[MesonToolchain] Showing a warning message if raw options are used

[franramirez688]

Changelog: Feature: MesonToolchain shows a warning message if any options are used directly.
Docs: conan-io/docs#3381
Closes: #14453

[memsharded]

If this hasn't been released yet, just remove the Changelog in both PRs

[franramirez688]

If this hasn't been released yet, just remove the Changelog in both PRs

Keeping only the feature about showing the warning message

[SpaceIm]

Is it expected that boolean options display this warning?

In dav1d recipe, there is this warning now:

WARN: deprecated: Please, do not use a Conan option value directly. Convert 'options.assembly' into a valid Pythondata type, e.g, bool(self.options.shared)
WARN: deprecated: Please, do not use a Conan option value directly. Convert 'options.with_tools' into a valid Pythondata type, e.g, bool(self.options.shared)

Though, in recipe, there is:

    options = {
        "shared": [True, False],
        "fPIC": [True, False],
        "bit_depth": ["all", 8, 16],
        "with_tools": [True, False],
        "assembly": [True, False],
        "with_avx512": [True, False],
    }
    default_options = {
        "shared": False,
        "fPIC": True,
        "bit_depth": "all",
        "with_tools": True,
        "assembly": True,
        "with_avx512": False,
    }

    (...)

    def generate(self):
        env = VirtualBuildEnv(self)
        env.generate()

        tc = MesonToolchain(self)
        tc.project_options["enable_tests"] = False
        tc.project_options["enable_asm"] = self.options.assembly
        if Version(self.version) < "1.0.0":
            tc.project_options["enable_avx512"] = self.options.get_safe("with_avx512", False)
        tc.project_options["enable_tools"] = self.options.with_tools
        if self.options.bit_depth == "all":
            tc.project_options["bitdepths"] = "8,16"
        else:
            tc.project_options["bitdepths"] = str(self.options.bit_depth)
        tc.generate()

So why this warning? I though that boolean values were properly converted, unlike string. I don't understand why there can't be an automated conversion of PackageOption like in CMakeToolchain which has:

            elif isinstance(value, _PackageOption):
                if str(value).lower() in ["true", "false", "none"]:
                    cache_variables[name] = "ON" if bool(value) else "OFF"
                elif str(value).isdigit():
                    cache_variables[name] = int(value)
                else:
                    cache_variables[name] = str(value)

I would have expected such fix for #14453, to get consistent behavior of toolchains.

[memsharded]

Yes, it is expected. The options have to be explicitly converted to bool(self.options.xxx) if desired that Meson treats them as booleans. Right now it is working by luck, because being mapped as strings and meson accepts the casing.

[SpaceIm]

But why this inconsistency between CMakeToolchain and MesonToolchain? CMakeToolchain converts PackageOption evaluated as boolean or digits or string to their CMake format, but not MesonToolchain. It's weird.

[SpaceIm]

I see that @RubenRBS had the same concern #14633 (review)

[franramirez688]

But why this inconsistency between CMakeToolchain and MesonToolchain? CMakeToolchain converts PackageOption evaluated as boolean or digits or string to their CMake format, but not MesonToolchain. It's weird.

Indeed, I agree with both of you @SpaceIm and @RubenRBS. The thing is that I don't see the point of converting anything like CMakeToolchain is doing under the hood. Actually, it's doing that only for cache_variables and not for the rest of the variables so that's the weirdest thing. IMHO, we should not convert anything at all, and we should manage those conversions through the internal _PackageOption class instead somehow. Also, I cannot prune that conversion from CMakeToolchain because of likely breaking changes. It's clear that it's a limitation of this class for now, and we should solve it in the future.

[franramirez688]

Related issue: #14590