ILVerification fails unexpectedly on delegate construction

[jcouv]

Description

Assignments of an extension method to Action trips ILVerification.

Reproduction Steps

Compile the following C# code and verify it.

The verification fails with:
Unrecognized arguments for delegate .ctor. { Offset = 21 } // that's 0x15
Unrecognized arguments for delegate .ctor. { Offset = 59 } // that's 0x3B

using System;
static class Program
{
    static void Main()
    {
        "ABC".Goo();
        Action a = "123".Goo;
        a();
        a = new Action(a);
        a();
        a = new Action("xyz".Goo);
        a();
    }
    static void Goo(this string x)
    {
        Console.WriteLine(x);
    }
}

// ILVerify:
//     Unrecognized arguments for delegate .ctor. { Offset = 21 } // that's 0x15
//     Unrecognized arguments for delegate .ctor. { Offset = 59 } // that's 0x3B
.class private auto ansi abstract sealed beforefieldinit Program
	extends [netstandard]System.Object
{
	.custom instance void [netstandard]System.Runtime.CompilerServices.ExtensionAttribute::.ctor() = (
		01 00 00 00
	)
	// Methods
	.method private hidebysig static 
		void Main () cil managed 
	{
		// Method begins at RVA 0x2050
		// Code size 70 (0x46)
		.maxstack 2
		.entrypoint
		IL_0000: ldstr "ABC"
		IL_0005: call void Program::Goo(string)
		IL_000a: ldstr "123"
		IL_000f: ldftn void Program::Goo(string)
		IL_0015: newobj instance void [netstandard]System.Action::.ctor(object, native int)
		IL_001a: dup
		IL_001b: callvirt instance void [netstandard]System.Action::Invoke()
		IL_0020: ldftn instance void [netstandard]System.Action::Invoke()
		IL_0026: newobj instance void [netstandard]System.Action::.ctor(object, native int)
		IL_002b: callvirt instance void [netstandard]System.Action::Invoke()
		IL_0030: ldstr "xyz"
		IL_0035: ldftn void Program::Goo(string)
		IL_003b: newobj instance void [netstandard]System.Action::.ctor(object, native int)
		IL_0040: callvirt instance void [netstandard]System.Action::Invoke()
		IL_0045: ret
	} // end of method Program::Main
	.method private hidebysig static 
		void Goo (
			string x
		) cil managed 
	{
		.custom instance void [netstandard]System.Runtime.CompilerServices.ExtensionAttribute::.ctor() = (
			01 00 00 00
		)
		// Method begins at RVA 0x20a2
		// Code size 7 (0x7)
		.maxstack 8
		IL_0000: ldarg.0
		IL_0001: call void [netstandard]System.Console::WriteLine(string)
		IL_0006: ret
	} // end of method Program::Goo
} // end of class Program

This was found in Roslyn, test: ExtensionMethodTests.ExtensionMethodInTheSameClass. Discussion

Expected behavior

No error (ie. same behavior as PEVerify)

Actual behavior

Unrecognized arguments for delegate .ctor. { Offset = 21 }
Unrecognized arguments for delegate .ctor. { Offset = 59 }

Regression?

No response

Known Workarounds

No response

Configuration

No response

Other information

No response

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Issue Details

---

Description

Assignments of an extension method to Action trips ILVerification.

Reproduction Steps

Compile the following C# code and verify it.

The verification fails with:
Unrecognized arguments for delegate .ctor. { Offset = 21 } // that's 0x15
Unrecognized arguments for delegate .ctor. { Offset = 59 } // that's 0x3B

using System;
static class Program
{
    static void Main()
    {
        "ABC".Goo();
        Action a = "123".Goo;
        a();
        a = new Action(a);
        a();
        a = new Action("xyz".Goo);
        a();
    }
    static void Goo(this string x)
    {
        Console.WriteLine(x);
    }
}

// ILVerify:
//     Unrecognized arguments for delegate .ctor. { Offset = 21 } // that's 0x15
//     Unrecognized arguments for delegate .ctor. { Offset = 59 } // that's 0x3B
.class private auto ansi abstract sealed beforefieldinit Program
	extends [netstandard]System.Object
{
	.custom instance void [netstandard]System.Runtime.CompilerServices.ExtensionAttribute::.ctor() = (
		01 00 00 00
	)
	// Methods
	.method private hidebysig static 
		void Main () cil managed 
	{
		// Method begins at RVA 0x2050
		// Code size 70 (0x46)
		.maxstack 2
		.entrypoint
		IL_0000: ldstr "ABC"
		IL_0005: call void Program::Goo(string)
		IL_000a: ldstr "123"
		IL_000f: ldftn void Program::Goo(string)
		IL_0015: newobj instance void [netstandard]System.Action::.ctor(object, native int)
		IL_001a: dup
		IL_001b: callvirt instance void [netstandard]System.Action::Invoke()
		IL_0020: ldftn instance void [netstandard]System.Action::Invoke()
		IL_0026: newobj instance void [netstandard]System.Action::.ctor(object, native int)
		IL_002b: callvirt instance void [netstandard]System.Action::Invoke()
		IL_0030: ldstr "xyz"
		IL_0035: ldftn void Program::Goo(string)
		IL_003b: newobj instance void [netstandard]System.Action::.ctor(object, native int)
		IL_0040: callvirt instance void [netstandard]System.Action::Invoke()
		IL_0045: ret
	} // end of method Program::Main
	.method private hidebysig static 
		void Goo (
			string x
		) cil managed 
	{
		.custom instance void [netstandard]System.Runtime.CompilerServices.ExtensionAttribute::.ctor() = (
			01 00 00 00
		)
		// Method begins at RVA 0x20a2
		// Code size 7 (0x7)
		.maxstack 8
		IL_0000: ldarg.0
		IL_0001: call void [netstandard]System.Console::WriteLine(string)
		IL_0006: ret
	} // end of method Program::Goo
} // end of class Program

This was found in Roslyn, test: ExtensionMethodTests.ExtensionMethodInTheSameClass. Discussion

Expected behavior

No error (ie. same behavior as PEVerify)

Actual behavior

Unrecognized arguments for delegate .ctor. { Offset = 21 }
Unrecognized arguments for delegate .ctor. { Offset = 59 }

Regression?

No response

Known Workarounds

No response

Configuration

No response

Other information

No response

Author:	jcouv
Assignees:	-
Labels:	area-ILVerification
Milestone:	-