internal: hoist a single embedding in ToExpr

Fixes #368
Fixes #369

Change-Id: I0161fbd14f59685f559c992a82a999df41522224
Reviewed-on: https://cue-review.googlesource.com/c/cue/+/7362
Reviewed-by: CUE cueckoo <cueckoo@gmail.com>
Reviewed-by: Marcel van Lohuizen <mpvl@golang.org>

cmd/cue/cmd/orphans.go

@@ -150,11 +150,6 @@ func (b *buildPlan) placeOrphans(i *build.Instance) (ok bool, err error) {
 	return true, nil
 }
 
-func toExpr(f *ast.File) (expr ast.Expr, pkg *ast.Package) {
-	p := len(f.Preamble())
-	return &ast.StructLit{Elts: f.Decls[p:]}, pkg
-}
-
 func placeOrphans(cmd *Command, filename, pkg string, objs ...*ast.File) (*ast.File, error) {
 	f := &ast.File{}
 
@@ -163,7 +158,8 @@ func placeOrphans(cmd *Command, filename, pkg string, objs ...*ast.File) (*ast.F
 		if i == 0 {
 			astutil.CopyMeta(f, file)
 		}
-		expr, p := toExpr(file)
+		expr := internal.ToExpr(file)
+		p, _, _ := internal.PackageInfo(file)
 
 		var pathElems []ast.Label
 		var pathTokens []token.Token

cmd/cue/cmd/testdata/script/import_list.txt

@@ -1,6 +1,14 @@
-cue import -o - -f -l "\(strings.ToLower(kind))" --list ./import
-cmp stdout expect-stdout
--- expect-stdout --
+cue import -o - -f -l "\(strings.ToLower(kind))" --list ./import1
+cmp stdout expect-stdout1
+
+# Issue #368
+cue import -o - -f --list ./import2
+cmp stdout expect-stdout2
+
+# Issue #369
+cue import --with-context -l '"\(path.Ext(filename))": data' ./import3/data.json
+cmpenv import3/data.cue expect3
+-- expect-stdout1 --
 service: [{
 	kind: "Service"
 	name: "booster"
@@ -17,7 +25,11 @@ deployment: [{
 	name:     "booster"
 	replicas: 1
 }]
--- import/services.jsonl --
+-- expect-stdout2 --
+[[{a: 1}], [{b: 2}]]
+-- expect3 --
+".json": [1]
+-- import1/services.jsonl --
 {
     "kind": "Service",
     "name": "booster"
@@ -32,4 +44,9 @@ deployment: [{
     "name": "supplement\nfoo",
     "json": "[1, 2]"
 }
+-- import2/data.jsonl --
+[{"a": 1}]
+[{"b": 2}]
+-- import3/data.json --
+[1]
 -- cue.mod --

internal/internal.go

@@ -259,7 +259,13 @@ func ToExpr(n ast.Node) ast.Expr {
 				break outer
 			}
 		}
-		return &ast.StructLit{Elts: x.Decls[start:]}
+		decls := x.Decls[start:]
+		if len(decls) == 1 {
+			if e, ok := decls[0].(*ast.EmbedDecl); ok {
+				return e.Expr
+			}
+		}
+		return &ast.StructLit{Elts: decls}
 
 	default:
 		panic(fmt.Sprintf("Unsupported node type %T", x))