mod/modfile: deprecate LatestKnownSchemaVersion

The "latest known schema version" is defined to be the
current language version which is now available as part
of the cue API. This function is not used, so deprecate
it, making it return `cueversion.LanguageVersion()` instead.

Signed-off-by: Roger Peppe <[email protected]>
Change-Id: Ie77d8225fbc5e12c888a7bff3d453c6e061fdf0f
Reviewed-on: https://review.gerrithub.io/c/cue-lang/cue/+/1196821
Reviewed-by: Paul Jolly <[email protected]>
TryBot-Result: CUEcueckoo <[email protected]>
Unity-Result: CUE porcuepine <[email protected]>

Author: rogpeppe

mod/modfile/modfile.go

@@ -232,32 +232,31 @@ func lookup(v cue.Value, sels ...cue.Selector) cue.Value {
 // should be at least this, because that's when we added the language.version
 // field itself.
 func EarliestClosedSchemaVersion() string {
-	return schemaVersionLimits()[0]
+	return earliestClosedSchemaVersion()
 }
 
-// LatestKnownSchemaVersion returns the language version
-// associated with the most recent known schema.
-func LatestKnownSchemaVersion() string {
-	return schemaVersionLimits()[1]
-}
-
-var schemaVersionLimits = sync.OnceValue(func() [2]string {
-	limits, _ := moduleSchemaDo(func(info *schemaInfo) ([2]string, error) {
+var earliestClosedSchemaVersion = sync.OnceValue(func() string {
+	earliest, _ := moduleSchemaDo(func(info *schemaInfo) (string, error) {
 		earliest := ""
-		latest := ""
 		for v := range info.Versions {
 			if earliest == "" || semver.Compare(v, earliest) < 0 {
 				earliest = v
 			}
-			if latest == "" || semver.Compare(v, latest) > 0 {
-				latest = v
-			}
 		}
-		return [2]string{earliest, latest}, nil
+		return earliest, nil
 	})
-	return limits
+	return earliest
 })
 
+// LatestKnownSchemaVersion returns the language version
+// associated with the most recent known schema.
+//
+// Deprecated: use [cuelang.org/go/cue.LanguageVersion] instead. This
+// function will be removed in v0.11.
+func LatestKnownSchemaVersion() string {
+	return cueversion.LanguageVersion()
+}
+
 // Parse verifies that the module file has correct syntax
 // and follows the schema following the required language.version field.
 // The file name is used for error messages.

mod/modfile/modfile_test.go

@@ -23,6 +23,7 @@ import (
 
 	"cuelang.org/go/cue/errors"
 	"cuelang.org/go/internal/cuetest"
+	"cuelang.org/go/internal/cueversion"
 	"cuelang.org/go/mod/module"
 )
 
@@ -545,7 +546,7 @@ func TestEarliestClosedSchemaVersion(t *testing.T) {
 }
 
 func TestLatestKnownSchemaVersion(t *testing.T) {
-	qt.Assert(t, qt.Equals(LatestKnownSchemaVersion(), "v0.9.0-alpha.0"))
+	qt.Assert(t, qt.Equals(LatestKnownSchemaVersion(), cueversion.LanguageVersion()))
 }
 
 func parseVersions(vs ...string) []module.Version {