C#: How does trim/AOT compilation work in .NET?

Trimming — remove unused code at publish time.

Trim modes:

• full: Aggressive, may break reflection.
• partial: Conservative, preserves public API.

.csproj config:

1<PropertyGroup>
2    <PublishTrimmed>true</PublishTrimmed>
3    <TrimMode>full</TrimMode>
4    <PublishAot>true</PublishAot>
5    <IlcOptimizationPreference>Size</IlcOptimizationPreference>
6</PropertyGroup>

AOT (Ahead-of-Time):

• Compiles to native code.
• No JIT needed at runtime.
• Smaller, faster startup.
• Larger binary size.

Compatibility warnings:

• Reflection-based serialization may fail.
• Dynamic code generation unsupported.
• Use source generators instead.

Tips:

• Test with ILTrimming warnings enabled.
• Prefer interfaces over reflection.
• Use [DynamicallyAccessedMembers] attributes.