Is there a symbol for aot?

[WeihanLi]

I'd like to write some code excluded for AOT, wondering if there's something like #if AOT to write conditional code for AOT only or none AOT only?

[huoyaoyuan]

You can use RuntimeFeature.IsDynamicCodeSupported as a feature guard. Preprocessors won't work here because AOT uses the same C# compilation.

[WeihanLi]

get it, thanks very much

[am11]

IsDynamicCodeSupported is not reliable either: dotnet/BenchmarkDotNet#2561 (comment). If you want to check if PublishAot=true, you can propagate it via <DefineConstants Condition="'$(PublishAot)' == 'true'">$(DefineConstants);NATIVEAOT</DefineConstants> and check #if NATIVEAOT, like runtime repo is doing:

runtime/src/coreclr/nativeaot/Directory.Build.props

Line 43 in be013ed

<DefineConstants>NATIVEAOT;NETCOREAPP</DefineConstants>

runtime/src/libraries/System.Private.CoreLib/src/System/Threading/ThreadBlockingInfo.cs

Line 115 in be013ed

#if NATIVEAOT

[vitek-karas]

In general we recommend to try

• Write the code in an AOT compatible way for every target (the core libraries should take of most of this for you)
• Determine what exact functionality you rely on (dynamic code generation, assembly files, ...) and use the appropriate feature check like IsDynamicCodeSupported.
• If it's not possible to make the code AOT compatible at all, decorate it with RequiresDynamicCodeAttribute so that whoever calls it is notified that it will not work with AOT.