Support global platform.local.txt

[anno73]

It would be nice to be able to use ...\arduino-x.y.z\hardware\platform.local.txt file for customization (not only in the hardware related directories).
My goal: one place to define hook-scripts (recipe.hooks.sketch.prebuild) that search in the arduino sketch locations for predefined scripts and execute them. e.g. textually insert some text before compilation (https://forum.arduino.cc/index.php?topic=586019.msg3986846#msg3986846).
If in combination with Global system platform.txt arduino/arduino-cli#999, even better.

[per1234]

Thanks for your request @anno73.

The platform.local.txt feature is useful in order to allow the user to inject arbitrary platform properties without needing to modify the platform.txt file.

In Arduino IDE versions <1.8.10, a global platform.txt was distributed by Arduino as part of the IDE installation. In that context, the requested support for the user to inject their own global platform properties via a global platform.local.txt would indeed have been a useful feature.

However, the situation has changed since the time of your request. The need for a global platform.txt as part of the stock Arduino IDE installation was later eliminated: arduino/arduino-builder@85c6dd0. This means that, when using any version of Arduino IDE >=1.8.10, the global platform.txt feature is dedicated exclusively to use by the user. For this reason, there is no need to also support a global platform.local.txt. Just define your hooks (or any other platform properties) via the global platform.txt file.

Even though the change I mentioned above occurred years ago, some other factors made the situation regarding the global platform.txt and your request a bit murky:

• Loss of the global platform.txt feature: Global platform.txt is not recognized #469
• Faulty documentation/understanding of the scope of support for the feature (which was the root of Global platform.txt is not supported #999)

The first of these was resolved long ago by #472, but the feature was incorrectly understood to be specific to the IDE-bundled packages folder (as you put it ...\arduino-x.y.z\hardware) that is unique to the Arduino IDE 1.x application. Due to the misunderstanding that Arduino CLI and Arduino IDE 2.x did not have support for a global platform.txt, the request was not considered to be resolved/obviated by arduino/arduino-builder@85c6dd0 and #472. However, it turns out that global platform.txt files are (and always were) recognized in any of the packages folders; not the Arduino IDE 1.x bundled packages folder exclusively. Thus, we now understand that this issue is resolved.

The misinformation in the Arduino Platform Specification regarding the scope of the global platform.txt file has been corrected: #2952. In addition, the locations of all the packages folders have been documented:

https://arduino.github.io/arduino-cli/dev/platform-specification/#global-platformtxt

The packages folder under the Arduino sketchbook folder (referred to as directories.user in the context of Arduino CLI) will be the most convenient place to store your global platform.txt file.