[question] platform_tool_requires in build or host profile?

[pbs3141]

What is your question?

Should platform_tool_requires tools be added to the build profile, the host profile, or both?

In conan 2.17, if you added e.g. cmake/3.24.2 to the build profile, then it would show up under both the build and host profiles,

======== Input profiles ========
Profile host:
[platform_tool_requires]
cmake/3.24.2

Profile build:
[platform_tool_requires]
cmake/3.24.2

which is a bit strange, but nonetheless everything worked (recipes could find and use cmake).

In conan 2.18, doing the same thing causes it to only show up in the build profile:

======== Input profiles ========
Profile host:

Profile build:
[platform_tool_requires]
cmake/3.24.2

as expected, but it does not work (recipes cannot find or use cmake).

On the other hand, adding it to the host profile does work - unexpectedly, since cmake is a property of the build system not the host system.

So is this behaviour really correct, and intended?

Note the documentation (linked above) says

Given this situation, it could make sense to want to use your already installed CMake version, so it’s enough to declare it as a platform_tool_requires in your profile:

but never says which profile (when cross-compiling), so whatever the correct answer is, it should also be clarified in the documentation.

Have you read the CONTRIBUTING guide?

• I've read the CONTRIBUTING guide

[AbrilRBS]

Hi @pbs3141 thanks a lot for your question.

I understand the confusion about which profile should get the platform_tool_requires section defined. The key point here to note is that this key means "for every recipe in this context that defines a tool_requires, check if the platform version should be used".

That is to say that the host context profile should contain this, so that recipes that define tool_requires in the host context are properly replaced.

(Note that if you also want the build context packages to use this replacement, then you should add it to the build context profile too. This would be useful for example if you had application A living in the build context, which itself needs CMake to build)

As for the first part of your question, could you please share which commands you are running specifically to see the difference in behaviour between Conan 2.17 and 2.18? I'd like to investigate that further, thanks! :)

[pbs3141]

Thanks for the explanation! This could do with going in the docs.

(The first part of my question can be ignored; it was caused by adding/removing an include in the profile.)

[AbrilRBS]

Closing as solved in the linked PR