~/temp_code » ./greetings
  Traceback (most recent call last)
  greetings.nim(9)        greetings
  greetings.nim(6)        hola
  SIGSEGV: Illegal storage access. (Attempt to read from nil?)

  type
    Greetings = ref object
      name: string

  proc hola(g: Greetings) =
    echo g.name

  var g: Greetings
  g.hola()

  $ cat main.d
  import std.stdio;

  class Greetings {
	void hello() {
		writeln("hello");
	}
  }

  void main()
  {
	Greetings g = null;
	g.hello();
  }
  $ dmd -g main.d && ./main
  Segmentation fault: 11
  $ uname -a
  Darwin Johan-Ride-Mac.local 15.0.0 Darwin Kernel Version 15.0.0: Sat Sep 19 15:53:46 PDT 2015; root:xnu-3247.10.11~1/RELEASE_X86_64 x86_64
  $ dmd --version
  DMD64 D Compiler v2.069.0
  Copyright (c) 1999-2015 by Digital Mars written by Walter Bright

I know it's because I'm trying to call a method on "null", but If I'm working on a huge code base, how do I debug this kind of issues if I don't have stack trace with line and error number of the error?

I'd like to get at least the stack trace and the error number with the line of the source code that caused the problem, like in golang:

  $ cat main.go
  package main
  
  type Greetings struct {
  }
  
  func (g Greetings) hello() {

  }

  func main() {
	g := &Greetings{} // heap instance
	g = nil           // intentionally shooting myself in the foot like I did in D
	g.hello()
  }
  $ go run main.go
  panic: runtime error: invalid memory address or nil pointer dereference
  [signal 0xb code=0x1 addr=0x0 pc=0x2025]

  goroutine 1 [running]:
  main.main()
	/Users/ride/Documents/main.go:13 +0x15

  goroutine 2 [runnable]:
  runtime.forcegchelper()
	/opt/boxen/homebrew/Cellar/go/1.4.2/libexec/src/runtime/proc.go:90
  runtime.goexit()
	/opt/boxen/homebrew/Cellar/go/1.4.2/libexec/src/runtime/asm_amd64.s:2232 +0x1
  exit status 2

If you are working in a big codebase and have this come up, you can enable core dumps and run it in a debugger to get far more information than just a line number (and line numbers are there too at least if compiled in debug mode).

http://vibed.org/docs#handling-segmentation-faults

  $ dmd -g main.d && ./main
  Segmentation fault: 11

I'm OSX El Capitan 10.11.1

  import etc.linux.memoryerror;
  
  shared static this() {
   	static if (is(typeof(registerMemoryErrorHandler)))
   		registerMemoryErrorHandler();
  }

to be honest, it's better than nothing but still kinda difficult to work with:

  etc.linux.memoryerror.NullPointerError@src/etc/linux/memoryerror.d(325)
  ----------------
  ??:? void etc.linux.memoryerror.sigsegvUserspaceProcess(void*) [0x439045]
  ??:? void etc.linux.memoryerror.sigsegvDataHandler() [0x438f92]
  ??:? _Dmain [0x435c17]
  ??:? _D2rt6dmain211_d_run_mainUiPPaPUAAaZiZ6runAllMFZ9__lambda1MFZv [0x4376da]
  ??:? void rt.dmain2._d_run_main(int, char**, extern (C) int function(char[][])*).tryExec(scope void delegate()) [0x437630]
  ??:? void rt.dmain2._d_run_main(int, char**, extern (C) int function(char[][])*).runAll() [0x437696]
  ??:? void rt.dmain2._d_run_main(int, char**, extern (C) int function(char[][])*).tryExec(scope void delegate()) [0x437630]
  ??:? _d_run_main [0x43758d]
  ??:? main [0x436075]
  ??:? __libc_start_main [0xb0fa1ec4]

You can also do it manually btw with `addr2line -e your_executable 0x435c17` and the sort.

  $ dmd -g main.d && ./main
  etc.linux.memoryerror.NullPointerError@src/etc/linux/memoryerror.d(325)
  ----------------
  ??:? void etc.linux.memoryerror.sigsegvUserspaceProcess(void*) [0x423321]
  ??:? void etc.linux.memoryerror.sigsegvDataHandler() [0x42326e]
  main.d:12 _Dmain [0x4204e5]
  ??:? _D2rt6dmain211_d_run_mainUiPPaPUAAaZiZ6runAllMFZ9__lambda1MFZv [0x421b8a]
  ??:? void rt.dmain2._d_run_main(int, char**, extern (C) int function(char[][])*).tryExec(scope void delegate()) [0x421ae0]
  ??:? void rt.dmain2._d_run_main(int, char**, extern (C) int function(char[][])*).runAll() [0x421b46]
  ??:? void rt.dmain2._d_run_main(int, char**, extern (C) int function(char[][])*).tryExec(scope void delegate()) [0x421ae0]
  ??:? _d_run_main [0x421a3d]
  ??:? main [0x420597]
  ??:? __libc_start_main [0xdb825ec4]

2) Spanish ?