缓存变量的自定义CMake属性？

CMake文档描述了一种为（除其他外）缓存变量创建和自定义属性的方法。但是我不能让它工作。假设我有一个最小的例子：

cmake_minimum_required(VERSION 3.7)
project(x)

define_property(CACHED_VARIABLE PROPERTY A_PROPERTY BRIEF_DOCS "brief" FULL_DOCS "full")
set(A_VARIABLE "variable value" CACHE STRING "helpstring")
set_property(CACHE A_VARIABLE PROPERTY A_PROPERTY "property value")

尝试配置时会出现错误：

$ cmake .
-- The C compiler identification is GNU 8.3.0
-- The CXX compiler identification is GNU 8.3.0
-- Check for working C compiler: /usr/bin/cc
-- Check for working C compiler: /usr/bin/cc -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Detecting C compile features
-- Detecting C compile features - done
-- Check for working CXX compiler: /usr/bin/c++
-- Check for working CXX compiler: /usr/bin/c++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
CMake Error at CMakeLists.txt:6 (set_property):
  set_property given invalid CACHE property A_PROPERTY.  Settable CACHE
  properties are: ADVANCED, HELPSTRING, STRINGS, TYPE, and VALUE.


-- Configuring incomplete, errors occurred!
See also "/tmp/x/CMakeFiles/CMakeOutput.log".

---

这项功能到底应该如何工作？

似乎CMake实现只是硬代码哪些缓存属性是可写的。从：

bool cmSetPropertyCommand:：HandleCacheMode（）
{
如果（此->属性名称==“高级”）{
...
}else if（this->PropertyName==“TYPE”）{
...
}else if（此->属性名称！=“帮助字符串”&&
此->属性名称！=“字符串”&&
此->属性名称！=“值”）{
std：：ostringstream e；
您可以设置缓存条目，而不是您自己的。完成-我们将看到这是如何发展的。
bool cmSetPropertyCommand::HandleCacheMode()
{
  if (this->PropertyName == "ADVANCED") {
    ...
  } else if (this->PropertyName == "TYPE") {
    ...
  } else if (this->PropertyName != "HELPSTRING" &&
             this->PropertyName != "STRINGS" &&
             this->PropertyName != "VALUE") {
    std::ostringstream e;
    e << "given invalid CACHE property " << this->PropertyName << ".  "
      << "Settable CACHE properties are: "
      << "ADVANCED, HELPSTRING, STRINGS, TYPE, and VALUE.";
    this->SetError(e.str());
    return false;
  }
  ...
}