Prevent In-source builds

CMakeLists.txt

@@ -16,7 +16,19 @@ project(
         "The 'build-all' instructions for all examples for the book CMake Best Practices"
     LANGUAGES CXX
 )
-include(CTest)
+
+# TODO(CK) only needed if working as "Dashboard Client" include(CTest)
+enable_testing()
+
+# cmake-format: off
+# see the CMAKE_SOURCE_DIR like readonly!
+if(CMAKE_SOURCE_DIR STREQUAL CMAKE_BINARY_DIR)
+    message(
+        FATAL_ERROR
+            "In-source builds are not supported! "
+            "You may need to delete 'CMakeCache.txt' and 'CMakeFiles/' first."
+    )
+endif()
 
 # Add additional targets to your CMake project:
 if(EXISTS Format.cmake/CMakeLists.txt)
@@ -25,6 +37,24 @@ if(EXISTS Format.cmake/CMakeLists.txt)
     # cmake-format fix-clang-format fix-cmake-format fix-format format
 endif()
 
+if(PROJECT_IS_TOP_LEVEL)
+    option(BUILD_SHARED_LIBS "Build shared libs." OFF)
+    option(BUILD_TESTING "Build SelfTest project" ON)
+endif()
+
+# This property setting also needs to be consistent between the installed shared
+# library and its consumer, otherwise most toolchains will once again reject the
+# consumer's generated BMI.
+if(NOT DEFINED CMAKE_CXX_STANDARD)
+    set(CMAKE_CXX_STANDARD 20)
+    set(CMAKE_CXX_EXTENSIONS FALSE)
+    set(CMAKE_CXX_STANDARD_REQUIRED TRUE)
+
+    set(CMAKE_CXX_VISIBILITY_PRESET hidden)
+    set(CMAKE_VISIBILITY_INLINES_HIDDEN TRUE)
+endif()
+# cmake-format: on
+
 # Set the default build type for single-config generators. The build type
 # variable is still overridable from outside.
 set(CMAKE_BUILD_TYPE

chapter13/ex03_external_cmake_module/CMakeLists.txt

@@ -22,6 +22,7 @@ fetchcontent_declare(
     GIT_TAG 7d0447fcadf8e93d25f242b9bb251ecbcf67f8cb
     SOURCE_DIR "${CMAKE_CURRENT_LIST_DIR}/.hadouken"
 )
+# FIXME(CK): see the CMAKE_SOURCE_DIR like readonly!
 
 # Fetch hadouken
 fetchcontent_makeavailable(hadouken)
@@ -30,7 +31,7 @@ fetchcontent_makeavailable(hadouken)
 list(
     APPEND
     CMAKE_MODULE_PATH
-    ${CMAKE_CURRENT_LIST_DIR}/.hadouken/cmake/modules
+    ${hadouken_SOURCE_DIR}/cmake/modules
 )
 
 # Include some CMake modules provided by the Hadouken