How Can My Code Access "Global" or "Module-Level" Methods from C#?

Curtis Schlak

I've played with .NET/CLI for a while and have started learning MSIL/CIL.The following code compiles to a .NET executable without warning or error messages. ILASM reports in its output "Assembled global method HelloWorld."

.module HelloWorld.exe

.assembly extern mscorlib {}

.assembly MyAssembly
{
.ver 1: 0: 0: 0 /* Spaces because of smiley face replacement */
}

.method public hidebysig static void HelloWorldHelper() cil managed
{
ldstr "Hello, World!"
call void [mscorlib]System.Console::WriteLine(class System.String)
ret
}

.class public auto ansi HelloWorld
extends [mscorlib]System.Object
{
.method public hidebysig static void HelloWorld() cil managed
{
.entrypoint
call void HelloWorldHelper()
ret
}
}

My question: how can consuming C# code access the HelloWorldHelper method? For example:

/* consumer.cs */
public class Program
{
public static void Main(string[] args)
{
HelloWorldHelper();
}
}
/* end consumer.cs */

will fail to compile with "csc /r:HelloWorld.exe consumer.cs" with "error CS0103: The name 'HelloWorldHelper' does not exist in the current context." (In case you wonder why I care about this arcane use, I am writing a compiler that targets the .NET run time.)

"we must lose precision to make significant statements about complex systems." -deKorvin on uncertainty

Pete OHanlon

What would you expect to happen here? Your Main calls HelloWorldHelper which does not exist as a static method in the Program class.

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Curtis Schlak

Don't worry. I just did some more research and found that cross-assembly global references are not supported. I did this through writing MSIL code to consume the global function in another assembly and received a compile error informing me of this issue. For anyone interested, here's the code and command lines:

/* File: helloworld.il */

.assembly extern mscorlib {}

.assembly helloworld
{
.ver 1: 0: 0: 0 /* Remove spaces for compilation. They make smilies on CP. */
}

.method public static void HelloWorld()
{
ldstr "Hello World!"
call void [mscorlib]System.Console::WriteLine(class System.String)
ret
}

Compile with ilasm /DLL helloworld.il

/* File: printer.il */

.assembly extern mscorlib {}

.assembly extern helloworld
{
.ver 1: 0: 0: 0 /* Remove spaces for compilation. They make smilies on CP. */
}

.assembly Moo
{
.ver 1: 0: 0: 0 /* Remove spaces for compilation. They make smilies on CP. */
}

.class public auto ansi Program extends [mscorlib]System.Object
{
.method public hidebysig static void Main() cil managed
{
.entrypoint
call void [helloworld]::HelloWorld()
ret
}
}

Compile with ilasm printer.il You will receive something similar to the following error:

printer.il(17) : error -- Cross-assembly global references are not supported ('HelloWorld')
Assembled method Program::Main

***** FAILURE *****

"we must lose precision to make significant statements about complex systems." -deKorvin on uncertainty