fix(sem): nimsuggest crashing for ill-formed AST

[bung87]

Summary

Fix nimsuggest, and other tooling that uses a custom structured
report hook, crashing when encountering ill-formed AST that has the
wrong number of nodes.

Details

Many of the semantic analysis procedures first verify that the input
PNode has the right number of child nodes. This is done via the
checkSonsLen and checkMinSonsLen procedures, with the expectation
being that both raise an ERecoverableError (through globalReport)
when the check fails.

However, since reporting the error happens via handleReport, it's
possible that the error handling strategy is overridden with a mode
(e.g., doNothing) that results in execution to continue without any
exception being raised. nimsuggest sets the error handling mode to
doNothing, which then resulted in checkSonsLen and
checkMinSonsLen not ending the active routine, usually leading to
IndexDefects or other crashes.

As an interim solution, the reportAndFail procedure is introduced.
reportAndForceRaise works similar to similar to handleReport, but
it ensures that at least an exception is raised -- both
checkSonsLen and checkMinSonsLen use it to ensure that the calling
routine is exited.

[zerbina]

Thank you. Can the other PR be closed now?

The details section in the PR message is good, but the title and summary need to be adjusted. This PR represents a significant fix for nimsuggest, but it also affects compiles, both which needs to be highlighted.

Regarding the implementation, I've left some requests regarding code style, documentation, and test improvements.

[zerbina]

Sorry for not noticing this earlier. As is, the implementation ignores the default actions, which means that --errorMax is ignored by reportAndForceRaise.

You need to change reportAndForceRaise to first go through errorActions (refer to handleReport for how this should look like), before forcing doNothing to doRaise.

At this point, I think that reportAndFail would be a better name for the procedure.

[bung87]

like this?

case conf.report(rep)
of doAbort:
  quit 1
of doDefault:
  let (action, trace) = errorActions(conf, rep, eh)
  case action
  of doAbort:
    quit 1
  of doRaise, doNothing:
    raiseRecoverableError("report")
of doRaise, doNothing:
  raiseRecoverableError("report")

[zerbina]

Hmm, I just noticed a much simpler and also more broad fix that also fixes internalError being turned into a no-op by the hook. The reporting subsystem is quite convoluted, and I have some trouble navigating it.

However, I don't want to block this PR any longer, and would thus make a follow-up PR myself. In the meantime, this fix works well enough. Sorry for all the detours, and thank you for working on this.

[zerbina]

@bung87 I've updated the PR message and title, please take a look at it:

• I reworded the title so that it's a bit shorter
• the summary gives a broad overview of what failed and what works now. For a tooling-related fix, this should focus on user-facing behaviour. The previous summary listed the implementation details, but didn't summarize the fixed issue

Once the remaining suggestion is applied, this PR is good to be merged.

[bung87]

Hmm, I just noticed a much simpler and also more broad fix that also fixes internalError being turned into a no-op by the hook. The reporting subsystem is quite convoluted, and I have some trouble navigating it.

However, I don't want to block this PR any longer, and would thus make a follow-up PR myself. In the meantime, this fix works well enough. Sorry for all the detours, and thank you for working on this.

I also think this can be simpler, eg. the condition can depends on config.cmd that give a default handling that doesn't need TErrorHandling returns from user side. but I didn't think further.

[zerbina]

/merge

[github-actions]

Merge requested by: @zerbina

Contents after the first section break of the PR description has been removed and preserved below:

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Notes for Reviewers

this is made for following @zerbina suggestion.