internal/upload: Add support for upload to GCP and CLI tool using it

Add new internal upload target for Google Cloud Platform and
osbuild-upload-gcp CLI tool which uses the API.

Supported features are:
- Authenticate with GCP using explicitly provided JSON credentials
  file or let the authentication be handled automatically by the
  Google cloud client library. The later is useful e.g. when the worker
  is running in GCP VM instance, which has associated permissions with
  it.
- Upload an existing image file into existing Storage bucket.
- Verify MD5 checksum of the uploaded image file against the local
  file's checksum.
- Import the uploaded image file into Compute Node as an Image.
- Delete the uploaded image file after a successful image import.
- Delete all cache files from storage created as part of the image
  import build job.
- Share the imported image with a list of specified accounts.

GCP-specific image type is not yet added, since GCP supports importing
VMDK and VHD images, which the osbuild-composer already supports.

Update go.mod, vendor/ content and SPEC file with new dependencies.

Signed-off-by: Tomas Hozza <thozza@redhat.com>

vendor/github.com/google/go-cmp/cmp/compare.go

@@ -1,11 +1,15 @@
 // Copyright 2017, The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE.md file.
+// license that can be found in the LICENSE file.
 
 // Package cmp determines equality of values.
 //
 // This package is intended to be a more powerful and safer alternative to
 // reflect.DeepEqual for comparing whether two values are semantically equal.
+// It is intended to only be used in tests, as performance is not a goal and
+// it may panic if it cannot compare the values. Its propensity towards
+// panicking means that its unsuitable for production environments where a
+// spurious panic may be fatal.
 //
 // The primary features of cmp are:
 //
@@ -22,8 +26,8 @@
 // equality is determined by recursively comparing the primitive kinds on both
 // values, much like reflect.DeepEqual. Unlike reflect.DeepEqual, unexported
 // fields are not compared by default; they result in panics unless suppressed
-// by using an Ignore option (see cmpopts.IgnoreUnexported) or explicitly compared
-// using the AllowUnexported option.
+// by using an Ignore option (see cmpopts.IgnoreUnexported) or explicitly
+// compared using the Exporter option.
 package cmp
 
 import (
@@ -62,8 +66,8 @@ import (
 //
 // Structs are equal if recursively calling Equal on all fields report equal.
 // If a struct contains unexported fields, Equal panics unless an Ignore option
-// (e.g., cmpopts.IgnoreUnexported) ignores that field or the AllowUnexported
-// option explicitly permits comparing the unexported field.
+// (e.g., cmpopts.IgnoreUnexported) ignores that field or the Exporter option
+// explicitly permits comparing the unexported field.
 //
 // Slices are equal if they are both nil or both non-nil, where recursively
 // calling Equal on all non-ignored slice or array elements report equal.
@@ -80,7 +84,58 @@ import (
 // Pointers and interfaces are equal if they are both nil or both non-nil,
 // where they have the same underlying concrete type and recursively
 // calling Equal on the underlying values reports equal.
+//
+// Before recursing into a pointer, slice element, or map, the current path
+// is checked to detect whether the address has already been visited.
+// If there is a cycle, then the pointed at values are considered equal
+// only if both addresses were previously visited in the same path step.
 func Equal(x, y interface{}, opts ...Option) bool {
+	s := newState(opts)
+	s.compareAny(rootStep(x, y))
+	return s.result.Equal()
+}
+
+// Diff returns a human-readable report of the differences between two values:
+// y - x. It returns an empty string if and only if Equal returns true for the
+// same input values and options.
+//
+// The output is displayed as a literal in pseudo-Go syntax.
+// At the start of each line, a "-" prefix indicates an element removed from x,
+// a "+" prefix to indicates an element added from y, and the lack of a prefix
+// indicates an element common to both x and y. If possible, the output
+// uses fmt.Stringer.String or error.Error methods to produce more humanly
+// readable outputs. In such cases, the string is prefixed with either an
+// 's' or 'e' character, respectively, to indicate that the method was called.
+//
+// Do not depend on this output being stable. If you need the ability to
+// programmatically interpret the difference, consider using a custom Reporter.
+func Diff(x, y interface{}, opts ...Option) string {
+	s := newState(opts)
+
+	// Optimization: If there are no other reporters, we can optimize for the
+	// common case where the result is equal (and thus no reported difference).
+	// This avoids the expensive construction of a difference tree.
+	if len(s.reporters) == 0 {
+		s.compareAny(rootStep(x, y))
+		if s.result.Equal() {
+			return ""
+		}
+		s.result = diff.Result{} // Reset results
+	}
+
+	r := new(defaultReporter)
+	s.reporters = append(s.reporters, reporter{r})
+	s.compareAny(rootStep(x, y))
+	d := r.String()
+	if (d == "") != s.result.Equal() {
+		panic("inconsistent difference and equality results")
+	}
+	return d
+}
+
+// rootStep constructs the first path step. If x and y have differing types,
+// then they are stored within an empty interface type.
+func rootStep(x, y interface{}) PathStep {
 	vx := reflect.ValueOf(x)
 	vy := reflect.ValueOf(y)
 
@@ -103,33 +158,7 @@ func Equal(x, y interface{}, opts ...Option) bool {
 		t = vx.Type()
 	}
 
-	s := newState(opts)
-	s.compareAny(&pathStep{t, vx, vy})
-	return s.result.Equal()
-}
-
-// Diff returns a human-readable report of the differences between two values.
-// It returns an empty string if and only if Equal returns true for the same
-// input values and options.
-//
-// The output is displayed as a literal in pseudo-Go syntax.
-// At the start of each line, a "-" prefix indicates an element removed from x,
-// a "+" prefix to indicates an element added to y, and the lack of a prefix
-// indicates an element common to both x and y. If possible, the output
-// uses fmt.Stringer.String or error.Error methods to produce more humanly
-// readable outputs. In such cases, the string is prefixed with either an
-// 's' or 'e' character, respectively, to indicate that the method was called.
-//
-// Do not depend on this output being stable. If you need the ability to
-// programmatically interpret the difference, consider using a custom Reporter.
-func Diff(x, y interface{}, opts ...Option) string {
-	r := new(defaultReporter)
-	eq := Equal(x, y, Options(opts), Reporter(r))
-	d := r.String()
-	if (d == "") != eq {
-		panic("inconsistent difference and equality results")
-	}
-	return d
+	return &pathStep{t, vx, vy}
 }
 
 type state struct {
@@ -137,6 +166,7 @@ type state struct {
 	// Calling statelessCompare must not result in observable changes to these.
 	result    diff.Result // The current result of comparison
 	curPath   Path        // The current path in the value tree
+	curPtrs   pointerPath // The current set of visited pointers
 	reporters []reporter  // Optional reporters
 
 	// recChecker checks for infinite cycles applying the same set of
@@ -148,13 +178,14 @@ type state struct {
 	dynChecker dynChecker
 
 	// These fields, once set by processOption, will not change.
-	exporters map[reflect.Type]bool // Set of structs with unexported field visibility
-	opts      Options               // List of all fundamental and filter options
+	exporters []exporter // List of exporters for structs with unexported fields
+	opts      Options    // List of all fundamental and filter options
 }
 
 func newState(opts []Option) *state {
 	// Always ensure a validator option exists to validate the inputs.
 	s := &state{opts: Options{validator{}}}
+	s.curPtrs.Init()
 	s.processOption(Options(opts))
 	return s
 }
@@ -174,13 +205,8 @@ func (s *state) processOption(opt Option) {
 			panic(fmt.Sprintf("cannot use an unfiltered option: %v", opt))
 		}
 		s.opts = append(s.opts, opt)
-	case visibleStructs:
-		if s.exporters == nil {
-			s.exporters = make(map[reflect.Type]bool)
-		}
-		for t := range opt {
-			s.exporters[t] = true
-		}
+	case exporter:
+		s.exporters = append(s.exporters, opt)
 	case reporter:
 		s.reporters = append(s.reporters, opt)
 	default:
@@ -192,9 +218,9 @@ func (s *state) processOption(opt Option) {
 // This function is stateless in that it does not alter the current result,
 // or output to any registered reporters.
 func (s *state) statelessCompare(step PathStep) diff.Result {
-	// We do not save and restore the curPath because all of the compareX
-	// methods should properly push and pop from the path.
-	// It is an implementation bug if the contents of curPath differs from
+	// We do not save and restore curPath and curPtrs because all of the
+	// compareX methods should properly push and pop from them.
+	// It is an implementation bug if the contents of the paths differ from
 	// when calling this function to when returning from it.
 
 	oldResult, oldReporters := s.result, s.reporters
@@ -216,9 +242,17 @@ func (s *state) compareAny(step PathStep) {
 	}
 	s.recChecker.Check(s.curPath)
 
-	// Obtain the current type and values.
+	// Cycle-detection for slice elements (see NOTE in compareSlice).
 	t := step.Type()
 	vx, vy := step.Values()
+	if si, ok := step.(SliceIndex); ok && si.isSlice && vx.IsValid() && vy.IsValid() {
+		px, py := vx.Addr(), vy.Addr()
+		if eq, visited := s.curPtrs.Push(px, py); visited {
+			s.report(eq, reportByCycle)
+			return
+		}
+		defer s.curPtrs.Pop(px, py)
+	}
 
 	// Rule 1: Check whether an option applies on this node in the value tree.
 	if s.tryOptions(t, vx, vy) {
@@ -342,7 +376,7 @@ func detectRaces(c chan<- reflect.Value, f reflect.Value, vs ...reflect.Value) {
 // assuming that T is assignable to R.
 // Otherwise, it returns the input value as is.
 func sanitizeValue(v reflect.Value, t reflect.Type) reflect.Value {
-	// TODO(dsnet): Workaround for reflect bug (https://golang.org/issue/22143).
+	// TODO(≥go1.10): Workaround for reflect bug (https://golang.org/issue/22143).
 	if !flags.AtLeastGo110 {
 		if v.Kind() == reflect.Interface && v.IsNil() && v.Type() != t {
 			return reflect.New(t).Elem()
@@ -352,8 +386,10 @@ func sanitizeValue(v reflect.Value, t reflect.Type) reflect.Value {
 }
 
 func (s *state) compareStruct(t reflect.Type, vx, vy reflect.Value) {
+	var addr bool
 	var vax, vay reflect.Value // Addressable versions of vx and vy
 
+	var mayForce, mayForceInit bool
 	step := StructField{&structField{}}
 	for i := 0; i < t.NumField(); i++ {
 		step.typ = t.Field(i).Type
@@ -372,10 +408,18 @@ func (s *state) compareStruct(t reflect.Type, vx, vy reflect.Value) {
 				// For retrieveUnexportedField to work, the parent struct must
 				// be addressable. Create a new copy of the values if
 				// necessary to make them addressable.
+				addr = vx.CanAddr() || vy.CanAddr()
 				vax = makeAddressable(vx)
 				vay = makeAddressable(vy)
 			}
-			step.mayForce = s.exporters[t]
+			if !mayForceInit {
+				for _, xf := range s.exporters {
+					mayForce = mayForce || xf(t)
+				}
+				mayForceInit = true
+			}
+			step.mayForce = mayForce
+			step.paddr = addr
 			step.pvx = vax
 			step.pvy = vay
 			step.field = t.Field(i)
@@ -391,9 +435,21 @@ func (s *state) compareSlice(t reflect.Type, vx, vy reflect.Value) {
 		return
 	}
 
-	// TODO: Support cyclic data structures.
+	// NOTE: It is incorrect to call curPtrs.Push on the slice header pointer
+	// since slices represents a list of pointers, rather than a single pointer.
+	// The pointer checking logic must be handled on a per-element basis
+	// in compareAny.
+	//
+	// A slice header (see reflect.SliceHeader) in Go is a tuple of a starting
+	// pointer P, a length N, and a capacity C. Supposing each slice element has
+	// a memory size of M, then the slice is equivalent to the list of pointers:
+	//	[P+i*M for i in range(N)]
+	//
+	// For example, v[:0] and v[:1] are slices with the same starting pointer,
+	// but they are clearly different values. Using the slice pointer alone
+	// violates the assumption that equal pointers implies equal values.
 
-	step := SliceIndex{&sliceIndex{pathStep: pathStep{typ: t.Elem()}}}
+	step := SliceIndex{&sliceIndex{pathStep: pathStep{typ: t.Elem()}, isSlice: isSlice}}
 	withIndexes := func(ix, iy int) SliceIndex {
 		if ix >= 0 {
 			step.vx, step.xkey = vx.Index(ix), ix
@@ -470,7 +526,12 @@ func (s *state) compareMap(t reflect.Type, vx, vy reflect.Value) {
 		return
 	}
 
-	// TODO: Support cyclic data structures.
+	// Cycle-detection for maps.
+	if eq, visited := s.curPtrs.Push(vx, vy); visited {
+		s.report(eq, reportByCycle)
+		return
+	}
+	defer s.curPtrs.Pop(vx, vy)
 
 	// We combine and sort the two map keys so that we can perform the
 	// comparisons in a deterministic order.
@@ -507,7 +568,12 @@ func (s *state) comparePtr(t reflect.Type, vx, vy reflect.Value) {
 		return
 	}
 
-	// TODO: Support cyclic data structures.
+	// Cycle-detection for pointers.
+	if eq, visited := s.curPtrs.Push(vx, vy); visited {
+		s.report(eq, reportByCycle)
+		return
+	}
+	defer s.curPtrs.Pop(vx, vy)
 
 	vx, vy = vx.Elem(), vy.Elem()
 	s.compareAny(Indirect{&indirect{pathStep{t.Elem(), vx, vy}}})

vendor/github.com/google/go-cmp/cmp/export_panic.go

@@ -1,6 +1,6 @@
 // Copyright 2017, The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE.md file.
+// license that can be found in the LICENSE file.
 
 // +build purego
 
@@ -8,8 +8,8 @@ package cmp
 
 import "reflect"
 
-const supportAllowUnexported = false
+const supportExporters = false
 
-func retrieveUnexportedField(reflect.Value, reflect.StructField) reflect.Value {
-	panic("retrieveUnexportedField is not implemented")
+func retrieveUnexportedField(reflect.Value, reflect.StructField, bool) reflect.Value {
+	panic("no support for forcibly accessing unexported fields")
 }

vendor/github.com/google/go-cmp/cmp/export_unsafe.go

@@ -1,6 +1,6 @@
 // Copyright 2017, The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE.md file.
+// license that can be found in the LICENSE file.
 
 // +build !purego
 
@@ -11,13 +11,25 @@ import (
 	"unsafe"
 )
 
-const supportAllowUnexported = true
+const supportExporters = true
 
 // retrieveUnexportedField uses unsafe to forcibly retrieve any field from
 // a struct such that the value has read-write permissions.
 //
 // The parent struct, v, must be addressable, while f must be a StructField
-// describing the field to retrieve.
-func retrieveUnexportedField(v reflect.Value, f reflect.StructField) reflect.Value {
-	return reflect.NewAt(f.Type, unsafe.Pointer(v.UnsafeAddr()+f.Offset)).Elem()
+// describing the field to retrieve. If addr is false,
+// then the returned value will be shallowed copied to be non-addressable.
+func retrieveUnexportedField(v reflect.Value, f reflect.StructField, addr bool) reflect.Value {
+	ve := reflect.NewAt(f.Type, unsafe.Pointer(uintptr(unsafe.Pointer(v.UnsafeAddr()))+f.Offset)).Elem()
+	if !addr {
+		// A field is addressable if and only if the struct is addressable.
+		// If the original parent value was not addressable, shallow copy the
+		// value to make it non-addressable to avoid leaking an implementation
+		// detail of how forcibly exporting a field works.
+		if ve.Kind() == reflect.Interface && ve.IsNil() {
+			return reflect.Zero(f.Type)
+		}
+		return reflect.ValueOf(ve.Interface()).Convert(f.Type)
+	}
+	return ve
 }

vendor/github.com/google/go-cmp/cmp/internal/diff/debug_disable.go

@@ -1,6 +1,6 @@
 // Copyright 2017, The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE.md file.
+// license that can be found in the LICENSE file.
 
 // +build !cmp_debug
 

vendor/github.com/google/go-cmp/cmp/internal/diff/debug_enable.go

@@ -1,6 +1,6 @@
 // Copyright 2017, The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE.md file.
+// license that can be found in the LICENSE file.
 
 // +build cmp_debug
 

vendor/github.com/google/go-cmp/cmp/internal/diff/diff.go

@@ -1,6 +1,6 @@
 // Copyright 2017, The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE.md file.
+// license that can be found in the LICENSE file.
 
 // Package diff implements an algorithm for producing edit-scripts.
 // The edit-script is a sequence of operations needed to transform one list
@@ -12,6 +12,13 @@
 // is more important than obtaining a minimal Levenshtein distance.
 package diff
 
+import (
+	"math/rand"
+	"time"
+
+	"github.com/google/go-cmp/cmp/internal/flags"
+)
+
 // EditType represents a single operation within an edit-script.
 type EditType uint8
 
@@ -112,6 +119,8 @@ func (r Result) Similar() bool {
 	return r.NumSame+1 >= r.NumDiff
 }
 
+var randBool = rand.New(rand.NewSource(time.Now().Unix())).Intn(2) == 0
+
 // Difference reports whether two lists of lengths nx and ny are equal
 // given the definition of equality provided as f.
 //
@@ -177,6 +186,11 @@ func Difference(nx, ny int, f EqualFunc) (es EditScript) {
 	// approximately the square-root of the search budget.
 	searchBudget := 4 * (nx + ny) // O(n)
 
+	// Running the tests with the "cmp_debug" build tag prints a visualization
+	// of the algorithm running in real-time. This is educational for
+	// understanding how the algorithm works. See debug_enable.go.
+	f = debug.Begin(nx, ny, f, &fwdPath.es, &revPath.es)
+
 	// The algorithm below is a greedy, meet-in-the-middle algorithm for
 	// computing sub-optimal edit-scripts between two lists.
 	//
@@ -194,20 +208,26 @@ func Difference(nx, ny int, f EqualFunc) (es EditScript) {
 	//	frontier towards the opposite corner.
 	//	• This algorithm terminates when either the X coordinates or the
 	//	Y coordinates of the forward and reverse frontier points ever intersect.
-	//
+
 	// This algorithm is correct even if searching only in the forward direction
 	// or in the reverse direction. We do both because it is commonly observed
 	// that two lists commonly differ because elements were added to the front
 	// or end of the other list.
 	//
-	// Running the tests with the "cmp_debug" build tag prints a visualization
-	// of the algorithm running in real-time. This is educational for
-	// understanding how the algorithm works. See debug_enable.go.
-	f = debug.Begin(nx, ny, f, &fwdPath.es, &revPath.es)
-	for {
+	// Non-deterministically start with either the forward or reverse direction
+	// to introduce some deliberate instability so that we have the flexibility
+	// to change this algorithm in the future.
+	if flags.Deterministic || randBool {
+		goto forwardSearch
+	} else {
+		goto reverseSearch
+	}
+
+forwardSearch:
+	{
 		// Forward search from the beginning.
 		if fwdFrontier.X >= revFrontier.X || fwdFrontier.Y >= revFrontier.Y || searchBudget == 0 {
-			break
+			goto finishSearch
 		}
 		for stop1, stop2, i := false, false, 0; !(stop1 && stop2) && searchBudget > 0; i++ {
 			// Search in a diagonal pattern for a match.
@@ -242,10 +262,14 @@ func Difference(nx, ny int, f EqualFunc) (es EditScript) {
 		} else {
 			fwdFrontier.Y++
 		}
+		goto reverseSearch
+	}
 
+reverseSearch:
+	{
 		// Reverse search from the end.
 		if fwdFrontier.X >= revFrontier.X || fwdFrontier.Y >= revFrontier.Y || searchBudget == 0 {
-			break
+			goto finishSearch
 		}
 		for stop1, stop2, i := false, false, 0; !(stop1 && stop2) && searchBudget > 0; i++ {
 			// Search in a diagonal pattern for a match.
@@ -280,8 +304,10 @@ func Difference(nx, ny int, f EqualFunc) (es EditScript) {
 		} else {
 			revFrontier.Y--
 		}
+		goto forwardSearch
 	}
 
+finishSearch:
 	// Join the forward and reverse paths and then append the reverse path.
 	fwdPath.connect(revPath.point, f)
 	for i := len(revPath.es) - 1; i >= 0; i-- {

vendor/github.com/google/go-cmp/cmp/internal/flags/flags.go

@@ -1,6 +1,6 @@
 // Copyright 2019, The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE.md file.
+// license that can be found in the LICENSE file.
 
 package flags
 

vendor/github.com/google/go-cmp/cmp/internal/flags/toolchain_legacy.go

@@ -1,6 +1,6 @@
 // Copyright 2019, The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE.md file.
+// license that can be found in the LICENSE file.
 
 // +build !go1.10
 

vendor/github.com/google/go-cmp/cmp/internal/flags/toolchain_recent.go

@@ -1,6 +1,6 @@
 // Copyright 2019, The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE.md file.
+// license that can be found in the LICENSE file.
 
 // +build go1.10
 

vendor/github.com/google/go-cmp/cmp/internal/function/func.go

@@ -1,6 +1,6 @@
 // Copyright 2017, The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE.md file.
+// license that can be found in the LICENSE file.
 
 // Package function provides functionality for identifying function types.
 package function

vendor/github.com/google/go-cmp/cmp/internal/value/name.go

@@ -0,0 +1,157 @@
+// Copyright 2020, The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package value
+
+import (
+	"reflect"
+	"strconv"
+)
+
+// TypeString is nearly identical to reflect.Type.String,
+// but has an additional option to specify that full type names be used.
+func TypeString(t reflect.Type, qualified bool) string {
+	return string(appendTypeName(nil, t, qualified, false))
+}
+
+func appendTypeName(b []byte, t reflect.Type, qualified, elideFunc bool) []byte {
+	// BUG: Go reflection provides no way to disambiguate two named types
+	// of the same name and within the same package,
+	// but declared within the namespace of different functions.
+
+	// Named type.
+	if t.Name() != "" {
+		if qualified && t.PkgPath() != "" {
+			b = append(b, '"')
+			b = append(b, t.PkgPath()...)
+			b = append(b, '"')
+			b = append(b, '.')
+			b = append(b, t.Name()...)
+		} else {
+			b = append(b, t.String()...)
+		}
+		return b
+	}
+
+	// Unnamed type.
+	switch k := t.Kind(); k {
+	case reflect.Bool, reflect.String, reflect.UnsafePointer,
+		reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64,
+		reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr,
+		reflect.Float32, reflect.Float64, reflect.Complex64, reflect.Complex128:
+		b = append(b, k.String()...)
+	case reflect.Chan:
+		if t.ChanDir() == reflect.RecvDir {
+			b = append(b, "<-"...)
+		}
+		b = append(b, "chan"...)
+		if t.ChanDir() == reflect.SendDir {
+			b = append(b, "<-"...)
+		}
+		b = append(b, ' ')
+		b = appendTypeName(b, t.Elem(), qualified, false)
+	case reflect.Func:
+		if !elideFunc {
+			b = append(b, "func"...)
+		}
+		b = append(b, '(')
+		for i := 0; i < t.NumIn(); i++ {
+			if i > 0 {
+				b = append(b, ", "...)
+			}
+			if i == t.NumIn()-1 && t.IsVariadic() {
+				b = append(b, "..."...)
+				b = appendTypeName(b, t.In(i).Elem(), qualified, false)
+			} else {
+				b = appendTypeName(b, t.In(i), qualified, false)
+			}
+		}
+		b = append(b, ')')
+		switch t.NumOut() {
+		case 0:
+			// Do nothing
+		case 1:
+			b = append(b, ' ')
+			b = appendTypeName(b, t.Out(0), qualified, false)
+		default:
+			b = append(b, " ("...)
+			for i := 0; i < t.NumOut(); i++ {
+				if i > 0 {
+					b = append(b, ", "...)
+				}
+				b = appendTypeName(b, t.Out(i), qualified, false)
+			}
+			b = append(b, ')')
+		}
+	case reflect.Struct:
+		b = append(b, "struct{ "...)
+		for i := 0; i < t.NumField(); i++ {
+			if i > 0 {
+				b = append(b, "; "...)
+			}
+			sf := t.Field(i)
+			if !sf.Anonymous {
+				if qualified && sf.PkgPath != "" {
+					b = append(b, '"')
+					b = append(b, sf.PkgPath...)
+					b = append(b, '"')
+					b = append(b, '.')
+				}
+				b = append(b, sf.Name...)
+				b = append(b, ' ')
+			}
+			b = appendTypeName(b, sf.Type, qualified, false)
+			if sf.Tag != "" {
+				b = append(b, ' ')
+				b = strconv.AppendQuote(b, string(sf.Tag))
+			}
+		}
+		if b[len(b)-1] == ' ' {
+			b = b[:len(b)-1]
+		} else {
+			b = append(b, ' ')
+		}
+		b = append(b, '}')
+	case reflect.Slice, reflect.Array:
+		b = append(b, '[')
+		if k == reflect.Array {
+			b = strconv.AppendUint(b, uint64(t.Len()), 10)
+		}
+		b = append(b, ']')
+		b = appendTypeName(b, t.Elem(), qualified, false)
+	case reflect.Map:
+		b = append(b, "map["...)
+		b = appendTypeName(b, t.Key(), qualified, false)
+		b = append(b, ']')
+		b = appendTypeName(b, t.Elem(), qualified, false)
+	case reflect.Ptr:
+		b = append(b, '*')
+		b = appendTypeName(b, t.Elem(), qualified, false)
+	case reflect.Interface:
+		b = append(b, "interface{ "...)
+		for i := 0; i < t.NumMethod(); i++ {
+			if i > 0 {
+				b = append(b, "; "...)
+			}
+			m := t.Method(i)
+			if qualified && m.PkgPath != "" {
+				b = append(b, '"')
+				b = append(b, m.PkgPath...)
+				b = append(b, '"')
+				b = append(b, '.')
+			}
+			b = append(b, m.Name...)
+			b = appendTypeName(b, m.Type, qualified, true)
+		}
+		if b[len(b)-1] == ' ' {
+			b = b[:len(b)-1]
+		} else {
+			b = append(b, ' ')
+		}
+		b = append(b, '}')
+	default:
+		panic("invalid kind: " + k.String())
+	}
+	return b
+}

vendor/github.com/google/go-cmp/cmp/internal/value/pointer_purego.go

@@ -1,6 +1,6 @@
 // Copyright 2018, The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE.md file.
+// license that can be found in the LICENSE file.
 
 // +build purego
 
@@ -21,3 +21,13 @@ func PointerOf(v reflect.Value) Pointer {
 	// assumes that the GC implementation does not use a moving collector.
 	return Pointer{v.Pointer(), v.Type()}
 }
+
+// IsNil reports whether the pointer is nil.
+func (p Pointer) IsNil() bool {
+	return p.p == 0
+}
+
+// Uintptr returns the pointer as a uintptr.
+func (p Pointer) Uintptr() uintptr {
+	return p.p
+}

vendor/github.com/google/go-cmp/cmp/internal/value/pointer_unsafe.go

@@ -1,6 +1,6 @@
 // Copyright 2018, The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE.md file.
+// license that can be found in the LICENSE file.
 
 // +build !purego
 
@@ -24,3 +24,13 @@ func PointerOf(v reflect.Value) Pointer {
 	// which is necessary if the GC ever uses a moving collector.
 	return Pointer{unsafe.Pointer(v.Pointer()), v.Type()}
 }
+
+// IsNil reports whether the pointer is nil.
+func (p Pointer) IsNil() bool {
+	return p.p == nil
+}
+
+// Uintptr returns the pointer as a uintptr.
+func (p Pointer) Uintptr() uintptr {
+	return uintptr(p.p)
+}

vendor/github.com/google/go-cmp/cmp/internal/value/sort.go

@@ -1,6 +1,6 @@
 // Copyright 2017, The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE.md file.
+// license that can be found in the LICENSE file.
 
 package value
 

vendor/github.com/google/go-cmp/cmp/internal/value/zero.go

@@ -1,6 +1,6 @@
 // Copyright 2017, The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE.md file.
+// license that can be found in the LICENSE file.
 
 package value
 

vendor/github.com/google/go-cmp/cmp/options.go

@@ -1,6 +1,6 @@
 // Copyright 2017, The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE.md file.
+// license that can be found in the LICENSE file.
 
 package cmp
 
@@ -225,8 +225,23 @@ func (validator) apply(s *state, vx, vy reflect.Value) {
 
 	// Unable to Interface implies unexported field without visibility access.
 	if !vx.CanInterface() || !vy.CanInterface() {
-		const help = "consider using a custom Comparer; if you control the implementation of type, you can also consider AllowUnexported or cmpopts.IgnoreUnexported"
-		panic(fmt.Sprintf("cannot handle unexported field: %#v\n%s", s.curPath, help))
+		help := "consider using a custom Comparer; if you control the implementation of type, you can also consider using an Exporter, AllowUnexported, or cmpopts.IgnoreUnexported"
+		var name string
+		if t := s.curPath.Index(-2).Type(); t.Name() != "" {
+			// Named type with unexported fields.
+			name = fmt.Sprintf("%q.%v", t.PkgPath(), t.Name()) // e.g., "path/to/package".MyType
+			if _, ok := reflect.New(t).Interface().(error); ok {
+				help = "consider using cmpopts.EquateErrors to compare error values"
+			}
+		} else {
+			// Unnamed type with unexported fields. Derive PkgPath from field.
+			var pkgPath string
+			for i := 0; i < t.NumField() && pkgPath == ""; i++ {
+				pkgPath = t.Field(i).PkgPath
+			}
+			name = fmt.Sprintf("%q.(%v)", pkgPath, t.String()) // e.g., "path/to/package".(struct { a int })
+		}
+		panic(fmt.Sprintf("cannot handle unexported field at %#v:\n\t%v\n%s", s.curPath, name, help))
 	}
 
 	panic("not reachable")
@@ -360,9 +375,8 @@ func (cm comparer) String() string {
 	return fmt.Sprintf("Comparer(%s)", function.NameOf(cm.fnc))
 }
 
-// AllowUnexported returns an Option that forcibly allows operations on
-// unexported fields in certain structs, which are specified by passing in a
-// value of each struct type.
+// Exporter returns an Option that specifies whether Equal is allowed to
+// introspect into the unexported fields of certain struct types.
 //
 // Users of this option must understand that comparing on unexported fields
 // from external packages is not safe since changes in the internal
@@ -386,10 +400,24 @@ func (cm comparer) String() string {
 //
 // In other cases, the cmpopts.IgnoreUnexported option can be used to ignore
 // all unexported fields on specified struct types.
-func AllowUnexported(types ...interface{}) Option {
-	if !supportAllowUnexported {
-		panic("AllowUnexported is not supported on purego builds, Google App Engine Standard, or GopherJS")
+func Exporter(f func(reflect.Type) bool) Option {
+	if !supportExporters {
+		panic("Exporter is not supported on purego builds")
 	}
+	return exporter(f)
+}
+
+type exporter func(reflect.Type) bool
+
+func (exporter) filter(_ *state, _ reflect.Type, _, _ reflect.Value) applicableOption {
+	panic("not implemented")
+}
+
+// AllowUnexported returns an Options that allows Equal to forcibly introspect
+// unexported fields of the specified struct types.
+//
+// See Exporter for the proper use of this option.
+func AllowUnexported(types ...interface{}) Option {
 	m := make(map[reflect.Type]bool)
 	for _, typ := range types {
 		t := reflect.TypeOf(typ)
@@ -398,13 +426,7 @@ func AllowUnexported(types ...interface{}) Option {
 		}
 		m[t] = true
 	}
-	return visibleStructs(m)
-}
-
-type visibleStructs map[reflect.Type]bool
-
-func (visibleStructs) filter(_ *state, _ reflect.Type, _, _ reflect.Value) applicableOption {
-	panic("not implemented")
+	return exporter(func(t reflect.Type) bool { return m[t] })
 }
 
 // Result represents the comparison result for a single node and
@@ -436,6 +458,11 @@ func (r Result) ByFunc() bool {
 	return r.flags&reportByFunc != 0
 }
 
+// ByCycle reports whether a reference cycle was detected.
+func (r Result) ByCycle() bool {
+	return r.flags&reportByCycle != 0
+}
+
 type resultFlags uint
 
 const (
@@ -446,6 +473,7 @@ const (
 	reportByIgnore
 	reportByMethod
 	reportByFunc
+	reportByCycle
 )
 
 // Reporter is an Option that can be passed to Equal. When Equal traverses

vendor/github.com/google/go-cmp/cmp/path.go

@@ -1,6 +1,6 @@
 // Copyright 2017, The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE.md file.
+// license that can be found in the LICENSE file.
 
 package cmp
 
@@ -10,6 +10,8 @@ import (
 	"strings"
 	"unicode"
 	"unicode/utf8"
+
+	"github.com/google/go-cmp/cmp/internal/value"
 )
 
 // Path is a list of PathSteps describing the sequence of operations to get
@@ -41,7 +43,7 @@ type PathStep interface {
 	// In some cases, one or both may be invalid or have restrictions:
 	//	• For StructField, both are not interface-able if the current field
 	//	is unexported and the struct type is not explicitly permitted by
-	//	AllowUnexported to traverse unexported fields.
+	//	an Exporter to traverse unexported fields.
 	//	• For SliceIndex, one may be invalid if an element is missing from
 	//	either the x or y slice.
 	//	• For MapIndex, one may be invalid if an entry is missing from
@@ -175,7 +177,8 @@ type structField struct {
 	// pvx, pvy, and field are only valid if unexported is true.
 	unexported bool
 	mayForce   bool                // Forcibly allow visibility
-	pvx, pvy   reflect.Value       // Parent values
+	paddr      bool                // Was parent addressable?
+	pvx, pvy   reflect.Value       // Parent values (always addressible)
 	field      reflect.StructField // Field information
 }
 
@@ -187,8 +190,8 @@ func (sf StructField) Values() (vx, vy reflect.Value) {
 
 	// Forcibly obtain read-write access to an unexported struct field.
 	if sf.mayForce {
-		vx = retrieveUnexportedField(sf.pvx, sf.field)
-		vy = retrieveUnexportedField(sf.pvy, sf.field)
+		vx = retrieveUnexportedField(sf.pvx, sf.field, sf.paddr)
+		vy = retrieveUnexportedField(sf.pvy, sf.field, sf.paddr)
 		return vx, vy // CanInterface reports true
 	}
 	return sf.vx, sf.vy // CanInterface reports false
@@ -207,6 +210,7 @@ type SliceIndex struct{ *sliceIndex }
 type sliceIndex struct {
 	pathStep
 	xkey, ykey int
+	isSlice    bool // False for reflect.Array
 }
 
 func (si SliceIndex) Type() reflect.Type             { return si.typ }
@@ -301,6 +305,72 @@ func (tf Transform) Func() reflect.Value { return tf.trans.fnc }
 // The == operator can be used to detect the exact option used.
 func (tf Transform) Option() Option { return tf.trans }
 
+// pointerPath represents a dual-stack of pointers encountered when
+// recursively traversing the x and y values. This data structure supports
+// detection of cycles and determining whether the cycles are equal.
+// In Go, cycles can occur via pointers, slices, and maps.
+//
+// The pointerPath uses a map to represent a stack; where descension into a
+// pointer pushes the address onto the stack, and ascension from a pointer
+// pops the address from the stack. Thus, when traversing into a pointer from
+// reflect.Ptr, reflect.Slice element, or reflect.Map, we can detect cycles
+// by checking whether the pointer has already been visited. The cycle detection
+// uses a seperate stack for the x and y values.
+//
+// If a cycle is detected we need to determine whether the two pointers
+// should be considered equal. The definition of equality chosen by Equal
+// requires two graphs to have the same structure. To determine this, both the
+// x and y values must have a cycle where the previous pointers were also
+// encountered together as a pair.
+//
+// Semantically, this is equivalent to augmenting Indirect, SliceIndex, and
+// MapIndex with pointer information for the x and y values.
+// Suppose px and py are two pointers to compare, we then search the
+// Path for whether px was ever encountered in the Path history of x, and
+// similarly so with py. If either side has a cycle, the comparison is only
+// equal if both px and py have a cycle resulting from the same PathStep.
+//
+// Using a map as a stack is more performant as we can perform cycle detection
+// in O(1) instead of O(N) where N is len(Path).
+type pointerPath struct {
+	// mx is keyed by x pointers, where the value is the associated y pointer.
+	mx map[value.Pointer]value.Pointer
+	// my is keyed by y pointers, where the value is the associated x pointer.
+	my map[value.Pointer]value.Pointer
+}
+
+func (p *pointerPath) Init() {
+	p.mx = make(map[value.Pointer]value.Pointer)
+	p.my = make(map[value.Pointer]value.Pointer)
+}
+
+// Push indicates intent to descend into pointers vx and vy where
+// visited reports whether either has been seen before. If visited before,
+// equal reports whether both pointers were encountered together.
+// Pop must be called if and only if the pointers were never visited.
+//
+// The pointers vx and vy must be a reflect.Ptr, reflect.Slice, or reflect.Map
+// and be non-nil.
+func (p pointerPath) Push(vx, vy reflect.Value) (equal, visited bool) {
+	px := value.PointerOf(vx)
+	py := value.PointerOf(vy)
+	_, ok1 := p.mx[px]
+	_, ok2 := p.my[py]
+	if ok1 || ok2 {
+		equal = p.mx[px] == py && p.my[py] == px // Pointers paired together
+		return equal, true
+	}
+	p.mx[px] = py
+	p.my[py] = px
+	return false, false
+}
+
+// Pop ascends from pointers vx and vy.
+func (p pointerPath) Pop(vx, vy reflect.Value) {
+	delete(p.mx, value.PointerOf(vx))
+	delete(p.my, value.PointerOf(vy))
+}
+
 // isExported reports whether the identifier is exported.
 func isExported(id string) bool {
 	r, _ := utf8.DecodeRuneInString(id)

vendor/github.com/google/go-cmp/cmp/report.go

@@ -1,6 +1,6 @@
 // Copyright 2017, The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE.md file.
+// license that can be found in the LICENSE file.
 
 package cmp
 
@@ -41,7 +41,10 @@ func (r *defaultReporter) String() string {
 	if r.root.NumDiff == 0 {
 		return ""
 	}
-	return formatOptions{}.FormatDiff(r.root).String()
+	ptrs := new(pointerReferences)
+	text := formatOptions{}.FormatDiff(r.root, ptrs)
+	resolveReferences(text)
+	return text.String()
 }
 
 func assert(ok bool) {

vendor/github.com/google/go-cmp/cmp/report_compare.go

@@ -1,6 +1,6 @@
 // Copyright 2019, The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE.md file.
+// license that can be found in the LICENSE file.
 
 package cmp
 
@@ -11,14 +11,6 @@ import (
 	"github.com/google/go-cmp/cmp/internal/value"
 )
 
-// TODO: Enforce limits?
-//	* Enforce maximum number of records to print per node?
-//	* Enforce maximum size in bytes allowed?
-//	* As a heuristic, use less verbosity for equal nodes than unequal nodes.
-// TODO: Enforce unique outputs?
-//	* Avoid Stringer methods if it results in same output?
-//	* Print pointer address if outputs still equal?
-
 // numContextRecords is the number of surrounding equal records to print.
 const numContextRecords = 2
 
@@ -71,24 +63,66 @@ func (opts formatOptions) WithTypeMode(t typeMode) formatOptions {
 	opts.TypeMode = t
 	return opts
 }
+func (opts formatOptions) WithVerbosity(level int) formatOptions {
+	opts.VerbosityLevel = level
+	opts.LimitVerbosity = true
+	return opts
+}
+func (opts formatOptions) verbosity() uint {
+	switch {
+	case opts.VerbosityLevel < 0:
+		return 0
+	case opts.VerbosityLevel > 16:
+		return 16 // some reasonable maximum to avoid shift overflow
+	default:
+		return uint(opts.VerbosityLevel)
+	}
+}
+
+const maxVerbosityPreset = 3
+
+// verbosityPreset modifies the verbosity settings given an index
+// between 0 and maxVerbosityPreset, inclusive.
+func verbosityPreset(opts formatOptions, i int) formatOptions {
+	opts.VerbosityLevel = int(opts.verbosity()) + 2*i
+	if i > 0 {
+		opts.AvoidStringer = true
+	}
+	if i >= maxVerbosityPreset {
+		opts.PrintAddresses = true
+		opts.QualifiedNames = true
+	}
+	return opts
+}
 
 // FormatDiff converts a valueNode tree into a textNode tree, where the later
 // is a textual representation of the differences detected in the former.
-func (opts formatOptions) FormatDiff(v *valueNode) textNode {
+func (opts formatOptions) FormatDiff(v *valueNode, ptrs *pointerReferences) (out textNode) {
+	if opts.DiffMode == diffIdentical {
+		opts = opts.WithVerbosity(1)
+	} else {
+		opts = opts.WithVerbosity(3)
+	}
+
 	// Check whether we have specialized formatting for this node.
 	// This is not necessary, but helpful for producing more readable outputs.
 	if opts.CanFormatDiffSlice(v) {
 		return opts.FormatDiffSlice(v)
 	}
 
+	var parentKind reflect.Kind
+	if v.parent != nil && v.parent.TransformerName == "" {
+		parentKind = v.parent.Type.Kind()
+	}
+
 	// For leaf nodes, format the value based on the reflect.Values alone.
 	if v.MaxDepth == 0 {
 		switch opts.DiffMode {
 		case diffUnknown, diffIdentical:
 			// Format Equal.
 			if v.NumDiff == 0 {
-				outx := opts.FormatValue(v.ValueX, visitedPointers{})
-				outy := opts.FormatValue(v.ValueY, visitedPointers{})
+				outx := opts.FormatValue(v.ValueX, parentKind, ptrs)
+				outy := opts.FormatValue(v.ValueY, parentKind, ptrs)
 				if v.NumIgnored > 0 && v.NumSame == 0 {
 					return textEllipsis
 				} else if outx.Len() < outy.Len() {
@@ -101,8 +135,13 @@ func (opts formatOptions) FormatDiff(v *valueNode) textNode {
 			// Format unequal.
 			assert(opts.DiffMode == diffUnknown)
 			var list textList
-			outx := opts.WithTypeMode(elideType).FormatValue(v.ValueX, visitedPointers{})
-			outy := opts.WithTypeMode(elideType).FormatValue(v.ValueY, visitedPointers{})
+			outx := opts.WithTypeMode(elideType).FormatValue(v.ValueX, parentKind, ptrs)
+			outy := opts.WithTypeMode(elideType).FormatValue(v.ValueY, parentKind, ptrs)
+			for i := 0; i <= maxVerbosityPreset && outx != nil && outy != nil && outx.Equal(outy); i++ {
+				opts2 := verbosityPreset(opts, i).WithTypeMode(elideType)
+				outx = opts2.FormatValue(v.ValueX, parentKind, ptrs)
+				outy = opts2.FormatValue(v.ValueY, parentKind, ptrs)
+			}
 			if outx != nil {
 				list = append(list, textRecord{Diff: '-', Value: outx})
 			}
@@ -111,34 +150,57 @@ func (opts formatOptions) FormatDiff(v *valueNode) textNode {
 			}
 			return opts.WithTypeMode(emitType).FormatType(v.Type, list)
 		case diffRemoved:
-			return opts.FormatValue(v.ValueX, visitedPointers{})
+			return opts.FormatValue(v.ValueX, parentKind, ptrs)
 		case diffInserted:
-			return opts.FormatValue(v.ValueY, visitedPointers{})
+			return opts.FormatValue(v.ValueY, parentKind, ptrs)
 		default:
 			panic("invalid diff mode")
 		}
 	}
 
+	// Register slice element to support cycle detection.
+	if parentKind == reflect.Slice {
+		ptrRefs := ptrs.PushPair(v.ValueX, v.ValueY, opts.DiffMode, true)
+		defer ptrs.Pop()
+		defer func() { out = wrapTrunkReferences(ptrRefs, out) }()
+	}
+
 	// Descend into the child value node.
 	if v.TransformerName != "" {
-		out := opts.WithTypeMode(emitType).FormatDiff(v.Value)
-		out = textWrap{"Inverse(" + v.TransformerName + ", ", out, ")"}
+		out := opts.WithTypeMode(emitType).FormatDiff(v.Value, ptrs)
+		out = &textWrap{Prefix: "Inverse(" + v.TransformerName + ", ", Value: out, Suffix: ")"}
 		return opts.FormatType(v.Type, out)
 	} else {
 		switch k := v.Type.Kind(); k {
-		case reflect.Struct, reflect.Array, reflect.Slice, reflect.Map:
-			return opts.FormatType(v.Type, opts.formatDiffList(v.Records, k))
+		case reflect.Struct, reflect.Array, reflect.Slice:
+			out = opts.formatDiffList(v.Records, k, ptrs)
+			out = opts.FormatType(v.Type, out)
+		case reflect.Map:
+			// Register map to support cycle detection.
+			ptrRefs := ptrs.PushPair(v.ValueX, v.ValueY, opts.DiffMode, false)
+			defer ptrs.Pop()
+
+			out = opts.formatDiffList(v.Records, k, ptrs)
+			out = wrapTrunkReferences(ptrRefs, out)
+			out = opts.FormatType(v.Type, out)
 		case reflect.Ptr:
-			return textWrap{"&", opts.FormatDiff(v.Value), ""}
+			// Register pointer to support cycle detection.
+			ptrRefs := ptrs.PushPair(v.ValueX, v.ValueY, opts.DiffMode, false)
+			defer ptrs.Pop()
+
+			out = opts.FormatDiff(v.Value, ptrs)
+			out = wrapTrunkReferences(ptrRefs, out)
+			out = &textWrap{Prefix: "&", Value: out}
 		case reflect.Interface:
-			return opts.WithTypeMode(emitType).FormatDiff(v.Value)
+			out = opts.WithTypeMode(emitType).FormatDiff(v.Value, ptrs)
 		default:
 			panic(fmt.Sprintf("%v cannot have children", k))
 		}
+		return out
 	}
 }
 
-func (opts formatOptions) formatDiffList(recs []reportRecord, k reflect.Kind) textNode {
+func (opts formatOptions) formatDiffList(recs []reportRecord, k reflect.Kind, ptrs *pointerReferences) textNode {
 	// Derive record name based on the data structure kind.
 	var name string
 	var formatKey func(reflect.Value) string
@@ -154,7 +216,17 @@ func (opts formatOptions) formatDiffList(recs []reportRecord, k reflect.Kind) te
 	case reflect.Map:
 		name = "entry"
 		opts = opts.WithTypeMode(elideType)
-		formatKey = formatMapKey
+		formatKey = func(v reflect.Value) string { return formatMapKey(v, false, ptrs) }
+	}
+
+	maxLen := -1
+	if opts.LimitVerbosity {
+		if opts.DiffMode == diffIdentical {
+			maxLen = ((1 << opts.verbosity()) >> 1) << 2 // 0, 4, 8, 16, 32, etc...
+		} else {
+			maxLen = (1 << opts.verbosity()) << 1 // 2, 4, 8, 16, 32, 64, etc...
+		}
+		opts.VerbosityLevel--
 	}
 
 	// Handle unification.
@@ -163,6 +235,11 @@ func (opts formatOptions) formatDiffList(recs []reportRecord, k reflect.Kind) te
 		var list textList
 		var deferredEllipsis bool // Add final "..." to indicate records were dropped
 		for _, r := range recs {
+			if len(list) == maxLen {
+				deferredEllipsis = true
+				break
+			}
+
 			// Elide struct fields that are zero value.
 			if k == reflect.Struct {
 				var isZero bool
@@ -186,23 +263,31 @@ func (opts formatOptions) formatDiffList(recs []reportRecord, k reflect.Kind) te
 				}
 				continue
 			}
-			if out := opts.FormatDiff(r.Value); out != nil {
+			if out := opts.FormatDiff(r.Value, ptrs); out != nil {
 				list = append(list, textRecord{Key: formatKey(r.Key), Value: out})
 			}
 		}
 		if deferredEllipsis {
 			list.AppendEllipsis(diffStats{})
 		}
-		return textWrap{"{", list, "}"}
+		return &textWrap{Prefix: "{", Value: list, Suffix: "}"}
 	case diffUnknown:
 	default:
 		panic("invalid diff mode")
 	}
 
 	// Handle differencing.
+	var numDiffs int
 	var list textList
+	var keys []reflect.Value // invariant: len(list) == len(keys)
 	groups := coalesceAdjacentRecords(name, recs)
+	maxGroup := diffStats{Name: name}
 	for i, ds := range groups {
+		if maxLen >= 0 && numDiffs >= maxLen {
+			maxGroup = maxGroup.Append(ds)
+			continue
+		}
+
 		// Handle equal records.
 		if ds.NumDiff() == 0 {
 			// Compute the number of leading and trailing records to print.
@@ -226,16 +311,21 @@ func (opts formatOptions) formatDiffList(recs []reportRecord, k reflect.Kind) te
 
 			// Format the equal values.
 			for _, r := range recs[:numLo] {
-				out := opts.WithDiffMode(diffIdentical).FormatDiff(r.Value)
+				out := opts.WithDiffMode(diffIdentical).FormatDiff(r.Value, ptrs)
 				list = append(list, textRecord{Key: formatKey(r.Key), Value: out})
+				keys = append(keys, r.Key)
 			}
 			if numEqual > numLo+numHi {
 				ds.NumIdentical -= numLo + numHi
 				list.AppendEllipsis(ds)
+				for len(keys) < len(list) {
+					keys = append(keys, reflect.Value{})
+				}
 			}
 			for _, r := range recs[numEqual-numHi : numEqual] {
-				out := opts.WithDiffMode(diffIdentical).FormatDiff(r.Value)
+				out := opts.WithDiffMode(diffIdentical).FormatDiff(r.Value, ptrs)
 				list = append(list, textRecord{Key: formatKey(r.Key), Value: out})
+				keys = append(keys, r.Key)
 			}
 			recs = recs[numEqual:]
 			continue
@@ -247,24 +337,70 @@ func (opts formatOptions) formatDiffList(recs []reportRecord, k reflect.Kind) te
 			case opts.CanFormatDiffSlice(r.Value):
 				out := opts.FormatDiffSlice(r.Value)
 				list = append(list, textRecord{Key: formatKey(r.Key), Value: out})
+				keys = append(keys, r.Key)
 			case r.Value.NumChildren == r.Value.MaxDepth:
-				outx := opts.WithDiffMode(diffRemoved).FormatDiff(r.Value)
-				outy := opts.WithDiffMode(diffInserted).FormatDiff(r.Value)
+				outx := opts.WithDiffMode(diffRemoved).FormatDiff(r.Value, ptrs)
+				outy := opts.WithDiffMode(diffInserted).FormatDiff(r.Value, ptrs)
+				for i := 0; i <= maxVerbosityPreset && outx != nil && outy != nil && outx.Equal(outy); i++ {
+					opts2 := verbosityPreset(opts, i)
+					outx = opts2.WithDiffMode(diffRemoved).FormatDiff(r.Value, ptrs)
+					outy = opts2.WithDiffMode(diffInserted).FormatDiff(r.Value, ptrs)
+				}
 				if outx != nil {
 					list = append(list, textRecord{Diff: diffRemoved, Key: formatKey(r.Key), Value: outx})
+					keys = append(keys, r.Key)
 				}
 				if outy != nil {
 					list = append(list, textRecord{Diff: diffInserted, Key: formatKey(r.Key), Value: outy})
+					keys = append(keys, r.Key)
 				}
 			default:
-				out := opts.FormatDiff(r.Value)
+				out := opts.FormatDiff(r.Value, ptrs)
 				list = append(list, textRecord{Key: formatKey(r.Key), Value: out})
+				keys = append(keys, r.Key)
 			}
 		}
 		recs = recs[ds.NumDiff():]
+		numDiffs += ds.NumDiff()
 	}
-	assert(len(recs) == 0)
-	return textWrap{"{", list, "}"}
+	if maxGroup.IsZero() {
+		assert(len(recs) == 0)
+	} else {
+		list.AppendEllipsis(maxGroup)
+		for len(keys) < len(list) {
+			keys = append(keys, reflect.Value{})
+		}
+	}
+	assert(len(list) == len(keys))
+
+	// For maps, the default formatting logic uses fmt.Stringer which may
+	// produce ambiguous output. Avoid calling String to disambiguate.
+	if k == reflect.Map {
+		var ambiguous bool
+		seenKeys := map[string]reflect.Value{}
+		for i, currKey := range keys {
+			if currKey.IsValid() {
+				strKey := list[i].Key
+				prevKey, seen := seenKeys[strKey]
+				if seen && prevKey.CanInterface() && currKey.CanInterface() {
+					ambiguous = prevKey.Interface() != currKey.Interface()
+					if ambiguous {
+						break
+					}
+				}
+				seenKeys[strKey] = currKey
+			}
+		}
+		if ambiguous {
+			for i, k := range keys {
+				if k.IsValid() {
+					list[i].Key = formatMapKey(k, true, ptrs)
+				}
+			}
+		}
+	}
+
+	return &textWrap{Prefix: "{", Value: list, Suffix: "}"}
 }
 
 // coalesceAdjacentRecords coalesces the list of records into groups of

vendor/github.com/google/go-cmp/cmp/report_references.go

@@ -0,0 +1,264 @@
+// Copyright 2020, The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package cmp
+
+import (
+	"fmt"
+	"reflect"
+	"strings"
+
+	"github.com/google/go-cmp/cmp/internal/flags"
+	"github.com/google/go-cmp/cmp/internal/value"
+)
+
+const (
+	pointerDelimPrefix = "⟪"
+	pointerDelimSuffix = "⟫"
+)
+
+// formatPointer prints the address of the pointer.
+func formatPointer(p value.Pointer, withDelims bool) string {
+	v := p.Uintptr()
+	if flags.Deterministic {
+		v = 0xdeadf00f // Only used for stable testing purposes
+	}
+	if withDelims {
+		return pointerDelimPrefix + formatHex(uint64(v)) + pointerDelimSuffix
+	}
+	return formatHex(uint64(v))
+}
+
+// pointerReferences is a stack of pointers visited so far.
+type pointerReferences [][2]value.Pointer
+
+func (ps *pointerReferences) PushPair(vx, vy reflect.Value, d diffMode, deref bool) (pp [2]value.Pointer) {
+	if deref && vx.IsValid() {
+		vx = vx.Addr()
+	}
+	if deref && vy.IsValid() {
+		vy = vy.Addr()
+	}
+	switch d {
+	case diffUnknown, diffIdentical:
+		pp = [2]value.Pointer{value.PointerOf(vx), value.PointerOf(vy)}
+	case diffRemoved:
+		pp = [2]value.Pointer{value.PointerOf(vx), value.Pointer{}}
+	case diffInserted:
+		pp = [2]value.Pointer{value.Pointer{}, value.PointerOf(vy)}
+	}
+	*ps = append(*ps, pp)
+	return pp
+}
+
+func (ps *pointerReferences) Push(v reflect.Value) (p value.Pointer, seen bool) {
+	p = value.PointerOf(v)
+	for _, pp := range *ps {
+		if p == pp[0] || p == pp[1] {
+			return p, true
+		}
+	}
+	*ps = append(*ps, [2]value.Pointer{p, p})
+	return p, false
+}
+
+func (ps *pointerReferences) Pop() {
+	*ps = (*ps)[:len(*ps)-1]
+}
+
+// trunkReferences is metadata for a textNode indicating that the sub-tree
+// represents the value for either pointer in a pair of references.
+type trunkReferences struct{ pp [2]value.Pointer }
+
+// trunkReference is metadata for a textNode indicating that the sub-tree
+// represents the value for the given pointer reference.
+type trunkReference struct{ p value.Pointer }
+
+// leafReference is metadata for a textNode indicating that the value is
+// truncated as it refers to another part of the tree (i.e., a trunk).
+type leafReference struct{ p value.Pointer }
+
+func wrapTrunkReferences(pp [2]value.Pointer, s textNode) textNode {
+	switch {
+	case pp[0].IsNil():
+		return &textWrap{Value: s, Metadata: trunkReference{pp[1]}}
+	case pp[1].IsNil():
+		return &textWrap{Value: s, Metadata: trunkReference{pp[0]}}
+	case pp[0] == pp[1]:
+		return &textWrap{Value: s, Metadata: trunkReference{pp[0]}}
+	default:
+		return &textWrap{Value: s, Metadata: trunkReferences{pp}}
+	}
+}
+func wrapTrunkReference(p value.Pointer, printAddress bool, s textNode) textNode {
+	var prefix string
+	if printAddress {
+		prefix = formatPointer(p, true)
+	}
+	return &textWrap{Prefix: prefix, Value: s, Metadata: trunkReference{p}}
+}
+func makeLeafReference(p value.Pointer, printAddress bool) textNode {
+	out := &textWrap{Prefix: "(", Value: textEllipsis, Suffix: ")"}
+	var prefix string
+	if printAddress {
+		prefix = formatPointer(p, true)
+	}
+	return &textWrap{Prefix: prefix, Value: out, Metadata: leafReference{p}}
+}
+
+// resolveReferences walks the textNode tree searching for any leaf reference
+// metadata and resolves each against the corresponding trunk references.
+// Since pointer addresses in memory are not particularly readable to the user,
+// it replaces each pointer value with an arbitrary and unique reference ID.
+func resolveReferences(s textNode) {
+	var walkNodes func(textNode, func(textNode))
+	walkNodes = func(s textNode, f func(textNode)) {
+		f(s)
+		switch s := s.(type) {
+		case *textWrap:
+			walkNodes(s.Value, f)
+		case textList:
+			for _, r := range s {
+				walkNodes(r.Value, f)
+			}
+		}
+	}
+
+	// Collect all trunks and leaves with reference metadata.
+	var trunks, leaves []*textWrap
+	walkNodes(s, func(s textNode) {
+		if s, ok := s.(*textWrap); ok {
+			switch s.Metadata.(type) {
+			case leafReference:
+				leaves = append(leaves, s)
+			case trunkReference, trunkReferences:
+				trunks = append(trunks, s)
+			}
+		}
+	})
+
+	// No leaf references to resolve.
+	if len(leaves) == 0 {
+		return
+	}
+
+	// Collect the set of all leaf references to resolve.
+	leafPtrs := make(map[value.Pointer]bool)
+	for _, leaf := range leaves {
+		leafPtrs[leaf.Metadata.(leafReference).p] = true
+	}
+
+	// Collect the set of trunk pointers that are always paired together.
+	// This allows us to assign a single ID to both pointers for brevity.
+	// If a pointer in a pair ever occurs by itself or as a different pair,
+	// then the pair is broken.
+	pairedTrunkPtrs := make(map[value.Pointer]value.Pointer)
+	unpair := func(p value.Pointer) {
+		if !pairedTrunkPtrs[p].IsNil() {
+			pairedTrunkPtrs[pairedTrunkPtrs[p]] = value.Pointer{} // invalidate other half
+		}
+		pairedTrunkPtrs[p] = value.Pointer{} // invalidate this half
+	}
+	for _, trunk := range trunks {
+		switch p := trunk.Metadata.(type) {
+		case trunkReference:
+			unpair(p.p) // standalone pointer cannot be part of a pair
+		case trunkReferences:
+			p0, ok0 := pairedTrunkPtrs[p.pp[0]]
+			p1, ok1 := pairedTrunkPtrs[p.pp[1]]
+			switch {
+			case !ok0 && !ok1:
+				// Register the newly seen pair.
+				pairedTrunkPtrs[p.pp[0]] = p.pp[1]
+				pairedTrunkPtrs[p.pp[1]] = p.pp[0]
+			case ok0 && ok1 && p0 == p.pp[1] && p1 == p.pp[0]:
+				// Exact pair already seen; do nothing.
+			default:
+				// Pair conflicts with some other pair; break all pairs.
+				unpair(p.pp[0])
+				unpair(p.pp[1])
+			}
+		}
+	}
+
+	// Correlate each pointer referenced by leaves to a unique identifier,
+	// and print the IDs for each trunk that matches those pointers.
+	var nextID uint
+	ptrIDs := make(map[value.Pointer]uint)
+	newID := func() uint {
+		id := nextID
+		nextID++
+		return id
+	}
+	for _, trunk := range trunks {
+		switch p := trunk.Metadata.(type) {
+		case trunkReference:
+			if print := leafPtrs[p.p]; print {
+				id, ok := ptrIDs[p.p]
+				if !ok {
+					id = newID()
+					ptrIDs[p.p] = id
+				}
+				trunk.Prefix = updateReferencePrefix(trunk.Prefix, formatReference(id))
+			}
+		case trunkReferences:
+			print0 := leafPtrs[p.pp[0]]
+			print1 := leafPtrs[p.pp[1]]
+			if print0 || print1 {
+				id0, ok0 := ptrIDs[p.pp[0]]
+				id1, ok1 := ptrIDs[p.pp[1]]
+				isPair := pairedTrunkPtrs[p.pp[0]] == p.pp[1] && pairedTrunkPtrs[p.pp[1]] == p.pp[0]
+				if isPair {
+					var id uint
+					assert(ok0 == ok1) // must be seen together or not at all
+					if ok0 {
+						assert(id0 == id1) // must have the same ID
+						id = id0
+					} else {
+						id = newID()
+						ptrIDs[p.pp[0]] = id
+						ptrIDs[p.pp[1]] = id
+					}
+					trunk.Prefix = updateReferencePrefix(trunk.Prefix, formatReference(id))
+				} else {
+					if print0 && !ok0 {
+						id0 = newID()
+						ptrIDs[p.pp[0]] = id0
+					}
+					if print1 && !ok1 {
+						id1 = newID()
+						ptrIDs[p.pp[1]] = id1
+					}
+					switch {
+					case print0 && print1:
+						trunk.Prefix = updateReferencePrefix(trunk.Prefix, formatReference(id0)+","+formatReference(id1))
+					case print0:
+						trunk.Prefix = updateReferencePrefix(trunk.Prefix, formatReference(id0))
+					case print1:
+						trunk.Prefix = updateReferencePrefix(trunk.Prefix, formatReference(id1))
+					}
+				}
+			}
+		}
+	}
+
+	// Update all leaf references with the unique identifier.
+	for _, leaf := range leaves {
+		if id, ok := ptrIDs[leaf.Metadata.(leafReference).p]; ok {
+			leaf.Prefix = updateReferencePrefix(leaf.Prefix, formatReference(id))
+		}
+	}
+}
+
+func formatReference(id uint) string {
+	return fmt.Sprintf("ref#%d", id)
+}
+
+func updateReferencePrefix(prefix, ref string) string {
+	if prefix == "" {
+		return pointerDelimPrefix + ref + pointerDelimSuffix
+	}
+	suffix := strings.TrimPrefix(prefix, pointerDelimPrefix)
+	return pointerDelimPrefix + ref + ": " + suffix
+}

vendor/github.com/google/go-cmp/cmp/report_reflect.go

@@ -1,17 +1,18 @@
 // Copyright 2019, The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE.md file.
+// license that can be found in the LICENSE file.
 
 package cmp
 
 import (
+	"bytes"
 	"fmt"
 	"reflect"
 	"strconv"
 	"strings"
 	"unicode"
+	"unicode/utf8"
 
-	"github.com/google/go-cmp/cmp/internal/flags"
 	"github.com/google/go-cmp/cmp/internal/value"
 )
 
@@ -20,14 +21,22 @@ type formatValueOptions struct {
 	// methods like error.Error or fmt.Stringer.String.
 	AvoidStringer bool
 
-	// ShallowPointers controls whether to avoid descending into pointers.
-	// Useful when printing map keys, where pointer comparison is performed
-	// on the pointer address rather than the pointed-at value.
-	ShallowPointers bool
-
 	// PrintAddresses controls whether to print the address of all pointers,
 	// slice elements, and maps.
 	PrintAddresses bool
+
+	// QualifiedNames controls whether FormatType uses the fully qualified name
+	// (including the full package path as opposed to just the package name).
+	QualifiedNames bool
+
+	// VerbosityLevel controls the amount of output to produce.
+	// A higher value produces more output. A value of zero or lower produces
+	// no output (represented using an ellipsis).
+	// If LimitVerbosity is false, then the level is treated as infinite.
+	VerbosityLevel int
+
+	// LimitVerbosity specifies that formatting should respect VerbosityLevel.
+	LimitVerbosity bool
 }
 
 // FormatType prints the type as if it were wrapping s.
@@ -44,12 +53,15 @@ func (opts formatOptions) FormatType(t reflect.Type, s textNode) textNode {
 		default:
 			return s
 		}
+		if opts.DiffMode == diffIdentical {
+			return s // elide type for identical nodes
+		}
 	case elideType:
 		return s
 	}
 
 	// Determine the type label, applying special handling for unnamed types.
-	typeName := t.String()
+	typeName := value.TypeString(t, opts.QualifiedNames)
 	if t.Name() == "" {
 		// According to Go grammar, certain type literals contain symbols that
 		// do not strongly bind to the next lexicographical token (e.g., *T).
@@ -57,39 +69,77 @@ func (opts formatOptions) FormatType(t reflect.Type, s textNode) textNode {
 		case reflect.Chan, reflect.Func, reflect.Ptr:
 			typeName = "(" + typeName + ")"
 		}
-		typeName = strings.Replace(typeName, "struct {", "struct{", -1)
-		typeName = strings.Replace(typeName, "interface {", "interface{", -1)
 	}
+	return &textWrap{Prefix: typeName, Value: wrapParens(s)}
+}
 
-	// Avoid wrap the value in parenthesis if unnecessary.
-	if s, ok := s.(textWrap); ok {
-		hasParens := strings.HasPrefix(s.Prefix, "(") && strings.HasSuffix(s.Suffix, ")")
-		hasBraces := strings.HasPrefix(s.Prefix, "{") && strings.HasSuffix(s.Suffix, "}")
+// wrapParens wraps s with a set of parenthesis, but avoids it if the
+// wrapped node itself is already surrounded by a pair of parenthesis or braces.
+// It handles unwrapping one level of pointer-reference nodes.
+func wrapParens(s textNode) textNode {
+	var refNode *textWrap
+	if s2, ok := s.(*textWrap); ok {
+		// Unwrap a single pointer reference node.
+		switch s2.Metadata.(type) {
+		case leafReference, trunkReference, trunkReferences:
+			refNode = s2
+			if s3, ok := refNode.Value.(*textWrap); ok {
+				s2 = s3
+			}
+		}
+
+		// Already has delimiters that make parenthesis unnecessary.
+		hasParens := strings.HasPrefix(s2.Prefix, "(") && strings.HasSuffix(s2.Suffix, ")")
+		hasBraces := strings.HasPrefix(s2.Prefix, "{") && strings.HasSuffix(s2.Suffix, "}")
 		if hasParens || hasBraces {
-			return textWrap{typeName, s, ""}
+			return s
 		}
 	}
-	return textWrap{typeName + "(", s, ")"}
+	if refNode != nil {
+		refNode.Value = &textWrap{Prefix: "(", Value: refNode.Value, Suffix: ")"}
+		return s
+	}
+	return &textWrap{Prefix: "(", Value: s, Suffix: ")"}
 }
 
 // FormatValue prints the reflect.Value, taking extra care to avoid descending
-// into pointers already in m. As pointers are visited, m is also updated.
-func (opts formatOptions) FormatValue(v reflect.Value, m visitedPointers) (out textNode) {
+// into pointers already in ptrs. As pointers are visited, ptrs is also updated.
+func (opts formatOptions) FormatValue(v reflect.Value, parentKind reflect.Kind, ptrs *pointerReferences) (out textNode) {
 	if !v.IsValid() {
 		return nil
 	}
 	t := v.Type()
 
+	// Check slice element for cycles.
+	if parentKind == reflect.Slice {
+		ptrRef, visited := ptrs.Push(v.Addr())
+		if visited {
+			return makeLeafReference(ptrRef, false)
+		}
+		defer ptrs.Pop()
+		defer func() { out = wrapTrunkReference(ptrRef, false, out) }()
+	}
+
 	// Check whether there is an Error or String method to call.
 	if !opts.AvoidStringer && v.CanInterface() {
 		// Avoid calling Error or String methods on nil receivers since many
 		// implementations crash when doing so.
 		if (t.Kind() != reflect.Ptr && t.Kind() != reflect.Interface) || !v.IsNil() {
-			switch v := v.Interface().(type) {
-			case error:
-				return textLine("e" + formatString(v.Error()))
-			case fmt.Stringer:
-				return textLine("s" + formatString(v.String()))
+			var prefix, strVal string
+			func() {
+				// Swallow and ignore any panics from String or Error.
+				defer func() { recover() }()
+				switch v := v.Interface().(type) {
+				case error:
+					strVal = v.Error()
+					prefix = "e"
+				case fmt.Stringer:
+					strVal = v.String()
+					prefix = "s"
+				}
+			}()
+			if prefix != "" {
+				return opts.formatString(prefix, strVal)
 			}
 		}
 	}
@@ -102,94 +152,140 @@ func (opts formatOptions) FormatValue(v reflect.Value, m visitedPointers) (out t
 		}
 	}()
 
-	var ptr string
 	switch t.Kind() {
 	case reflect.Bool:
 		return textLine(fmt.Sprint(v.Bool()))
 	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
 		return textLine(fmt.Sprint(v.Int()))
-	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
-		// Unnamed uints are usually bytes or words, so use hexadecimal.
-		if t.PkgPath() == "" || t.Kind() == reflect.Uintptr {
+	case reflect.Uint, reflect.Uint16, reflect.Uint32, reflect.Uint64:
+		return textLine(fmt.Sprint(v.Uint()))
+	case reflect.Uint8:
+		if parentKind == reflect.Slice || parentKind == reflect.Array {
 			return textLine(formatHex(v.Uint()))
 		}
 		return textLine(fmt.Sprint(v.Uint()))
+	case reflect.Uintptr:
+		return textLine(formatHex(v.Uint()))
 	case reflect.Float32, reflect.Float64:
 		return textLine(fmt.Sprint(v.Float()))
 	case reflect.Complex64, reflect.Complex128:
 		return textLine(fmt.Sprint(v.Complex()))
 	case reflect.String:
-		return textLine(formatString(v.String()))
+		return opts.formatString("", v.String())
 	case reflect.UnsafePointer, reflect.Chan, reflect.Func:
-		return textLine(formatPointer(v))
+		return textLine(formatPointer(value.PointerOf(v), true))
 	case reflect.Struct:
 		var list textList
+		v := makeAddressable(v) // needed for retrieveUnexportedField
+		maxLen := v.NumField()
+		if opts.LimitVerbosity {
+			maxLen = ((1 << opts.verbosity()) >> 1) << 2 // 0, 4, 8, 16, 32, etc...
+			opts.VerbosityLevel--
+		}
 		for i := 0; i < v.NumField(); i++ {
 			vv := v.Field(i)
 			if value.IsZero(vv) {
 				continue // Elide fields with zero values
 			}
-			s := opts.WithTypeMode(autoType).FormatValue(vv, m)
-			list = append(list, textRecord{Key: t.Field(i).Name, Value: s})
+			if len(list) == maxLen {
+				list.AppendEllipsis(diffStats{})
+				break
+			}
+			sf := t.Field(i)
+			if supportExporters && !isExported(sf.Name) {
+				vv = retrieveUnexportedField(v, sf, true)
+			}
+			s := opts.WithTypeMode(autoType).FormatValue(vv, t.Kind(), ptrs)
+			list = append(list, textRecord{Key: sf.Name, Value: s})
 		}
-		return textWrap{"{", list, "}"}
+		return &textWrap{Prefix: "{", Value: list, Suffix: "}"}
 	case reflect.Slice:
 		if v.IsNil() {
 			return textNil
 		}
-		if opts.PrintAddresses {
-			ptr = formatPointer(v)
+
+		// Check whether this is a []byte of text data.
+		if t.Elem() == reflect.TypeOf(byte(0)) {
+			b := v.Bytes()
+			isPrintSpace := func(r rune) bool { return unicode.IsPrint(r) && unicode.IsSpace(r) }
+			if len(b) > 0 && utf8.Valid(b) && len(bytes.TrimFunc(b, isPrintSpace)) == 0 {
+				out = opts.formatString("", string(b))
+				return opts.WithTypeMode(emitType).FormatType(t, out)
+			}
 		}
+
 		fallthrough
 	case reflect.Array:
+		maxLen := v.Len()
+		if opts.LimitVerbosity {
+			maxLen = ((1 << opts.verbosity()) >> 1) << 2 // 0, 4, 8, 16, 32, etc...
+			opts.VerbosityLevel--
+		}
 		var list textList
 		for i := 0; i < v.Len(); i++ {
-			vi := v.Index(i)
-			if vi.CanAddr() { // Check for cyclic elements
-				p := vi.Addr()
-				if m.Visit(p) {
-					var out textNode
-					out = textLine(formatPointer(p))
-					out = opts.WithTypeMode(emitType).FormatType(p.Type(), out)
-					out = textWrap{"*", out, ""}
-					list = append(list, textRecord{Value: out})
-					continue
-				}
+			if len(list) == maxLen {
+				list.AppendEllipsis(diffStats{})
+				break
 			}
-			s := opts.WithTypeMode(elideType).FormatValue(vi, m)
+			s := opts.WithTypeMode(elideType).FormatValue(v.Index(i), t.Kind(), ptrs)
 			list = append(list, textRecord{Value: s})
 		}
-		return textWrap{ptr + "{", list, "}"}
+
+		out = &textWrap{Prefix: "{", Value: list, Suffix: "}"}
+		if t.Kind() == reflect.Slice && opts.PrintAddresses {
+			header := fmt.Sprintf("ptr:%v, len:%d, cap:%d", formatPointer(value.PointerOf(v), false), v.Len(), v.Cap())
+			out = &textWrap{Prefix: pointerDelimPrefix + header + pointerDelimSuffix, Value: out}
+		}
+		return out
 	case reflect.Map:
 		if v.IsNil() {
 			return textNil
 		}
-		if m.Visit(v) {
-			return textLine(formatPointer(v))
-		}
 
+		// Check pointer for cycles.
+		ptrRef, visited := ptrs.Push(v)
+		if visited {
+			return makeLeafReference(ptrRef, opts.PrintAddresses)
+		}
+		defer ptrs.Pop()
+
+		maxLen := v.Len()
+		if opts.LimitVerbosity {
+			maxLen = ((1 << opts.verbosity()) >> 1) << 2 // 0, 4, 8, 16, 32, etc...
+			opts.VerbosityLevel--
+		}
 		var list textList
 		for _, k := range value.SortKeys(v.MapKeys()) {
-			sk := formatMapKey(k)
-			sv := opts.WithTypeMode(elideType).FormatValue(v.MapIndex(k), m)
+			if len(list) == maxLen {
+				list.AppendEllipsis(diffStats{})
+				break
+			}
+			sk := formatMapKey(k, false, ptrs)
+			sv := opts.WithTypeMode(elideType).FormatValue(v.MapIndex(k), t.Kind(), ptrs)
 			list = append(list, textRecord{Key: sk, Value: sv})
 		}
-		if opts.PrintAddresses {
-			ptr = formatPointer(v)
-		}
-		return textWrap{ptr + "{", list, "}"}
+
+		out = &textWrap{Prefix: "{", Value: list, Suffix: "}"}
+		out = wrapTrunkReference(ptrRef, opts.PrintAddresses, out)
+		return out
 	case reflect.Ptr:
 		if v.IsNil() {
 			return textNil
 		}
-		if m.Visit(v) || opts.ShallowPointers {
-			return textLine(formatPointer(v))
-		}
-		if opts.PrintAddresses {
-			ptr = formatPointer(v)
+
+		// Check pointer for cycles.
+		ptrRef, visited := ptrs.Push(v)
+		if visited {
+			out = makeLeafReference(ptrRef, opts.PrintAddresses)
+			return &textWrap{Prefix: "&", Value: out}
 		}
+		defer ptrs.Pop()
+
 		skipType = true // Let the underlying value print the type instead
-		return textWrap{"&" + ptr, opts.FormatValue(v.Elem(), m), ""}
+		out = opts.FormatValue(v.Elem(), t.Kind(), ptrs)
+		out = wrapTrunkReference(ptrRef, opts.PrintAddresses, out)
+		out = &textWrap{Prefix: "&", Value: out}
+		return out
 	case reflect.Interface:
 		if v.IsNil() {
 			return textNil
@@ -197,19 +293,67 @@ func (opts formatOptions) FormatValue(v reflect.Value, m visitedPointers) (out t
 		// Interfaces accept different concrete types,
 		// so configure the underlying value to explicitly print the type.
 		skipType = true // Print the concrete type instead
-		return opts.WithTypeMode(emitType).FormatValue(v.Elem(), m)
+		return opts.WithTypeMode(emitType).FormatValue(v.Elem(), t.Kind(), ptrs)
 	default:
 		panic(fmt.Sprintf("%v kind not handled", v.Kind()))
 	}
 }
 
+func (opts formatOptions) formatString(prefix, s string) textNode {
+	maxLen := len(s)
+	maxLines := strings.Count(s, "\n") + 1
+	if opts.LimitVerbosity {
+		maxLen = (1 << opts.verbosity()) << 5   // 32, 64, 128, 256, etc...
+		maxLines = (1 << opts.verbosity()) << 2 //  4, 8, 16, 32, 64, etc...
+	}
+
+	// For multiline strings, use the triple-quote syntax,
+	// but only use it when printing removed or inserted nodes since
+	// we only want the extra verbosity for those cases.
+	lines := strings.Split(strings.TrimSuffix(s, "\n"), "\n")
+	isTripleQuoted := len(lines) >= 4 && (opts.DiffMode == '-' || opts.DiffMode == '+')
+	for i := 0; i < len(lines) && isTripleQuoted; i++ {
+		lines[i] = strings.TrimPrefix(strings.TrimSuffix(lines[i], "\r"), "\r") // trim leading/trailing carriage returns for legacy Windows endline support
+		isPrintable := func(r rune) bool {
+			return unicode.IsPrint(r) || r == '\t' // specially treat tab as printable
+		}
+		line := lines[i]
+		isTripleQuoted = !strings.HasPrefix(strings.TrimPrefix(line, prefix), `"""`) && !strings.HasPrefix(line, "...") && strings.TrimFunc(line, isPrintable) == "" && len(line) <= maxLen
+	}
+	if isTripleQuoted {
+		var list textList
+		list = append(list, textRecord{Diff: opts.DiffMode, Value: textLine(prefix + `"""`), ElideComma: true})
+		for i, line := range lines {
+			if numElided := len(lines) - i; i == maxLines-1 && numElided > 1 {
+				comment := commentString(fmt.Sprintf("%d elided lines", numElided))
+				list = append(list, textRecord{Diff: opts.DiffMode, Value: textEllipsis, ElideComma: true, Comment: comment})
+				break
+			}
+			list = append(list, textRecord{Diff: opts.DiffMode, Value: textLine(line), ElideComma: true})
+		}
+		list = append(list, textRecord{Diff: opts.DiffMode, Value: textLine(prefix + `"""`), ElideComma: true})
+		return &textWrap{Prefix: "(", Value: list, Suffix: ")"}
+	}
+
+	// Format the string as a single-line quoted string.
+	if len(s) > maxLen+len(textEllipsis) {
+		return textLine(prefix + formatString(s[:maxLen]) + string(textEllipsis))
+	}
+	return textLine(prefix + formatString(s))
+}
+
 // formatMapKey formats v as if it were a map key.
 // The result is guaranteed to be a single line.
-func formatMapKey(v reflect.Value) string {
+func formatMapKey(v reflect.Value, disambiguate bool, ptrs *pointerReferences) string {
 	var opts formatOptions
+	opts.DiffMode = diffIdentical
 	opts.TypeMode = elideType
-	opts.ShallowPointers = true
-	s := opts.FormatValue(v, visitedPointers{}).String()
+	opts.PrintAddresses = disambiguate
+	opts.AvoidStringer = disambiguate
+	opts.QualifiedNames = disambiguate
+	opts.VerbosityLevel = maxVerbosityPreset
+	opts.LimitVerbosity = true
+	s := opts.FormatValue(v, reflect.Map, ptrs).String()
 	return strings.TrimSpace(s)
 }
 
@@ -227,7 +371,7 @@ func formatString(s string) string {
 	rawInvalid := func(r rune) bool {
 		return r == '`' || r == '\n' || !(unicode.IsPrint(r) || r == '\t')
 	}
-	if strings.IndexFunc(s, rawInvalid) < 0 {
+	if utf8.ValidString(s) && strings.IndexFunc(s, rawInvalid) < 0 {
 		return "`" + s + "`"
 	}
 	return qs
@@ -256,23 +400,3 @@ func formatHex(u uint64) string {
 	}
 	return fmt.Sprintf(f, u)
 }
-
-// formatPointer prints the address of the pointer.
-func formatPointer(v reflect.Value) string {
-	p := v.Pointer()
-	if flags.Deterministic {
-		p = 0xdeadf00f // Only used for stable testing purposes
-	}
-	return fmt.Sprintf("⟪0x%x⟫", p)
-}
-
-type visitedPointers map[value.Pointer]struct{}
-
-// Visit inserts pointer v into the visited map and reports whether it had
-// already been visited before.
-func (m visitedPointers) Visit(v reflect.Value) bool {
-	p := value.PointerOf(v)
-	_, visited := m[p]
-	m[p] = struct{}{}
-	return visited
-}

vendor/github.com/google/go-cmp/cmp/report_slices.go

@@ -1,6 +1,6 @@
 // Copyright 2019, The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE.md file.
+// license that can be found in the LICENSE file.
 
 package cmp
 
@@ -8,6 +8,7 @@ import (
 	"bytes"
 	"fmt"
 	"reflect"
+	"strconv"
 	"strings"
 	"unicode"
 	"unicode/utf8"
@@ -23,11 +24,25 @@ func (opts formatOptions) CanFormatDiffSlice(v *valueNode) bool {
 		return false // Must be formatting in diff mode
 	case v.NumDiff == 0:
 		return false // No differences detected
-	case v.NumIgnored+v.NumCompared+v.NumTransformed > 0:
-		// TODO: Handle the case where someone uses bytes.Equal on a large slice.
-		return false // Some custom option was used to determined equality
 	case !v.ValueX.IsValid() || !v.ValueY.IsValid():
 		return false // Both values must be valid
+	case v.Type.Kind() == reflect.Slice && (v.ValueX.Len() == 0 || v.ValueY.Len() == 0):
+		return false // Both slice values have to be non-empty
+	case v.NumIgnored > 0:
+		return false // Some ignore option was used
+	case v.NumTransformed > 0:
+		return false // Some transform option was used
+	case v.NumCompared > 1:
+		return false // More than one comparison was used
+	case v.NumCompared == 1 && v.Type.Name() != "":
+		// The need for cmp to check applicability of options on every element
+		// in a slice is a significant performance detriment for large []byte.
+		// The workaround is to specify Comparer(bytes.Equal),
+		// which enables cmp to compare []byte more efficiently.
+		// If they differ, we still want to provide batched diffing.
+		// The logic disallows named types since they tend to have their own
+		// String method, with nicer formatting than what this provides.
+		return false
 	}
 
 	switch t := v.Type; t.Kind() {
@@ -82,7 +97,7 @@ func (opts formatOptions) FormatDiffSlice(v *valueNode) textNode {
 	}
 	if isText || isBinary {
 		var numLines, lastLineIdx, maxLineLen int
-		isBinary = false
+		isBinary = !utf8.ValidString(sx) || !utf8.ValidString(sy)
 		for i, r := range sx + sy {
 			if !(unicode.IsPrint(r) || unicode.IsSpace(r)) || r == utf8.RuneError {
 				isBinary = true
@@ -97,7 +112,7 @@ func (opts formatOptions) FormatDiffSlice(v *valueNode) textNode {
 			}
 		}
 		isText = !isBinary
-		isLinedText = isText && numLines >= 4 && maxLineLen <= 256
+		isLinedText = isText && numLines >= 4 && maxLineLen <= 1024
 	}
 
 	// Format the string into printable records.
@@ -117,6 +132,83 @@ func (opts formatOptions) FormatDiffSlice(v *valueNode) textNode {
 			},
 		)
 		delim = "\n"
+
+		// If possible, use a custom triple-quote (""") syntax for printing
+		// differences in a string literal. This format is more readable,
+		// but has edge-cases where differences are visually indistinguishable.
+		// This format is avoided under the following conditions:
+		//	• A line starts with `"""`
+		//	• A line starts with "..."
+		//	• A line contains non-printable characters
+		//	• Adjacent different lines differ only by whitespace
+		//
+		// For example:
+		//		"""
+		//		... // 3 identical lines
+		//		foo
+		//		bar
+		//	-	baz
+		//	+	BAZ
+		//		"""
+		isTripleQuoted := true
+		prevRemoveLines := map[string]bool{}
+		prevInsertLines := map[string]bool{}
+		var list2 textList
+		list2 = append(list2, textRecord{Value: textLine(`"""`), ElideComma: true})
+		for _, r := range list {
+			if !r.Value.Equal(textEllipsis) {
+				line, _ := strconv.Unquote(string(r.Value.(textLine)))
+				line = strings.TrimPrefix(strings.TrimSuffix(line, "\r"), "\r") // trim leading/trailing carriage returns for legacy Windows endline support
+				normLine := strings.Map(func(r rune) rune {
+					if unicode.IsSpace(r) {
+						return -1 // drop whitespace to avoid visually indistinguishable output
+					}
+					return r
+				}, line)
+				isPrintable := func(r rune) bool {
+					return unicode.IsPrint(r) || r == '\t' // specially treat tab as printable
+				}
+				isTripleQuoted = !strings.HasPrefix(line, `"""`) && !strings.HasPrefix(line, "...") && strings.TrimFunc(line, isPrintable) == ""
+				switch r.Diff {
+				case diffRemoved:
+					isTripleQuoted = isTripleQuoted && !prevInsertLines[normLine]
+					prevRemoveLines[normLine] = true
+				case diffInserted:
+					isTripleQuoted = isTripleQuoted && !prevRemoveLines[normLine]
+					prevInsertLines[normLine] = true
+				}
+				if !isTripleQuoted {
+					break
+				}
+				r.Value = textLine(line)
+				r.ElideComma = true
+			}
+			if !(r.Diff == diffRemoved || r.Diff == diffInserted) { // start a new non-adjacent difference group
+				prevRemoveLines = map[string]bool{}
+				prevInsertLines = map[string]bool{}
+			}
+			list2 = append(list2, r)
+		}
+		if r := list2[len(list2)-1]; r.Diff == diffIdentical && len(r.Value.(textLine)) == 0 {
+			list2 = list2[:len(list2)-1] // elide single empty line at the end
+		}
+		list2 = append(list2, textRecord{Value: textLine(`"""`), ElideComma: true})
+		if isTripleQuoted {
+			var out textNode = &textWrap{Prefix: "(", Value: list2, Suffix: ")"}
+			switch t.Kind() {
+			case reflect.String:
+				if t != reflect.TypeOf(string("")) {
+					out = opts.FormatType(t, out)
+				}
+			case reflect.Slice:
+				// Always emit type for slices since the triple-quote syntax
+				// looks like a string (not a slice).
+				opts = opts.WithTypeMode(emitType)
+				out = opts.FormatType(t, out)
+			}
+			return out
+		}
+
 	// If the text appears to be single-lined text,
 	// then perform differencing in approximately fixed-sized chunks.
 	// The output is printed as quoted strings.
@@ -129,6 +221,7 @@ func (opts formatOptions) FormatDiffSlice(v *valueNode) textNode {
 			},
 		)
 		delim = ""
+
 	// If the text appears to be binary data,
 	// then perform differencing in approximately fixed-sized chunks.
 	// The output is inspired by hexdump.
@@ -145,6 +238,7 @@ func (opts formatOptions) FormatDiffSlice(v *valueNode) textNode {
 				return textRecord{Diff: d, Value: textLine(s), Comment: comment}
 			},
 		)
+
 	// For all other slices of primitive types,
 	// then perform differencing in approximately fixed-sized chunks.
 	// The size of each chunk depends on the width of the element kind.
@@ -172,7 +266,9 @@ func (opts formatOptions) FormatDiffSlice(v *valueNode) textNode {
 					switch t.Elem().Kind() {
 					case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
 						ss = append(ss, fmt.Sprint(v.Index(i).Int()))
-					case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
+					case reflect.Uint, reflect.Uint16, reflect.Uint32, reflect.Uint64:
+						ss = append(ss, fmt.Sprint(v.Index(i).Uint()))
+					case reflect.Uint8, reflect.Uintptr:
 						ss = append(ss, formatHex(v.Index(i).Uint()))
 					case reflect.Bool, reflect.Float32, reflect.Float64, reflect.Complex64, reflect.Complex128:
 						ss = append(ss, fmt.Sprint(v.Index(i).Interface()))
@@ -185,7 +281,7 @@ func (opts formatOptions) FormatDiffSlice(v *valueNode) textNode {
 	}
 
 	// Wrap the output with appropriate type information.
-	var out textNode = textWrap{"{", list, "}"}
+	var out textNode = &textWrap{Prefix: "{", Value: list, Suffix: "}"}
 	if !isText {
 		// The "{...}" byte-sequence literal is not valid Go syntax for strings.
 		// Emit the type for extra clarity (e.g. "string{...}").
@@ -196,12 +292,12 @@ func (opts formatOptions) FormatDiffSlice(v *valueNode) textNode {
 	}
 	switch t.Kind() {
 	case reflect.String:
-		out = textWrap{"strings.Join(", out, fmt.Sprintf(", %q)", delim)}
+		out = &textWrap{Prefix: "strings.Join(", Value: out, Suffix: fmt.Sprintf(", %q)", delim)}
 		if t != reflect.TypeOf(string("")) {
 			out = opts.FormatType(t, out)
 		}
 	case reflect.Slice:
-		out = textWrap{"bytes.Join(", out, fmt.Sprintf(", %q)", delim)}
+		out = &textWrap{Prefix: "bytes.Join(", Value: out, Suffix: fmt.Sprintf(", %q)", delim)}
 		if t != reflect.TypeOf([]byte(nil)) {
 			out = opts.FormatType(t, out)
 		}
@@ -242,9 +338,22 @@ func (opts formatOptions) formatDiffSlice(
 		return n0 - v.Len()
 	}
 
+	var numDiffs int
+	maxLen := -1
+	if opts.LimitVerbosity {
+		maxLen = (1 << opts.verbosity()) << 2 // 4, 8, 16, 32, 64, etc...
+		opts.VerbosityLevel--
+	}
+
 	groups := coalesceAdjacentEdits(name, es)
 	groups = coalesceInterveningIdentical(groups, chunkSize/4)
+	maxGroup := diffStats{Name: name}
 	for i, ds := range groups {
+		if maxLen >= 0 && numDiffs >= maxLen {
+			maxGroup = maxGroup.Append(ds)
+			continue
+		}
+
 		// Print equal.
 		if ds.NumDiff() == 0 {
 			// Compute the number of leading and trailing equal bytes to print.
@@ -273,12 +382,18 @@ func (opts formatOptions) formatDiffSlice(
 		}
 
 		// Print unequal.
+		len0 := len(list)
 		nx := appendChunks(vx.Slice(0, ds.NumIdentical+ds.NumRemoved+ds.NumModified), diffRemoved)
 		vx = vx.Slice(nx, vx.Len())
 		ny := appendChunks(vy.Slice(0, ds.NumIdentical+ds.NumInserted+ds.NumModified), diffInserted)
 		vy = vy.Slice(ny, vy.Len())
+		numDiffs += len(list) - len0
+	}
+	if maxGroup.IsZero() {
+		assert(vx.Len() == 0 && vy.Len() == 0)
+	} else {
+		list.AppendEllipsis(maxGroup)
 	}
-	assert(vx.Len() == 0 && vy.Len() == 0)
 	return list
 }
 

vendor/github.com/google/go-cmp/cmp/report_text.go

@@ -1,6 +1,6 @@
 // Copyright 2019, The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE.md file.
+// license that can be found in the LICENSE file.
 
 package cmp
 
@@ -10,12 +10,15 @@ import (
 	"math/rand"
 	"strings"
 	"time"
+	"unicode/utf8"
 
 	"github.com/google/go-cmp/cmp/internal/flags"
 )
 
 var randBool = rand.New(rand.NewSource(time.Now().Unix())).Intn(2) == 0
 
+const maxColumnLength = 80
+
 type indentMode int
 
 func (n indentMode) appendIndent(b []byte, d diffMode) []byte {
@@ -91,21 +94,22 @@ type textNode interface {
 // textWrap is a wrapper that concatenates a prefix and/or a suffix
 // to the underlying node.
 type textWrap struct {
-	Prefix string   // e.g., "bytes.Buffer{"
-	Value  textNode // textWrap | textList | textLine
-	Suffix string   // e.g., "}"
+	Prefix   string      // e.g., "bytes.Buffer{"
+	Value    textNode    // textWrap | textList | textLine
+	Suffix   string      // e.g., "}"
+	Metadata interface{} // arbitrary metadata; has no effect on formatting
 }
 
-func (s textWrap) Len() int {
+func (s *textWrap) Len() int {
 	return len(s.Prefix) + s.Value.Len() + len(s.Suffix)
 }
-func (s1 textWrap) Equal(s2 textNode) bool {
-	if s2, ok := s2.(textWrap); ok {
+func (s1 *textWrap) Equal(s2 textNode) bool {
+	if s2, ok := s2.(*textWrap); ok {
 		return s1.Prefix == s2.Prefix && s1.Value.Equal(s2.Value) && s1.Suffix == s2.Suffix
 	}
 	return false
 }
-func (s textWrap) String() string {
+func (s *textWrap) String() string {
 	var d diffMode
 	var n indentMode
 	_, s2 := s.formatCompactTo(nil, d)
@@ -114,7 +118,7 @@ func (s textWrap) String() string {
 	b = append(b, '\n')              // Trailing newline
 	return string(b)
 }
-func (s textWrap) formatCompactTo(b []byte, d diffMode) ([]byte, textNode) {
+func (s *textWrap) formatCompactTo(b []byte, d diffMode) ([]byte, textNode) {
 	n0 := len(b) // Original buffer length
 	b = append(b, s.Prefix...)
 	b, s.Value = s.Value.formatCompactTo(b, d)
@@ -124,7 +128,7 @@ func (s textWrap) formatCompactTo(b []byte, d diffMode) ([]byte, textNode) {
 	}
 	return b, s
 }
-func (s textWrap) formatExpandedTo(b []byte, d diffMode, n indentMode) []byte {
+func (s *textWrap) formatExpandedTo(b []byte, d diffMode, n indentMode) []byte {
 	b = append(b, s.Prefix...)
 	b = s.Value.formatExpandedTo(b, d, n)
 	b = append(b, s.Suffix...)
@@ -136,22 +140,23 @@ func (s textWrap) formatExpandedTo(b []byte, d diffMode, n indentMode) []byte {
 // of the textList.formatCompactTo method.
 type textList []textRecord
 type textRecord struct {
-	Diff    diffMode     // e.g., 0 or '-' or '+'
-	Key     string       // e.g., "MyField"
-	Value   textNode     // textWrap | textLine
-	Comment fmt.Stringer // e.g., "6 identical fields"
+	Diff       diffMode     // e.g., 0 or '-' or '+'
+	Key        string       // e.g., "MyField"
+	Value      textNode     // textWrap | textLine
+	ElideComma bool         // avoid trailing comma
+	Comment    fmt.Stringer // e.g., "6 identical fields"
 }
 
 // AppendEllipsis appends a new ellipsis node to the list if none already
 // exists at the end. If cs is non-zero it coalesces the statistics with the
 // previous diffStats.
 func (s *textList) AppendEllipsis(ds diffStats) {
-	hasStats := ds != diffStats{}
+	hasStats := !ds.IsZero()
 	if len(*s) == 0 || !(*s)[len(*s)-1].Value.Equal(textEllipsis) {
 		if hasStats {
-			*s = append(*s, textRecord{Value: textEllipsis, Comment: ds})
+			*s = append(*s, textRecord{Value: textEllipsis, ElideComma: true, Comment: ds})
 		} else {
-			*s = append(*s, textRecord{Value: textEllipsis})
+			*s = append(*s, textRecord{Value: textEllipsis, ElideComma: true})
 		}
 		return
 	}
@@ -191,7 +196,7 @@ func (s1 textList) Equal(s2 textNode) bool {
 }
 
 func (s textList) String() string {
-	return textWrap{"{", s, "}"}.String()
+	return (&textWrap{Prefix: "{", Value: s, Suffix: "}"}).String()
 }
 
 func (s textList) formatCompactTo(b []byte, d diffMode) ([]byte, textNode) {
@@ -221,7 +226,7 @@ func (s textList) formatCompactTo(b []byte, d diffMode) ([]byte, textNode) {
 	}
 	// Force multi-lined output when printing a removed/inserted node that
 	// is sufficiently long.
-	if (d == diffInserted || d == diffRemoved) && len(b[n0:]) > 80 {
+	if (d == diffInserted || d == diffRemoved) && len(b[n0:]) > maxColumnLength {
 		multiLine = true
 	}
 	if !multiLine {
@@ -236,16 +241,50 @@ func (s textList) formatExpandedTo(b []byte, d diffMode, n indentMode) []byte {
 			_, isLine := r.Value.(textLine)
 			return r.Key == "" || !isLine
 		},
-		func(r textRecord) int { return len(r.Key) },
+		func(r textRecord) int { return utf8.RuneCountInString(r.Key) },
 	)
 	alignValueLens := s.alignLens(
 		func(r textRecord) bool {
 			_, isLine := r.Value.(textLine)
 			return !isLine || r.Value.Equal(textEllipsis) || r.Comment == nil
 		},
-		func(r textRecord) int { return len(r.Value.(textLine)) },
+		func(r textRecord) int { return utf8.RuneCount(r.Value.(textLine)) },
 	)
 
+	// Format lists of simple lists in a batched form.
+	// If the list is sequence of only textLine values,
+	// then batch multiple values on a single line.
+	var isSimple bool
+	for _, r := range s {
+		_, isLine := r.Value.(textLine)
+		isSimple = r.Diff == 0 && r.Key == "" && isLine && r.Comment == nil
+		if !isSimple {
+			break
+		}
+	}
+	if isSimple {
+		n++
+		var batch []byte
+		emitBatch := func() {
+			if len(batch) > 0 {
+				b = n.appendIndent(append(b, '\n'), d)
+				b = append(b, bytes.TrimRight(batch, " ")...)
+				batch = batch[:0]
+			}
+		}
+		for _, r := range s {
+			line := r.Value.(textLine)
+			if len(batch)+len(line)+len(", ") > maxColumnLength {
+				emitBatch()
+			}
+			batch = append(batch, line...)
+			batch = append(batch, ", "...)
+		}
+		emitBatch()
+		n--
+		return n.appendIndent(append(b, '\n'), d)
+	}
+
 	// Format the list as a multi-lined output.
 	n++
 	for i, r := range s {
@@ -256,7 +295,7 @@ func (s textList) formatExpandedTo(b []byte, d diffMode, n indentMode) []byte {
 		b = alignKeyLens[i].appendChar(b, ' ')
 
 		b = r.Value.formatExpandedTo(b, d|r.Diff, n)
-		if !r.Value.Equal(textEllipsis) {
+		if !r.ElideComma {
 			b = append(b, ',')
 		}
 		b = alignValueLens[i].appendChar(b, ' ')
@@ -332,6 +371,11 @@ type diffStats struct {
 	NumModified  int
 }
 
+func (s diffStats) IsZero() bool {
+	s.Name = ""
+	return s == diffStats{}
+}
+
 func (s diffStats) NumDiff() int {
 	return s.NumRemoved + s.NumInserted + s.NumModified
 }

vendor/github.com/google/go-cmp/cmp/report_value.go

@@ -1,6 +1,6 @@
 // Copyright 2019, The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE.md file.
+// license that can be found in the LICENSE file.
 
 package cmp
 

vendor/github.com/google/uuid/README.md

@@ -16,4 +16,4 @@ change is the ability to represent an invalid UUID (vs a NIL UUID).
 
 Full `go doc` style documentation for the package can be viewed online without
 installing this package by using the GoDoc site here: 
-http://godoc.org/github.com/google/uuid
+http://pkg.go.dev/github.com/google/uuid

vendor/github.com/google/uuid/marshal.go

@@ -16,10 +16,11 @@ func (uuid UUID) MarshalText() ([]byte, error) {
 // UnmarshalText implements encoding.TextUnmarshaler.
 func (uuid *UUID) UnmarshalText(data []byte) error {
 	id, err := ParseBytes(data)
-	if err == nil {
-		*uuid = id
+	if err != nil {
+		return err
 	}
-	return err
+	*uuid = id
+	return nil
 }
 
 // MarshalBinary implements encoding.BinaryMarshaler.

vendor/github.com/google/uuid/version1.go

@@ -17,12 +17,6 @@ import (
 //
 // In most cases, New should be used.
 func NewUUID() (UUID, error) {
-	nodeMu.Lock()
-	if nodeID == zeroID {
-		setNodeInterface("")
-	}
-	nodeMu.Unlock()
-
 	var uuid UUID
 	now, seq, err := GetTime()
 	if err != nil {
@@ -38,7 +32,13 @@ func NewUUID() (UUID, error) {
 	binary.BigEndian.PutUint16(uuid[4:], timeMid)
 	binary.BigEndian.PutUint16(uuid[6:], timeHi)
 	binary.BigEndian.PutUint16(uuid[8:], seq)
+
+	nodeMu.Lock()
+	if nodeID == zeroID {
+		setNodeInterface("")
+	}
 	copy(uuid[10:], nodeID[:])
+	nodeMu.Unlock()
 
 	return uuid, nil
 }

vendor/github.com/google/uuid/version4.go

@@ -27,8 +27,13 @@ func New() UUID {
 //  equivalent to the odds of creating a few tens of trillions of UUIDs in a
 //  year and having one duplicate.
 func NewRandom() (UUID, error) {
+	return NewRandomFromReader(rander)
+}
+
+// NewRandomFromReader returns a UUID based on bytes read from a given io.Reader.
+func NewRandomFromReader(r io.Reader) (UUID, error) {
 	var uuid UUID
-	_, err := io.ReadFull(rander, uuid[:])
+	_, err := io.ReadFull(r, uuid[:])
 	if err != nil {
 		return Nil, err
 	}