`VCPKG_CHAINLOAD_TOOLCHAIN_FILE` has two different meanings

[sharadhr]

I believe VCPKG_CHAINLOAD_TOOLCHAIN_FILE may be set in two different places, affecting different parts of a project using CMake and vcpkg:

• The project scope, which sets the toolchain for the consuming project;
• in a triplet file, which is in vcpkg's 'scope' (for lack of a better word). This sets the toolchain that ports will be compiled with.

This is documented for the above two use-cases respectively:

• vcpkg in CMake projects: Using multiple toolchain files
• Triplets: VCPKG_CHAINLOAD_TOOLCHAIN_FILE

This dual behaviour is clearly noted in the first link above:

[!NOTE] vcpkg does not automatically apply your toolchain's settings, such as your compiler or compilation flags, while building libraries. To change vcpkg's library settings, you must make a custom triplet file (which can share your toolchain)**

Furthermore, note that the URL further up in the same page is also misleading (it goes to the triplets page, rather than linking to the section further down). I am guessing even the documentation writer had mixed the two variables up.

I suggest renaming both to clarify the scope of these variables. For instance:

• VCPKG_PROJECT_CHAINLOAD_TOOLCHAIN_FILE
• VCPKG_PORTS_CHAINLOAD_TOOLCHAIN_FILE

This is, in my opinion, so much clearer.

Furthermore, it would be good to implement some sort of boolean option in vcpkg that would automatically compile all ports with the project's toolchain, rather than requiring users to set up a custom triplet and then re-include a toolchain. Perhaps, VCPKG_USE_PROJECT_TOOLCHAIN_FOR_PORTS?

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[sharadhr]

Do not close!

[FrankXie05]

@data-queue Could you help take a look at this issue?