[SR-2605] Cascading failures trying to parse if <expr> else #45210
Description
| Previous ID | SR-2605 |
| Radar | None |
| Original Reporter | @jckarter |
| Type | Bug |
| Status | Closed |
| Resolution | Done |
Additional Detail from JIRA
| Votes | 0 |
| Component/s | Compiler |
| Labels | Bug, DiagnosticsQoI, Parser, StarterBug |
| Assignee | @modocache |
| Priority | Medium |
md5: 4700a3a0330dc628a2226b9d21b6eb4b
Issue Description:
If you're refactoring a guard into an if, it's easy to accidentally end up with invalid code like this in the transition:
if condition else {
}The parser rightly complains about the else, but has poor recovery afterward, interpreting the following brace as a closure, which may in turn lead to other unhelpful errors after:
/Users/jgroff/src/s/swift/stdlib/public/core/Optional.swift:517:32: error: expected '{' after 'if' condition
if source === _nilSentinel else {
^
/Users/jgroff/src/s/swift/stdlib/public/core/Optional.swift:517:37: error: braced block of statements is an unused closure
if source === _nilSentinel else {
^It might be friendlier to recognize this pattern and instead recover as if the else wasn't there, or as if there were an empty block before it.