Java min version for master sources?

[Stephan Bergmann]

On 21/05/2019 10:53, julien2412 wrote:
> Meanwhile, I took a look about prerequisites.
> For MacOs, it seems Java min version is 1.8 (see
> https://wiki.documentfoundation.org/Development/BuildingOnMac)
> On Window, it's 1.7 min (see
> https://wiki.documentfoundation.org/Development/BuildingOnWindows)

The baseline is actually Java 6.  We use `javac --target 1.6` (see 
JAVA_TARGET_VER in configure.ac) to generate code that is compatible 
with the Java 6 JVM spec, and our source code must only use Java API 
features that are present in Java 6 (though `javac --source 1.6 --target 
1.6` apparently doesn't check that).

> To simplify all this, can we move to Java 1.8 min for every OS for master
> sources? (future 6.3) Or is it too late and we should wait for 6.3 branching
> and so it'd be for future 6.4?

Increasing the baseline should mainly be a compatible change, as old 
code (e.g., extensions) should continue to work with newer Java 
installations.  The only drawback is that code compiled against the 
newer baseline (e.g., the URE jars from our builds being distributed 
somewhere on the Maven infrastructure?) cannot be used with older Java 
installations.

But with LO 6.3 branch-off just around the corner, I'd make any 
discussion of increasing the baseline only target LO 6.4.