remove all instances of: raises: [Defect]

[timotheecour]

rationale 1

procs should be able to raise a Defect by default. Future work can add ability to specify that a proc does not (recursively) generate a Defect. This PR doesn't contradict such design.

rationale 2

compiler (correctly) gives: Hint: 'fn' cannot raise 'Defect' [XCannotRaiseY] here:

when true:
  proc fn*(input: string) {.raises: [Defect].} =
    if input == "asdfadfadf1": raise newException(AssertionDefect, "asdf")
    if input == "asdfadfadf2": doAssert false
    if input == "asdfadfadf3": (var a = 500; var b = a.int8)
  fn("bar")

rationale 3

this doesn't give any warnings/errors

when true:
  proc fn*(input: string) {.raises: [].} =
    if input == "asdfadfadf1": raise newException(AssertionDefect, "asdf")
    if input == "asdfadfadf2": doAssert false
    if input == "asdfadfadf3": (var a = 500; var b = a.int8)
  fn("bar")

rationale 4

nim doc generates: proc fn(input: string) {.raises: [], tags: [].}

  proc fn*(input: string) =
    if input == "asdfadfadf1": raise newException(AssertionDefect, "asdf")
    if input == "asdfadfadf2": doAssert false
    if input == "asdfadfadf3": (var a = 500; var b = a.int8)
  fn("bar")

note

this holds true regardless of --panics:on|off

TODO

• this seems to fail because of bootstrap, eg:

$nim_1402_X c --lib:lib koch # works
$nim_csources_local_X c --lib:lib koch # fails: options.nim(176, 5) Error: can raise an unlisted exception: ref UnpackDefect
$nim_120_X c --lib:lib koch # ditto

• simplify assert/doAssert: the cast isn't needed anymore since 1.4.0:

proc failedAssertImpl*(msg: string) {.raises: [], tags: [].} =
  # trick the compiler to not list ``AssertionDefect`` when called
  # by ``assert``.
  type Hide = proc (msg: string) {.noinline, raises: [], noSideEffect,
                                    tags: [].}
  cast[Hide](raiseAssert)(msg)

links

• json module incompatible with checked exceptions #17399

[Araq]

Off topic: New csources are on hold until my M1 machine arrives which will be by the end of January.

[timotheecour]

this PR has to wait until csources_v1 is updated to >= 1.4.0 (which is now possible to do without breaking client code thanks to recent improvements in build_all.sh, CI + related logic)
refs timotheecour#251

[stale]

This pull request has been automatically marked as stale because it has not had recent activity. If you think it is still a valid PR, please rebase it on the latest devel; otherwise it will be closed. Thank you for your contributions.

[Araq]

Outdated and of minor importance.