modfile: fix Cleanup clobbering Line reference

Fixes golang/go#45130

Change-Id: I2dccba5e958911177f10a5104a182f86ff8378d9
Reviewed-on: https://go-review.googlesource.com/c/mod/+/303234
Reviewed-by: Michael Matloob <matloob@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: David Chase <drchase@google.com>

modfile/read.go

@@ -226,16 +226,17 @@ func (x *FileSyntax) Cleanup() {
  continue
  }
  if ww == 1 && len(stmt.RParen.Comments.Before) == 0 {
- // Collapse block into single line.
- line := &Line{
+ // Collapse block into single line but keep the Line reference used by the
+ // parsed File structure.
+ *stmt.Line[0] = Line{
  Comments: Comments{
  Before: commentsAdd(stmt.Before, stmt.Line[0].Before),
  Suffix: commentsAdd(stmt.Line[0].Suffix, stmt.Suffix),
  After: commentsAdd(stmt.Line[0].After, stmt.After),
  },
  Token: stringsAdd(stmt.Token, stmt.Line[0].Token),
  }
- x.Stmt[w] = line
+ x.Stmt[w] = stmt.Line[0]
  w++
  continue
  }

modfile/read_test.go

@@ -603,3 +603,134 @@ comments before "// k"
  })
  }
 }
+
+func TestCleanup(t *testing.T) {
+ for _, test := range []struct {
+ desc string
+ want string
+ input []Expr
+ }{
+ {
+ desc: "simple_lines",
+ want: `line: module a
+line: require b v1.0.0
+`,
+ input: []Expr{
+ &Line{
+ Token: []string{"module", "a"},
+ },
+ &Line{
+ Token: []string{"require", "b", "v1.0.0"},
+ },
+ &Line{
+ Token: nil,
+ },
+ },
+ }, {
+ desc: "line_block",
+ want: `line: module a
+block: require
+blockline: b v1.0.0
+blockline: c v1.0.0
+`,
+ input: []Expr{
+ &Line{
+ Token: []string{"module", "a"},
+ },
+ &LineBlock{
+ Token: []string{"require"},
+ Line: []*Line{
+ {
+ Token: []string{"b", "v1.0.0"},
+ InBlock: true,
+ },
+ {
+ Token: nil,
+ InBlock: true,
+ },
+ {
+ Token: []string{"c", "v1.0.0"},
+ InBlock: true,
+ },
+ },
+ },
+ },
+ }, {
+ desc: "collapse",
+ want: `line: module a
+line: require b v1.0.0
+`,
+ input: []Expr{
+ &Line{
+ Token: []string{"module", "a"},
+ },
+ &LineBlock{
+ Token: []string{"require"},
+ Line: []*Line{
+ {
+ Token: []string{"b", "v1.0.0"},
+ InBlock: true,
+ },
+ {
+ Token: nil,
+ InBlock: true,
+ },
+ },
+ },
+ },
+ },
+ } {
+ t.Run(test.desc, func(t *testing.T) {
+ syntax := &FileSyntax{
+ Stmt: test.input,
+ }
+ syntax.Cleanup()
+
+ buf := &bytes.Buffer{}
+ for _, stmt := range syntax.Stmt {
+ switch stmt := stmt.(type) {
+ case *Line:
+ fmt.Fprintf(buf, "line: %v\n", strings.Join(stmt.Token, " "))
+ case *LineBlock:
+ fmt.Fprintf(buf, "block: %v\n", strings.Join(stmt.Token, " "))
+ for _, line := range stmt.Line {
+ fmt.Fprintf(buf, "blockline: %v\n", strings.Join(line.Token, " "))
+ }
+ }
+ }
+
+ got := strings.TrimSpace(buf.String())
+ want := strings.TrimSpace(test.want)
+ if got != want {
+ t.Errorf("got:\n%s\nwant:\n%s", got, want)
+ }
+ })
+ }
+}
+
+// Issue 45130: File.Cleanup breaks references so future edits do nothing
+func TestCleanupMaintainsRefs(t *testing.T) {
+ lineB := &Line{
+ Token: []string{"b", "v1.0.0"},
+ InBlock: true,
+ }
+ syntax := &FileSyntax{
+ Stmt: []Expr{
+ &LineBlock{
+ Token: []string{"require"},
+ Line: []*Line{
+ lineB,
+ {
+ Token: nil,
+ InBlock: true,
+ },
+ },
+ },
+ },
+ }
+ syntax.Cleanup()
+
+ if syntax.Stmt[0] != lineB {
+ t.Errorf("got:\n%v\nwant:\n%v", syntax.Stmt[0], lineB)
+ }
+}