Question about ancient TARGET_CFLAGS in rules.mk?

[Ansuel Smith]

Hi,
some background about this.

I'm trying to improve our CI system more and more by finally adding
support for real
EXTERNAL_TOOLCHAIN_SUPPORT... I'm running (and abusing) the github CI
to make sure everything works and all compiles correctly...

While testing it I notice a specific target fails to compile ubox package.
While still to investigate why this is only present on that target, i
found out why
this happen with EXTERNAL_TOOLCHAIN and doesn't fail on a normal build.

The error is this

kmodloader.c: In function 'main_loader':
1339kmodloader.c:1027:41: error: ignoring return value of 'asprintf'
declared with attribute 'warn_unused_result' [-Werror=unused-result]
1340make[1]: *** [package/Makefile:116: package/system/ubox/compile] Error 1
1341 1027 | asprintf(&m->opts, "%s %s", prev, opts);
1342 | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1343cc1: all warnings being treated as errors

The package is compiled with -Wall so it does make sense that the
error is printed...

Fact is that the error(warning) is actually correct but I couldn't
understand why it was
not flagged on normal build and here the reason...

In rules.mk we have
TARGET_CFLAGS+= -fhonour-copts -Wno-error=unused-but-set-variable
-Wno-error=unused-result
and this is only applied if EXTERNAL_TOOLCHAIN is not selected...

Now the question... WHY?

Considering even the linux kernel started to use Wall by default,
should we also start
enforcing correct code and fix every package that present such error?
Fixing these kind of error is trivial enough and IMHO we should drop these
warning disable.

I will create a PR in the next few days but wonder if anyone wants to
give some feedback
about why these extra flags are set. To me it seems they are just
leftover from older times?