Add variable CMAKE_ADD_CUSTOM_COMMAND_DEPENDS_EXPLICIT_ONLY

Add CMake variable `CMAKE_ADD_CUSTOM_COMMAND_DEPENDS_EXPLICIT_ONLY` to enable
option `DEPENDS_EXPLICIT_ONLY` on all uses of `add_custom_command`.

Fixes: #17097

2 files changed, 48 insertions, 10 deletions

diff --git a/Tests/RunCMake/Ninja/CustomCommandExplicitDepends.cmake b/Tests/RunCMake/Ninja/CustomCommandExplicitDepends.cmake
index e0c2434..fefd86a 100644
--- a/Tests/RunCMake/Ninja/CustomCommandExplicitDepends.cmake
+++ b/Tests/RunCMake/Ninja/CustomCommandExplicitDepends.cmake
@@ -2,17 +2,35 @@ cmake_minimum_required(VERSION 3.26)
 project(CustomCommandExplicitDepends C)
 
 add_custom_command(
-  OUTPUT  "${CMAKE_CURRENT_BINARY_DIR}/command.h"
+  OUTPUT  "${CMAKE_CURRENT_BINARY_DIR}/command-option.h"
   COMMAND "${CMAKE_COMMAND}" -E touch
-          "${CMAKE_CURRENT_BINARY_DIR}/command.h"
-  COMMENT "Creating command.h"
+          "${CMAKE_CURRENT_BINARY_DIR}/command-option.h"
+  COMMENT "Creating command-option.h"
   DEPENDS_EXPLICIT_ONLY
 )
 
-add_library(dep STATIC dep.c)
+set(CMAKE_ADD_CUSTOM_COMMAND_DEPENDS_EXPLICIT_ONLY ON)
+add_custom_command(
+  OUTPUT  "${CMAKE_CURRENT_BINARY_DIR}/command-variable-on.h"
+  COMMAND "${CMAKE_COMMAND}" -E touch
+          "${CMAKE_CURRENT_BINARY_DIR}/command-variable-on.h"
+  COMMENT "Creating command-variable-on.h"
+)
+
+set(CMAKE_ADD_CUSTOM_COMMAND_DEPENDS_EXPLICIT_ONLY OFF)
+add_custom_command(
+  OUTPUT  "${CMAKE_CURRENT_BINARY_DIR}/command-variable-off.h"
+  COMMAND "${CMAKE_COMMAND}" -E touch
+          "${CMAKE_CURRENT_BINARY_DIR}/command-variable-off.h"
+  COMMENT "Creating command-variable-off.h"
+)
+
+add_library(dep SHARED dep.c)
 
-add_library(top STATIC
+add_library(top SHARED
   top.c
-  "${CMAKE_CURRENT_BINARY_DIR}/command.h"
+  "${CMAKE_CURRENT_BINARY_DIR}/command-option.h"
+  "${CMAKE_CURRENT_BINARY_DIR}/command-variable-on.h"
+  "${CMAKE_CURRENT_BINARY_DIR}/command-variable-off.h"
 )
 target_link_libraries(top PRIVATE dep)
diff --git a/Tests/RunCMake/Ninja/RunCMakeTest.cmake b/Tests/RunCMake/Ninja/RunCMakeTest.cmake
index 17ad035..91c48c6 100644
--- a/Tests/RunCMake/Ninja/RunCMakeTest.cmake
+++ b/Tests/RunCMake/Ninja/RunCMakeTest.cmake
@@ -193,11 +193,31 @@ run_LooseObjectDepends()
 function (run_CustomCommandExplictDepends)
   set(RunCMake_TEST_BINARY_DIR ${RunCMake_BINARY_DIR}/CustomCommandExplicitDepends-build)
   run_cmake(CustomCommandExplicitDepends)
-  run_ninja("${RunCMake_TEST_BINARY_DIR}" "command.h")
-  if (EXISTS "${RunCMake_TEST_BINARY_DIR}/${CMAKE_STATIC_LIBRARY_PREFIX}dep${CMAKE_STATIC_LIBRARY_SUFFIX}")
+
+  set(DEP_LIB "${RunCMake_TEST_BINARY_DIR}/${CMAKE_SHARED_LIBRARY_PREFIX}dep${CMAKE_SHARED_LIBRARY_SUFFIX}")
+
+  run_ninja("${RunCMake_TEST_BINARY_DIR}" "command-option.h")
+  if (EXISTS "${DEP_LIB}")
+    message(FATAL_ERROR
+      "The `dep` library was created when requesting a custom command to be "
+      "generated; this should no longer be necessary when passing "
+      "DEPENDS_EXPLICIT_ONLY option.")
+  endif ()
+
+  run_ninja("${RunCMake_TEST_BINARY_DIR}" "command-variable-on.h")
+  if (EXISTS "${DEP_LIB}")
+    message(FATAL_ERROR
+      "The `dep` library was created when requesting a custom command to be "
+      "generated; this should no longer be necessary when setting "
+      "CMAKE_ADD_CUSTOM_COMMAND_DEPENDS_EXPLICIT_ONLY variable to ON.")
+  endif ()
+
+  run_ninja("${RunCMake_TEST_BINARY_DIR}" "command-variable-off.h")
+  if (NOT EXISTS "${DEP_LIB}")
     message(FATAL_ERROR
-      "The `dep` library was created when requesting an custom command to be "
-      "generated; this should no longer be necessary when passing DEPENDS_EXPLICIT_ONLY keyword.")
+      "The `dep` library was not created when requesting a custom command to be "
+      "generated; this should be necessary when setting "
+      "CMAKE_ADD_CUSTOM_COMMAND_DEPENDS_EXPLICIT_ONLY variable to OFF.")
   endif ()
 endfunction ()
 run_CustomCommandExplictDepends()