[NativeAOT] env var timing at startup

[jonathanpeppers]

Android framework version

net11.0-android (Preview)

Affected platform version

.NET 11

Description

There is a timing issue for startup on NativeAOT:

• If you set an env var specific to the runtime, like $DOTNET_STARTUP_HOOKS
• NativeAOT runs startup hooks before any of our managed code runs
• Then our startup code is called, and we populate env vars
• But then its too late, $DOTNET_STARTUP_HOOKS was already read

Hot Reload doesn't work on NativeAOT, but this could be problematic for other runtime-specific env vars.

To fix, I think we'd have to call Java -> native code, to set env vars earlier at startup.

Steps to Reproduce

Run tests\Mono.Android-Tests\Mono.Android-Tests\Mono.Android.NET-Tests.csproj.

But remove the check for NativeAOT:

<!-- Set STARTUP_HOOKS via RuntimeHostConfigurationOption for MonoVM and NativeAOT (read via AppContext.GetData) -->
<RuntimeHostConfigurationOption Include="STARTUP_HOOKS" Value="StartupHook" Condition=" '$(UseMonoRuntime)' == 'true' or '$(PublishAot)' == 'true' " />

To rely on $DOTNET_STARTUP_HOOKS=StartupHook instead.

Did you find any workaround?

Set STARTUP_HOOKS app context switch.

Relevant log output