Merge bitcoin/bitcoin#31181: cmake: Revamp FindLibevent module

5a96767 depends, libevent: Do not install *.pc files and remove patches for them (Hennadii Stepanov)
ffda355 cmake, refactor: Move `HAVE_EVHTTP_...` to `libevent` interface (Hennadii Stepanov)
b619bdc cmake: Revamp `FindLibevent` module (Hennadii Stepanov)

Pull request description:

  This PR generalizes the use of `find_package` / `pkg_check_modules`, prioritizing the former.

  Addresses bitcoin/bitcoin#30903 (comment):
  > We should also follow up with refactoring the libevent module, to more generically use CMake/pkg-config, rather than restricting the CMake usage to `vcpkg`. At that point, we'd likely be able to dump pkg-config for the depends path entirely.

  Similar to bitcoin/bitcoin#30903.

ACKs for top commit:
  fanquake:
    ACK 5a96767

Tree-SHA512: 181020c16ccd2821e718c73f264badcdc5e62980c4a8d9691e759efe2ea00da2326e26308d1dcfdeac01e9e27930428ecace9f36941deee951b751b138d7266c

Author: fanquake

cmake/bitcoin-build-config.h.in

@@ -71,9 +71,6 @@
    */
 #cmakedefine01 HAVE_DECL_SETSID
 
-/* Define this symbol if evhttp_connection_get_peer expects const char** */
-#cmakedefine HAVE_EVHTTP_CONNECTION_GET_PEER_CONST_CHAR 1
-
 /* Define to 1 if fdatasync is available. */
 #cmakedefine HAVE_FDATASYNC 1
 

cmake/module/FindLibevent.cmake

@@ -35,46 +35,52 @@ function(check_evhttp_connection_get_peer target)
     " HAVE_EVHTTP_CONNECTION_GET_PEER_CONST_CHAR
   )
   cmake_pop_check_state()
-  set(HAVE_EVHTTP_CONNECTION_GET_PEER_CONST_CHAR ${HAVE_EVHTTP_CONNECTION_GET_PEER_CONST_CHAR} PARENT_SCOPE)
+  target_compile_definitions(${target} INTERFACE
+    $<$<BOOL:${HAVE_EVHTTP_CONNECTION_GET_PEER_CONST_CHAR}>:HAVE_EVHTTP_CONNECTION_GET_PEER_CONST_CHAR>
+  )
 endfunction()
 
+set(_libevent_components core extra)
+if(NOT WIN32)
+  list(APPEND _libevent_components pthreads)
+endif()
+
+find_package(Libevent ${Libevent_FIND_VERSION} QUIET
+  NO_MODULE
+)
 
 include(FindPackageHandleStandardArgs)
-if(VCPKG_TARGET_TRIPLET)
-  find_package(Libevent ${Libevent_FIND_VERSION} NO_MODULE QUIET
-    COMPONENTS extra
+if(Libevent_FOUND)
+  find_package(Libevent ${Libevent_FIND_VERSION} QUIET
+    REQUIRED COMPONENTS ${_libevent_components}
+    NO_MODULE
   )
   find_package_handle_standard_args(Libevent
     REQUIRED_VARS Libevent_DIR
     VERSION_VAR Libevent_VERSION
   )
   check_evhttp_connection_get_peer(libevent::extra)
-  add_library(libevent::libevent ALIAS libevent::extra)
-  mark_as_advanced(Libevent_DIR)
-  mark_as_advanced(_event_h)
-  mark_as_advanced(_event_lib)
 else()
   find_package(PkgConfig REQUIRED)
-  pkg_check_modules(libevent QUIET
-    IMPORTED_TARGET
-    libevent>=${Libevent_FIND_VERSION}
-  )
-  set(_libevent_required_vars libevent_LIBRARY_DIRS libevent_FOUND)
-  if(NOT WIN32)
-    pkg_check_modules(libevent_pthreads QUIET
-      IMPORTED_TARGET
-      libevent_pthreads>=${Libevent_FIND_VERSION}
+  foreach(component IN LISTS _libevent_components)
+    pkg_check_modules(libevent_${component}
+      REQUIRED QUIET
+      IMPORTED_TARGET GLOBAL
+      libevent_${component}>=${Libevent_FIND_VERSION}
     )
-    list(APPEND _libevent_required_vars libevent_pthreads_FOUND)
-  endif()
+    if(TARGET PkgConfig::libevent_${component} AND NOT TARGET libevent::${component})
+      add_library(libevent::${component} ALIAS PkgConfig::libevent_${component})
+    endif()
+  endforeach()
   find_package_handle_standard_args(Libevent
-    REQUIRED_VARS ${_libevent_required_vars}
-    VERSION_VAR libevent_VERSION
+    REQUIRED_VARS libevent_core_LIBRARY_DIRS
+    VERSION_VAR libevent_core_VERSION
   )
-  unset(_libevent_required_vars)
-  check_evhttp_connection_get_peer(PkgConfig::libevent)
-  add_library(libevent::libevent ALIAS PkgConfig::libevent)
-  if(NOT WIN32)
-    add_library(libevent::pthreads ALIAS PkgConfig::libevent_pthreads)
-  endif()
+  check_evhttp_connection_get_peer(PkgConfig::libevent_extra)
 endif()
+
+unset(_libevent_components)
+
+mark_as_advanced(Libevent_DIR)
+mark_as_advanced(_event_h)
+mark_as_advanced(_event_lib)

depends/packages/libevent.mk

@@ -4,7 +4,6 @@ $(package)_download_path=https://github.com/libevent/libevent/releases/download/
 $(package)_file_name=$(package)-$($(package)_version).tar.gz
 $(package)_sha256_hash=92e6de1be9ec176428fd2367677e61ceffc2ee1cb119035037a27d346b0403bb
 $(package)_patches=cmake_fixups.patch
-$(package)_patches+=fix_mingw_link.patch
 $(package)_build_subdir=build
 
 # When building for Windows, we set _WIN32_WINNT to target the same Windows
@@ -23,8 +22,7 @@ define $(package)_set_vars
 endef
 
 define $(package)_preprocess_cmds
-  patch -p1 < $($(package)_patch_dir)/cmake_fixups.patch && \
-  patch -p1 < $($(package)_patch_dir)/fix_mingw_link.patch
+  patch -p1 < $($(package)_patch_dir)/cmake_fixups.patch
 endef
 
 define $(package)_config_cmds
@@ -40,7 +38,8 @@ define $(package)_stage_cmds
 endef
 
 define $(package)_postprocess_cmds
-  rm -rf bin && \
+  rm -rf bin lib/pkgconfig && \
   rm include/ev*.h && \
-  rm include/event2/*_compat.h
+  rm include/event2/*_compat.h && \
+  rm lib/libevent.a
 endef

depends/patches/libevent/cmake_fixups.patch

@@ -1,8 +1,5 @@
 cmake: set minimum version to 3.5
 
-Fix generated pkg-config files, see
-https://github.com/libevent/libevent/pull/1165.
-
 --- a/CMakeLists.txt
 +++ b/CMakeLists.txt
 @@ -19,7 +19,7 @@
@@ -14,22 +11,3 @@ https://github.com/libevent/libevent/pull/1165.
 
  if (POLICY CMP0054)
      cmake_policy(SET CMP0054 NEW)
-diff --git a/cmake/AddEventLibrary.cmake b/cmake/AddEventLibrary.cmake
-index 04f5837e..d8ea42c4 100644
---- a/cmake/AddEventLibrary.cmake
-+++ b/cmake/AddEventLibrary.cmake
-@@ -20,12 +20,12 @@ macro(generate_pkgconfig LIB_NAME)
- 
-     set(LIBS         "")
-     foreach (LIB ${LIB_PLATFORM})
--        set(LIBS "${LIBS} -L${LIB}")
-+        set(LIBS "${LIBS} -l${LIB}")
-     endforeach()
- 
-     set(OPENSSL_LIBS "")
-     foreach(LIB ${OPENSSL_LIBRARIES})
--        set(OPENSSL_LIBS "${OPENSSL_LIBS} -L${LIB}")
-+        set(OPENSSL_LIBS "${OPENSSL_LIBS} -l${LIB}")
-     endforeach()
- 
-     configure_file("lib${LIB_NAME}.pc.in" "lib${LIB_NAME}.pc" @ONLY)

depends/patches/libevent/fix_mingw_link.patch

@@ -182,7 +182,7 @@ Setup and Build Example: Arch Linux
 -----------------------------------
 This example lists the steps necessary to setup and build a command line only distribution of the latest changes on Arch Linux:
 
-    pacman --sync --needed cmake boost gcc git libevent make pkgconf python sqlite
+    pacman --sync --needed cmake boost gcc git libevent make python sqlite
     git clone https://github.com/bitcoin/bitcoin.git
     cd bitcoin/
     cmake -B build

doc/build-unix.md

@@ -290,13 +290,14 @@ target_link_libraries(bitcoin_node
     core_interface
     bitcoin_common
     bitcoin_util
+    $<TARGET_NAME_IF_EXISTS:bitcoin_zmq>
     leveldb
     minisketch
     univalue
     Boost::headers
-    $<TARGET_NAME_IF_EXISTS:libevent::libevent>
+    libevent::core
+    libevent::extra
     $<TARGET_NAME_IF_EXISTS:libevent::pthreads>
-    $<TARGET_NAME_IF_EXISTS:bitcoin_zmq>
     $<TARGET_NAME_IF_EXISTS:USDT::headers>
 )
 
@@ -366,7 +367,8 @@ if(BUILD_CLI)
     bitcoin_cli
     bitcoin_common
     bitcoin_util
-    $<TARGET_NAME_IF_EXISTS:libevent::libevent>
+    libevent::core
+    libevent::extra
   )
   list(APPEND installable_targets bitcoin-cli)
 endif()

src/CMakeLists.txt

@@ -2,8 +2,6 @@
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
-#include <bitcoin-build-config.h> // IWYU pragma: keep
-
 #include <httpserver.h>
 
 #include <chainparamsbase.h>

src/httpserver.cpp

@@ -154,7 +154,7 @@ target_link_libraries(test_bitcoin
   minisketch
   secp256k1
   Boost::headers
-  $<TARGET_NAME_IF_EXISTS:libevent::libevent>
+  libevent::extra
 )
 
 if(ENABLE_WALLET)

src/test/CMakeLists.txt

@@ -140,7 +140,7 @@ target_link_libraries(fuzz
   univalue
   secp256k1
   Boost::headers
-  $<TARGET_NAME_IF_EXISTS:libevent::libevent>
+  libevent::extra
 )
 
 if(ENABLE_WALLET)