Fix pkg-config description parser

[uilianries]

Changelog: Fix: Throw error when the recipe description is not a string.
Docs: Omit

fixes #8142

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[memsharded]

Is a tuple an allowed description? I don't recall that it is.

[uilianries]

Not a description, but a python feature. Months ago I watched a python meetup where that usage was more pythonic. And here is the reference: https://www.python.org/dev/peps/pep-0008/#maximum-line-length

The preferred way of wrapping long lines is by using Python's implied line continuation inside parentheses, brackets and braces. Long lines can be broken over multiple lines by wrapping expressions in parentheses.

[memsharded]

That is without the comma @uilianries

description = ("Conan, "
               " the C++ package manager")

That will resolve to a single string, not a tuple

[uilianries]

I see, so it's more a prone error than a bug. Anyway, if we pass a tuple, we have an exception which doesn't help. So we could accept tuple, or raise a better error.

[memsharded]

Lets make a better error. I don't see here a use case in which we want to support tuples, lists, or other different ways of inputting the data, it should always be a string.

[uilianries]

Done.

[Croydon]

This change breaks some existing recipes, like conan-io/conan-center-index#4726

Shouldn't such changes only happen with Conan 2.0?

[memsharded]

Hi @Croydon

It is not a breaking change, it is a bug fix. As described in the documentation (https://docs.conan.io/en/latest/reference/conanfile/attributes.html#description), the description field is a string. Passing any other type, like a tuple, is an error and the recipe should fail (or could have undefined behavior if the error is not managed)