Make WrapExernal work with external TribitsExProj packages (#63)

So for there is just one test for this.

To make this work, I had to grab the include directories off of the upstream
targets, which are returned as generator expressions.  And with that, I had to
switch the generation of the makefile for external_func to build time with a
custom command so it would evaluate the generator expressions.  (There is no
way to run a general command at generation time.)

test/core/ExamplesUnitTests/TribitsExampleProject_Tests.cmake

@@ -3274,7 +3274,7 @@ tribits_add_advanced_test( TribitsExampleProject_SimpleCxx_External
       -DTribitsExProj_ENABLE_SECONDARY_TESTED_CODE=ON
       -DTribitsExProj_ENABLE_ALL_PACKAGES=ON
       -DTribitsExProj_ENABLE_TESTS=ON
-      #-DTribitsExProj_ENABLE_INSTALL_CMAKE_CONFIG_FILES=OFF # Allow WrapExternal enable
+      -DTribitsExProj_ENABLE_INSTALL_CMAKE_CONFIG_FILES=OFF # Allow WrapExternal enable
       -DTPL_ENABLE_SimpleCxx=ON
       -DCMAKE_PREFIX_PATH=../install/simple_cxx
       -DTPL_ENABLE_MPI=OFF
@@ -3300,7 +3300,7 @@ tribits_add_advanced_test( TribitsExampleProject_SimpleCxx_External
     SKIP_CLEAN_WORKING_DIRECTORY
     CMND ${CMAKE_CTEST_COMMAND}
     PASS_REGULAR_EXPRESSION_ALL
-      "100% tests passed, 0 tests failed out of 7"
+      "100% tests passed, 0 tests failed out of 8"
     ALWAYS_FAIL_ON_NONZERO_RETURN
 
   ADDED_TEST_NAME_OUT TribitsExampleProject_SimpleCxx_External_NAME

tribits/examples/TribitsExampleProject/packages/wrap_external/CMakeLists.txt

@@ -7,21 +7,6 @@
 # provides libraries that need to be cast as TriBITS CMake libraries.  To
 # make this even more interesting, the external software has dependencies on
 # upstream TriBITS packages.
-#
-# An overview of the basic tasks required are:
-#
-# a) Enumerate the upstream packages and TPLs needed (this is done in the
-# cmake/Dependencies.cmake file).
-#
-# b) Generate an export makefile for the upstream packages and TPLs
-#
-# c) Call the configure script for the external package passing the compilers,
-# compiler flags, and a pointer to the export makefile (which is just used to
-# lift the include dirs and libs).
-#
-# d) Define library targets for the external project and define a build rule
-# for generating those libraries given the list of header and source files in
-# the external project.
 
 tribits_package(WrapExternal)
 
@@ -66,41 +51,51 @@ endif()
 
 string(TOUPPER "${CMAKE_BUILD_TYPE}" upperBuildType)
 
-set(includeDirsList
-  -I ${WithSubpackagesA_SOURCE_DIR}
-  -I ${SimpleCxx_SOURCE_DIR}/src
-  -I ${SimpleCxx_BINARY_DIR}/src
-  )
+get_target_property(simpleCxx_IncludeDirs
+  SimpleCxx::simplecxx  INTERFACE_INCLUDE_DIRECTORIES)
+
+get_target_property(withSubpackagesA_IncludeDirs
+  WithSubpackagesA::pws_a  INTERFACE_INCLUDE_DIRECTORIES)
+
+set(includeDirsList ${withSubpackagesA_IncludeDirs} ${simpleCxx_IncludeDirs})
+
 if (${PACKAGE_NAME}_ENABLE_MixedLang)
-  list(PREPEND includeDirsList
-    -I ${MixedLang_SOURCE_DIR}/src
-    -I ${MixedLang_BINARY_DIR}/src
-    )
+  get_target_property(mixedLang_IncludeDirs
+    MixedLang::mixedlang  INTERFACE_INCLUDE_DIRECTORIES)
+  list(PREPEND includeDirsList ${mixedLang_IncludeDirs})
 endif()
-list(JOIN includeDirsList " " includeDirs)
-# NOTE: TriBITS export Makefile support used to handle the above stuff
-# automatically but that is what you give up when moving to modern CMake.
+list(JOIN includeDirsList " -I" includeDirsCompileOptions)
+set(includeDirsCompileOptions "-I${includeDirsCompileOptions}")
 
 #
-# C) Do configuration of the external project
+# C) Do configuration of the external project as a build target
 #
 
 set(EXTERNAL_FUNC_SOURCE_DIR ${CMAKE_CURRENT_SOURCE_DIR}/external_func)
 set(EXTERNAL_FUNC_BINARY_DIR ${CMAKE_CURRENT_BINARY_DIR}/external_func)
 set(EXTERNAL_FUNC_LIB_FILE ${EXTERNAL_FUNC_BINARY_DIR}/libexternal_func.a)
+set(EXTERNAL_FUNC_MAKEFILE ${EXTERNAL_FUNC_BINARY_DIR}/Makefile)
 
 file(MAKE_DIRECTORY ${EXTERNAL_FUNC_BINARY_DIR})
 
-execute_process(
+add_custom_command(
+  OUTPUT ${EXTERNAL_FUNC_MAKEFILE}
+  DEPENDS ${CMAKE_CURRENT_SOURCE_DIR}/CMakeLists.txt
+    ${EXTERNAL_FUNC_SOURCE_DIR}/configure.py
   COMMAND ${PYTHON_EXECUTABLE} ${EXTERNAL_FUNC_SOURCE_DIR}/configure.py
     "--cxx=${CMAKE_CXX_COMPILER}"
     "--cxx-flags=${CMAKE_CXX_FLAGS} ${CMAKE_CXX_FLAGS_${upperBuildType}}"
     "--ar=${CMAKE_AR}"
-    "--include-dirs=${includeDirs}"
+    "--include-dirs=${includeDirsCompileOptions}"
     "--src-dir=${EXTERNAL_FUNC_SOURCE_DIR}"
     "--build-dir=${EXTERNAL_FUNC_BINARY_DIR}"
   )
 
+# NOTE: Above, we have to run the configure.py script at build time after
+# generation because ${includeDirsCompileOptions} contains generation
+# expressions that are evaluated at generation time by the
+# add_custom_command() call.
+
 #
 # D) Define a custom build rule and target to create external_func library
 #
@@ -109,6 +104,7 @@ add_custom_command(
   OUTPUT ${EXTERNAL_FUNC_LIB_FILE}
   DEPENDS ${EXTERNAL_FUNC_SOURCE_DIR}/external_func.hpp
     ${EXTERNAL_FUNC_SOURCE_DIR}/external_func.cpp
+    ${EXTERNAL_FUNC_MAKEFILE}
   COMMAND make ${CTEST_BUILD_FLAGS}
   WORKING_DIRECTORY ${EXTERNAL_FUNC_BINARY_DIR}
   )