Make $<INSTALL_INTERFACE... use INCLUDE_INSTALL_DIR, and install headers to include/${PROJECT_NAME} (#2535)

* Make INSTALL_INTERFACE use INCLUDE_INSTALL_DIR

Signed-off-by: Shane Loretz <sloretz@osrfoundation.org>

* Install headers to include/${PROJECT_NAME}

Signed-off-by: Shane Loretz <sloretz@osrfoundation.org>

* Add option APPEND_PROJECT_NAME_TO_INCLUDEDIR

Signed-off-by: Shane Loretz <sloretz@osrfoundation.org>

* Misc fixes

Signed-off-by: Shane Loretz <sloretz@osrfoundation.org>

* Unset _include_dir when finished with it

Signed-off-by: Shane Loretz <sloretz@osrfoundation.org>

Author: sloretz

CMakeLists.txt

@@ -97,8 +97,19 @@ check_endianness()
 ###############################################################################
 # Installation paths
 ###############################################################################
+option(APPEND_PROJECT_NAME_TO_INCLUDEDIR
+  "When ON headers are installed to a path ending with a folder called \
+  ${PROJECT_NAME}. This avoids include directory search order issues when \
+  overriding this package from a merged catkin, ament, or colcon workspace."
+  OFF)
+
 set(BIN_INSTALL_DIR bin/ CACHE PATH "Installation directory for binaries")
-set(INCLUDE_INSTALL_DIR include/ CACHE PATH "Installation directory for C++ headers")
+set(_include_dir "include/")
+if(APPEND_PROJECT_NAME_TO_INCLUDEDIR)
+  string(APPEND _include_dir "${PROJECT_NAME}/")
+endif()
+set(INCLUDE_INSTALL_DIR "${_include_dir}" CACHE PATH "Installation directory for C++ headers")
+unset(_include_dir)
 set(LIB_INSTALL_DIR lib/ CACHE PATH "Installation directory for libraries")
 set(DATA_INSTALL_DIR share/ CACHE PATH "Installation directory for data")
 if(WIN32)

src/cpp/CMakeLists.txt

@@ -416,7 +416,7 @@ target_include_directories(${PROJECT_NAME} PUBLIC
     $<BUILD_INTERFACE:${PROJECT_BINARY_DIR}/include>
     $<BUILD_INTERFACE:${PROJECT_BINARY_DIR}/include/${PROJECT_NAME}>
     $<BUILD_INTERFACE:${PROJECT_SOURCE_DIR}/src/cpp>
-    $<INSTALL_INTERFACE:include>
+    $<INSTALL_INTERFACE:${INCLUDE_INSTALL_DIR}>
     PRIVATE
     ${Asio_INCLUDE_DIR}
     $<$<BOOL:${TINYXML2_INCLUDE_DIR}>:${TINYXML2_INCLUDE_DIR}>