Member references

The full ILAsm form always works:

call void [System.Console]System.Console::WriteLine(string)
callvirt instance string [System.Runtime]System.Object::ToString()
newobj instance void [System.Runtime]System.Text.StringBuilder::.ctor()
ldsfld string [System.Runtime]System.String::Empty

Three shortcuts make the prompt friendlier:

• The [assembly] prefix is optional. Types are searched across every loaded assembly.
• A short name resolves through the common System namespaces, so Console, Math, StringBuilder, and List<int32> work as written.
• The return type is optional. It is only used to break ties between overloads.

Tab completes the type and, after ::, the member in these short forms. Each overload has its own row; the detail pane shows its complete signature.

For jmp, the palette offers targets whose calling convention, return type, and parameters match the enclosing method, including a compatible receiver for instance methods. At cell level it uses the cell’s object return type and .args declarations. ldftn does not require the target to share the enclosing signature.

call Console::WriteLine(string)
call Math::Max(int32, int32)
callvirt instance int32 List<int32>::get_Count()

Overloads are matched by exact parameter types. When several remain the error lists them:

il[1]> call Console::WriteLine
  error: ambiguous: Console::WriteLine; give parameter types. candidates:
      void Console::WriteLine()
      void Console::WriteLine(bool)
      void Console::WriteLine(char)
      void Console::WriteLine(char[])
      void Console::WriteLine(char[], int32, int32)
      void Console::WriteLine(Decimal)
      void Console::WriteLine(float64)
      void Console::WriteLine(float32)
      void Console::WriteLine(int32)
      void Console::WriteLine(uint32)
      void Console::WriteLine(int64)
      void Console::WriteLine(uint64)

If the name is mistyped, the error suggests a nearby name that binds the supplied reference:

il[1]> call Math::Mxa(int32, int32)
  error: no method 'Mxa' on Math (did you mean 'Max'?)
il[1]> newobj StringBuilderr::.ctor()
  error: type 'StringBuilderr' not found (did you mean 'StringBuilder'?)

Generics

Generic instantiations use ILAsm syntax with or without the arity suffix. Inside a member reference, !0 is the declaring type’s first type argument and !!0 is the method’s. The declaring type and explicit generic arguments use the caller’s scope. Completion also works when those arguments are still generic parameters. A retained suffix participates in constraint checks: int32[] satisfies class, while int32 satisfies valuetype.

newobj instance void class [System.Collections]System.Collections.Generic.List`1<int32>::.ctor()
callvirt instance void class List`1<int32>::Add(!0)
call !!0 [System.Linq]System.Linq.Enumerable::First<int32>(class IEnumerable`1<!!0>)

Fields and tokens

ldsfld string String::Empty
ldfld int32 Greeter.Counter::Count
ldtoken int32
ldtoken method void Console::WriteLine()
ldtoken field string String::Empty

Function pointers and varargs

ldftn int32 Math::Max(int32, int32)
calli int32(int32, int32)
calli unmanaged cdecl int32(int32)
call vararg int32 Greeter.Hello::CountArgs(..., int32, string)

The types after ... are the call site’s extra arguments. The runtime only supports the vararg calling convention on Windows; elsewhere the cell is refused with a message that says so.

Array signature bounds

Completion preserves the sizes and lower bounds encoded in a member signature. For example, int32[3] declares size 3 with lower bound zero, and int32[1...3] declares size 3 with lower bound one. These can identify different overloads even though reflection reports the same array type for both.

CLI metadata can also declare a size while omitting the lower bound entirely. ilrepl spells that shape int32[...+3], keeping it distinct from int32[3]. This spelling works in member references, completion, and disassembly. .save preserves the exact metadata in the exported assembly. Native ILAsm has no equivalent spelling, so .il reports this limitation and points to .save instead of producing a reference that could call a different overload.

Session methods

A method defined with .method is called by name, with no type in front of it. The return type is optional here too, and ldftn takes the same reference.

call int32 Fib(int32)
call Fib(int32)
ldftn int32 Fib(int32)

See Methods.

Your own assemblies

.load takes a path or an assembly name. After that its types resolve like any other, with or without the [assembly] prefix.

il[1]> .load samples/Greeter/bin/Debug/net10.0/Greeter.dll
  loaded Greeter 1.0.0.0 (22 public types)
il[1]> ldstr "IL"
  ┊ [string]
il[1]> call string Greeter.Hello::Say(string)
  ┊ [string]
il[1]> ret
  = "Hello, IL!" : string

A suggestion is qualified when the short name would be ambiguous:

il[2]> ldtoken Countr
  error: type 'Countr' not found (did you mean 'Greeter.Counter'?)