From edf031370e255cd4506cd8a17d7ddda78e697ed2 Mon Sep 17 00:00:00 2001
From: Olivier Stasse <ostasse@laas.fr>
Date: Thu, 18 Jun 2020 16:43:24 +0200
Subject: [PATCH] Handle no-target case through a user information.

---
 Config.cmake.in      |  5 ++++-
 package-config.cmake | 14 ++++++++++++--
 2 files changed, 16 insertions(+), 3 deletions(-)

diff --git a/Config.cmake.in b/Config.cmake.in
index ad10f7c87..16872f268 100644
--- a/Config.cmake.in
+++ b/Config.cmake.in
@@ -108,7 +108,10 @@ IF(COMMAND ADD_REQUIRED_DEPENDENCY)
   ENDFOREACH()
 ENDIF(COMMAND ADD_REQUIRED_DEPENDENCY)
 
-include("${CMAKE_CURRENT_LIST_DIR}/@TARGETS_EXPORT_NAME@.cmake")
+@EXPR_PROJECT_NAME_ZERO_TARGET@
+if(NOT @PROJECT_NAME@_ZERO_TARGET)
+  include("${CMAKE_CURRENT_LIST_DIR}/@TARGETS_EXPORT_NAME@.cmake")
+endif()
 
 foreach(component ${@PROJECT_NAME@_FIND_COMPONENTS})
   set(comp_file "${CMAKE_CURRENT_LIST_DIR}/${component}Config.cmake")
diff --git a/package-config.cmake b/package-config.cmake
index 8d7ae8349..f6f81018e 100644
--- a/package-config.cmake
+++ b/package-config.cmake
@@ -154,6 +154,13 @@ if(_PKG_CONFIG_REQUIRES)
   endforeach()
   list(REMOVE_DUPLICATES _PKG_CONFIG_REQUIRES_LIST)
 endif(_PKG_CONFIG_REQUIRES)
+
+if(NOT ${PROJECT_NAME}_ZERO_TARGET)
+  SET(EXPR_PROJECT_NAME_ZERO_TARGET "SET(${PROJECT_NAME}_ZERO_TARGET FALSE)")  
+else()
+  SET(EXPR_PROJECT_NAME_ZERO_TARGET "SET(${PROJECT_NAME}_ZERO_TARGET TRUE)")
+endif()
+
 configure_package_config_file(
     "cmake/Config.cmake.in"
     "${PROJECT_CONFIG}"
@@ -170,11 +177,14 @@ install(
 
 # Config
 #   * <prefix>/lib/cmake/Foo/FooTargets.cmake
-install(
+if(NOT ${PROJECT_NAME}_ZERO_TARGET)
+  install(
     EXPORT "${TARGETS_EXPORT_NAME}"
     NAMESPACE "${namespace}"
     DESTINATION "${CONFIG_INSTALL_DIR}"
-)
+    )
+endif()
+
 ENDMACRO(SETUP_PROJECT_PACKAGE_FINALIZE)
 
 #.rst: