Chandler Carruth 366cb1010b Recover an incomplete lambda as a complete expression. (#7435) ...

A lambda introducer (`fn` in expression context) with no parameters and
no body -- for example `(fn)`, where `)` immediately follows `fn` --
left `HandleLambdaAfterParams` calling `ReturnErrorOnState()` without
ever emitting a `Lambda` node. The orphaned `LambdaIntroducer` leaf was
then left where an expression was required, so `Parse` produced a tree
that failed its own verification and aborted via `CARBON_FATAL`.

Recover the way `HandleLambdaBody` already does for a missing body after
a return type: emit a placeholder `InvalidParse` body and finish a
complete `Lambda` node, so the lambda stays a valid expression and the
surrounding construct (here a `ParenExpr`) extracts cleanly.

Found by fuzzing.

Assisted-by: Claude Code

2026-06-29 21:12:58 +00:00

..

lambda.carbon

Recover an incomplete lambda as a complete expression. (#7435)

2026-06-29 21:12:58 +00:00