[TODO] [feature] Nim error messages should show line contents, would save lots of debugging time

[timotheecour]

• proposal: add an option --showLineContext:int

this would save tons of debugging time:

with --showLineContext:0 (default value), same as current behavior

/Users/timothee/git_clone/nim/timn/bugs/t15_tuple.nim(47, 17) template/generic instantiation from here
/Users/timothee/.nimble_choosenim/pkgs/tuples-0.1.0/tuples.nim(324, 7) template/generic instantiation from here
/Users/timothee/.nimble_choosenim/pkgs/tuples-0.1.0/tuples.nim(49, 15) template/generic instantiation from here
/Users/timothee/.nimble_choosenim/pkgs/tuples-0.1.0/tuples.nim(74, 16) Error: identifier expected, but found '0'

with --showLineContext:1

/Users/timothee/git_clone/nim/timn/bugs/t15_tuple.nim(47, 17) template/generic instantiation from here:  let a1 = a0 & ("8 / 2", 4).to1Tuple
/Users/timothee/.nimble_choosenim/pkgs/tuples-0.1.0/tuples.nim(324, 7) template/generic instantiation from here:   join((tup0, tup1))
/Users/timothee/.nimble_choosenim/pkgs/tuples-0.1.0/tuples.nim(49, 15) template/generic instantiation from here:     iteration a
/Users/timothee/.nimble_choosenim/pkgs/tuples-0.1.0/tuples.nim(74, 16) Error: identifier expected, but found '0':     iterateFor a, b

possible future extension: --showLineContext:2,3
shows 2 lines above(including self line), 3 lines below (strictly below)

/Users/timothee/git_clone/nim/timn/bugs/t15_tuple.nim(47, 17) template/generic instantiation from here:
  when true:
    let a1 = a0 & ("8 / 2", 4).to1Tuple
  else:
    let a1 = a0
  # when true:
/Users/timothee/.nimble_choosenim/pkgs/tuples-0.1.0/tuples.nim(324, 7) template/generic instantiation from here:
  ## ``join((tup0, tup1))``.
  join((tup0, tup1))

proc zipExpr(outerLen, innerLen: int): PNimrodNode {.compileTime.} =
  result = newPar()

• with --colorizeLineContext:true we'd also:

• highlight (say in green) line at context 0 to distinguish from context above/below
• highlight (say in blue) (with underscore, so it works with spaces too) column mentioned in error message EDIT

EDIT nimgrep's logic can be reused for that purpose

[dom96]

Pretty sure --verbosity:3 already shows this.

[timotheecour]

with --verbosity:3 all i get is 1 line context at the last entry; which is quite different and not as useful. Oftentimes, the relevant information the user is searching for is not in the last entry.

/Users/timothee/git_clone/nim/timn/bugs/t15_tuple.nim(47, 17) template/generic instantiation from here
/Users/timothee/.nimble_choosenim/pkgs/tuples-0.1.0/tuples.nim(324, 7) template/generic instantiation from here
/Users/timothee/.nimble_choosenim/pkgs/tuples-0.1.0/tuples.nim(49, 15) template/generic instantiation from here
/Users/timothee/.nimble_choosenim/pkgs/tuples-0.1.0/tuples.nim(74, 16) Error: identifier expected, but found '0'
      iterateFor a, b
                 ^

Also, it's doing other stuff too; it's good to keep features orthogonal

[alehander92]

I have to agree, I even think it's very useful to file context visible by default: would that somehow break anything depending on the output?

[alehander92]

verbosity:3 shows one line indeed, and it also shows too much stuff one usually doesn't need

[Araq]

----hint[source]:on is the switch to get this. Somebody needs to make it the default and/or document it.

[timotheecour]

@Araq
I added hint[Source]:on to nim.cfg and it still shows error messages without line contents, eg:

nim c -o:app -r bugs/t20_jester_type_mismatch.nim
Hint: used config file '/Users/timothee/.choosenim/toolchains/nim-#devel/config/nim.cfg' [Conf]
Hint: used config file '/Users/timothee/.config/nim.cfg' [Conf]
Hint: used config file '/Users/timothee/git_clone/nim/timn/nim.cfg' [Conf]
/Users/timothee/.nimble_choosenim/pkgs/jester-0.2.0/jester.nim(531, 21) Error: type mismatch: got <Time> but expected 'int'

(note: as for the error itself, i just filed dom96/jester#138)

also tried with: ----hint[source]:on or hint[source]:on

I would expect to see line contents instead, eg smthg like:

/Users/timothee/.nimble_choosenim/pkgs/jester-0.2.0/jester.nim(531, 21) Error: type mismatch: got <Time> but expected 'int': var tim = Time(int(getTime()) + days * (60 * 60 * 24))

[Araq]

@timotheecour, strange, I tested it from command line and it worked just fine. It's also enabled with --verbosity:2 fwiw.

[timotheecour]

NOTE: also, it's verbosity:2 or 3, not 3.

EDIT

It's also enabled with --verbosity:2 fwiw.

lol, hadn't seen your comment above, posted that at same time...
however still doesn't work with '--hint[Source]:on' unless i add --verbosity:2 or hack proc liMessage in msgs.nim ;

[timotheecour]

• not sure why it works for you but not in my setup; in any case even with --verbosity:2 it just prints last context, not all contexts
• a (partial) fix seems easy, with this patch it always prints context, so I just need to make it depend on hintSource or another cmd line param:

      # if msg in errMin..errMax and hintSource in gNotes:
      #   info.writeSurroundingSrc
      info.writeSurroundingSrc

• when color mode is enabled, using underline instead of a caret below would save 1 line
• not sure if it adds non-negligible processing time, if it does, it shd stay as a non-default option

i could try a PR tmrw

[timotheecour]

=> #7635

[CodeDoes]

this should be closed

[Araq]

I marked it with "documentation". The documentation has not been improved.

[drslump]

I had a go at documenting the hints #8625

[timotheecour]

/cc @dom96 could we reopen? the problem is still there:

proc foo2[]()=
  var foo2: int = 3.0
proc foo1[]()=
  foo2()
proc main()=
  foo1()

main()

nim c --hint:source:on issue_7586.nim

issue_7586.nim(5, 1) template/generic instantiation from here
issue_7586.nim(6, 7) template/generic instantiation from here
issue_7586.nim(4, 7) template/generic instantiation from here
issue_7586.nim(2, 19) Error: type mismatch: got <float64> but expected 'int'
    var foo2: int = 3.0
                    ^

instead of:

issue_7586.nim(7, 1) template/generic instantiation from here
    proc main()=
issue_7586.nim(8, 7) template/generic instantiation from here
    foo1()
issue_7586.nim(6, 7) template/generic instantiation from here
    foo2()
issue_7586.nim(4, 19) Error: type mismatch: got <float64> but expected 'int'
    var foo2: int = 3.0
                    ^

it doesn't have to be the default with --hint:source:on, it could be via --hint:sourceAll:on if needed, there needs to be a flag for that