Add dependencies using EXCLUDE_FROM_ALL flag (#198)

* add dependencies using EXCLUDE_FROM_ALL flag

* respect DOWNLOAD_ONLY flag

* set EXCLUDE_FROM_ALL as an optional flag

* use one value arg for consistency

* fix argument passing

* add unit test

* update cmake-format

.cmake-format

@@ -33,6 +33,7 @@ parse:
         DOWNLOAD_NO_EXTRACT: 1
         HTTP_USERNAME: 1
         HTTP_PASSWORD: 1
+        EXCLUDE_FROM_ALL: 1
         OPTIONS: +
     cpmfindpackage:
       pargs:

cmake/CPM.cmake

@@ -257,6 +257,7 @@ function(CPMAddPackage)
       FIND_PACKAGE_ARGUMENTS
       NO_CACHE
       GIT_SHALLOW
+      EXCLUDE_FROM_ALL
   )
 
   set(multiValueArgs OPTIONS)
@@ -387,7 +388,9 @@ function(CPMAddPackage)
       set(${CPM_ARGS_NAME}_ADDED YES)
       set(${CPM_ARGS_NAME}_SOURCE_DIR ${download_directory})
       if(NOT CPM_ARGS_DOWNLOAD_ONLY AND EXISTS ${download_directory}/CMakeLists.txt)
-        add_subdirectory(${download_directory} ${${CPM_ARGS_NAME}_BINARY_DIR})
+        cpm_add_subdirectory(
+          ${download_directory} ${${CPM_ARGS_NAME}_BINARY_DIR} "${CPM_ARGS_EXCLUDE_FROM_ALL}"
+        )
       endif()
       set(CPM_SKIP_FETCH TRUE)
       set(PACKAGE_INFO "${PACKAGE_INFO} at ${download_directory}")
@@ -427,7 +430,7 @@ function(CPMAddPackage)
     cpm_declare_fetch(
       "${CPM_ARGS_NAME}" "${CPM_ARGS_VERSION}" "${PACKAGE_INFO}" "${CPM_ARGS_UNPARSED_ARGUMENTS}"
     )
-    cpm_fetch_package("${CPM_ARGS_NAME}" "${DOWNLOAD_ONLY}")
+    cpm_fetch_package("${CPM_ARGS_NAME}" "${DOWNLOAD_ONLY}" "${CPM_ARGS_EXCLUDE_FROM_ALL}")
     cpm_get_fetch_properties("${CPM_ARGS_NAME}")
   endif()
 
@@ -550,24 +553,36 @@ function(cpm_get_fetch_properties PACKAGE)
   )
 endfunction()
 
+function(cpm_add_subdirectory SOURCE_DIR BINARY_DIR EXCLUDE)
+  if(EXCLUDE)
+    set(addSubdirectoryExtraArgs EXCLUDE_FROM_ALL)
+  else()
+    set(addSubdirectoryExtraArgs "")
+  endif()
+  add_subdirectory(${SOURCE_DIR} ${BINARY_DIR} ${addSubdirectoryExtraArgs})
+endfunction()
+
 # downloads a previously declared package via FetchContent
-function(cpm_fetch_package PACKAGE DOWNLOAD_ONLY)
+function(cpm_fetch_package PACKAGE DOWNLOAD_ONLY EXCLUDE)
   if(${CPM_DRY_RUN})
     message(STATUS "${CPM_INDENT} package ${PACKAGE} not fetched (dry run)")
     return()
   endif()
 
-  if(DOWNLOAD_ONLY)
   FetchContent_GetProperties(${PACKAGE})
-    if(NOT ${PACKAGE}_POPULATED)
+  string(TOLOWER "${PACKAGE}" lower_case_name)
+
+  if(NOT ${lower_case_name}_POPULATED)
     FetchContent_Populate(${PACKAGE})
-    endif()
+    if(NOT DOWNLOAD_ONLY AND EXISTS ${${lower_case_name}_SOURCE_DIR}/CMakeLists.txt)
-  else()
       set(CPM_OLD_INDENT "${CPM_INDENT}")
       set(CPM_INDENT "${CPM_INDENT} ${PACKAGE}:")
-    FetchContent_MakeAvailable(${PACKAGE})
+      cpm_add_subdirectory(
+        ${${lower_case_name}_SOURCE_DIR} ${${lower_case_name}_BINARY_DIR} "${EXCLUDE}"
+      )
       set(CPM_INDENT "${CPM_OLD_INDENT}")
     endif()
+  endif()
 endfunction()
 
 # splits a package option

cmake/testing.cmake

@@ -10,6 +10,18 @@ function(ASSERT_EQUAL)
   endif()
 endfunction()
 
+function(ASSERT_NOT_EQUAL)
+  if(NOT ARGC EQUAL 2)
+    message(FATAL_ERROR "assertion failed: invalid argument count: ${ARGC}")
+  endif()
+
+  if(${ARGV0} STREQUAL ${ARGV1})
+    message(FATAL_ERROR "assertion failed: '${ARGV0}' == '${ARGV1}'")
+  else()
+    message(STATUS "test passed: '${ARGV0}' != '${ARGV1}'")
+  endif()
+endfunction()
+
 function(ASSERT_EMPTY)
   if(NOT ARGC EQUAL 0)
     message(FATAL_ERROR "assertion failed: input ${ARGC} not empty: '${ARGV}'")

test/unit/broken_dependency/.gitignore

@@ -0,0 +1,2 @@
+/CMakeLists.txt
+/package-lock.cmake

test/unit/broken_dependency/CMakeLists.txt.in

@@ -0,0 +1,13 @@
+cmake_minimum_required(VERSION 3.14 FATAL_ERROR)
+
+project(CPMTest)
+
+# ---- Dependencies ----
+
+include(@CPM_PATH@/CPM.cmake)
+
+CPMAddPackage(
+  NAME BrokenDependency
+  SOURCE_DIR ${CMAKE_CURRENT_LIST_DIR}/dependency
+  EXCLUDE_FROM_ALL @EXCLUDE_FROM_ALL@
+)

test/unit/broken_dependency/dependency/CMakeLists.txt

@@ -0,0 +1,3 @@
+project(BrokenDependency)
+
+add_custom_target(error ALL ${CMAKE_COMMAND} -E false)

test/unit/exclude_from_all.cmake

@@ -0,0 +1,35 @@
+include(CMakePackageConfigHelpers)
+include(${CPM_PATH}/testing.cmake)
+
+set(TEST_BUILD_DIR ${CMAKE_CURRENT_BINARY_DIR}/exclude_from_all)
+
+function(init_project EXCLUDE_FROM_ALL)
+  configure_package_config_file(
+    "${CMAKE_CURRENT_LIST_DIR}/broken_dependency/CMakeLists.txt.in"
+    "${CMAKE_CURRENT_LIST_DIR}/broken_dependency/CMakeLists.txt"
+    INSTALL_DESTINATION ${CMAKE_CURRENT_BINARY_DIR}/junk
+  )
+
+  execute_process(
+    COMMAND ${CMAKE_COMMAND} "-H${CMAKE_CURRENT_LIST_DIR}/broken_dependency" "-B${TEST_BUILD_DIR}"
+    RESULT_VARIABLE ret
+  )
+
+  assert_equal(${ret} "0")
+endfunction()
+
+function(build_project expected_success)
+  execute_process(COMMAND ${CMAKE_COMMAND} "--build" "${TEST_BUILD_DIR}" RESULT_VARIABLE ret)
+
+  if(expected_success)
+    assert_equal(${ret} 0)
+  else()
+    assert_not_equal(${ret} 0)
+  endif()
+endfunction()
+
+init_project(FALSE)
+build_project(FALSE)
+
+init_project(TRUE)
+build_project(TRUE)