misc error msg

[timotheecour]

links

• [TODO] [feature] Nim error messages should show line contents, would save lots of debugging time · Issue #7586 · nim-lang/Nim

• [TODO] [error messages]: show col using visible marker instead of newline + caret, saves 2 lines per msg by timotheecour · Pull Request #7636 · nim-lang/Nim

• [TODO] address #7586: make hintsSource print context for all msgs, add by timotheecour · Pull Request #7635 · nim-lang/Nim

• [RFC] type mismatch error message improvement · Issue #87 · nim-lang/RFCs

• More colorful error messages by beef331 · Pull Request #16356 · nim-lang/Nim

[timotheecour]

• sigmatch err shd show loc of candidates
  eg: this is hard to grok:

when defined case2: # D20200419T033153
  var a = 10
  var b: uint = 12
  for i in a..b:
    echo $($type(i), i)

=> looks like some weird transfo was applied, and no clear reference to

  template dotdotImpl(t) {.dirty.} =
    iterator `..`*(a, b: t): t {.inline.} =

t10581.nim(37, 13) Error: type mismatch: got <HSlice[system.int, system.uint]>
but expected one of:
iterator items(E: typedesc[enum]): E:type
  first type mismatch at position: 1
  required type for E: type enum
  but expression 'a .. b' is of type: HSlice[system.int, system.uint]
iterator items(a: cstring): char
  first type mismatch at position: 1
  required type for a: cstring
  but expression 'a .. b' is of type: HSlice[system.int, system.uint]
iterator items(a: string): char
  first type mismatch at position: 1
  required type for a: string
  but expression 'a .. b' is of type: HSlice[system.int, system.uint]
iterator items[IX, T](a: array[IX, T]): T
  first type mismatch at position: 1
  required type for a: array[IX, T]
  but expression 'a .. b' is of type: HSlice[system.int, system.uint]
iterator items[T](a: openArray[T]): T
  first type mismatch at position: 1
  required type for a: openArray[T]
  but expression 'a .. b' is of type: HSlice[system.int, system.uint]
iterator items[T](a: seq[T]): T
  first type mismatch at position: 1
  required type for a: seq[T]
  but expression 'a .. b' is of type: HSlice[system.int, system.uint]
iterator items[T](a: set[T]): T
  first type mismatch at position: 1
  required type for a: set[T]
  but expression 'a .. b' is of type: HSlice[system.int, system.uint]
iterator items[T](s: HSlice[T, T]): T
  first type mismatch at position: 1
  required type for s: HSlice[items.T, items.T]
  but expression 'a .. b' is of type: HSlice[system.int, system.uint]

expression: items(a .. b)
    for i in a..b:

[timotheecour]

• allow show where msgs came from (liMessage + localError + globalError)
  => will fix CT sizeof(+friends) for {.importc, completeStruct.} types, enable ABI static checks nim-lang/Nim#13926 (comment) more generally

[timotheecour]

• hint:processing:on should show include files; also should show more info about modules (eg option for full path; module name, and whether it's include or import; and by what module it came from)

[timotheecour]

-[ ] and has to be used (or discarded); start of expression here: points to wrong location

D20200506T223706

nim r $timn_D/tests/nim/all/t10700.nim
/Users/timothee/git_clone/nim/timn/tests/nim/all/t10700.nim(9, 1) template/generic instantiation from here
/Users/timothee/git_clone/nim/timn/tests/nim/all/t10700.nim(12, 6) Error: expression 'ret2`gensym36362015' is of type 'int' and has to be used (or discarded); start of expression here: /Users/timothee/git_clone/nim/timn/tests/nim/all/t10700.nim(10, 3)
to2("12", int)
^

template to2*[S](a: S, T: typed): untyped =
  var ret2: T
  ret2

proc main()=
  var ret: int
  ret = 1
  to2("12", int)
main()

[timotheecour]

• report at most 1 error per line would go a long way and is easy to implement

refs nim-lang#16001 (comment)
refs TITLE: nim check (or --errormax:N) reports redundant errors · Issue #16178 · nim-lang/Nim

[timotheecour]

• see https://elm-lang.org/news/compiler-errors-for-humans

I've just read the elm blog and I'm very impressed - clear and explicit. The json output they have could be really useful for IDEs as well.

[timotheecour]

• fix #16150 improve type mismatch errors nim-lang/Nim#16152 (comment)

fix the column number in errmsg in nim-lang#16150 (comment)

[timotheecour]

• option to avoid template expansion when showing errmsgs via renderTree, and instead showing source code or renderTree before any template expansion / constant folding

refs: nim-lang#16152 (comment)

[timotheecour]

• borrow gives bad errmsgs D20200417T010112

type P = distinct pointer
proc fun(a: P): string {.borrow.}

t10570.nim(12, 6) Error: type mismatch: got <pointer>
but expected one of:
proc fun(a: P): string
  first type mismatch at position: 1
  required type for a: P
  but expression '' is of type: pointer

expression: fun()
  proc fun(a: P): string {.borrow.}

at very least, '' and fun() are wrong