Makefile.include: creation of CACHEDIR.TAG as a dependency of pkg-prepare

[bmewen]

Contribution description

The cached dir, only build for now, are not created by default so I added a small default target that will create the build dir and the CACHEDIR whenever a make command is called.

Testing procedure

Both commands should have the same behavior now. Previously pkg-prepare was not creating build/CACHEDIR.TAG and was creating the build/ directory through pkg/pkg.mk.

make pkg-prepare

make

Issues/PRs references

N/A

[bmewen]

@Enoch247 you can look at the way I've done it, not sure it's the best way but at least I think it's the intended behavior

[Enoch247]

You might consider taking a look at order only prerequisites to accomplish your goal.

You could leave the existing rule to create the tag file as-is. Then just add it as an order-only-prereq to any rules that should create the build dir.

[bmewen]

I am still waiting for a review whenever someone is available. Thank you

[kfessel]

I am still waiting for a review whenever someone is available. Thank you

From my POV this PR is a strange workaround abusing include for a minor problem (not many people call pkg-prepare directly)

• the include will search for the file at more than one location and include it if found https://www.gnu.org/software/make/manual/make.html#Include First, any directories you have specified with the ‘-I’ or ‘--include-dir’ options are searched (see [Summary of Options](https://www.gnu.org/software/make/manual/make.html#Options-Summary)). Then the following directories (if they exist) are searched, in this order: prefix/include (normally /usr/local/include [1](https://www.gnu.org/software/make/manual/make.html#FOOT1)) /usr/gnu/include, /usr/local/include, /usr/include.

• you identified one rule where the file should be generated but is not - there is a more straight forward fix for that ( just add a requirement to that rule

• searching for mkdir -p or ${BUILD_DIR} did not reveal an unmanageable number of instances that might need fixing in future

So in this form i don't think it is good to go (no positive from me)
but i also write this review as a comment -> easy to ignore (no negative)

[Enoch247]

The way you have used the include here is really clever, but not the right tool for the job in my opinion. The problem with doing it this way is that it is always run for every possible invocation of make even invocations that should not create anything such as any of the info-* recipes. This could be a bit of a surprise in environments when write access is not expected. Also, this causes the build dir to be create always, even if not needed (for example make BOARD=native examples/blinky).

[bmewen]

I removed what I have done previously to move the creation of CACHEDIR.TAG as a dependency of pkg-prepare, it fixes my issue and is anyway enough for me. I appreciate the review thanks.

[kfessel]

Thank you for your contribution

[riot-ci]

Murdock results

✔️ PASSED

b275e61 Makefile.include: creation of CACHEDIR.TAG as a dependency of pkg-prepare

Success	Failures	Total	Runtime
10161	0	10161	24m:38s

Artifacts

• Documentation preview

[Enoch247]

Thanks, I will test and review this weekend.

[Enoch247]

I would prefer to see the prepare target inside of pkg.mk depend on $(BUILD_DIR)/CACHEDIR.TAG, or the prepare target depending on '$(PKGDIRBASE)' and '$(PKGDIRBASE)' on $(BUILD_DIR)/CACHEDIR.TAG, but I won't insist on it.

If you decide to keep the current approach, please accept the suggested change for line 807.

[bmewen]

@Enoch247 this version is good for me if you have time to review it once more.

[Enoch247]

Thank you. I will take a look tomorrow.

[Enoch247]

I feel this recipe should be placed outside of this file, as it is at a broader scope than building packages. Perhaps as an include-able makefile in ./makefiles. However, I will approve as-is.