cmake -E: Add true and false commands

Help/manual/cmake.1.rst

@@ -604,6 +604,12 @@ Available commands are:
 .. note::
   Path to where ``<new>`` symbolic link will be created has to exist beforehand.
 
+``true``
+  Do nothing, with an exit code of 0.
+
+``false``
+  Do nothing, with an exit code of 1.
+
 Windows-specific Command-Line Tools
 -----------------------------------
 

Help/release/dev/cmake-e-true-false.rst

@@ -0,0 +1,5 @@
+cmake-e-true-false
+------------------
+
+* :manual:`cmake(1)` ``-E`` now supports ``true`` and ``false`` commands, which
+  do nothing while returning exit codes of 0 and 1, respectively.

Source/cmcmd.cxx

@@ -114,6 +114,8 @@ void CMakeCommandUsage(const char* program)
     << "  touch <file>...           - touch a <file>.\n"
     << "  touch_nocreate <file>...  - touch a <file> but do not create it.\n"
     << "  create_symlink old new    - create a symbolic link new -> old\n"
+    << "  true                      - do nothing with an exit code of 0\n"
+    << "  false                     - do nothing with an exit code of 1\n"
 #if defined(_WIN32) && !defined(__CYGWIN__)
     << "Available on Windows only:\n"
     << "  delete_regv key           - delete registry value\n"
@@ -891,6 +893,16 @@ int cmcmd::ExecuteCMakeCommand(std::vector<std::string> const& args)
       return 0;
     }
 
+    // Command to do nothing with an exit code of 0.
+    if (args[1] == "true") {
+      return 0;
+    }
+
+    // Command to do nothing with an exit code of 1.
+    if (args[1] == "false") {
+      return 1;
+    }
+
     // Internal CMake shared library support.
     if (args[1] == "cmake_symlink_library" && args.size() == 5) {
       return cmcmd::SymlinkLibrary(args);

Tests/RunCMake/CommandLine/E_false-extraargs-result.txt

@@ -0,0 +1 @@
+1

Tests/RunCMake/CommandLine/E_false-result.txt

@@ -0,0 +1 @@
+1

Tests/RunCMake/CommandLine/RunCMakeTest.cmake

@@ -26,6 +26,10 @@ run_cmake_command(E_echo_append ${CMAKE_COMMAND} -E echo_append)
 run_cmake_command(E_rename-no-arg ${CMAKE_COMMAND} -E rename)
 run_cmake_command(E_server-arg ${CMAKE_COMMAND} -E server --extra-arg)
 run_cmake_command(E_server-pipe ${CMAKE_COMMAND} -E server --pipe=)
+run_cmake_command(E_true ${CMAKE_COMMAND} -E true)
+run_cmake_command(E_true-extraargs ${CMAKE_COMMAND} -E true ignored)
+run_cmake_command(E_false ${CMAKE_COMMAND} -E false)
+run_cmake_command(E_false-extraargs ${CMAKE_COMMAND} -E false ignored)
 
 run_cmake_command(E_touch_nocreate-no-arg ${CMAKE_COMMAND} -E touch_nocreate)
 run_cmake_command(E_touch-nonexistent-dir ${CMAKE_COMMAND} -E touch "${RunCMake_BINARY_DIR}/touch-nonexistent-dir/foo")