nimTracelog

I developed this tool to debug the Nim compiler. Just copy tracelog.nim to Nim/compiler/ folder, and add {.trace.} macro to functions. For example in semexpr.nim just replace

proc semIs(c: PContext, n: PNode): PNode =
  ...

to

import tracelog
proc semIs(c: PContext, n: PNode): PNode {.trace.} =
  ...

After compiling the compiler with ./koch boot, you can enable this tool by running: tracelog=test.nim nim c -r test.nim where test.nim is an arbitrary file to compile.

The output contains all the stacktrace to your function:

nim.nim(115) nim
 nim.nim(71) handleCmdLine
  main.nim(253) mainCommand
   main.nim(64) commandCompileToC
    modules.nim(226) compileProject
     modules.nim(209) compileSystemModule
      modules.nim(172) compileModule
       passes.nim(203) processModule
        passes.nim(137) processTopLevelStmt
         sem.nim(461) myProcess
          sem.nim(433) semStmtAndGenerateGenerics
...

and also lists the variables and lines from the function:

                     +n: (PNode) {  "kind": "nkCommand",  "sons": [    { "kind": "nkIdent", "ident": "echo", "info": ["test.nim", 16, 0]    },    { "kind": "nkCall", "sons": [   {     "kind": "nkIdent",     "ident": "first",     "info": ["test.nim", 16, 5]   },   {     "kind": "nkPrefix",     "sons": [  {    "kind": "nkIdent",    "ident": "@",    "info": ["test.nim", 16, 11]  },  {    "kind": "nkBracket",    "sons": [      { "kind": "nkIntLit", "intVal": 10, "info": ["test.nim", 16, 13]      },      { "kind": "nkIntLit", "intVal": 11, "info": ["test.nim", 16, 16]      },      { "kind": "nkIntLit", "intVal": 12, "info": ["test.nim", 16, 19]      }    ],    "info": ["test.nim", 16, 12]  }     ],     "info": ["test.nim", 16, 11]   } ], "info": ["test.nim", 16, 10]    }  ],  "info": ["test.nim", 16, 5]}
                     |if m.magic in {mArrGet, mArrPut}:
                     |  m.state = csMatch
                     |  m.call = n
                     |  return
                     |var marker = initIntSet()
                     +marker: ???
                     |matchesAux(c, n, nOrig, m, marker)
                   sigmatch.nim(1795) matches
                    sigmatch.nim(1752) matchesAux
                     sigmatch.nim(1592) prepareOperand
                      semexprs.nim(26) semOperand
                       semexprs.nim(2342) semExpr
...

#tracelogsimple

The tracelogsimple.nim is a simplified version of tracelog.nim. You can use it in a regular (not compiler) nim program. For example:

import tracelogsimple
proc fib(n: int): int {.trace.} =
  if n < 2:
    return n
  result = fib(n-1) + fib(n-2)
  return result

echo fib(4)

Results:

fib.nim(8) fib
 tracelogsimple.nim(27) fib
   +n: (int) 4
   +result: (int) 0
   |if n < 2:
   |  return n
   |result = fib(n - 1) + fib(n - 2)
 fib.nim(5) fib
  tracelogsimple.nim(27) fib
    +n: (int) 3
    |if n < 2:
    |  return n
    |result = fib(n - 1) + fib(n - 2)
  fib.nim(5) fib
   tracelogsimple.nim(27) fib
     +n: (int) 2
     |if n < 2:
     |  return n
     |result = fib(n - 1) + fib(n - 2)
   fib.nim(5) fib
    tracelogsimple.nim(27) fib
      +n: (int) 1
      |if n < 2:
      |  return n
      +n: (int) 0
      |if n < 2:
      |  return n
   tracelogsimple.nim(27) fib
     +n: (int) 2
     +result: (int) 1
     |return result
     +n: (int) 1
     +result: (int) 0
     |if n < 2:
     |  return n
  tracelogsimple.nim(27) fib
    +n: (int) 3
    +result: (int) 2
    |return result
    +n: (int) 2
    +result: (int) 0
    |if n < 2:
    |  return n
    |result = fib(n - 1) + fib(n - 2)
  fib.nim(5) fib
   tracelogsimple.nim(27) fib
     +n: (int) 1
     |if n < 2:
     |  return n
     +n: (int) 0
     |if n < 2:
     |  return n
  tracelogsimple.nim(27) fib
    +n: (int) 2
    +result: (int) 1
    |return result
 tracelogsimple.nim(27) fib
   +n: (int) 4
   +result: (int) 3
   |return result
3