We've faced an issue that internal function get inlined in the public one and this in turn leads to MethodAccessException on caller side.

Repro steps

Repro zip is attached. just run MethodAccessBug console application in Release mode (not reproduced in Debug)

MethodAccessBug.zip

Expected behavior

Call to internal function is not inlined an no exception is thrown

Actual behavior

Call to internal function is inlined an exception is thrown

Unhandled exception. System.MethodAccessException: Attempt by method '<StartupCode$MethodAccessBug>.$Program.main@()' to access method 'InternalLib.InternalModule.doSmth()' failed.
   at <StartupCode$MethodAccessBug>.$Program.main@() in C:\Temp\MethodAccessBug\MethodAccessBug\Program.fs:line 3

Known workarounds

Decorate public method with

[<MethodImpl(MethodImplOptions.NoInlining)>]

or with

[<NoCompilerInlining>]

Related information

• Windows 11
• .NET 7