From: Mario Emmenlauer <mario@emmenlauer.de>
Date: Tue, 3 Mar 2020 18:02:24 +0000 (+0100)
Subject: LibeventConfig.cmake: restore CMAKE_FIND_LIBRARY_SUFFIXES and LIBEVENT_STATIC_LINK... 
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=1675a55620e6f0bbba5776f2df72cd48920421c2;p=libevent

LibeventConfig.cmake: restore CMAKE_FIND_LIBRARY_SUFFIXES and LIBEVENT_STATIC_LINK default

The current cmake/LibeventConfig.cmake.in has a few problems and I'm not
sure how cleanly developed it is. It seems rater complex for the little
things I would assume it needs to do.

I found two problems that are fixed in this PR:

- If the downstream user does not explicitly set LIBEVENT_STATIC_LINK
  before calling find_package(libevent) then they will not be able to
  detect the static library, even if its the only one that exists. Since
  this may be rather strict, I've changed the behavior so that
  LIBEVENT_STATIC_LINK can be set to ON or OFF, but if unset, it defaults
  to whatever configuration libevent was built as.

- The other problem is a bug. The package configuration needs to unset
  CMAKE_FIND_LIBRARY_SUFFIXES after use, otherwise all packages that are
  detected after libevent will be "infected" by this setting. This was a
  significant problem for us, and is very hard to detect in downstream
  project, because the order of dependencies will lead to different search
  results.
---

diff --git a/cmake/LibeventConfig.cmake.in b/cmake/LibeventConfig.cmake.in
index 5e2a3d8d..aeeff9aa 100644
--- a/cmake/LibeventConfig.cmake.in
+++ b/cmake/LibeventConfig.cmake.in
@@ -40,14 +40,20 @@ set(LIBEVENT_VERSION @EVENT_PACKAGE_VERSION@)
 set(LIBEVENT_STATIC_LIBRARIES "@LIBEVENT_STATIC_LIBRARIES@")
 set(LIBEVENT_SHARED_LIBRARIES "@LIBEVENT_SHARED_LIBRARIES@")
 
+# Default to the same type as libevent was built:
+if(NOT DEFINED LIBEVENT_STATIC_LINK)
+    set(LIBEVENT_STATIC_LINK NOT @BUILD_SHARED_LIBS@)
+endif()
+
+set(CMAKE_FIND_LIBRARY_SUFFIXES_SAVE "${CMAKE_FIND_LIBRARY_SUFFIXES}")
 if(LIBEVENT_STATIC_LINK)
     set(_LIB_TYPE static)
     set(CMAKE_FIND_LIBRARY_SUFFIXES ${CMAKE_STATIC_LIBRARY_SUFFIX})
-    set(_AVAILABLE_LIBS ${LIBEVENT_STATIC_LIBRARIES})
+    set(_AVAILABLE_LIBS "${LIBEVENT_STATIC_LIBRARIES}")
 else()
     set(_LIB_TYPE shared)
     set(CMAKE_FIND_LIBRARY_SUFFIXES ${CMAKE_SHARED_LIBRARY_SUFFIX})
-    set(_AVAILABLE_LIBS ${LIBEVENT_SHARED_LIBRARIES})
+    set(_AVAILABLE_LIBS "${LIBEVENT_SHARED_LIBRARIES}")
 endif()
 
 # Get the path of the current file.
@@ -105,47 +111,46 @@ macro(set_case_insensitive_found _comp)
 endmacro()
 
 if(CONFIG_FOR_INSTALL_TREE)
-## Config for install tree ----------------------------------------
-# Find includes
-unset(_event_h CACHE)
-find_path(_event_h
-          NAMES event2/event.h
-          PATHS "${_INSTALL_PREFIX}/include"
-          NO_DEFAULT_PATH)
-if(_event_h)
-    set(LIBEVENT_INCLUDE_DIRS "${_event_h}")
-    message_if_needed(STATUS "Found libevent include directory: ${_event_h}")
-else()
-    message_if_needed(WARNING "Your libevent library does not contain header files!")
-endif()
-
-# Find libraries
-macro(find_event_lib _comp)
-    unset(_event_lib CACHE)
-    find_library(_event_lib
-                NAMES "event_${_comp}"
-                PATHS "${_INSTALL_PREFIX}/lib"
-                NO_DEFAULT_PATH)
-    if(_event_lib)
-        list(APPEND LIBEVENT_LIBRARIES "libevent::${_comp}")
-        set_case_insensitive_found(${_comp})
-        message_if_needed(STATUS "Found libevent component: ${_event_lib}")
+    ## Config for install tree ----------------------------------------
+    # Find includes
+    unset(_event_h CACHE)
+    find_path(_event_h
+              NAMES event2/event.h
+              PATHS "${_INSTALL_PREFIX}/include"
+              NO_DEFAULT_PATH)
+    if(_event_h)
+        set(LIBEVENT_INCLUDE_DIRS "${_event_h}")
+        message_if_needed(STATUS "Found libevent include directory: ${_event_h}")
     else()
-        no_component_msg(${_comp})
+        message_if_needed(WARNING "Your libevent library does not contain header files!")
     endif()
-endmacro()
 
-foreach(comp ${_EVENT_COMPONENTS})
-    find_event_lib(${comp})
-endforeach()
-else()
-## Config for build tree ----------------------------------------
-set(LIBEVENT_INCLUDE_DIRS "@EVENT__INCLUDE_DIRS@")
-foreach(_comp ${_EVENT_COMPONENTS})
-    list(APPEND LIBEVENT_LIBRARIES "libevent::${_comp}")
-    set_case_insensitive_found(${_comp})
-endforeach()
+    # Find libraries
+    macro(find_event_lib _comp)
+        unset(_event_lib CACHE)
+        find_library(_event_lib
+                    NAMES "event_${_comp}"
+                    PATHS "${_INSTALL_PREFIX}/lib"
+                    NO_DEFAULT_PATH)
+        if(_event_lib)
+            list(APPEND LIBEVENT_LIBRARIES "libevent::${_comp}")
+            set_case_insensitive_found(${_comp})
+            message_if_needed(STATUS "Found libevent component: ${_event_lib}")
+        else()
+            no_component_msg(${_comp})
+        endif()
+    endmacro()
 
+    foreach(comp ${_EVENT_COMPONENTS})
+        find_event_lib(${comp})
+    endforeach()
+else()
+    ## Config for build tree ----------------------------------------
+    set(LIBEVENT_INCLUDE_DIRS "@EVENT__INCLUDE_DIRS@")
+    foreach(_comp ${_EVENT_COMPONENTS})
+        list(APPEND LIBEVENT_LIBRARIES "libevent::${_comp}")
+        set_case_insensitive_found(${_comp})
+    endforeach()
 endif()
 
 set(LIBEVENT_INCLUDE_DIR ${LIBEVENT_INCLUDE_DIRS})
@@ -170,6 +175,7 @@ else()
     endif()
 endif()
 
+set(CMAKE_FIND_LIBRARY_SUFFIXES "${CMAKE_FIND_LIBRARY_SUFFIXES_SAVE}")
 unset(_LIB_TYPE)
 unset(_AVAILABLE_LIBS)
 unset(_EVENT_COMPONENTS)