GH-48178: [C++] Use FetchContent for bundled RE2 (#48179)

### Rationale for this change

As a follow up of requiring a minimum CMake version >= 3.25 we discussed moving our dependencies from ExternalProject to FetchContent. This can simplify our third party dependency management. Moving RE2 is the next step before moving Protobuf and gRPC.

### What changes are included in this PR?

The general change is moving from `ExternalProject` to `FetchContent`. 

It also add some required integration due to other dependencies, like gRPC, using `ExternalProject`. We not only have to build but also install in order for those other dependencies to find RE2. This causes some timing issues between config, build, install that requires us to create a custom target to depend on so the other dependencies find abseil.

### Are these changes tested?

Yes, the changes are tested locally and on CI.

### Are there any user-facing changes?

No
* GitHub Issue: #48178

Authored-by: Raúl Cumplido <[email protected]>
Signed-off-by: Sutou Kouhei <[email protected]>

Author: raulcd

cpp/cmake_modules/ThirdpartyToolchain.cmake

@@ -2799,37 +2799,66 @@ if(ARROW_WITH_ZSTD)
 endif()
 
 # ----------------------------------------------------------------------
-# RE2 (required for Gandiva)
+# RE2 (required for Gandiva and gRPC)
 
-macro(build_re2)
-  message(STATUS "Building RE2 from source")
-  set(RE2_PREFIX "${CMAKE_CURRENT_BINARY_DIR}/re2_ep-install")
-  set(RE2_STATIC_LIB
-      "${RE2_PREFIX}/lib/${CMAKE_STATIC_LIBRARY_PREFIX}re2${CMAKE_STATIC_LIBRARY_SUFFIX}")
+function(build_re2)
+  list(APPEND CMAKE_MESSAGE_INDENT "RE2: ")
+  message(STATUS "Building RE2 from source using FetchContent")
+  set(RE2_VENDORED
+      TRUE
+      PARENT_SCOPE)
+  set(RE2_PREFIX "${CMAKE_CURRENT_BINARY_DIR}/re2_fc-install")
+  set(RE2_PREFIX
+      "${RE2_PREFIX}"
+      PARENT_SCOPE)
 
-  set(RE2_CMAKE_ARGS ${EP_COMMON_CMAKE_ARGS} "-DCMAKE_INSTALL_PREFIX=${RE2_PREFIX}")
+  fetchcontent_declare(re2
+                       URL ${RE2_SOURCE_URL}
+                       URL_HASH "SHA256=${ARROW_RE2_BUILD_SHA256_CHECKSUM}")
+  prepare_fetchcontent()
 
-  externalproject_add(re2_ep
-                      ${EP_COMMON_OPTIONS}
-                      INSTALL_DIR ${RE2_PREFIX}
-                      URL ${RE2_SOURCE_URL}
-                      URL_HASH "SHA256=${ARROW_RE2_BUILD_SHA256_CHECKSUM}"
-                      CMAKE_ARGS ${RE2_CMAKE_ARGS}
-                      BUILD_BYPRODUCTS "${RE2_STATIC_LIB}")
-
-  file(MAKE_DIRECTORY "${RE2_PREFIX}/include")
-  add_library(re2::re2 STATIC IMPORTED)
-  set_target_properties(re2::re2 PROPERTIES IMPORTED_LOCATION "${RE2_STATIC_LIB}")
-  target_include_directories(re2::re2 BEFORE INTERFACE "${RE2_PREFIX}/include")
-
-  add_dependencies(re2::re2 re2_ep)
-  set(RE2_VENDORED TRUE)
-  # Set values so that FindRE2 finds this too
-  set(RE2_LIB ${RE2_STATIC_LIB})
-  set(RE2_INCLUDE_DIR "${RE2_PREFIX}/include")
-
-  list(APPEND ARROW_BUNDLED_STATIC_LIBS re2::re2)
-endmacro()
+  # Unity build causes some build errors
+  set(CMAKE_UNITY_BUILD OFF)
+  fetchcontent_makeavailable(re2)
+
+  # This custom target ensures re2 is built before we install
+  add_custom_target(re2_built DEPENDS re2::re2)
+
+  add_custom_command(OUTPUT "${re2_BINARY_DIR}/cmake_install.cmake.saved"
+                     COMMAND ${CMAKE_COMMAND} -E copy_if_different
+                             "${re2_BINARY_DIR}/cmake_install.cmake"
+                             "${re2_BINARY_DIR}/cmake_install.cmake.saved"
+                     COMMAND ${CMAKE_COMMAND} -E echo
+                             "# RE2 install disabled to prevent double installation with Arrow"
+                             > "${re2_BINARY_DIR}/cmake_install.cmake"
+                     DEPENDS re2_built
+                     COMMENT "Disabling RE2 install to prevent double installation"
+                     VERBATIM)
+
+  add_custom_target(re2_install_disabled ALL
+                    DEPENDS "${re2_BINARY_DIR}/cmake_install.cmake.saved")
+
+  # Install RE2 to RE2_PREFIX for gRPC to find
+  add_custom_command(OUTPUT "${RE2_PREFIX}/.re2_installed"
+                     COMMAND ${CMAKE_COMMAND} -E copy_if_different
+                             "${re2_BINARY_DIR}/cmake_install.cmake.saved"
+                             "${re2_BINARY_DIR}/cmake_install.cmake.tmp"
+                     COMMAND ${CMAKE_COMMAND} -DCMAKE_INSTALL_PREFIX=${RE2_PREFIX}
+                             -DCMAKE_INSTALL_CONFIG_NAME=$<CONFIG> -P
+                             "${re2_BINARY_DIR}/cmake_install.cmake.tmp" ||
+                             ${CMAKE_COMMAND} -E true
+                     COMMAND ${CMAKE_COMMAND} -E touch "${RE2_PREFIX}/.re2_installed"
+                     DEPENDS re2_install_disabled
+                     COMMENT "Installing RE2 to ${RE2_PREFIX} for gRPC"
+                     VERBATIM)
+
+  add_custom_target(re2_fc DEPENDS "${RE2_PREFIX}/.re2_installed")
+
+  set(ARROW_BUNDLED_STATIC_LIBS
+      ${ARROW_BUNDLED_STATIC_LIBS} re2::re2
+      PARENT_SCOPE)
+  list(POP_BACK CMAKE_MESSAGE_INDENT)
+endfunction()
 
 if(ARROW_WITH_RE2)
   resolve_dependency(re2
@@ -3234,7 +3263,7 @@ macro(build_grpc)
   endif()
 
   if(RE2_VENDORED)
-    add_dependencies(grpc_dependencies re2_ep)
+    add_dependencies(grpc_dependencies re2_fc)
   endif()
 
   add_dependencies(grpc_dependencies ${ARROW_PROTOBUF_LIBPROTOBUF} c-ares::cares
@@ -3255,8 +3284,13 @@ macro(build_grpc)
     get_filename_component(GRPC_CARES_ROOT "${GRPC_CARES_INCLUDE_DIR}" DIRECTORY)
   endif()
 
-  get_target_property(GRPC_RE2_INCLUDE_DIR re2::re2 INTERFACE_INCLUDE_DIRECTORIES)
-  get_filename_component(GRPC_RE2_ROOT "${GRPC_RE2_INCLUDE_DIR}" DIRECTORY)
+  # For FetchContent RE2, use the install prefix directly
+  if(RE2_VENDORED)
+    set(GRPC_RE2_ROOT "${RE2_PREFIX}")
+  else()
+    get_target_property(GRPC_RE2_INCLUDE_DIR re2::re2 INTERFACE_INCLUDE_DIRECTORIES)
+    get_filename_component(GRPC_RE2_ROOT "${GRPC_RE2_INCLUDE_DIR}" DIRECTORY)
+  endif()
 
   # Put Abseil, etc. first so that local directories are searched
   # before (what are likely) system directories