tests/sys/libc_newlib: drop test

[maribu]

Contribution description

This tests makes little sense to have for a number of reasons:

1. One should not use iprintf() for a number of reasons:
   1. It is non-standard and using it over printf() makes the code less portable (e.g. it cannot be used on AVR)
   2. The idea of adding a leaner variant of printf() in addition to the larger one is bogus, as apps will end up using both resulting in a larger firmware instead of a smaller
   3. RIOT's build system already has the printf_float module to control whether formatting of floating point numbers should be suppered. This mechanism will actually result in smaller builds, if floating point support is not needed, as it prevents two variants of printf to be linked in.
2. The test checks some implementation details (e.g. whether the address of two functions is identical), rather than correct behavior of the implementation. This is completely bogus.

Testing procedure

Happy CI

Issues/PRs references

#9599 introduced this test.

As can be seen in the PR, the point of the test is to check whether using nano.specs from newlib via the module newlib_nano has the intended effect. But since it is up to whoever is building / packaging newlib to decide whether to provide a nano.specs at all and how the nano.specs variant is configured, this way of testing does not appear to be super valid.

[crasbe]

Was that test ever executed by our CI system? I don't think there is a test configuration which would set USEMODULE += newlib, which would be a precondition for this test to compile & run 🤔

[maribu]

The boards that use newlib by default have a newlib feature, which then is mirrored as a module, so that C code can check for its usage. (For some reason we have defines to check against for modules, but not for features.)

So this should indeed be executed. The fact that this fails in a PR that makes mpaland-printf the default for most newlib boards also supports that this is indeed used.

[Enoch247]

I concur with your assessment. As this test is broken when replacing newlib's printf implementation by pkg/mpaland-printf, I think we can drop this test since it is a bit fragile anyway.

[riot-ci]

Murdock results

✔️ PASSED

7410255 tests/sys/libc_newlib: drop test

Success	Failures	Total	Runtime
10538	0	10538	16m:58s

Artifacts

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