cmake: set CMAKE_{RUNTIME,LIBRARY,ARCHIVE}_OUTPUT_DIRECTORY they are not defined

This will allow overriding them in parent cmake rules, i.e. if libevent
is used via add_subdirectory().

Closes: #931

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 5b2537d5bd67c22945b4eb3768f2fcc2c4990b2f..1efda0e9867ebf7560e90ba9ad223ee4477d845d 100644 (file)
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -159,9 +159,18 @@ option(EVENT__COVERAGE
 
 # Put the libaries and binaries that get built into directories at the
 # top of the build tree rather than in hard-to-find leaf directories.
-set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${PROJECT_BINARY_DIR}/bin)
-set(CMAKE_LIBRARY_OUTPUT_DIRECTORY ${PROJECT_BINARY_DIR}/lib)
-set(CMAKE_ARCHIVE_OUTPUT_DIRECTORY ${PROJECT_BINARY_DIR}/lib)
+#
+# But only if this variables are not defined yet
+# (i.e. libevent is used via add_subdirectory())
+if (NOT DEFINED CMAKE_RUNTIME_OUTPUT_DIRECTORY)
+    set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${PROJECT_BINARY_DIR}/bin)
+endif()
+if (NOT DEFINED CMAKE_LIBRARY_OUTPUT_DIRECTORY)
+    set(CMAKE_LIBRARY_OUTPUT_DIRECTORY ${PROJECT_BINARY_DIR}/lib)
+endif()
+if (NOT DEFINED CMAKE_ARCHIVE_OUTPUT_DIRECTORY)
+    set(CMAKE_ARCHIVE_OUTPUT_DIRECTORY ${PROJECT_BINARY_DIR}/lib)
+endif()
 
 if (EVENT__ENABLE_VERBOSE_DEBUG)
     add_definitions(-DUSE_DEBUG=1)