CODEWITHSUNDEEP
cmake
Freddie Chopin
Freddie Chopin

Reputation: 8860

Custom CMake property for cache variable?

CMake docs describe a way to define and set custom properties for (among others) cache variables. However I cannot make it work. Lets say I have this minimal example:

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")

Trying to configure it gives an error:

$ 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".

How exactly is this feature supposed to work?

Upvotes: 0

Views: 1098

Answers (1)

Tsyvarev
Tsyvarev

Reputation: 65928

It seems that CMake implementation simply hardcodes which CACHE properties are writable. From the cmSetPropertyCommand.cxx:

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;
  }
  ...
}

I agree that such hardcode is not the one which is expected according to the description of define_property(CACHED_VARIABLE) command flow. (What is a reason to define a property which no one can set?)

So you may fill a bug report on this topic.

Upvotes: 1

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