[build] default $(JavacSource/TargetVersion) to 1.8 for Android code
#10050
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Fixes: #9922 Fixes: #9925 In 165cef7, we started compiling with Java 17 by default. This causes warnings in #9922 such as: "/Users/builder/android-toolchain/jdk-21/bin/java" -classpath "/Users/builder/azdo/_work/11/s/xamarin-android/bin/Release/lib/packs/Microsoft.Android.Sdk.Darwin/35.99.0/tools/r8.jar" com.android.tools.r8.D8 --release --no-desugaring --output "obj/Release/release" "/Users/builder/azdo/_work/11/s/xamarin-android/bin/Release/lib/packs/Microsoft.Android.Sdk.Darwin/35.99.0/tools/java_runtime.jar" Warning in /Users/builder/azdo/_work/11/s/xamarin-android/bin/Release/lib/packs/Microsoft.Android.Sdk.Darwin/35.99.0/tools/java_runtime.jar:mono/MonoPackageManager.class at Lmono/MonoPackageManager;LoadApplication(Landroid/content/Context;)V: Invoke-customs are only supported starting with Android O (--min-api 26) This also happens if we go back to Java 9. We can get rid of the warning by desugaring the code to API 21: * #10039 However, we think desugaring in itself could break something (especially for servicing). For now, we think the safest option is: * Target 1.8 for Java code targeting Android. * Desktop Java projects can still target 17. With these changes, tests like `BuildHasNoWarnings()` fail due to build warnings. Next: * When using the `-source` and `-target` switches in the `<Javac/>` MSBuild task, we can pass `-Xlint:-options` to `javac` to prevent warnings about these switches being deprecated. This change is suitable for servicing in .NET 9 and the `BuildHasNoWarnings()` test now passes.
dellis1972
approved these changes
Apr 17, 2025
jonathanpeppers
commented
Apr 17, 2025
Comment on lines
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to
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| <PropertyGroup> | ||
| <JavacSourceVersion Condition=" '$(JavacSourceVersion)' == '' And '$(AndroidApiLevel)' != '' And $(AndroidApiLevel) > 23 ">1.8</JavacSourceVersion> | ||
| <JavacSourceVersion Condition=" '$(JavacSourceVersion)' == '' ">1.6</JavacSourceVersion> | ||
| </PropertyGroup> |
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Note that this block wasn't doing anything, as $(AndroidApiLevel) is the latest stable in .NET 6+. It's always 36 now in main.
This was referenced Apr 17, 2025
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Fixes: #9922
Fixes: #9925
In 165cef7, we started compiling with Java 17 by default. This causes warnings in #9922 such as:
This also happens if we go back to Java 9.
We can get rid of the warning by desugaring the code to API 21:
Invoke-customswarning #10039However, we think desugaring in itself could break something (especially for servicing).
For now, we think the safest option is:
Target 1.8 for Java code targeting Android.
Desktop Java projects can still target 17.
With these changes, tests like
BuildHasNoWarnings()fail due to build warnings.Next:
-sourceand-targetswitches in the<Javac/>MSBuild task, we can pass-Xlint:-optionstojavacto prevent warnings about these switches being deprecated.This change is suitable for servicing in .NET 9 and the
BuildHasNoWarnings()test now passes.