When looking up methods via reflection, be trimming/AOT-friendly

[roji]

• [x] Stop using GetRequiredRuntimeMethod (see this comment)
• [ ] When looking up generic methods, use the pattern described here (thanks @hez2010)

[0xced]

I just got this exception when executing a self-contained, trimmed executable with EF Core 6.0.0:

System.TypeInitializationException: The type initializer for 'Microsoft.EntityFrameworkCore.SqlServer.Query.Internal.SqlServerMathTranslator' threw an exception.
---> System.InvalidOperationException: Could not find method 'Ceiling' on type 'System.Math'
at System.SharedTypeExtensions.GetRequiredRuntimeMethod(Type type, String name, Type[] parameters)
at Microsoft.EntityFrameworkCore.SqlServer.Query.Internal.SqlServerMathTranslator..cctor()

I quickly realized it was because of trimming and I had to disable it.

I see you explicitly mention GetRequiredRuntimeMethod which appears in this stack trace so I'm looking forward to a trimming friendly version of EF Core. 😉

[roji]

@0xced yeah, this is one of the high-priority items for EF7 - stay tuned, it'll hopefully make it into an early preview.

[seriouz]

We ran in this issue, too when switching to .NET6 / EF6 with trimmed binaries on production systems (Docker Images). Very annoying, now the builds can't be trimmed anymore 😢

[roji]

For a workaround with EF Core 6, see this (thanks @EjaYF).

[lechgu]

verified, workaround fixes the issue for my scenario, thanks @EjaYF, @roji. Will this be officially fixed in .net 6?

[roji]

This issue is in the 7.0.0 milestone. There's little chance we'll be fixing this in 6.0.0, but we'll discuss that after the fix is done and the general trimming situation is clearer.

[seriouz]

EF6 is LTS so people will use it until 8. November 2024. In my opinion the trimming fix should be made in EF6 when it will be supported for such a long time.

[roji]

@seriouz @lechgu @EjaYF if someone can share a minimal, trimmed console application which works with EF Core 5.0 (i.e. executes some trivial query), that would help push this forward. I'm seeing various linker-related failures when doing that, since EF Core 5.0 (and 6.0) weren't annotated for trimming in any way.

[roji]

Never mind, I've managed to get a trimmed version working here. I'll update soon.

[roji]

FYI I've merged #27098 for 6.0.2 - that's a temporary fix which specifically fixes the Math-related errors; in my testing it allowed at least basic queries to run properly in trimmed applications. This isn't a guarantee that everything will work - just an attempt to unblock people for basic usage. I'm tackling trimming in a more serious way for 7.0, please report any further problems you run across.