[feature] force a rebuild if already installed but not for dependencies

Hi there, I like to force a rebuild of a recipe but not nessecarily of the dependencies.

Normally I would use the environment variable CONAN_BUILD_POLICY and set it to outdated. But this would apply this setting to the recipe to be processed and to the dependencies. And if the package already exists Conan returns with Already installed.

With a normal conan create call I could set the arguments --build=recipe-name --build=outdated. But CPT does not use multiple build policies (according to the docs).

[Johnnyxy]

A complete new setting? As I am aware the CONAN_BUILD_POLICY is a switch to set the --build parameter of Conan calls. A complete new setting would not be in sync with Conan’s settings. Ok, the currently new setting cascade is missing too, but that just has to be added to sync it with Conan’s actual parameter values.

Maybe it would be possible to make CONAN_BUILD_POLICY a list like CONAN_OPTIONS. This would not break existing code of CI or something similar which calls CPT.

set "CONAN_BUILD_POLICY=RECIPE_NAME,outdated"

what would in turn be mapped to

--build # for the recipe itself
--build=outdated # for everything else 

Or a more complex example:

set "CONAN_BUILD_POLICY=RECIPE_NAME,fnpattern,DEPENDENCY2,DEPENDENCY3,outdated"

what would in turn be mapped to

--build
--build=fnpattern
--build=DEPENDENCY2
--build=DEPENDENCY3
--build=outdated

[boussaffawalid]

@uilianries @lasote checking the source code of CPT here https://github.com/conan-io/conan-package-tools/blob/b50c952d167dbb54e8f82f1ebfab08199214841f/cpt/runner.py#L91 it seems that conan api supports a list of build policies already. so why not make this available in CPT as well ?

I think it is only one line of change: self._build_policy = self._build_policy.split(",") instead of self._build_policy = [self._build_policy]

or did I miss something here?