RFR: JDK-8276572: Fake libsyslookup.so library causes tooling issues

[Aleksey Shipilev]

On Thu, 4 Nov 2021 04:19:02 GMT, Andrew John Hughes <andrew at openjdk.org> wrote:

> The lack of anything to compile in `syslookup.c` is leading to a number of issues in our tooling, on some architectures more than others (s390x seems to be the most problematic).  They expect to be able to retrieve debuginfo and compiler flags from generated .so files and fail with libsyslookup.so
> 
> This simple patch adds a dummy function to `syslookup.c` so it appears more like a regular file to be compiled. I can't see this causing a problem with the symbol lookup, but we could filter it out on the Java side if need be.

Marked as reviewed by shade (Reviewer).

What do we have to lose if we have the non-static method in this library? I think it is less risky and intrusive than disabling warnings, making sure linkers are not removing the unused definiton, etc. IIRC, some toolchains (S390?) have linkers configured to strip unused symbols. Let's go with the PR in its current form.

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PR: https://git.openjdk.java.net/jdk/pull/6245