fix(audience): prevent IL2CPP stripping of Unity hooks assembly#790
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Games using IL2CPP with High stripping and no project-level link.xml lose all Unity context fields (userAgent, locale, screen, timezone). The linker strips Immutable.Audience.Unity entirely when it finds no call sites, so the [RuntimeInitializeOnLoadMethod] hooks never fire and ContextProvider is never registered. [assembly: AlwaysLinkAssembly] forces the linker to process the assembly regardless of call sites. [Preserve] on AudienceUnityHooks keeps Install() alive once the assembly is included. [Preserve] alone is insufficient because the linker skips the assembly before evaluating attributes. Fixes SDK-480. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
bkbooth
approved these changes
Jun 10, 2026
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Fixes SDK-480.
Problem
Games built with IL2CPP + High stripping silently lose all Unity context fields (
userAgent,locale,screen,timezone) from every event. The linker strips the entireImmutable.Audience.Unityassembly when it finds no call sites into it — so the[RuntimeInitializeOnLoadMethod]hook never fires andContextProvideris never registered. OnlylibraryandlibraryVersionsurvive because they come fromImmutable.Audience.Runtime, which has direct references keeping it alive.The SDK ships a
link.xmlto guard against this, but Unity's linker skips it for packages loaded via afile:path outside the project tree. Studios without a project-levellink.xmlfallback hit this silently.Confirmed in production on project 18282: ~97% of 0.3.0 events are missing
userAgent. All 0.2.2 events from the same project had it — the regression correlates with them switching to an IL2CPP + High stripping build around the 0.3.0 upgrade.Fix
Two lines in
AudienceUnityHooks.cs:[assembly: AlwaysLinkAssembly]— forces the linker to process the assembly regardless of call sites[Preserve]on the class — keepsInstall()alive once the assembly is included[Preserve]alone is not enough: if the linker skips the assembly entirely, it never evaluates the attribute.Test plan
link.xmluserAgent,locale,screen,timezone)PersistentDataPath is requiredcrash on init