roslyn: Cannot change initonly field outside its .ctor regression

Version Used: 2.6.0.62126 (1758d50b)

Steps to Reproduce:

Compile following code

struct S
{
	public enum Type
	{
		Error
	}

	readonly Type type;

	public override string ToString ()
	{
		return type.ToString ();
	}

	public static void Main ()
	{
	}
}

peverify output.exe

Expected Behavior:

No error (as in previous releases)

Actual Behavior:

[IL]: Error: [output.exe : S::ToString][offset 0x00000002] Cannot change initonly field outside its .ctor.

About this issue

Original URL
State: closed
Created 7 years ago
Comments: 28 (26 by maintainers)

Most upvoted comments

I started using VS 2017 update 15.7.0 yesterday. I switched a SQL CLR project to using <LangVersion>latest</LangVersion> (for C# 7.3), and I changed several member fields to use readonly per the IDE0044 recommendation. Then I started getting the “Cannot change initonly field outside its .ctor.” error when trying to use SQL’s CREATE ASSEMBLY command. Thankfully, I found this issue, and the fix was just adding <Features>peverify-compat</Features> into my .csproj file.

I wanted to post this here in case anyone else runs into SQL CLR errors with this like I did. My full error message was this:

System.Data.SqlClient.SqlException: CREATE ASSEMBLY for assembly ‘XXX.Sql.Common’ failed because assembly ‘XXX.Sql.Common’ failed verification. Check if the referenced assemblies are up-to-date and trusted (for external_access or unsafe) to execute in the database. CLR Verifier error messages if any will follow this message [ : XXX.Data.XxxCommand::PostExecute][mdToken=0x6000361][offset 0x0000006E] Cannot change initonly field outside its .ctor.

FWIW, I’m using [assembly: AllowPartiallyTrustedCallers] per Microsoft’s recommendation for SQL CLR assemblies. But after going to the C# 7.3 compiler, the peverify-compat feature is required.

I also wanted to mention this here since @jaredpar said above on Oct 4, 2017, “The runtime team is generally skeptical that PEVerify is in significant use.” For anyone using SQL CLR with safe or external_access assemblies, we’re stuck with PEVerify. We may not count as “significant use”, but we don’t want to be left out of using the latest language changes. 😃

menees on May 8, 2018

@Suchiman Yes, that’s indeed the effort that we’re counting on.

jcouv on Oct 22, 2017

Yes it is /features:peverify-compat

jaredpar on Oct 4, 2017