[feature] Binary Conan options should be expressed as an `option()` in CMake when generated with CMakeToolchain

This is common to have True/False options in conanfile.py. For example:

    options = {
        "build_docs": [True, False]
    }

the above is translated by the CMakeToolchain to

set(UNITS_BUILD_DOCS "True" CACHE STRING "Variable UNITS_BUILD_DOCS conan-toolchain defined")

This is seen in a GUI as:

However, it would be nicer if those would be generated either as:

set(UNITS_BUILD_DOCS "True" CACHE BOOL "Variable UNITS_BUILD_DOCS conan-toolchain defined")

or

option(UNITS_BUILD_DOCS "Variable UNITS_BUILD_DOCS conan-toolchain defined" ON)

The new behavior better states the purpose of the option and also improves CMake cache variable presentation in GUIs:

• I’ve read the CONTRIBUTING guide.

[memsharded]

Now I get it, thanks!

What I see is that by the moment you define the tc.variables, the option value is already a string, not a value. All Conan options and settings are converted to strings. So it is not possible to deduce it from the option value, it would require a explicit cast in user code like

tc.variables["UNITS_BUILD_DOCS"] = bool(self.options.build_docs)

this is basically equal to https://github.com/conan-io/conan/issues/8632, but for variables and not preprocessor_definitions

[mpusz]

But you are right, probably it should be a property of tc.variables.