Add .inc as a header file type.

[bridadan]

Description

This was brought up by a thread on one of the TF-M prs. They are integrating an existing project into Mbed OS, and the existing project uses .inc files for some generated headers.

Currently, if you were to add a directory that only contained .inc files, this file would not be passed as an include path to the compiler. This ensures that .inc files are also considered header files.

Their build just so happens to work because the .inc files are generated in a directory that also contains a .h file. So the directory is marked as an include path.

I think this qualifies as a "fix" but let me know if I should change it.

Pull request type

[x] Fix
[ ] Refactor
[ ] Target update
[ ] Functionality change
[ ] Docs update
[ ] Test update
[ ] Breaking change

Reviewers

@theotherjimmy

[cmonr]

It's a fix and it's fine, but do we want to support this as a valid header file type?

[cmonr]

#9653 (comment)

Ah, that would be why. Poop.

[0xc0170]

I initially approved but rethink this

Do we want to support .inc , is this valid extension and not just "one project has it, we add it" ? When should I choose .h/hh/hpp or inc ? I find .inc to have special meaning , some projects do it that way.

If this approved, do we have this documented ? extensions supported and why inc is in there (what should be in the file, is it regular header file, is it special like only templates, or even some code file) .

TF-M actually generated these files according to their secure partitions manifests.

Probably this will be the description for having .inc supported.

[mikisch81]

@0xc0170 than what do you suggest? patching an external imported code and replace all includes of .inc files to .h? Raising a bug to TF-M to replace their extension? How will you explain the reason for it?

From a short googling I can see that it is a valid extention for headers:
https://fileinfo.com/extension/inc.

[0xc0170]

I just want to have this documented if we support it - "what extensions we support" that is it. Not repatching external code as .inc is valid extension.

[mikisch81]

Where should it be documented?

[0xc0170]

Here https://os.mbed.com/docs/mbed-os/latest/reference/mbed-os-build-rules.html

[bridadan]

Hi @0xc0170, I wasn't aware of that doc, I'll add it to the list

[bridadan]

Hi @0xc0170, I've read that .inc files are sometimes used to differentiate written .h files and generated .inc files. @mikisch81 can confirm but I believe these .inc files are generated in this case.

I've also added a corresponding doc update, thanks again for the prod: ARMmbed/mbed-os-5-docs#952

[cmonr]

CI started

[mbed-ci]

Test run: SUCCESS

Summary: 12 of 12 test jobs passed
Build number : 1
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