add SecondClosestCommentLines to go2idl types.Type

cmd/libs/go2idl/parser/parse.go

@@ -300,7 +300,13 @@ func (b *Builder) FindTypes() (types.Universe, error) {
 			tn, ok := obj.(*tc.TypeName)
 			if ok {
 				t := b.walkType(u, nil, tn.Type())
-				t.CommentLines = b.priorCommentLines(obj.Pos())
+				c1 := b.priorCommentLines(obj.Pos(), 1)
+				t.CommentLines = c1.Text()
+				if c1 == nil {
+					t.SecondClosestCommentLines = b.priorCommentLines(obj.Pos(), 2).Text()
+				} else {
+					t.SecondClosestCommentLines = b.priorCommentLines(c1.List[0].Slash, 2).Text()
+				}
 			}
 			tf, ok := obj.(*tc.Func)
 			// We only care about functions, not concrete/abstract methods.
@@ -319,14 +325,11 @@ func (b *Builder) FindTypes() (types.Universe, error) {
 	return u, nil
 }
 
-// if there's a comment on the line before pos, return its text, otherwise "".
-func (b *Builder) priorCommentLines(pos token.Pos) string {
+// if there's a comment on the line `lines` before pos, return its text, otherwise "".
+func (b *Builder) priorCommentLines(pos token.Pos, lines int) *ast.CommentGroup {
 	position := b.fset.Position(pos)
-	key := fileLine{position.Filename, position.Line - 1}
-	if c, ok := b.endLineToCommentGroup[key]; ok {
-		return c.Text()
-	}
-	return ""
+	key := fileLine{position.Filename, position.Line - lines}
+	return b.endLineToCommentGroup[key]
 }
 
 func tcFuncNameToName(in string) types.Name {
@@ -401,7 +404,7 @@ func (b *Builder) walkType(u types.Universe, useName *types.Name, in tc.Type) *t
 				Embedded:     f.Anonymous(),
 				Tags:         t.Tag(i),
 				Type:         b.walkType(u, nil, f.Type()),
-				CommentLines: b.priorCommentLines(f.Pos()),
+				CommentLines: b.priorCommentLines(f.Pos(), 1).Text(),
 			}
 			out.Members = append(out.Members, m)
 		}

cmd/libs/go2idl/parser/parse_test.go

@@ -211,6 +211,47 @@ type Blah struct {
 	}
 }
 
+func TestParseSecondClosestCommentLines(t *testing.T) {
+	const fileName = "base/foo/proto/foo.go"
+	testCases := []struct {
+		testFile map[string]string
+		expected string
+	}{
+		{
+			map[string]string{fileName: `package foo
+// Blah's SecondClosestCommentLines.
+// Another line.
+
+// Blah is a test.
+// A test, I tell you.
+type Blah struct {
+	a int
+}
+`},
+			"Blah's SecondClosestCommentLines.\nAnother line.\n",
+		},
+		{
+			map[string]string{fileName: `package foo
+// Blah's SecondClosestCommentLines.
+// Another line.
+
+type Blah struct {
+	a int
+}
+`},
+			"Blah's SecondClosestCommentLines.\nAnother line.\n",
+		},
+	}
+	for _, test := range testCases {
+		_, u, o := construct(t, test.testFile, namer.NewPublicNamer(0))
+		t.Logf("%#v", o)
+		blahT := u.Type(types.Name{Package: "base/foo/proto", Name: "Blah"})
+		if e, a := test.expected, blahT.SecondClosestCommentLines; e != a {
+			t.Errorf("struct second closest comment wrong, wanted %v, got %v", e, a)
+		}
+	}
+}
+
 func TestTypeKindParse(t *testing.T) {
 	var testFiles = map[string]string{
 		"a/foo.go": "package a\ntype Test string\n",

cmd/libs/go2idl/types/types.go

@@ -231,6 +231,23 @@ type Type struct {
 	// they will be recorded here.
 	CommentLines string
 
+	// If there are comment lines preceding the `CommentLines`, they will be
+	// recorded here. There are two cases:
+	// ---
+	// SecondClosestCommentLines
+	// a blank line
+	// CommentLines
+	// type definition
+	// ---
+	//
+	// or
+	// ---
+	// SecondClosestCommentLines
+	// a blank line
+	// type definition
+	// ---
+	SecondClosestCommentLines string
+
 	// If Kind == Struct
 	Members []Member