Evaluator

Fix two regressions introduced in earlier v0.18 pre-releases: a hang when selecting through optional fields of an inline struct, as in {x: y?: z?: int}.x.y.z (#4561), and __reclose structs written by cue fix which could stay open depending on evaluation order.

Fix a hang when a comprehension ranges over a field which is part of a structural cycle; the cycle is now reported as an error.

cmd/cue

Fix a panic in cue def when an aliased field refers to itself from within a quoted label of the same name, and avoid new names clashing with an import which cue def adds.

Modules

Fetching modules through a registry proxy which compresses its responses or omits Content-Length now works.

LSP server

The language server no longer fails to load a package whose directory holds a symbolic link to a directory, a broken link, or an unreadable file, and no longer blocks on a FIFO (#4491).

Fix a regression introduced in v0.17.0 where finding definitions and references failed through an import of a package from a transitive module dependency (#4553).

Go API

Fix a data race in cue.Iterator.Next and cue.Value.LookupPath on a value shared between goroutines, as well as spurious cycle errors and a panic in cue.Value.MarshalJSON when a for clause ranges over a field sharing a definition.

Fix a panic in cue.Value.Unify on a field of a definition which other fields share (#4549).

cue.Value.Subsume no longer overflows the stack when comparing recursive definitions such as #A: [...#A], and with cue.Final it now accepts data lists such as [] against [...string] under the openlists experiment (#4545).

Fix regressions introduced in earlier v0.18 pre-releases: in cue/format, an explicit indent width of zero indented with spaces, and an unsupported node type gave empty output rather than an error; and subsumption failed between open lists of different lengths.

cue/parser no longer takes quadratic or worse time on some pathological inputs, such as deeply nested parentheses, calls, or function signatures, long runs of invalid bytes, and many comment groups.