Bug#218893: Autodetecting existence of build-arch target

[Andreas Metzler <ametzler@downhill.at.eu.org>]

Hello,
I have recently asked Scott James Remnant[1] on IRC for comments on this
problem and the proposed solution (#229357), to add Build-Options:
build-arch' to debian/control if the package supported this target.

I gathered that he was not in favour of it and prompted for alternate
solutions he suggested

make -f debian/rules -pn | grep '^binary-arch:'

This is different to the solution dpkg-buildpackage tried and dropped
some time ago:

| dpkg (1.10.15) unstable; urgency=low
[...]
|   * Back out debian/rules build-arch detection.  It is *not* possible *at
|     all* to detect available targets in a rules file.  Period.
[...]
| dpkg (1.10.11) unstable; urgency=low
[...]
|   * Patch dpkg-buildpackage to call debian/rules -qn build-arch, and if
|     it's available, modify -B handling appropriately.  If build-arch is not
|     available, then when -B was called, do *not* pass -B on to
|     dpkg-checkbuilddeps.  Closes: #203097

Of course all the examples I tried work with both variants. debian-dpkg
does not yield any reference to example that failed during the short
interval build-arch detection was tried.
               cu andreas
[1] cced to make sure I do not misrepresent him.
-- 
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