ast/astutil: deprecate Cursor.Import

Cursor.Import always creates name-mangled imports to avoid collisions.
It was created before astutil.Sanitize, which does a much better job of
detecting whether name manglation is required or not.

Remove the one remaining use of Cursor.Import, in cmd/import.go;
Mark the Cursor.Import API as deprecated.

Sadly, it's a public API so we can't just remove it.

Signed-off-by: Matthew Sackman <matthew@cue.works>
Change-Id: I2adc92f93198e4988af7d9277b894262d0a5a8ce
Dispatch-Trailer: {"type":"trybot","CL":1200507,"patchset":2,"ref":"refs/changes/07/1200507/2","targetBranch":"master"}

cmd/cue/cmd/import.go

@@ -551,17 +551,15 @@ func (h *hoister) hoist(f *ast.File) {
 				return false
 			}
 
-			pkg := c.Import("encoding/" + enc)
-			if pkg == nil {
-				return false
+			importIdent := &ast.Ident{
+				Name: enc,
+				Node: ast.NewImport(nil, "encoding/"+enc),
 			}
 
 			// found a replaceable string
 			dataField := h.uniqueName(name, "_", "cue_")
 
-			f.Value = ast.NewCall(
-				ast.NewSel(pkg, "Marshal"),
-				ast.NewIdent(dataField))
+			f.Value = ast.NewCall(ast.NewSel(importIdent, "Marshal"), ast.NewIdent(dataField))
 
 			// TODO: use definitions instead
 			c.InsertAfter(astutil.ApplyRecursively(&ast.LetClause{
@@ -571,6 +569,7 @@ func (h *hoister) hoist(f *ast.File) {
 		}
 		return true
 	})
+	astutil.Sanitize(f)
 }
 
 func tryParse(str string) (s ast.Expr, pkg string) {

cmd/cue/cmd/testdata/script/import_hoiststr.txtar

@@ -2,24 +2,24 @@ exec cue import -o - --recursive ./import/data.json
 cmp stdout expect-stdout
 -- expect-stdout --
 import (
-	json656e63 "encoding/json"
-	yaml656e63 "encoding/yaml"
+	"encoding/json"
+	"encoding/yaml"
 )
 
 foo: {
 	name:  "something"
-	json1: json656e63.Marshal(_cue_json1)
+	json1: json.Marshal(_cue_json1)
 	let _cue_json1 = [1, 2]
-	json2: json656e63.Marshal(_cue_json2)
+	json2: json.Marshal(_cue_json2)
 	let _cue_json2 = {
 		key: "value"
 	}
-	yaml1: yaml656e63.Marshal(_cue_yaml1)
+	yaml1: yaml.Marshal(_cue_yaml1)
 	let _cue_yaml1 = {
 		a: "b"
 		c: "d"
 	}
-	yaml2: yaml656e63.Marshal(_cue_yaml2)
+	yaml2: yaml.Marshal(_cue_yaml2)
 	let _cue_yaml2 = [
 		"one",
 		"two",

cue/ast/astutil/apply.go

@@ -46,6 +46,9 @@ type Cursor interface {
 	// Import reports an opaque identifier that refers to the given package. It
 	// may only be called if the input to apply was an ast.File. If the import
 	// does not exist, it will be added.
+	//
+	// Deprecated: use [ast.NewImport] as an [ast.Ident.Node], and then
+	// [Sanitize].
 	Import(path string) *ast.Ident
 
 	// Replace replaces the current Node with n.
@@ -120,6 +123,8 @@ func (c *cursor) Parent() Cursor { return c.parent }
 func (c *cursor) Index() int     { return c.index }
 func (c *cursor) Node() ast.Node { return c.node }
 
+// Deprecated: use [ast.NewImport] as an [ast.Ident.Node], and then
+// [Sanitize].
 func (c *cursor) Import(importPath string) *ast.Ident {
 	info := fileInfo(c)
 	if info == nil {