diff --git a/src/go/types/api.go b/src/go/types/api.go
index eda41b366a..d9d561c25d 100644
--- a/src/go/types/api.go
+++ b/src/go/types/api.go
@@ -143,6 +143,9 @@ type Config struct {
 	// It is an error to set both FakeImportC and go115UsesCgo.
 	go115UsesCgo bool
 
+	// If trace is set, a debug trace is printed to stdout.
+	trace bool
+
 	// If Error != nil, it is called with each error found
 	// during type checking; err has dynamic type Error.
 	// Secondary errors (for instance, to enumerate all types
diff --git a/src/go/types/call.go b/src/go/types/call.go
index db603b5260..f0d612d018 100644
--- a/src/go/types/call.go
+++ b/src/go/types/call.go
@@ -65,7 +65,7 @@ func (check *Checker) instantiateSignature(pos token.Pos, typ *Signature, targs
 	assert(check != nil)
 	assert(len(targs) == typ.TypeParams().Len())
 
-	if trace {
+	if check.conf.trace {
 		check.trace(pos, "-- instantiating signature %s with %s", typ, targs)
 		check.indent++
 		defer func() {
diff --git a/src/go/types/check.go b/src/go/types/check.go
index 50d8afe4e3..76be498042 100644
--- a/src/go/types/check.go
+++ b/src/go/types/check.go
@@ -16,10 +16,7 @@ import (
 )
 
 // debugging/development support
-const (
-	debug = false // leave on during development
-	trace = false // turn on for detailed type resolution traces
-)
+const debug = false // leave on during development
 
 // exprInfo stores information about an untyped expression.
 type exprInfo struct {
@@ -313,7 +310,7 @@ func (check *Checker) checkFiles(files []*ast.File) (err error) {
 	defer check.handleBailout(&err)
 
 	print := func(msg string) {
-		if trace {
+		if check.conf.trace {
 			fmt.Println()
 			fmt.Println(msg)
 		}
@@ -377,7 +374,7 @@ func (check *Checker) processDelayed(top int) {
 	// this is a sufficiently bounded process.
 	for i := top; i < len(check.delayed); i++ {
 		a := &check.delayed[i]
-		if trace {
+		if check.conf.trace {
 			if a.desc != nil {
 				check.trace(a.desc.pos.Pos(), "-- "+a.desc.format, a.desc.args...)
 			} else {
@@ -385,7 +382,7 @@ func (check *Checker) processDelayed(top int) {
 			}
 		}
 		a.f() // may append to check.delayed
-		if trace {
+		if check.conf.trace {
 			fmt.Println()
 		}
 	}
diff --git a/src/go/types/check_test.go b/src/go/types/check_test.go
index 638355049e..1107f9592a 100644
--- a/src/go/types/check_test.go
+++ b/src/go/types/check_test.go
@@ -145,7 +145,7 @@ func testFiles(t *testing.T, sizes Sizes, filenames []string, srcs [][]byte, man
 	flags := flag.NewFlagSet("", flag.PanicOnError)
 	flags.StringVar(&conf.GoVersion, "lang", "", "")
 	flags.BoolVar(&conf.FakeImportC, "fakeImportC", false, "")
-	flags.BoolVar(addrOldComparableSemantics(&conf), "oldComparableSemantics", false, "")
+	flags.BoolVar(boolFieldAddr(&conf, "oldComparableSemantics"), "oldComparableSemantics", false, "")
 	if err := parseFlags(filenames[0], srcs[0], flags); err != nil {
 		t.Fatal(err)
 	}
@@ -166,6 +166,7 @@ func testFiles(t *testing.T, sizes Sizes, filenames []string, srcs [][]byte, man
 	}
 
 	// typecheck and collect typechecker errors
+	*boolFieldAddr(&conf, "trace") = manual && testing.Verbose()
 	if imp == nil {
 		imp = importer.Default()
 	}
@@ -299,10 +300,11 @@ func readCode(err Error) int {
 	return int(v.FieldByName("go116code").Int())
 }
 
-// addrOldComparableSemantics(conf) returns &conf.oldComparableSemantics (unexported field).
-func addrOldComparableSemantics(conf *Config) *bool {
+// boolFieldAddr(conf, name) returns the address of the boolean field conf.<name>.
+// For accessing unexported fields.
+func boolFieldAddr(conf *Config, name string) *bool {
 	v := reflect.Indirect(reflect.ValueOf(conf))
-	return (*bool)(v.FieldByName("oldComparableSemantics").Addr().UnsafePointer())
+	return (*bool)(v.FieldByName(name).Addr().UnsafePointer())
 }
 
 // TestManual is for manual testing of a package - either provided
diff --git a/src/go/types/decl.go b/src/go/types/decl.go
index adc485c400..018ff7f38e 100644
--- a/src/go/types/decl.go
+++ b/src/go/types/decl.go
@@ -54,7 +54,7 @@ func pathString(path []Object) string {
 // objDecl type-checks the declaration of obj in its respective (file) environment.
 // For the meaning of def, see Checker.definedType, in typexpr.go.
 func (check *Checker) objDecl(obj Object, def *Named) {
-	if trace && obj.Type() == nil {
+	if check.conf.trace && obj.Type() == nil {
 		if check.indent == 0 {
 			fmt.Println() // empty line between top-level objects for readability
 		}
@@ -264,7 +264,7 @@ loop:
 		}
 	}
 
-	if trace {
+	if check.conf.trace {
 		check.trace(obj.Pos(), "## cycle detected: objPath = %s->%s (len = %d)", pathString(cycle), obj.Name(), len(cycle))
 		if tparCycle {
 			check.trace(obj.Pos(), "## cycle contains: generic type in a type parameter list")
@@ -707,7 +707,7 @@ func (check *Checker) declareTypeParams(tparams []*TypeParam, names []*ast.Ident
 		tparams = append(tparams, tpar)
 	}
 
-	if trace && len(names) > 0 {
+	if check.conf.trace && len(names) > 0 {
 		check.trace(names[0].Pos(), "type params = %v", tparams[len(tparams)-len(names):])
 	}
 
diff --git a/src/go/types/errors.go b/src/go/types/errors.go
index b52019ddf5..4c4cd03814 100644
--- a/src/go/types/errors.go
+++ b/src/go/types/errors.go
@@ -266,7 +266,7 @@ func (check *Checker) report(errp *error_) {
 		check.firstErr = err
 	}
 
-	if trace {
+	if check.conf.trace {
 		pos := e.Pos
 		msg := e.Msg
 		check.trace(pos, "ERROR: %s", msg)
diff --git a/src/go/types/expr.go b/src/go/types/expr.go
index aa90145b36..adf3d21fce 100644
--- a/src/go/types/expr.go
+++ b/src/go/types/expr.go
@@ -1224,7 +1224,7 @@ const (
 // If allowGeneric is set, the operand type may be an uninstantiated
 // parameterized type or function value.
 func (check *Checker) rawExpr(x *operand, e ast.Expr, hint Type, allowGeneric bool) exprKind {
-	if trace {
+	if check.conf.trace {
 		check.trace(e.Pos(), "-- expr %s", e)
 		check.indent++
 		defer func() {
diff --git a/src/go/types/named.go b/src/go/types/named.go
index c08997aa77..04638abbdc 100644
--- a/src/go/types/named.go
+++ b/src/go/types/named.go
@@ -581,7 +581,7 @@ func (check *Checker) context() *Context {
 // returning the result. Returns Typ[Invalid] if there was an error.
 func (n *Named) expandUnderlying() Type {
 	check := n.check
-	if check != nil && trace {
+	if check != nil && check.conf.trace {
 		check.trace(n.obj.pos, "-- Named.expandUnderlying %s", n)
 		check.indent++
 		defer func() {
diff --git a/src/go/types/stmt.go b/src/go/types/stmt.go
index ac6255d42a..1a4c58888a 100644
--- a/src/go/types/stmt.go
+++ b/src/go/types/stmt.go
@@ -19,7 +19,7 @@ func (check *Checker) funcBody(decl *declInfo, name string, sig *Signature, body
 		panic("function body not ignored")
 	}
 
-	if trace {
+	if check.conf.trace {
 		check.trace(body.Pos(), "-- %s: %s", name, sig)
 	}
 
diff --git a/src/go/types/subst.go b/src/go/types/subst.go
index 5a49c0447f..5876b61edf 100644
--- a/src/go/types/subst.go
+++ b/src/go/types/subst.go
@@ -204,7 +204,7 @@ func (subst *subster) typ(typ Type) Type {
 	case *Named:
 		// dump is for debugging
 		dump := func(string, ...any) {}
-		if subst.check != nil && trace {
+		if subst.check != nil && subst.check.conf.trace {
 			subst.check.indent++
 			defer func() {
 				subst.check.indent--
diff --git a/src/go/types/typeset.go b/src/go/types/typeset.go
index d68446df66..35fb155bfa 100644
--- a/src/go/types/typeset.go
+++ b/src/go/types/typeset.go
@@ -170,7 +170,7 @@ func computeInterfaceTypeSet(check *Checker, pos token.Pos, ityp *Interface) *_T
 		return &topTypeSet
 	}
 
-	if check != nil && trace {
+	if check != nil && check.conf.trace {
 		// Types don't generally have position information.
 		// If we don't have a valid pos provided, try to use
 		// one close enough.
diff --git a/src/go/types/typexpr.go b/src/go/types/typexpr.go
index 03817dded1..6a92dcb9b7 100644
--- a/src/go/types/typexpr.go
+++ b/src/go/types/typexpr.go
@@ -214,7 +214,7 @@ func goTypeName(typ Type) string {
 // typInternal drives type checking of types.
 // Must only be called by definedType or genericType.
 func (check *Checker) typInternal(e0 ast.Expr, def *Named) (T Type) {
-	if trace {
+	if check.conf.trace {
 		check.trace(e0.Pos(), "-- type %s", e0)
 		check.indent++
 		defer func() {
@@ -395,7 +395,7 @@ func (check *Checker) typInternal(e0 ast.Expr, def *Named) (T Type) {
 }
 
 func (check *Checker) instantiatedType(ix *typeparams.IndexExpr, def *Named) (res Type) {
-	if trace {
+	if check.conf.trace {
 		check.trace(ix.Pos(), "-- instantiating type %s with %s", ix.X, ix.Indices)
 		check.indent++
 		defer func() {