Build error -target 7 and -source 7 is not supported in 21.0.2

[chouzz]

Operating System

Windows

Version of Prism Launcher

Prism Launcher 8.2

Version of Qt

Qt6

Description of bug

Build Prism launcher error, -target 7 and -source 7 is not supported in 21.0.2

Steps to reproduce

• Fllowing build instruction in msys2 in windows https://prismlauncher.org/wiki/development/build-instructions/
• Installed jdk21.0.2 in https://adoptium.net/
• Cmake and run Ninja

Get errors about java compiler option -target 7 and -source 7, it said these options is not supported in jdk21.0.2

Suspected cause

The problem is clear, higher version does not support -source 7 option, maybe Prisim Launcher should make it clearer in

PrismLauncher/libraries/javacheck/CMakeLists.txt

Line 7 in 51443fc

set(CMAKE_JAVA_COMPILE_FLAGS -target 7 -source 7 -Xlint:deprecation -Xlint:unchecked)

, at least send a message tell the user if it builds an error.

This issue is unique

• I have searched the issue tracker and did not find an issue describing my bug.

[AndrewAmmerlaan]

See #1013

FWIW, in Gentoo we now patch java 7 to java 8 conditional to whether the version of openjdk is larger then 20. This avoids the problem but, as noted in the linked issue, may introduce problems for very old versions of Minecraft. We therefore print a warning when we do this and instruct the user to select an older openjdk version if they experience problems. Perhaps something similar could be done upstream to avoid the compile failure.