sem: fix crash due to incorrect error handling

zerbina commented 4 months ago

Summary

Wrap usage of erroneous symbols in quiet errors, so that error propagation works as expected. This fixes compiler/nimsuggest crashes when the iterable expression in for loops has an error.

Fixes https://github.com/nim-works/nimskull/issues/1369.

Details

The Problem

If the iterable slot of a for loop is an error, tyError is assigned as the forvars' type. When such forvar appears as an argument in a call expression, errors

The Solution

add the adWrappedSymError diagnostic, which is a quiet diagnostic like adWrappedError, meaning that it's only used for error propagation and never reported
move newSymNode2 from ast to sem and change it so that it creates adWrappedSymError error nodes for symbols where the definition has an error
rename newSymNode2 to newSymNodeOrError
update the few usages of newSymNode2
add test for the for-loop-related compiler crash to the new error_propagation category

The introduction of adWrappedSymError is meant to be a foundational work for changing skError to only represent errors (instead of both errors and symbols whose definition has an error).

zerbina commented 4 months ago

Thank you, I've changed the name.

zerbina commented 4 months ago

/merge

github-actions[bot] commented 4 months ago

Merge requested by: @zerbina

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

## Notes for Reviewers * next up is removing `adSemCalleeHasAnError` and `transitionToError`

nim-works / nimskull