diff --git a/src/go/types/builtins.go b/src/go/types/builtins.go
index 785daec331a..afe5f5d0fcb 100644
--- a/src/go/types/builtins.go
+++ b/src/go/types/builtins.go
@@ -623,7 +623,7 @@ func (check *Checker) builtin(x *operand, call *ast.CallExpr, id builtinId) (_ b
 		// Note: trace is only available in self-test mode.
 		// (no argument evaluated yet)
 		if nargs == 0 {
-			check.dump("%s: trace() without arguments", call.Pos())
+			check.dump("%v: trace() without arguments", call.Pos())
 			x.mode = novalue
 			break
 		}
@@ -631,7 +631,7 @@ func (check *Checker) builtin(x *operand, call *ast.CallExpr, id builtinId) (_ b
 		x1 := x
 		for _, arg := range call.Args {
 			check.rawExpr(x1, arg, nil) // permit trace for types, e.g.: new(trace(T))
-			check.dump("%s: %s", x1.pos(), x1)
+			check.dump("%v: %s", x1.pos(), x1)
 			x1 = &t // use incoming x only for first argument
 		}
 		// trace is only available in test mode - no need to record signature
diff --git a/src/go/types/call.go b/src/go/types/call.go
index ba9e45f7afc..1b40651b734 100644
--- a/src/go/types/call.go
+++ b/src/go/types/call.go
@@ -274,7 +274,7 @@ func (check *Checker) argument(fun ast.Expr, sig *Signature, i int, x *operand,
 		typ = sig.params.vars[n-1].typ
 		if debug {
 			if _, ok := typ.(*Slice); !ok {
-				check.dump("%s: expected unnamed slice type, got %s", sig.params.vars[n-1].Pos(), typ)
+				check.dump("%v: expected unnamed slice type, got %s", sig.params.vars[n-1].Pos(), typ)
 			}
 		}
 	default:
@@ -448,7 +448,7 @@ func (check *Checker) selector(x *operand, e *ast.SelectorExpr) {
 				// lookup.
 				mset := NewMethodSet(typ)
 				if m := mset.Lookup(check.pkg, sel); m == nil || m.obj != obj {
-					check.dump("%s: (%s).%v -> %s", e.Pos(), typ, obj.name, m)
+					check.dump("%v: (%s).%v -> %s", e.Pos(), typ, obj.name, m)
 					check.dump("%s\n", mset)
 					panic("method sets and lookup don't agree")
 				}
diff --git a/src/go/types/check.go b/src/go/types/check.go
index d1b7155cf59..177065fded5 100644
--- a/src/go/types/check.go
+++ b/src/go/types/check.go
@@ -249,7 +249,7 @@ func (check *Checker) recordUntyped() {
 
 	for x, info := range check.untyped {
 		if debug && isTyped(info.typ) {
-			check.dump("%s: %s (type %s) is typed", x.Pos(), x, info.typ)
+			check.dump("%v: %s (type %s) is typed", x.Pos(), x, info.typ)
 			unreachable()
 		}
 		check.recordTypeAndValue(x, info.mode, info.typ, info.val)
diff --git a/src/go/types/decl.go b/src/go/types/decl.go
index 8278fab2adf..288ba8e4479 100644
--- a/src/go/types/decl.go
+++ b/src/go/types/decl.go
@@ -67,7 +67,7 @@ func (check *Checker) objDecl(obj Object, def *Named, path []*TypeName) {
 
 	d := check.objMap[obj]
 	if d == nil {
-		check.dump("%s: %s should have been declared", obj.Pos(), obj)
+		check.dump("%v: %s should have been declared", obj.Pos(), obj)
 		unreachable()
 	}
 
diff --git a/src/go/types/expr.go b/src/go/types/expr.go
index 04d6b72bc21..0a2a811bd88 100644
--- a/src/go/types/expr.go
+++ b/src/go/types/expr.go
@@ -382,7 +382,7 @@ func (check *Checker) updateExprType(x ast.Expr, typ Type, final bool) {
 		// The respective sub-expressions got their final types
 		// upon assignment or use.
 		if debug {
-			check.dump("%s: found old type(%s): %s (new: %s)", x.Pos(), x, old.typ, typ)
+			check.dump("%v: found old type(%s): %s (new: %s)", x.Pos(), x, old.typ, typ)
 			unreachable()
 		}
 		return
diff --git a/src/go/types/interfaces.go b/src/go/types/interfaces.go
index 1ce5e1ed976..b4efebae5d0 100644
--- a/src/go/types/interfaces.go
+++ b/src/go/types/interfaces.go
@@ -144,7 +144,7 @@ func (check *Checker) infoFromTypeLit(scope *Scope, iface *ast.InterfaceType, tn
 	}
 
 	if trace {
-		check.trace(iface.Pos(), "-- collect methods for %s (path = %s)", iface, pathString(path))
+		check.trace(iface.Pos(), "-- collect methods for %v (path = %s)", iface, pathString(path))
 		check.indent++
 		defer func() {
 			check.indent--
diff --git a/src/go/types/typexpr.go b/src/go/types/typexpr.go
index 18234cb19d0..5e48edef706 100644
--- a/src/go/types/typexpr.go
+++ b/src/go/types/typexpr.go
@@ -487,7 +487,7 @@ func (check *Checker) interfaceType(ityp *Interface, iface *ast.InterfaceType, d
 	interfaceContext := check.context // capture for use in closure below
 	check.later(func() {
 		if trace {
-			check.trace(iface.Pos(), "-- delayed checking embedded interfaces of %s", iface)
+			check.trace(iface.Pos(), "-- delayed checking embedded interfaces of %v", iface)
 			check.indent++
 			defer func() {
 				check.indent--
@@ -524,7 +524,7 @@ func (check *Checker) interfaceType(ityp *Interface, iface *ast.InterfaceType, d
 				// don't just assert, but report error since this
 				// used to be the underlying cause for issue #18395.
 				if embed.allMethods == nil {
-					check.dump("%s: incomplete embedded interface %s", f.Type.Pos(), typ)
+					check.dump("%v: incomplete embedded interface %s", f.Type.Pos(), typ)
 					unreachable()
 				}
 				// collect interface