND_PACKAGE_PREFER_CONFIG TRUE)
 
 # libprotobuf force us to depends on ZLIB::ZLIB target
-if(NOT BUILD_ZLIB)
+if(NOT BUILD_ZLIB AND NOT TARGET ZLIB::ZLIB)
  find_package(ZLIB REQUIRED)
 endif()
 
-if(NOT BUILD_absl)
+if(NOT BUILD_absl AND NOT TARGET absl::base)
   find_package(absl REQUIRED)
 endif()
 
-if(NOT BUILD_Protobuf)
+if(NOT BUILD_Protobuf AND NOT TARGET protobuf::libprotobuf)
   find_package(Protobuf REQUIRED)
 endif()
 
+if(NOT BUILD_re2 AND NOT TARGET re2::re2)
+  find_package(re2 REQUIRED)
+endif()
+
 # CXX Test
 if(BUILD_TESTING)
-  if(NOT BUILD_re2)
-    find_package(re2 REQUIRED)
+  if(NOT BUILD_googletest AND NOT TARGET GTest::gtest_main)
+    find_package(GTest REQUIRED)
   endif()
 
-  if(NOT BUILD_googletest)
-    find_package(GTest REQUIRED)
+  if(NOT BUILD_benchmark AND NOT TARGET benchmark::benchmark)
+    find_package(benchmark REQUIRED)
   endif()
 endif()