build: streamline CMAKE_MODULE_PATH interaction

.gitignore

@@ -1 +1,6 @@
-build
+# clangd working space (see emacs+lsp)
+.cache
+# typical cmake build directory (source-tree-nephew)
+.build*
+# symlink to builddir/compile_commands.json;  should be set manually in dev sandbox
+compile_commands.json

CMakeLists.txt

@@ -5,8 +5,7 @@ cmake_minimum_required(VERSION 3.10)
 project(xo_statistics VERSION 1.0)
 enable_language(CXX)
 
-include(xo_macros/xo_cxx)
-include(xo_macros/code-coverage)
+include(cmake/xo-bootstrap-macros.cmake)
 
 # ----------------------------------------------------------------
 # unit test setup

cmake/xo-bootstrap-macros.cmake

@@ -0,0 +1,12 @@
+if (("${CMAKE_MODULE_PATH}" STREQUAL "") OR ("${CMAKE_MODULE_PATH}" STREQUAL "prefix"))
+    # default to typical install location for xo-project-macros
+    set(CMAKE_MODULE_PATH ${CMAKE_INSTALL_PREFIX}/share/cmake)
+endif()
+
+message("-- CMAKE_INSTALL_PREFIX=${CMAKE_INSTALL_PREFIX}")
+message("-- CMAKE_MODULE_PATH=${CMAKE_MODULE_PATH}")
+
+# needs to have been installed somewhere on CMAKE_MODULE_PATH,
+# (e.g. from xo-cmake with the same value for CMAKE_INSTALL_PREFIX)
+#
+include(xo_macros/xo-project-macros)