Get method signature location (line/column numbers) through mono.cecil

[xi-liu-ds]

Hi,

As it is easy to get the location of method body instructions through MethodDefinition.DebugInformation.SequencePoints of mono.cecil, I am wondering can we get the location, such as line number and column number, of method name and signature through mono.cecil?

Thanks!

[huynhit24]

You can check it out this way.
Source

[xi-liu-ds]

You can check it out this way. Source

Thanks for your prompt response! However, I was actually asking if we can get the location of method signature or method name, like what is indicated in the attached code snippet below.

using System;

namespace HelloWorld
{
  class Program
  {
    static void Main(string[] args)        // <- location of this part of the code
    {
      Console.WriteLine("Hello World!");    
    }
  }
}

[Zastai]

Unfortunately, no. The MethodDef table in the CLR metadata doesn't store source information, and the Portable PDB metadata's method debug info is based on IL offsets within methods (docs). The sequence points, if present, are stored in offset order, so if there are sequence points, the first one will be the one closest to the method declaration, but that's the best you can do.

[Zastai]

Usually (i.e. if it's the result of a normal C# compilation using the Microsoft compiler), certainly in a Debug build (not 100% about Release builds), there'll be a sequence point attached to a nop instruction at the top for the { of the method.

So if you use the standard MS style with the { on a line of its own, then you could have a basic heuristic of:

• if there are sequence points
• the method starts with a nop which has a sequence point
• that sequence point describes a single character
• then the method declaration will be one line before that (obviously, longer signatures may start earlier)

Looking now, constructors seem different; they don't get a nop, but they start with an invocation of Object::.ctor which has a sequence point covering the signature.

Of course, none of the above is guaranteed in any way.

[ltrzesniewski]

Methods start with a nop only in debug builds for instance 🙂