cue-lang/cue v0.18.0-rc.1

on GitHub

Changes which may break some users are marked below with: ⚠️

Language

File attributes such as @experiment(...) and @extern(embed) are now honored between the package clause and the import declarations, where the spec allows them, rather than being silently ignored or rejected (#2371).

Evaluator

⚠️ Closedness now follows what a reference denotes rather than where it is evaluated. A reference which reaches into a definition from outside now closes the value it selects even when it is evaluated inside that definition, such as outside.s below, which was previously accepted. Conversely, a definition which refers to a regular struct no longer rejects a field which a sibling reference in that struct supplies, fixing a regression introduced in v0.18.0-alpha.3 (#4501).

outside: #Out
let Out = {s: {a: 1}, u: outside.s & {b: 2}} // error: field not allowed
#Out: Out

#P: {a?: int}
x: {q: {}, s: #P & q & {a: 3}}
#L: {v: x} // no longer rejects a

Disjuncts which differ only in constraints that can never apply, such as [...int] & [] and [...string] & [], or only in whether they were closed by close or by a definition, are deduplicated again, so that such a disjunction resolves rather than staying ambiguous. A disjunction whose disjuncts carry the same data but different constraints now gives the same result whichever disjunct comes first (#4503).

Errors in a value which is only reachable through a hidden field, a let, or an imported package are now reported by cue vet and cue.Value.Validate, where they were skipped.

cmd/cue

cue vet now checks every data file, and every document of a stream, against the schema and reports all of their errors, rather than stopping at the first one which fails to unify (#2511). cue eval likewise carries on past a failing data file, honoring --out and -i, and no longer writes its --outfile once any error has been reported.

Incomplete errors, such as missing required fields, are now reported alongside other errors when the input is a package too, as v0.18.0-alpha.3 already did for individual files (#3358).

cue eval --ignore --concrete now shows non-concrete values and reference cycles as errors in its output, as documented, rather than printing them as their expressions (#2342). The cue.Concrete option to cue.Value.Syntax behaves the same way.

cue fmt now keeps the source's line breaks between consecutive import declarations, as gofmt does, rather than forcing a blank line after each (#1545).

A number of formatting regressions compared with the old formatter have been fixed, most of them involving comments. Comments inside index brackets, after a unary operator, before an operand, before the closing brace of a struct, after a call argument, in an interpolation, in a pattern label, or between the clauses of a comprehension are now kept in place rather than dropped or moved where they swallowed the code which followed. Blank lines between comprehension clauses are kept, parentheses grouping a right-nested disjunction are kept, fields sharing a line are no longer padded to align with the rows around them, and the Compact option no longer drops comments.

cue def output of a file which enables aliasv2 in a module below language version v0.18.0 is now valid, keeping the @experiment attribute ahead of a package clause added via -p (#4434).

tool/exec.Run now fills stderr whether or not stdout is captured and whether or not the command succeeds, and fills either field with bytes when it is constrained to that type.

Modules

A ./... pattern now matches packages when the current directory is reached through a symbolic link.

Concurrent cue processes no longer fail to read logins.json on Windows while another one is updating it.

LSP server

Go-to-definition in a file reached through a symbolic link now reports the file which was actually imported. In a file shared by several packages, go-to-definition, find references, and rename no longer silently return nothing after an edit elsewhere in one of those packages.

The language server is more robust against clients: a workspace folder keeps working when the client does not support configuration requests or fails one, rather than crashing on the next edit, and requests sent before initialization or after shutdown are rejected as the protocol describes rather than crashing the server.

As always, the language server is under active development: please report any bugs or missing features you encounter via the Issue tracker or via the #lsp channels on Discord or Slack. See our Getting Started wiki page for instructions on how to set it up with your editor.

Encodings

The YAML encoder introduced in v0.18.0-alpha.1 fixes a number of regressions compared with the old one, and now documents the rules it follows: its output is valid YAML 1.2 which decodes back to the same value. Strings which go-yaml decoders such as the one used by Kubernetes would read as numbers, like 0X1F, and strings starting with --- or ... are quoted; strings with characters such as a no-break space no longer gain literal backslash escapes; strings consisting of only newlines, or with leading newlines before an indented line, no longer lose content; keys longer than 1024 characters are written in explicit form; comments on a flow collection stay outside of its brackets; and number literals are written only in the core schema's forms.

A @yaml tag can now be given to a list element or an embedded value via a declaration attribute, as in {"x", @yaml(,tag="!Env")}, and tags are written as valid YAML tags, reporting an error for a tag such as Env which is neither local nor a URI (#4269).

cue get go now emits an embedded Go struct as a spread embedding, #Embedded..., in modules at language version v0.18.0 or later, so that the generated definition keeps its own fields under strict embedding. Invalid flags are now reported before the Go packages are loaded, and loading is faster as function bodies are no longer type-checked.

Standard library

list.Sum, list.Product, list.Avg, list.Min, and list.Max once again compute over the elements present in an open list, as len and comprehensions do, undoing the change announced in v0.18.0-alpha.3 which reported any open list as incomplete (#2569).

list.Sort, list.SortStable, and list.IsSorted no longer panic on a comparator whose less field comes from a comprehension, an embedding, or a unification (#3063), and now report a comparator which lacks x or y or whose less is not a boolean as an error, which list.IsSorted used to drop.

⚠️ uuid.ToInt now decodes the 128-bit value of its UUID, as documented, rather than converting the bytes of its string form, so its results change. Any form accepted by uuid.Parse yields the same value, which round-trips through uuid.FromInt.

math.Pow now returns 1 for a zero exponent with any base, including zero, as documented (#4506).

The Windows functions of path now follow Go's path/filepath in handling UNC paths such as \\host\share, cleaning the result of path.Rel, and no longer turning a relative path into one with a volume name.

Go API

cue.Attribute.Kind now reports the kind of the attribute rather than zero for every attribute.

In cue/ast/astutil, Apply now updates references when any node is replaced, so that Sanitize no longer binds references to a replaced alias expression with a spurious let; Cursor.Modified reports a change to the last element of a list or call; and Cursor.Replace moves the comments of the old node to the new one rather than leaving both holding them, which printed each comment twice.

Syntax trees produced by exporting a value, such as via cue.Value.Syntax, no longer share nodes with the syntax from which the value was built, so that editing or formatting the result in place no longer alters later exports. Likewise, cue/load no longer modifies a syntax tree given as an overlay via FromFile when injecting tag values, and injects each tag value once into a file shared by several instances.

cue.Context.Encode now encodes a nil pointer of any type as null, including types implementing json.Marshaler or error, rather than panicking. cuego.Validate and cuego.Complete now report an error for a nil value rather than panicking while holding the package's lock, which left every later call blocked.

A tools/flow task returning ErrAbort no longer fails the whole flow: its results are dropped and the tasks depending on it are terminated with its error, as documented.