[dev.types] all: merge master into dev.typesdev.types

Change-Id: Ia6964cb4e09153c15cc9c5b441373d1b3cb8f757

16 files changed, 257 insertions, 149 deletions

diff --git a/src/go/ast/ast.go b/src/go/ast/ast.go
index 81c64589d0..1061f1d3ce 100644
--- a/src/go/ast/ast.go
+++ b/src/go/ast/ast.go
@@ -285,6 +285,12 @@ type (
 	}
 
 	// A BasicLit node represents a literal of basic type.
+	//
+	// Note that for the CHAR and STRING kinds, the literal is stored
+	// with its quotes. For example, for a double-quoted STRING, the
+	// first and the last rune in the Value field will be ". The
+	// Unquote and UnquoteChar functions in the strconv package can be
+	// used to unquote STRING and CHAR values, respectively.
 	BasicLit struct {
 		ValuePos token.Pos   // literal position
 		Kind     token.Token // token.INT, token.FLOAT, token.IMAG, token.CHAR, or token.STRING
diff --git a/src/go/build/build.go b/src/go/build/build.go
index 4a5da308a0..39bc3591a7 100644
--- a/src/go/build/build.go
+++ b/src/go/build/build.go
@@ -793,6 +793,12 @@ Found:
 		if d.IsDir() {
 			continue
 		}
+		if (d.Mode() & os.ModeSymlink) != 0 {
+			if fi, err := os.Stat(filepath.Join(p.Dir, d.Name())); err == nil && fi.IsDir() {
+				// Symlinks to directories are not source files.
+				continue
+			}
+		}
 
 		name := d.Name()
 		ext := nameExt(name)
diff --git a/src/go/types/api_test.go b/src/go/types/api_test.go
index 798c09bbff..75cebc9826 100644
--- a/src/go/types/api_test.go
+++ b/src/go/types/api_test.go
@@ -1243,6 +1243,9 @@ func TestConvertibleTo(t *testing.T) {
 		{newDefined(new(Struct)), new(Struct), true},
 		{newDefined(Typ[Int]), new(Struct), false},
 		{Typ[UntypedInt], Typ[Int], true},
+		// Untyped string values are not permitted by the spec, so the below
+		// behavior is undefined.
+		{Typ[UntypedString], Typ[String], true},
 	} {
 		if got := ConvertibleTo(test.v, test.t); got != test.want {
 			t.Errorf("ConvertibleTo(%v, %v) = %t, want %t", test.v, test.t, got, test.want)
@@ -1260,6 +1263,12 @@ func TestAssignableTo(t *testing.T) {
 		{newDefined(Typ[Int]), Typ[Int], false},
 		{newDefined(new(Struct)), new(Struct), true},
 		{Typ[UntypedBool], Typ[Bool], true},
+		{Typ[UntypedString], Typ[Bool], false},
+		// Neither untyped string nor untyped numeric assignments arise during
+		// normal type checking, so the below behavior is technically undefined by
+		// the spec.
+		{Typ[UntypedString], Typ[String], true},
+		{Typ[UntypedInt], Typ[Int], true},
 	} {
 		if got := AssignableTo(test.v, test.t); got != test.want {
 			t.Errorf("AssignableTo(%v, %v) = %t, want %t", test.v, test.t, got, test.want)
diff --git a/src/go/types/assignments.go b/src/go/types/assignments.go
index 34a9d7843d..4e8ec278fc 100644
--- a/src/go/types/assignments.go
+++ b/src/go/types/assignments.go
@@ -7,6 +7,7 @@
 package types
 
 import (
+	"errors"
 	"go/ast"
 	"go/token"
 )
@@ -33,8 +34,8 @@ func (check *Checker) assignment(x *operand, T Type, context string) {
 		// spec: "If an untyped constant is assigned to a variable of interface
 		// type or the blank identifier, the constant is first converted to type
 		// bool, rune, int, float64, complex128 or string respectively, depending
-		// on whether the value is a boolean, rune, integer, floating-point, complex,
-		// or string constant."
+		// on whether the value is a boolean, rune, integer, floating-point,
+		// complex, or string constant."
 		if T == nil || IsInterface(T) {
 			if T == nil && x.typ == Typ[UntypedNil] {
 				check.errorf(x.pos(), "use of untyped nil in %s", context)
@@ -43,8 +44,16 @@ func (check *Checker) assignment(x *operand, T Type, context string) {
 			}
 			target = Default(x.typ)
 		}
-		check.convertUntyped(x, target)
-		if x.mode == invalid {
+		if err := check.canConvertUntyped(x, target); err != nil {
+			var internalErr Error
+			var msg string
+			if errors.As(err, &internalErr) {
+				msg = internalErr.Msg
+			} else {
+				msg = err.Error()
+			}
+			check.errorf(x.pos(), "cannot use %s as %s value in %s: %v", x, target, context, msg)
+			x.mode = invalid
 			return
 		}
 	}
diff --git a/src/go/types/check_test.go b/src/go/types/check_test.go
index 89122d75ff..e01c3de13b 100644
--- a/src/go/types/check_test.go
+++ b/src/go/types/check_test.go
@@ -34,6 +34,7 @@ import (
 	"go/token"
 	"internal/testenv"
 	"io/ioutil"
+	"path/filepath"
 	"regexp"
 	"strings"
 	"testing"
@@ -93,11 +94,6 @@ var tests = [][]string{
 	{"testdata/issues.src"},
 	{"testdata/blank.src"},
 	{"testdata/issue25008b.src", "testdata/issue25008a.src"}, // order (b before a) is crucial!
-	{"testdata/issue26390.src"},                              // stand-alone test to ensure case is triggered
-	{"testdata/issue23203a.src"},
-	{"testdata/issue23203b.src"},
-	{"testdata/issue28251.src"},
-	{"testdata/issue6977.src"},
 }
 
 var fset = token.NewFileSet()
@@ -259,7 +255,7 @@ func checkFiles(t *testing.T, testfiles []string) {
 	// typecheck and collect typechecker errors
 	var conf Config
 	// special case for importC.src
-	if len(testfiles) == 1 && testfiles[0] == "testdata/importC.src" {
+	if len(testfiles) == 1 && strings.HasSuffix(testfiles[0], "importC.src") {
 		conf.FakeImportC = true
 	}
 	conf.Importer = importer.Default()
@@ -316,3 +312,27 @@ func TestCheck(t *testing.T) {
 		checkFiles(t, files)
 	}
 }
+
+func TestFixedBugs(t *testing.T) { testDir(t, "fixedbugs") }
+
+func testDir(t *testing.T, dir string) {
+	testenv.MustHaveGoBuild(t)
+
+	fis, err := ioutil.ReadDir(dir)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	for _, fi := range fis {
+		testname := filepath.Base(fi.Name())
+		testname = strings.TrimSuffix(testname, filepath.Ext(testname))
+		t.Run(testname, func(t *testing.T) {
+			filename := filepath.Join(dir, fi.Name())
+			if fi.IsDir() {
+				t.Errorf("skipped directory %q", filename)
+				return
+			}
+			checkFiles(t, []string{filename})
+		})
+	}
+}
diff --git a/src/go/types/errors.go b/src/go/types/errors.go
index 91b077163c..88e41c5713 100644
--- a/src/go/types/errors.go
+++ b/src/go/types/errors.go
@@ -7,6 +7,7 @@
 package types
 
 import (
+	"errors"
 	"fmt"
 	"go/ast"
 	"go/token"
@@ -72,22 +73,33 @@ func (check *Checker) dump(format string, args ...interface{}) {
 	fmt.Println(check.sprintf(format, args...))
 }
 
-func (check *Checker) err(pos token.Pos, msg string, soft bool) {
+func (check *Checker) err(err error) {
+	if err == nil {
+		return
+	}
+	var e Error
+	isInternal := errors.As(err, &e)
 	// Cheap trick: Don't report errors with messages containing
 	// "invalid operand" or "invalid type" as those tend to be
 	// follow-on errors which don't add useful information. Only
 	// exclude them if these strings are not at the beginning,
 	// and only if we have at least one error already reported.
-	if check.firstErr != nil && (strings.Index(msg, "invalid operand") > 0 || strings.Index(msg, "invalid type") > 0) {
+	isInvalidErr := isInternal && (strings.Index(e.Msg, "invalid operand") > 0 || strings.Index(e.Msg, "invalid type") > 0)
+	if check.firstErr != nil && isInvalidErr {
 		return
 	}
 
-	err := Error{check.fset, pos, msg, soft}
 	if check.firstErr == nil {
 		check.firstErr = err
 	}
 
 	if trace {
+		pos := e.Pos
+		msg := e.Msg
+		if !isInternal {
+			msg = err.Error()
+			pos = token.NoPos
+		}
 		check.trace(pos, "ERROR: %s", msg)
 	}
 
@@ -99,15 +111,30 @@ func (check *Checker) err(pos token.Pos, msg string, soft bool) {
 }
 
 func (check *Checker) error(pos token.Pos, msg string) {
-	check.err(pos, msg, false)
+	check.err(Error{Fset: check.fset, Pos: pos, Msg: msg})
+}
+
+// newErrorf creates a new Error, but does not handle it.
+func (check *Checker) newErrorf(pos token.Pos, format string, args ...interface{}) error {
+	return Error{
+		Fset: check.fset,
+		Pos:  pos,
+		Msg:  check.sprintf(format, args...),
+		Soft: false,
+	}
 }
 
 func (check *Checker) errorf(pos token.Pos, format string, args ...interface{}) {
-	check.err(pos, check.sprintf(format, args...), false)
+	check.error(pos, check.sprintf(format, args...))
 }
 
 func (check *Checker) softErrorf(pos token.Pos, format string, args ...interface{}) {
-	check.err(pos, check.sprintf(format, args...), true)
+	check.err(Error{
+		Fset: check.fset,
+		Pos:  pos,
+		Msg:  check.sprintf(format, args...),
+		Soft: true,
+	})
 }
 
 func (check *Checker) invalidAST(pos token.Pos, format string, args ...interface{}) {
diff --git a/src/go/types/expr.go b/src/go/types/expr.go
index d1e892a9b7..94d98f0fbb 100644
--- a/src/go/types/expr.go
+++ b/src/go/types/expr.go
@@ -329,8 +329,16 @@ func representableConst(x constant.Value, check *Checker, typ *Basic, rounded *c
 	return false
 }
 
-// representable checks that a constant operand is representable in the given basic type.
+// representable checks that a constant operand is representable in the given
+// basic type.
 func (check *Checker) representable(x *operand, typ *Basic) {
+	if err := check.isRepresentable(x, typ); err != nil {
+		x.mode = invalid
+		check.err(err)
+	}
+}
+
+func (check *Checker) isRepresentable(x *operand, typ *Basic) error {
 	assert(x.mode == constant_)
 	if !representableConst(x.val, check, typ, &x.val) {
 		var msg string
@@ -350,9 +358,9 @@ func (check *Checker) representable(x *operand, typ *Basic) {
 		} else {
 			msg = "cannot convert %s to %s"
 		}
-		check.errorf(x.pos(), msg, x, typ)
-		x.mode = invalid
+		return check.newErrorf(x.pos(), msg, x, typ)
 	}
+	return nil
 }
 
 // updateExprType updates the type of x to typ and invokes itself
@@ -488,12 +496,16 @@ func (check *Checker) updateExprVal(x ast.Expr, val constant.Value) {
 
 // convertUntyped attempts to set the type of an untyped value to the target type.
 func (check *Checker) convertUntyped(x *operand, target Type) {
-	if x.mode == invalid || isTyped(x.typ) || target == Typ[Invalid] {
-		return
+	if err := check.canConvertUntyped(x, target); err != nil {
+		x.mode = invalid
+		check.err(err)
 	}
+}
 
-	// TODO(gri) Sloppy code - clean up. This function is central
-	//           to assignment and expression checking.
+func (check *Checker) canConvertUntyped(x *operand, target Type) error {
+	if x.mode == invalid || isTyped(x.typ) || target == Typ[Invalid] {
+		return nil
+	}
 
 	if isUntyped(target) {
 		// both x and target are untyped
@@ -505,82 +517,91 @@ func (check *Checker) convertUntyped(x *operand, target Type) {
 				check.updateExprType(x.expr, target, false)
 			}
 		} else if xkind != tkind {
-			goto Error
+			return check.newErrorf(x.pos(), "cannot convert %s to %s", x, target)
 		}
-		return
+		return nil
+	}
+
+	if t, ok := target.Underlying().(*Basic); ok && x.mode == constant_ {
+		if err := check.isRepresentable(x, t); err != nil {
+			return err
+		}
+		// Expression value may have been rounded - update if needed.
+		check.updateExprVal(x.expr, x.val)
+	} else {
+		newTarget := check.implicitType(x, target)
+		if newTarget == nil {
+			return check.newErrorf(x.pos(), "cannot convert %s to %s", x, target)
+		}
+		target = newTarget
 	}
+	x.typ = target
+	// Even though implicitType can return UntypedNil, this value is final: the
+	// predeclared identifier nil has no type.
+	check.updateExprType(x.expr, target, true)
+	return nil
+}
 
-	// typed target
+// implicitType returns the implicit type of x when used in a context where the
+// target type is expected. If no such implicit conversion is possible, it
+// returns nil.
+func (check *Checker) implicitType(x *operand, target Type) Type {
+	assert(isUntyped(x.typ))
 	switch t := target.Underlying().(type) {
 	case *Basic:
-		if x.mode == constant_ {
-			check.representable(x, t)
-			if x.mode == invalid {
-				return
+		assert(x.mode != constant_)
+		// Non-constant untyped values may appear as the
+		// result of comparisons (untyped bool), intermediate
+		// (delayed-checked) rhs operands of shifts, and as
+		// the value nil.
+		switch x.typ.(*Basic).kind {
+		case UntypedBool:
+			if !isBoolean(target) {
+				return nil
 			}
-			// expression value may have been rounded - update if needed
-			check.updateExprVal(x.expr, x.val)
-		} else {
-			// Non-constant untyped values may appear as the
-			// result of comparisons (untyped bool), intermediate
-			// (delayed-checked) rhs operands of shifts, and as
-			// the value nil.
-			switch x.typ.(*Basic).kind {
-			case UntypedBool:
-				if !isBoolean(target) {
-					goto Error
-				}
-			case UntypedInt, UntypedRune, UntypedFloat, UntypedComplex:
-				if !isNumeric(target) {
-					goto Error
-				}
-			case UntypedString:
-				// Non-constant untyped string values are not
-				// permitted by the spec and should not occur.
-				unreachable()
-			case UntypedNil:
-				// Unsafe.Pointer is a basic type that includes nil.
-				if !hasNil(target) {
-					goto Error
-				}
-			default:
-				goto Error
+		case UntypedInt, UntypedRune, UntypedFloat, UntypedComplex:
+			if !isNumeric(target) {
+				return nil
+			}
+		case UntypedString:
+			// Non-constant untyped string values are not permitted by the spec and
+			// should not occur during normal typechecking passes, but this path is
+			// reachable via the AssignableTo API.
+			if !isString(target) {
+				return nil
+			}
+		case UntypedNil:
+			// Unsafe.Pointer is a basic type that includes nil.
+			if !hasNil(target) {
+				return nil
 			}
+		default:
+			return nil
 		}
 	case *Interface:
-		// Update operand types to the default type rather then
-		// the target (interface) type: values must have concrete
-		// dynamic types. If the value is nil, keep it untyped
-		// (this is important for tools such as go vet which need
-		// the dynamic type for argument checking of say, print
+		// Values must have concrete dynamic types. If the value is nil,
+		// keep it untyped (this is important for tools such as go vet which
+		// need the dynamic type for argument checking of say, print
 		// functions)
 		if x.isNil() {
-			target = Typ[UntypedNil]
-		} else {
-			// cannot assign untyped values to non-empty interfaces
-			check.completeInterface(t)
-			if !t.Empty() {
-				goto Error
-			}
-			target = Default(x.typ)
+			return Typ[UntypedNil]
+		}
+		// cannot assign untyped values to non-empty interfaces
+		check.completeInterface(t)
+		if !t.Empty() {
+			return nil
 		}
+		return Default(x.typ)
 	case *Pointer, *Signature, *Slice, *Map, *Chan:
 		if !x.isNil() {
-			goto Error
+			return nil
 		}
-		// keep nil untyped - see comment for interfaces, above
-		target = Typ[UntypedNil]
+		// Keep nil untyped - see comment for interfaces, above.
+		return Typ[UntypedNil]
 	default:
-		goto Error
+		return nil
 	}
-
-	x.typ = target
-	check.updateExprType(x.expr, target, true) // UntypedNils are final
-	return
-
-Error:
-	check.errorf(x.pos(), "cannot convert %s to %s", x, target)
-	x.mode = invalid
+	return target
 }
 
 func (check *Checker) comparison(x, y *operand, op token.Token) {
diff --git a/src/go/types/testdata/issue23203a.src b/src/go/types/fixedbugs/issue23203a.src
index 48cb5889cd..48cb5889cd 100644
--- a/src/go/types/testdata/issue23203a.src
+++ b/src/go/types/fixedbugs/issue23203a.src
diff --git a/src/go/types/testdata/issue23203b.src b/src/go/types/fixedbugs/issue23203b.src
index 638ec6c5ce..638ec6c5ce 100644
--- a/src/go/types/testdata/issue23203b.src
+++ b/src/go/types/fixedbugs/issue23203b.src
diff --git a/src/go/types/testdata/issue26390.src b/src/go/types/fixedbugs/issue26390.src
index b8e67e9bdd..9e0101f581 100644
--- a/src/go/types/testdata/issue26390.src
+++ b/src/go/types/fixedbugs/issue26390.src
@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// stand-alone test to ensure case is triggered
+
 package issue26390
 
 type A = T
diff --git a/src/go/types/testdata/issue28251.src b/src/go/types/fixedbugs/issue28251.src
index cd79e0e8b5..cd79e0e8b5 100644
--- a/src/go/types/testdata/issue28251.src
+++ b/src/go/types/fixedbugs/issue28251.src
diff --git a/src/go/types/testdata/issue6977.src b/src/go/types/fixedbugs/issue6977.src
index 8f4e9ba2b2..8f4e9ba2b2 100644
--- a/src/go/types/testdata/issue6977.src
+++ b/src/go/types/fixedbugs/issue6977.src
diff --git a/src/go/types/operand.go b/src/go/types/operand.go
index 80d11e2f21..6fbfe09627 100644
--- a/src/go/types/operand.go
+++ b/src/go/types/operand.go
@@ -205,15 +205,11 @@ func (x *operand) isNil() bool {
 	return x.mode == value && x.typ == Typ[UntypedNil]
 }
 
-// TODO(gri) The functions operand.assignableTo, checker.convertUntyped,
-//           checker.representable, and checker.assignment are
-//           overlapping in functionality. Need to simplify and clean up.
-
-// assignableTo reports whether x is assignable to a variable of type T.
-// If the result is false and a non-nil reason is provided, it may be set
-// to a more detailed explanation of the failure (result != "").
-// The check parameter may be nil if assignableTo is invoked through
-// an exported API call, i.e., when all methods have been type-checked.
+// assignableTo reports whether x is assignable to a variable of type T. If the
+// result is false and a non-nil reason is provided, it may be set to a more
+// detailed explanation of the failure (result != ""). The check parameter may
+// be nil if assignableTo is invoked through an exported API call, i.e., when
+// all methods have been type-checked.
 func (x *operand) assignableTo(check *Checker, T Type, reason *string) bool {
 	if x.mode == invalid || T == Typ[Invalid] {
 		return true // avoid spurious errors
@@ -229,34 +225,17 @@ func (x *operand) assignableTo(check *Checker, T Type, reason *string) bool {
 	Vu := V.Underlying()
 	Tu := T.Underlying()
 
-	// x is an untyped value representable by a value of type T
-	// TODO(gri) This is borrowing from checker.convertUntyped and
-	//           checker.representable. Need to clean up.
+	// x is an untyped value representable by a value of type T.
 	if isUntyped(Vu) {
-		switch t := Tu.(type) {
-		case *Basic:
-			if x.isNil() && t.kind == UnsafePointer {
-				return true
-			}
-			if x.mode == constant_ {
-				return representableConst(x.val, check, t, nil)
-			}
-			// The result of a comparison is an untyped boolean,
-			// but may not be a constant.
-			if Vb, _ := Vu.(*Basic); Vb != nil {
-				return Vb.kind == UntypedBool && isBoolean(Tu)
-			}
-		case *Interface:
-			check.completeInterface(t)
-			return x.isNil() || t.Empty()
-		case *Pointer, *Signature, *Slice, *Map, *Chan:
-			return x.isNil()
+		if t, ok := Tu.(*Basic); ok && x.mode == constant_ {
+			return representableConst(x.val, check, t, nil)
 		}
+		return check.implicitType(x, Tu) != nil
 	}
 	// Vu is typed
 
-	// x's type V and T have identical underlying types
-	// and at least one of V or T is not a named type
+	// x's type V and T have identical underlying types and at least one of V or
+	// T is not a named type.
 	if check.identical(Vu, Tu) && (!isNamed(V) || !isNamed(T)) {
 		return true
 	}
diff --git a/src/go/types/self_test.go b/src/go/types/self_test.go
index 10ad06fbca..04c9cd3458 100644
--- a/src/go/types/self_test.go
+++ b/src/go/types/self_test.go
@@ -47,8 +47,13 @@ func TestBenchmark(t *testing.T) {
 	// We're not using testing's benchmarking mechanism directly
 	// because we want custom output.
 
-	for _, p := range []string{"types", "constant", filepath.Join("internal", "gcimporter")} {
-		path := filepath.Join("..", p)
+	for _, p := range []string{
+		"net/http",
+		"go/parser",
+		"go/constant",
+		filepath.Join("go", "internal", "gcimporter"),
+	} {
+		path := filepath.Join("..", "..", p)
 		runbench(t, path, false)
 		runbench(t, path, true)
 		fmt.Println()
@@ -64,8 +69,13 @@ func runbench(t *testing.T, path string, ignoreFuncBodies bool) {
 
 	b := testing.Benchmark(func(b *testing.B) {
 		for i := 0; i < b.N; i++ {
-			conf := Config{IgnoreFuncBodies: ignoreFuncBodies}
-			conf.Check(path, fset, files, nil)
+			conf := Config{
+				IgnoreFuncBodies: ignoreFuncBodies,
+				Importer:         importer.Default(),
+			}
+			if _, err := conf.Check(path, fset, files, nil); err != nil {
+				t.Fatal(err)
+			}
 		}
 	})
 
@@ -77,10 +87,9 @@ func runbench(t *testing.T, path string, ignoreFuncBodies bool) {
 	})
 
 	d := time.Duration(b.NsPerOp())
-	fmt.Printf(
-		"%s: %s for %d lines (%d lines/s), ignoreFuncBodies = %v\n",
-		filepath.Base(path), d, lines, int64(float64(lines)/d.Seconds()), ignoreFuncBodies,
-	)
+	fmt.Printf("%s (ignoreFuncBodies = %v):\n", filepath.Base(path), ignoreFuncBodies)
+	fmt.Printf("\t%s for %d lines (%.0f lines/s)\n", d, lines, float64(lines)/d.Seconds())
+	fmt.Printf("\t%s\n", b.MemString())
 }
 
 func pkgFiles(fset *token.FileSet, path string) ([]*ast.File, error) {
diff --git a/src/go/types/stdlib_test.go b/src/go/types/stdlib_test.go
index 51ee0b1c36..f5a3273fa1 100644
--- a/src/go/types/stdlib_test.go
+++ b/src/go/types/stdlib_test.go
@@ -27,22 +27,21 @@ import (
 	. "go/types"
 )
 
-var (
-	pkgCount int // number of packages processed
-	start    time.Time
-
-	// Use the same importer for all std lib tests to
-	// avoid repeated importing of the same packages.
-	stdLibImporter = importer.Default()
-)
+// Use the same importer for all std lib tests to
+// avoid repeated importing of the same packages.
+var stdLibImporter = importer.Default()
 
 func TestStdlib(t *testing.T) {
 	testenv.MustHaveGoBuild(t)
 
-	start = time.Now()
-	walkDirs(t, filepath.Join(runtime.GOROOT(), "src"))
+	pkgCount := 0
+	duration := walkPkgDirs(filepath.Join(runtime.GOROOT(), "src"), func(dir string, filenames []string) {
+		typecheck(t, dir, filenames)
+		pkgCount++
+	}, t.Error)
+
 	if testing.Verbose() {
-		fmt.Println(pkgCount, "packages typechecked in", time.Since(start))
+		fmt.Println(pkgCount, "packages typechecked in", duration)
 	}
 }
 
@@ -235,7 +234,6 @@ func typecheck(t *testing.T, path string, filenames []string) {
 	}
 	info := Info{Uses: make(map[*ast.Ident]Object)}
 	conf.Check(path, fset, files, &info)
-	pkgCount++
 
 	// Perform checks of API invariants.
 
@@ -278,39 +276,48 @@ func pkgFilenames(dir string) ([]string, error) {
 	return filenames, nil
 }
 
-// Note: Could use filepath.Walk instead of walkDirs but that wouldn't
-//       necessarily be shorter or clearer after adding the code to
-//       terminate early for -short tests.
+func walkPkgDirs(dir string, pkgh func(dir string, filenames []string), errh func(args ...interface{})) time.Duration {
+	w := walker{time.Now(), 10 * time.Millisecond, pkgh, errh}
+	w.walk(dir)
+	return time.Since(w.start)
+}
 
-func walkDirs(t *testing.T, dir string) {
+type walker struct {
+	start time.Time
+	dmax  time.Duration
+	pkgh  func(dir string, filenames []string)
+	errh  func(args ...interface{})
+}
+
+func (w *walker) walk(dir string) {
 	// limit run time for short tests
-	if testing.Short() && time.Since(start) >= 10*time.Millisecond {
+	if testing.Short() && time.Since(w.start) >= w.dmax {
 		return
 	}
 
 	fis, err := ioutil.ReadDir(dir)
 	if err != nil {
-		t.Error(err)
+		w.errh(err)
 		return
 	}
 
-	// typecheck package in directory
+	// apply pkgh to the files in directory dir
 	// but ignore files directly under $GOROOT/src (might be temporary test files).
 	if dir != filepath.Join(runtime.GOROOT(), "src") {
 		files, err := pkgFilenames(dir)
 		if err != nil {
-			t.Error(err)
+			w.errh(err)
 			return
 		}
 		if files != nil {
-			typecheck(t, dir, files)
+			w.pkgh(dir, files)
 		}
 	}
 
 	// traverse subdirectories, but don't walk into testdata
 	for _, fi := range fis {
 		if fi.IsDir() && fi.Name() != "testdata" {
-			walkDirs(t, filepath.Join(dir, fi.Name()))
+			w.walk(filepath.Join(dir, fi.Name()))
 		}
 	}
 }
diff --git a/src/go/types/testdata/shifts.src b/src/go/types/testdata/shifts.src
index ebc95ba4d7..c9a38ae169 100644
--- a/src/go/types/testdata/shifts.src
+++ b/src/go/types/testdata/shifts.src
@@ -193,14 +193,27 @@ func shifts6() {
 	_ = float32(1.0 /* ERROR "must be integer" */ <<s)
 	_ = float32(1.1 /* ERROR "must be integer" */ <<s)
 
+	_ = int32(0x80000000 /* ERROR "overflows int32" */ << s)
+	// TODO(rfindley) Eliminate the redundant error here.
+	_ = int32(( /* ERROR "truncated to int32" */ 0x80000000 /* ERROR "truncated to int32" */ + 0i) << s)
+
+	_ = int(1+0i<<0)
+	_ = int((1+0i)<<s)
+	_ = int(1.0<<s)
+	_ = int(complex(1, 0)<<s)
+	_ = int(float32/* ERROR "must be integer" */(1.0) <<s)
+	_ = int(1.1 /* ERROR must be integer */ <<s)
+	_ = int(( /* ERROR "must be integer" */ 1+1i)  <<s)
+
+	_ = complex(1 /* ERROR "must be integer" */ <<s, 0)
+
 	var b []int
 	_ = append(b, 1<<s)
 	_ = append(b, 1.0<<s)
+	_ = append(b, (1+0i)<<s)
 	_ = append(b, 1.1 /* ERROR "must be integer" */ <<s)
-
-	_ = append(b, 1<<s)
-	_ = append(b, 1.0<<s) // should fail - see TODO in append code
-	_ = append(b, 1.1 /* ERROR "must be integer" */ <<s)
+	_ = append(b, (1 + 0i) <<s)
+	_ = append(b, ( /* ERROR "must be integer" */ 1 + 1i)  <<s)
 
 	_ = complex(1.0 /* ERROR "must be integer" */ <<s, 0)
 	_ = complex(1.1 /* ERROR "must be integer" */ <<s, 0)
@@ -379,4 +392,4 @@ func issue22969() {
 	var _ int8 = 0xff /* ERROR "overflows int8" */ << s
 	var _ int16 = 0xffff /* ERROR "overflows int16" */ << s
 	var _ int32 = 0x80000000 /* ERROR "overflows int32" */ << s
-}
\ No newline at end of file
+}