fix

minifier.go

@@ -217,6 +217,9 @@ func (m *minifier) printExpr(n ast.Expr) {
 	case *ast.InterfaceType:
 		m.printInterfaceType(n)
 
+	case *ast.IndexListExpr:
+		m.printIndexListExpr(n)
+
 	default:
 		m.panicUnhandled("printExpr", n)
 	}
@@ -476,6 +479,11 @@ func (m *minifier) printGenDecl(n *ast.GenDecl) {
 			}
 		case *ast.TypeSpec:
 			m.out.WriteString(spec.Name.Name)
+			if spec.TypeParams != nil {
+				m.out.WriteString("[")
+				m.printFieldList(spec.TypeParams, ',')
+				m.out.WriteString("]")
+			}
 			if spec.Assign != token.NoPos {
 				m.out.WriteByte('=')
 			} else {
@@ -514,6 +522,12 @@ func (m *minifier) printBinaryExpr(n *ast.BinaryExpr) {
 		}
 	}
 
+	// Handle `x / Y` so we don't output it as `x/Y` (where Y is an expression).
+	// TODO(cristaloleg): handle only a case when we dereference Y: `x / *y`.
+	if n.Op == token.QUO {
+		spaceBeforeY = true
+	}
+
 	m.printExpr(n.X)
 	m.out.WriteString(n.Op.String())
 	if spaceBeforeY {
@@ -523,6 +537,11 @@ func (m *minifier) printBinaryExpr(n *ast.BinaryExpr) {
 }
 
 func (m *minifier) printFuncType(n *ast.FuncType) {
+	if n.TypeParams != nil {
+		m.out.WriteString("[")
+		m.printFieldList(n.TypeParams, ',')
+		m.out.WriteString("]")
+	}
 	m.out.WriteString("(")
 	m.printFieldList(n.Params, ',')
 	m.out.WriteString(")")
@@ -560,6 +579,20 @@ func (m *minifier) printInterfaceType(n *ast.InterfaceType) {
 	m.out.WriteByte('}')
 }
 
+func (m *minifier) printIndexListExpr(n *ast.IndexListExpr) {
+	m.printExpr(n.X)
+	m.out.WriteString("[")
+
+	for i, ind := range n.Indices {
+		if i > 0 {
+			m.out.WriteByte(',')
+		}
+		m.printExpr(ind)
+	}
+
+	m.out.WriteByte(']')
+}
+
 func (m *minifier) printFieldList(n *ast.FieldList, sep byte) {
 	for j, field := range n.List {
 		for j, ident := range field.Names {

minifier_test.go

@@ -265,7 +265,7 @@ func TestGoroot(t *testing.T) {
 		fset2 := token.NewFileSet()
 		f2, err := parser.ParseFile(fset2, filename, minified.Bytes(), 0)
 		if err != nil {
-			return fmt.Errorf("re-parse minified: %w", err)
+			return fmt.Errorf("re-parse minified: %w\nminified: %s", err, minified.String())
 		}
 		if diff := astDiff(f, f2); diff != "" {
 			return fmt.Errorf("minified code produced different AST:\n%s", diff)
@@ -284,6 +284,18 @@ func TestGoroot(t *testing.T) {
 		if !strings.HasSuffix(info.Name(), ".go") {
 			return nil
 		}
+		// Skip some testdata dirs where not all files can be parsed.
+		// TODO(cristaloleg): skip file when we cannot parse it with go/parser.
+		if strings.Contains(path, "src/cmd/compile/internal/syntax/testdata") ||
+			strings.Contains(path, "src/cmd/compile/internal/types2/testdata") ||
+			strings.Contains(path, "src/cmd/go/internal/modindex/testdata") ||
+			strings.Contains(path, "src/cmd/go/parser/testdata") ||
+			strings.Contains(path, "src/cmd/internal/modindex/testdata") ||
+			strings.Contains(path, "src/go/parser/testdata") ||
+			strings.Contains(path, "src/internal/types/testdata") ||
+			strings.Contains(path, "src/cmd/compile/internal/syntax/testdata/smoketest.go") {
+			return nil
+		}
 		if err := visitFile(path); err != nil {
 			return fmt.Errorf("%s: %w", path, err)
 		}