Use PtrTo to not require Go 1.18 (#874)

Bumps [github.com/stretchr/testify](https://github.com/stretchr/testify) from 1.8.2 to 1.8.3.
- [Release notes](https://github.com/stretchr/testify/releases)
- [Commits](https://github.com/stretchr/testify/compare/v1.8.2...v1.8.3)

---
updated-dependencies:
- dependency-name: github.com/stretchr/testify
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

.github/workflows/cifuzz.yml

@@ -0,0 +1,26 @@
+name: CIFuzz
+on: [pull_request]
+jobs:
+  Fuzzing:
+    runs-on: ubuntu-latest
+    steps:
+    - name: Build Fuzzers
+      id: build
+      uses: google/oss-fuzz/infra/cifuzz/actions/build_fuzzers@master
+      with:
+        oss-fuzz-project-name: 'go-toml'
+        dry-run: false
+        language: go
+    - name: Run Fuzzers
+      uses: google/oss-fuzz/infra/cifuzz/actions/run_fuzzers@master
+      with:
+        oss-fuzz-project-name: 'go-toml'
+        fuzz-seconds: 300
+        dry-run: false
+        language: go
+    - name: Upload Crash
+      uses: actions/upload-artifact@v3
+      if: failure() && steps.build.outcome == 'success'
+      with:
+        name: artifacts
+        path: ./out/artifacts

.github/workflows/coverage.yml

@@ -13,8 +13,8 @@ jobs:
         with:
           fetch-depth: 0
       - name: Setup go
-        uses: actions/setup-go@v3
+        uses: actions/setup-go@v4
         with:
-          go-version: 1.19
+          go-version: "1.20"
       - name: Run tests with coverage
         run: ./ci.sh coverage -d "${GITHUB_BASE_REF-HEAD}"

.github/workflows/release.yml

@@ -20,9 +20,9 @@ jobs:
         with:
           fetch-depth: 0
       - name: Set up Go
-        uses: actions/setup-go@v3
+        uses: actions/setup-go@v4
         with:
-          go-version: 1.19
+          go-version: "1.20"
       - name: Login to GitHub Container Registry
         uses: docker/login-action@v2
         with:

.github/workflows/workflow.yml

@@ -12,7 +12,7 @@ jobs:
     strategy:
       matrix:
         os: [ 'ubuntu-latest', 'windows-latest', 'macos-latest']
-        go: [ '1.18', '1.19' ]
+        go: [ '1.19', '1.20' ]
     runs-on: ${{ matrix.os }}
     name: ${{ matrix.go }}/${{ matrix.os }}
     steps:
@@ -20,7 +20,7 @@ jobs:
         with:
           fetch-depth: 0
       - name: Setup go ${{ matrix.go }}
-        uses: actions/setup-go@v3
+        uses: actions/setup-go@v4
         with:
           go-version: ${{ matrix.go }}
       - name: Run unit tests

README.md

@@ -553,7 +553,7 @@ complete solutions exist out there.
 
 ## Versioning
 
-Go-toml follows [Semantic Versioning](http://semver.org/). The supported version
+Go-toml follows [Semantic Versioning](https://semver.org). The supported version
 of [TOML](https://github.com/toml-lang/toml) is indicated at the beginning of
 this document. The last two major versions of Go are supported
 (see [Go Release Policy](https://golang.org/doc/devel/release.html#policy)).

ci.sh

@@ -77,7 +77,7 @@ cover() {
 
     pushd "$dir"
     go test -covermode=atomic  -coverpkg=./... -coverprofile=coverage.out.tmp ./...
-    cat coverage.out.tmp | grep -v testsuite | grep -v tomltestgen | grep -v gotoml-test-decoder > coverage.out
+    cat coverage.out.tmp | grep -v fuzz | grep -v testsuite | grep -v tomltestgen | grep -v gotoml-test-decoder > coverage.out
     go tool cover -func=coverage.out
     popd
 

example_text_marshaling_test.go

@@ -0,0 +1,37 @@
+package toml_test
+
+import (
+	"fmt"
+	"log"
+	"strconv"
+
+	"github.com/pelletier/go-toml/v2"
+)
+
+type customInt int
+
+func (i *customInt) UnmarshalText(b []byte) error {
+	x, err := strconv.ParseInt(string(b), 10, 32)
+	if err != nil {
+		return err
+	}
+	*i = customInt(x * 100)
+	return nil
+}
+
+type doc struct {
+	Value customInt
+}
+
+func ExampleUnmarshal_textUnmarshal() {
+	var x doc
+
+	data := []byte(`value  = "42"`)
+	err := toml.Unmarshal(data, &x)
+	if err != nil {
+		log.Fatal(err)
+	}
+	fmt.Println(x)
+	// Output:
+	// {4200}
+}

fast_test.go

@@ -7,13 +7,20 @@ import (
 	"github.com/stretchr/testify/require"
 )
 
-func TestFastSimple(t *testing.T) {
+func TestFastSimpleInt(t *testing.T) {
 	m := map[string]int64{}
 	err := toml.Unmarshal([]byte(`a = 42`), &m)
 	require.NoError(t, err)
 	require.Equal(t, map[string]int64{"a": 42}, m)
 }
 
+func TestFastSimpleFloat(t *testing.T) {
+	m := map[string]float64{}
+	err := toml.Unmarshal([]byte("a = 42\nb = 1.1\nc = 12341234123412341234123412341234"), &m)
+	require.NoError(t, err)
+	require.Equal(t, map[string]float64{"a": 42, "b": 1.1, "c": 1.2341234123412342e+31}, m)
+}
+
 func TestFastSimpleString(t *testing.T) {
 	m := map[string]string{}
 	err := toml.Unmarshal([]byte(`a = "hello"`), &m)

fuzz_test.go

@@ -1,5 +1,5 @@
-//go:build go1.18 || go1.19
+//go:build go1.18 || go1.19 || go1.20
-// +build go1.18 go1.19
+// +build go1.18 go1.19 go1.20
 
 package toml_test
 

go.mod

@@ -2,4 +2,4 @@ module github.com/pelletier/go-toml/v2
 
 go 1.16
 
-require github.com/stretchr/testify v1.8.1
+require github.com/stretchr/testify v1.8.3

go.sum

@@ -8,8 +8,8 @@ github.com/stretchr/objx v0.4.0/go.mod h1:YvHI0jy2hoMjB+UWwv71VJQ9isScKT/TqJzVSS
 github.com/stretchr/objx v0.5.0/go.mod h1:Yh+to48EsGEfYuaHDzXPcE3xhTkx73EhmCGUpEOglKo=
 github.com/stretchr/testify v1.7.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
 github.com/stretchr/testify v1.8.0/go.mod h1:yNjHg4UonilssWZ8iaSj1OCr/vHnekPRkoO+kdMU+MU=
-github.com/stretchr/testify v1.8.1 h1:w7B6lhMri9wdJUVmEZPGGhZzrYTPvgJArz7wNPgYKsk=
+github.com/stretchr/testify v1.8.3 h1:RP3t2pwF7cMEbC1dqtB6poj3niw/9gnV4Cjg5oW5gtY=
-github.com/stretchr/testify v1.8.1/go.mod h1:w2LPCIKwWwSfY2zedu0+kehJoqGctiVI29o6fzry7u4=
+github.com/stretchr/testify v1.8.3/go.mod h1:sz/lmYIOXD/1dqDmKjjqLyZ2RngseejIcXlSw2iwfAo=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

internal/cli/cli.go

@@ -18,7 +18,7 @@ type Program struct {
 	Usage string
 	Fn    ConvertFn
 	// Inplace allows the command to take more than one file as argument and
-	// perform convertion in place on each provided file.
+	// perform conversion in place on each provided file.
 	Inplace bool
 }
 

internal/imported_tests/unmarshal_imported_test.go

@@ -1085,10 +1085,6 @@ func TestUnmarshalCheckConversionFloatInt(t *testing.T) {
 			desc:  "int",
 			input: `I = 1e300`,
 		},
-		{
-			desc:  "float",
-			input: `F = 9223372036854775806`,
-		},
 	}
 
 	for _, test := range testCases {

marshaler.go

@@ -357,9 +357,9 @@ func (enc *Encoder) encodeKv(b []byte, ctx encoderCtx, options valueOptions, v r
 
 	if !ctx.inline {
 		b = enc.encodeComment(ctx.indent, options.comment, b)
+		b = enc.indent(ctx.indent, b)
 	}
 
-	b = enc.indent(ctx.indent, b)
 	b = enc.encodeKey(b, ctx.key)
 	b = append(b, " = "...)
 
@@ -577,11 +577,23 @@ func (enc *Encoder) encodeKey(b []byte, k string) []byte {
 	}
 }
 
-func (enc *Encoder) encodeMap(b []byte, ctx encoderCtx, v reflect.Value) ([]byte, error) {
+func (enc *Encoder) keyToString(k reflect.Value) (string, error) {
-	if v.Type().Key().Kind() != reflect.String {
+	keyType := k.Type()
-		return nil, fmt.Errorf("toml: type %s is not supported as a map key", v.Type().Key().Kind())
+	switch {
-	}
+	case keyType.Kind() == reflect.String:
+		return k.String(), nil
 
+	case keyType.Implements(textMarshalerType):
+		keyB, err := k.Interface().(encoding.TextMarshaler).MarshalText()
+		if err != nil {
+			return "", fmt.Errorf("toml: error marshalling key %v from text: %w", k, err)
+		}
+		return string(keyB), nil
+	}
+	return "", fmt.Errorf("toml: type %s is not supported as a map key", keyType.Kind())
+}
+
+func (enc *Encoder) encodeMap(b []byte, ctx encoderCtx, v reflect.Value) ([]byte, error) {
 	var (
 		t                 table
 		emptyValueOptions valueOptions
@@ -589,13 +601,17 @@ func (enc *Encoder) encodeMap(b []byte, ctx encoderCtx, v reflect.Value) ([]byte
 
 	iter := v.MapRange()
 	for iter.Next() {
-		k := iter.Key().String()
 		v := iter.Value()
 
 		if isNil(v) {
 			continue
 		}
 
+		k, err := enc.keyToString(iter.Key())
+		if err != nil {
+			return nil, err
+		}
+
 		if willConvertToTableOrArrayTable(ctx, v) {
 			t.pushTable(k, v, emptyValueOptions)
 		} else {

marshaler_test.go

@@ -15,6 +15,21 @@ import (
 	"github.com/stretchr/testify/require"
 )
 
+type marshalTextKey struct {
+	A string
+	B string
+}
+
+func (k marshalTextKey) MarshalText() ([]byte, error) {
+	return []byte(k.A + "-" + k.B), nil
+}
+
+type marshalBadTextKey struct{}
+
+func (k marshalBadTextKey) MarshalText() ([]byte, error) {
+	return nil, fmt.Errorf("error")
+}
+
 func TestMarshal(t *testing.T) {
 	someInt := 42
 
@@ -97,6 +112,53 @@ also = 'that'
 a = 'test'
 `,
 		},
+		{
+			desc: `map with text key`,
+			v: map[marshalTextKey]string{
+				{A: "a", B: "1"}: "value 1",
+				{A: "a", B: "2"}: "value 2",
+				{A: "b", B: "1"}: "value 3",
+			},
+			expected: `a-1 = 'value 1'
+a-2 = 'value 2'
+b-1 = 'value 3'
+`,
+		},
+		{
+			desc: `table with text key`,
+			v: map[marshalTextKey]map[string]string{
+				{A: "a", B: "1"}: {"value": "foo"},
+			},
+			expected: `[a-1]
+value = 'foo'
+`,
+		},
+		{
+			desc: `map with ptr text key`,
+			v: map[*marshalTextKey]string{
+				{A: "a", B: "1"}: "value 1",
+				{A: "a", B: "2"}: "value 2",
+				{A: "b", B: "1"}: "value 3",
+			},
+			expected: `a-1 = 'value 1'
+a-2 = 'value 2'
+b-1 = 'value 3'
+`,
+		},
+		{
+			desc: `map with bad text key`,
+			v: map[marshalBadTextKey]string{
+				{}: "value 1",
+			},
+			err: true,
+		},
+		{
+			desc: `map with bad ptr text key`,
+			v: map[*marshalBadTextKey]string{
+				{}: "value 1",
+			},
+			err: true,
+		},
 		{
 			desc: "simple string array",
 			v: map[string][]string{
@@ -487,9 +549,14 @@ foo = 42
 		},
 		{
 			desc: "invalid map key",
-			v:    map[int]interface{}{},
+			v:    map[int]interface{}{1: "a"},
 			err:  true,
 		},
+		{
+			desc:     "invalid map key but empty",
+			v:        map[int]interface{}{},
+			expected: "",
+		},
 		{
 			desc: "unhandled type",
 			v: struct {
@@ -1190,6 +1257,27 @@ func TestMarshalUint64Overflow(t *testing.T) {
 	require.Error(t, err)
 }
 
+func TestIndentWithInlineTable(t *testing.T) {
+	x := map[string][]map[string]string{
+		"one": []map[string]string{
+			{"0": "0"},
+			{"1": "1"},
+		},
+	}
+	expected := `one = [
+  {0 = '0'},
+  {1 = '1'}
+]
+`
+	var buf bytes.Buffer
+	enc := toml.NewEncoder(&buf)
+	enc.SetIndentTables(true)
+	enc.SetTablesInline(true)
+	enc.SetArraysMultiline(true)
+	require.NoError(t, enc.Encode(x))
+	assert.Equal(t, expected, buf.String())
+}
+
 func ExampleMarshal() {
 	type MyConfig struct {
 		Version int

ossfuzz/fuzz.go

@@ -0,0 +1,45 @@
+//go:build go1.18 || go1.19 || go1.20
+// +build go1.18 go1.19 go1.20
+
+package ossfuzz
+
+import (
+	"fmt"
+	"reflect"
+	"strings"
+
+	"github.com/pelletier/go-toml/v2"
+)
+
+func FuzzToml(data []byte) int {
+	if len(data) >= 2048 {
+		return 0
+	}
+
+	if strings.Contains(string(data), "nan") {
+		return 0
+	}
+
+	var v interface{}
+	err := toml.Unmarshal(data, &v)
+	if err != nil {
+		return 0
+	}
+
+	encoded, err := toml.Marshal(v)
+	if err != nil {
+		panic(fmt.Sprintf("failed to marshal unmarshaled document: %s", err))
+	}
+
+	var v2 interface{}
+	err = toml.Unmarshal(encoded, &v2)
+	if err != nil {
+		panic(fmt.Sprintf("failed round trip: %s", err))
+	}
+
+	if !reflect.DeepEqual(v, v2) {
+		panic(fmt.Sprintf("not equal: %#+v %#+v", v, v2))
+	}
+
+	return 1
+}

unmarshaler.go

@@ -60,7 +60,7 @@ func (d *Decoder) DisallowUnknownFields() *Decoder {
 // are ignored. See Decoder.DisallowUnknownFields() to change this behavior.
 //
 // When a TOML local date, time, or date-time is decoded into a time.Time, its
-// value is represented in time.Local timezone. Otherwise the approriate Local*
+// value is represented in time.Local timezone. Otherwise the appropriate Local*
 // structure is used. For time values, precision up to the nanosecond is
 // supported by truncating extra digits.
 //
@@ -417,7 +417,10 @@ func (d *decoder) handleKeyPart(key unstable.Iterator, v reflect.Value, nextFn h
 		vt := v.Type()
 
 		// Create the key for the map element. Convert to key type.
-		mk := reflect.ValueOf(string(key.Node().Data)).Convert(vt.Key())
+		mk, err := d.keyFromData(vt.Key(), key.Node().Data)
+		if err != nil {
+			return reflect.Value{}, err
+		}
 
 		// If the map does not exist, create it.
 		if v.IsNil() {
@@ -746,7 +749,7 @@ func (d *decoder) unmarshalInlineTable(itable *unstable.Node, v reflect.Value) e
 		}
 		return d.unmarshalInlineTable(itable, elem)
 	default:
-		return unstable.NewParserError(itable.Data, "cannot store inline table in Go type %s", v.Kind())
+		return unstable.NewParserError(d.p.Raw(itable.Raw), "cannot store inline table in Go type %s", v.Kind())
 	}
 
 	it := itable.Children()
@@ -887,6 +890,11 @@ func init() {
 }
 
 func (d *decoder) unmarshalInteger(value *unstable.Node, v reflect.Value) error {
+	kind := v.Kind()
+	if kind == reflect.Float32 || kind == reflect.Float64 {
+		return d.unmarshalFloat(value, v)
+	}
+
 	i, err := parseInteger(value.Data)
 	if err != nil {
 		return err
@@ -894,7 +902,7 @@ func (d *decoder) unmarshalInteger(value *unstable.Node, v reflect.Value) error
 
 	var r reflect.Value
 
-	switch v.Kind() {
+	switch kind {
 	case reflect.Int64:
 		v.SetInt(i)
 		return nil
@@ -1004,6 +1012,31 @@ func (d *decoder) handleKeyValueInner(key unstable.Iterator, value *unstable.Nod
 	return reflect.Value{}, d.handleValue(value, v)
 }
 
+func (d *decoder) keyFromData(keyType reflect.Type, data []byte) (reflect.Value, error) {
+	switch {
+	case stringType.AssignableTo(keyType):
+		return reflect.ValueOf(string(data)), nil
+
+	case stringType.ConvertibleTo(keyType):
+		return reflect.ValueOf(string(data)).Convert(keyType), nil
+
+	case keyType.Implements(textUnmarshalerType):
+		mk := reflect.New(keyType.Elem())
+		if err := mk.Interface().(encoding.TextUnmarshaler).UnmarshalText(data); err != nil {
+			return reflect.Value{}, fmt.Errorf("toml: error unmarshalling key type %s from text: %w", stringType, err)
+		}
+		return mk, nil
+
+	case reflect.PtrTo(keyType).Implements(textUnmarshalerType):
+		mk := reflect.New(keyType)
+		if err := mk.Interface().(encoding.TextUnmarshaler).UnmarshalText(data); err != nil {
+			return reflect.Value{}, fmt.Errorf("toml: error unmarshalling key type %s from text: %w", stringType, err)
+		}
+		return mk.Elem(), nil
+	}
+	return reflect.Value{}, fmt.Errorf("toml: cannot convert map key of type %s to expected type %s", stringType, keyType)
+}
+
 func (d *decoder) handleKeyValuePart(key unstable.Iterator, value *unstable.Node, v reflect.Value) (reflect.Value, error) {
 	// contains the replacement for v
 	var rv reflect.Value
@@ -1014,16 +1047,9 @@ func (d *decoder) handleKeyValuePart(key unstable.Iterator, value *unstable.Node
 	case reflect.Map:
 		vt := v.Type()
 
-		mk := reflect.ValueOf(string(key.Node().Data))
+		mk, err := d.keyFromData(vt.Key(), key.Node().Data)
-		mkt := stringType
+		if err != nil {
-
+			return reflect.Value{}, err
-		keyType := vt.Key()
-		if !mkt.AssignableTo(keyType) {
-			if !mkt.ConvertibleTo(keyType) {
-				return reflect.Value{}, fmt.Errorf("toml: cannot convert map key of type %s to expected type %s", mkt, keyType)
-			}
-
-			mk = mk.Convert(keyType)
 		}
 
 		// If the map does not exist, create it.
@@ -1034,15 +1060,9 @@ func (d *decoder) handleKeyValuePart(key unstable.Iterator, value *unstable.Node
 
 		mv := v.MapIndex(mk)
 		set := false
-		if !mv.IsValid() {
+		if !mv.IsValid() || key.IsLast() {
 			set = true
 			mv = reflect.New(v.Type().Elem()).Elem()
-		} else {
-			if key.IsLast() {
-				var x interface{}
-				mv = reflect.ValueOf(&x).Elem()
-				set = true
-			}
 		}
 
 		nv, err := d.handleKeyValueInner(key, value, mv)
@@ -1072,6 +1092,19 @@ func (d *decoder) handleKeyValuePart(key unstable.Iterator, value *unstable.Node
 		d.errorContext.Field = path
 
 		f := fieldByIndex(v, path)
+
+		if !f.CanSet() {
+			// If the field is not settable, need to take a slower path and make a copy of
+			// the struct itself to a new location.
+			nvp := reflect.New(v.Type())
+			nvp.Elem().Set(v)
+			v = nvp.Elem()
+			_, err := d.handleKeyValuePart(key, value, v)
+			if err != nil {
+				return reflect.Value{}, err
+			}
+			return nvp.Elem(), nil
+		}
 		x, err := d.handleKeyValueInner(key, value, f)
 		if err != nil {
 			return reflect.Value{}, err

unmarshaler_test.go

@@ -16,6 +16,27 @@ import (
 	"github.com/stretchr/testify/require"
 )
 
+type unmarshalTextKey struct {
+	A string
+	B string
+}
+
+func (k *unmarshalTextKey) UnmarshalText(text []byte) error {
+	parts := strings.Split(string(text), "-")
+	if len(parts) != 2 {
+		return fmt.Errorf("invalid text key: %s", text)
+	}
+	k.A = parts[0]
+	k.B = parts[1]
+	return nil
+}
+
+type unmarshalBadTextKey struct{}
+
+func (k *unmarshalBadTextKey) UnmarshalText(text []byte) error {
+	return fmt.Errorf("error")
+}
+
 func ExampleDecoder_DisallowUnknownFields() {
 	type S struct {
 		Key1 string
@@ -69,7 +90,6 @@ func ExampleUnmarshal() {
 	fmt.Println("version:", cfg.Version)
 	fmt.Println("name:", cfg.Name)
 	fmt.Println("tags:", cfg.Tags)
-
 	// Output:
 	// version: 2
 	// name: go-toml
@@ -315,6 +335,7 @@ func TestUnmarshal(t *testing.T) {
 		target   interface{}
 		expected interface{}
 		err      bool
+		assert   func(t *testing.T, test test)
 	}
 	examples := []struct {
 		skip  bool
@@ -350,6 +371,96 @@ func TestUnmarshal(t *testing.T) {
 				}
 			},
 		},
+		{
+			desc:  "kv text key",
+			input: `a-1 = "foo"`,
+			gen: func() test {
+				type doc = map[unmarshalTextKey]string
+
+				return test{
+					target:   &doc{},
+					expected: &doc{{A: "a", B: "1"}: "foo"},
+				}
+			},
+		},
+		{
+			desc: "table text key",
+			input: `["a-1"]
+foo = "bar"`,
+			gen: func() test {
+				type doc = map[unmarshalTextKey]map[string]string
+
+				return test{
+					target:   &doc{},
+					expected: &doc{{A: "a", B: "1"}: map[string]string{"foo": "bar"}},
+				}
+			},
+		},
+		{
+			desc:  "kv ptr text key",
+			input: `a-1 = "foo"`,
+			gen: func() test {
+				type doc = map[*unmarshalTextKey]string
+
+				return test{
+					target:   &doc{},
+					expected: &doc{{A: "a", B: "1"}: "foo"},
+					assert: func(t *testing.T, test test) {
+						// Despite the documentation:
+						//     Pointer variable equality is determined based on the equality of the
+						// 		 referenced values (as opposed to the memory addresses).
+						// assert.Equal does not work properly with maps with pointer keys
+						// https://github.com/stretchr/testify/issues/1143
+						expected := make(map[unmarshalTextKey]string)
+						for k, v := range *(test.expected.(*doc)) {
+							expected[*k] = v
+						}
+						got := make(map[unmarshalTextKey]string)
+						for k, v := range *(test.target.(*doc)) {
+							got[*k] = v
+						}
+						assert.Equal(t, expected, got)
+					},
+				}
+			},
+		},
+		{
+			desc:  "kv bad text key",
+			input: `a-1 = "foo"`,
+			gen: func() test {
+				type doc = map[unmarshalBadTextKey]string
+
+				return test{
+					target: &doc{},
+					err:    true,
+				}
+			},
+		},
+		{
+			desc:  "kv bad ptr text key",
+			input: `a-1 = "foo"`,
+			gen: func() test {
+				type doc = map[*unmarshalBadTextKey]string
+
+				return test{
+					target: &doc{},
+					err:    true,
+				}
+			},
+		},
+		{
+			desc: "table bad text key",
+			input: `["a-1"]
+foo = "bar"`,
+			gen: func() test {
+				type doc = map[unmarshalBadTextKey]map[string]string
+
+				return test{
+					target: &doc{},
+					err:    true,
+				}
+			},
+		},
 		{
 			desc:  "time.time with negative zone",
 			input: `a = 1979-05-27T00:32:00-07:00 `, // space intentional
@@ -1521,6 +1632,16 @@ B = "data"`,
 				}
 			},
 		},
+		{
+			desc:  "empty map into map with invalid key type",
+			input: ``,
+			gen: func() test {
+				return test{
+					target:   &map[int]string{},
+					expected: &map[int]string{},
+				}
+			},
+		},
 		{
 			desc:  "into map with convertible key type",
 			input: `A = "hello"`,
@@ -1777,7 +1898,11 @@ B = "data"`,
 				require.Error(t, err)
 			} else {
 				require.NoError(t, err)
-				assert.Equal(t, test.expected, test.target)
+				if test.assert != nil {
+					test.assert(t, test)
+				} else {
+					assert.Equal(t, test.expected, test.target)
+				}
 			}
 		})
 	}
@@ -2466,6 +2591,91 @@ func TestIssue807(t *testing.T) {
 	require.Equal(t, "foo", m.Name)
 }
 
+func TestIssue850(t *testing.T) {
+	data := make(map[string]string)
+	err := toml.Unmarshal([]byte("foo = {}"), &data)
+	require.Error(t, err)
+}
+
+func TestIssue851(t *testing.T) {
+	type Target struct {
+		Params map[string]string `toml:"params"`
+	}
+
+	content := "params = {a=\"1\",b=\"2\"}"
+	var target Target
+	err := toml.Unmarshal([]byte(content), &target)
+	require.NoError(t, err)
+	require.Equal(t, map[string]string{"a": "1", "b": "2"}, target.Params)
+	err = toml.Unmarshal([]byte(content), &target)
+	require.NoError(t, err)
+	require.Equal(t, map[string]string{"a": "1", "b": "2"}, target.Params)
+}
+
+func TestIssue866(t *testing.T) {
+	type Pipeline struct {
+		Mapping map[string]struct {
+			Req [][]string `toml:"req"`
+			Res [][]string `toml:"res"`
+		} `toml:"mapping"`
+	}
+
+	type Pipelines struct {
+		PipelineMapping map[string]*Pipeline `toml:"pipelines"`
+	}
+
+	var badToml = `
+[pipelines.register]
+mapping.inst.req = [
+    ["param1", "value1"],
+]
+mapping.inst.res = [
+    ["param2", "value2"],
+]
+`
+
+	pipelines := new(Pipelines)
+	if err := toml.NewDecoder(bytes.NewBufferString(badToml)).DisallowUnknownFields().Decode(pipelines); err != nil {
+		t.Fatal(err)
+	}
+	if pipelines.PipelineMapping["register"].Mapping["inst"].Req[0][0] != "param1" {
+		t.Fatal("unmarshal failed with mismatch value")
+	}
+
+	var goodTooToml = `
+[pipelines.register]
+mapping.inst.req = [
+    ["param1", "value1"],
+]
+`
+
+	pipelines = new(Pipelines)
+	if err := toml.NewDecoder(bytes.NewBufferString(goodTooToml)).DisallowUnknownFields().Decode(pipelines); err != nil {
+		t.Fatal(err)
+	}
+	if pipelines.PipelineMapping["register"].Mapping["inst"].Req[0][0] != "param1" {
+		t.Fatal("unmarshal failed with mismatch value")
+	}
+
+	var goodToml = `
+[pipelines.register.mapping.inst]
+req = [
+    ["param1", "value1"],
+]
+res = [
+    ["param2", "value2"],
+]
+`
+
+	pipelines = new(Pipelines)
+	if err := toml.NewDecoder(bytes.NewBufferString(goodToml)).DisallowUnknownFields().Decode(pipelines); err != nil {
+		t.Fatal(err)
+	}
+	if pipelines.PipelineMapping["register"].Mapping["inst"].Req[0][0] != "param1" {
+		t.Fatal("unmarshal failed with mismatch value")
+	}
+}
+
 func TestUnmarshalDecodeErrors(t *testing.T) {
 	examples := []struct {
 		desc string
@@ -2742,7 +2952,7 @@ world'`,
 			data: "a = \"aaaa\xE2\x80\x00\"",
 		},
 		{
-			desc: "invalid 4rd byte of 4-byte utf8 character in string with no escape sequence",
+			desc: "invalid 4th byte of 4-byte utf8 character in string with no escape sequence",
 			data: "a = \"aaaa\xF2\x81\x81\x00\"",
 		},
 		{
@@ -2758,7 +2968,7 @@ world'`,
 			data: "a = 'aaaa\xE2\x80\x00'",
 		},
 		{
-			desc: "invalid 4rd byte of 4-byte utf8 character in literal string",
+			desc: "invalid 4th byte of 4-byte utf8 character in literal string",
 			data: "a = 'aaaa\xF2\x81\x81\x00'",
 		},
 		{

unstable/ast.go

@@ -58,7 +58,7 @@ func (c *Iterator) Node() *Node {
 //   - Table and ArrayTable's children represent a dotted key (same as
 //     KeyValue, but without the first node being the value).
 //
-// When relevant, Raw describes the range of bytes this node is refering to in
+// When relevant, Raw describes the range of bytes this node is referring to in
 // the input document. Use Parser.Raw() to retrieve the actual bytes.
 type Node struct {
 	Kind Kind

unstable/parser.go

@@ -49,8 +49,6 @@ func NewParserError(highlight []byte, format string, args ...interface{}) error
 // For performance reasons, go-toml doesn't make a copy of the input bytes to
 // the parser. Make sure to copy all the bytes you need to outlive the slice
 // given to the parser.
-//
-// The parser doesn't provide nodes for comments yet, nor for whitespace.
 type Parser struct {
 	data    []byte
 	builder builder
@@ -58,6 +56,8 @@ type Parser struct {
 	left    []byte
 	err     error
 	first   bool
+
+	KeepComments bool
 }
 
 // Data returns the slice provided to the last call to Reset.
@@ -132,16 +132,54 @@ func (p *Parser) NextExpression() bool {
 }
 
 // Expression returns a pointer to the node representing the last successfully
-// parsed expresion.
+// parsed expression.
 func (p *Parser) Expression() *Node {
 	return p.builder.NodeAt(p.ref)
 }
 
-// Error returns any error that has occured during parsing.
+// Error returns any error that has occurred during parsing.
 func (p *Parser) Error() error {
 	return p.err
 }
 
+// Position describes a position in the input.
+type Position struct {
+	// Number of bytes from the beginning of the input.
+	Offset int
+	// Line number, starting at 1.
+	Line int
+	// Column number, starting at 1.
+	Column int
+}
+
+// Shape describes the position of a range in the input.
+type Shape struct {
+	Start Position
+	End   Position
+}
+
+func (p *Parser) position(b []byte) Position {
+	offset := danger.SubsliceOffset(p.data, b)
+
+	lead := p.data[:offset]
+
+	return Position{
+		Offset: offset,
+		Line:   bytes.Count(lead, []byte{'\n'}) + 1,
+		Column: len(lead) - bytes.LastIndex(lead, []byte{'\n'}),
+	}
+}
+
+// Shape returns the shape of the given range in the input.  Will
+// panic if the range is not a subslice of the input.
+func (p *Parser) Shape(r Range) Shape {
+	raw := p.Raw(r)
+	return Shape{
+		Start: p.position(raw),
+		End:   p.position(raw[r.Length:]),
+	}
+}
+
 func (p *Parser) parseNewline(b []byte) ([]byte, error) {
 	if b[0] == '\n' {
 		return b[1:], nil
@@ -155,6 +193,19 @@ func (p *Parser) parseNewline(b []byte) ([]byte, error) {
 	return nil, NewParserError(b[0:1], "expected newline but got %#U", b[0])
 }
 
+func (p *Parser) parseComment(b []byte) (reference, []byte, error) {
+	ref := invalidReference
+	data, rest, err := scanComment(b)
+	if p.KeepComments && err == nil {
+		ref = p.builder.Push(Node{
+			Kind: Comment,
+			Raw:  p.Range(data),
+			Data: data,
+		})
+	}
+	return ref, rest, err
+}
+
 func (p *Parser) parseExpression(b []byte) (reference, []byte, error) {
 	// expression =  ws [ comment ]
 	// expression =/ ws keyval ws [ comment ]
@@ -168,7 +219,7 @@ func (p *Parser) parseExpression(b []byte) (reference, []byte, error) {
 	}
 
 	if b[0] == '#' {
-		_, rest, err := scanComment(b)
+		ref, rest, err := p.parseComment(b)
 		return ref, rest, err
 	}
 
@@ -190,7 +241,10 @@ func (p *Parser) parseExpression(b []byte) (reference, []byte, error) {
 	b = p.parseWhitespace(b)
 
 	if len(b) > 0 && b[0] == '#' {
-		_, rest, err := scanComment(b)
+		cref, rest, err := p.parseComment(b)
+		if cref != invalidReference {
+			p.builder.Chain(ref, cref)
+		}
 		return ref, rest, err
 	}
 
@@ -402,6 +456,7 @@ func (p *Parser) parseInlineTable(b []byte) (reference, []byte, error) {
 	// inline-table-keyvals = keyval [ inline-table-sep inline-table-keyvals ]
 	parent := p.builder.Push(Node{
 		Kind: InlineTable,
+		Raw:  p.Range(b[:1]),
 	})
 
 	first := true
@@ -470,17 +525,33 @@ func (p *Parser) parseValArray(b []byte) (reference, []byte, error) {
 		Kind: Array,
 	})
 
+	// First indicates whether the parser is looking for the first element
+	// (non-comment) of the array.
 	first := true
 
-	var lastChild reference
+	lastChild := invalidReference
+
+	addChild := func(valueRef reference) {
+		if lastChild == invalidReference {
+			p.builder.AttachChild(parent, valueRef)
+		} else {
+			p.builder.Chain(lastChild, valueRef)
+		}
+		lastChild = valueRef
+	}
 
 	var err error
 	for len(b) > 0 {
-		b, err = p.parseOptionalWhitespaceCommentNewline(b)
+		cref := invalidReference
+		cref, b, err = p.parseOptionalWhitespaceCommentNewline(b)
 		if err != nil {
 			return parent, nil, err
 		}
 
+		if cref != invalidReference {
+			addChild(cref)
+		}
+
 		if len(b) == 0 {
 			return parent, nil, NewParserError(arrayStart[:1], "array is incomplete")
 		}
@@ -495,10 +566,13 @@ func (p *Parser) parseValArray(b []byte) (reference, []byte, error) {
 			}
 			b = b[1:]
 
-			b, err = p.parseOptionalWhitespaceCommentNewline(b)
+			cref, b, err = p.parseOptionalWhitespaceCommentNewline(b)
 			if err != nil {
 				return parent, nil, err
 			}
+			if cref != invalidReference {
+				addChild(cref)
+			}
 		} else if !first {
 			return parent, nil, NewParserError(b[0:1], "array elements must be separated by commas")
 		}
@@ -514,17 +588,16 @@ func (p *Parser) parseValArray(b []byte) (reference, []byte, error) {
 			return parent, nil, err
 		}
 
-		if first {
+		addChild(valueRef)
-			p.builder.AttachChild(parent, valueRef)
-		} else {
-			p.builder.Chain(lastChild, valueRef)
-		}
-		lastChild = valueRef
 
-		b, err = p.parseOptionalWhitespaceCommentNewline(b)
+		cref, b, err = p.parseOptionalWhitespaceCommentNewline(b)
 		if err != nil {
 			return parent, nil, err
 		}
+		if cref != invalidReference {
+			addChild(cref)
+		}
+
 		first = false
 	}
 
@@ -533,15 +606,34 @@ func (p *Parser) parseValArray(b []byte) (reference, []byte, error) {
 	return parent, rest, err
 }
 
-func (p *Parser) parseOptionalWhitespaceCommentNewline(b []byte) ([]byte, error) {
+func (p *Parser) parseOptionalWhitespaceCommentNewline(b []byte) (reference, []byte, error) {
+	rootCommentRef := invalidReference
+	latestCommentRef := invalidReference
+
+	addComment := func(ref reference) {
+		if rootCommentRef == invalidReference {
+			rootCommentRef = ref
+		} else if latestCommentRef == invalidReference {
+			p.builder.AttachChild(rootCommentRef, ref)
+			latestCommentRef = ref
+		} else {
+			p.builder.Chain(latestCommentRef, ref)
+			latestCommentRef = ref
+		}
+	}
+
 	for len(b) > 0 {
 		var err error
 		b = p.parseWhitespace(b)
 
 		if len(b) > 0 && b[0] == '#' {
-			_, b, err = scanComment(b)
+			var ref reference
+			ref, b, err = p.parseComment(b)
 			if err != nil {
-				return nil, err
+				return invalidReference, nil, err
+			}
+			if ref != invalidReference {
+				addComment(ref)
 			}
 		}
 
@@ -552,14 +644,14 @@ func (p *Parser) parseOptionalWhitespaceCommentNewline(b []byte) ([]byte, error)
 		if b[0] == '\n' || b[0] == '\r' {
 			b, err = p.parseNewline(b)
 			if err != nil {
-				return nil, err
+				return invalidReference, nil, err
 			}
 		} else {
 			break
 		}
 	}
 
-	return b, nil
+	return rootCommentRef, b, nil
 }
 
 func (p *Parser) parseMultilineLiteralString(b []byte) ([]byte, []byte, []byte, error) {

unstable/parser_test.go

@@ -448,6 +448,163 @@ func TestParser_AST_DateTimes(t *testing.T) {
 	}
 }
 
+// This example demonstrates how to parse a TOML document and preserving
+// comments.  Comments are stored in the AST as Comment nodes. This example
+// displays the structure of the full AST generated by the parser using the
+// following structure:
+//
+//  1. Each root-level expression is separated by three dashes.
+//  2. Bytes associated to a node are displayed in square brackets.
+//  3. Siblings have the same indentation.
+//  4. Children of a node are indented one level.
+func ExampleParser_comments() {
+	doc := `# Top of the document comment.
+# Optional, any amount of lines.
+
+# Above table.
+[table] # Next to table.
+# Above simple value.
+key = "value" # Next to simple value.
+# Below simple value.
+
+# Some comment alone.
+
+# Multiple comments, on multiple lines.
+
+# Above inline table.
+name = { first = "Tom", last = "Preston-Werner" } # Next to inline table.
+# Below inline table.
+
+# Above array.
+array = [ 1, 2, 3 ] # Next to one-line array.
+# Below array.
+
+# Above multi-line array.
+key5 = [ # Next to start of inline array.
+  # Second line before array content.
+  1, # Next to first element.
+  # After first element.
+  # Before second element.
+  2,
+  3, # Next to last element
+  # After last element.
+] # Next to end of array.
+# Below multi-line array.
+
+# Before array table.
+[[products]] # Next to array table.
+# After array table.
+`
+
+	var printGeneric func(*Parser, int, *Node)
+	printGeneric = func(p *Parser, indent int, e *Node) {
+		if e == nil {
+			return
+		}
+		s := p.Shape(e.Raw)
+		x := fmt.Sprintf("%d:%d->%d:%d (%d->%d)", s.Start.Line, s.Start.Column, s.End.Line, s.End.Column, s.Start.Offset, s.End.Offset)
+		fmt.Printf("%-25s | %s%s [%s]\n", x, strings.Repeat("  ", indent), e.Kind, e.Data)
+		printGeneric(p, indent+1, e.Child())
+		printGeneric(p, indent, e.Next())
+	}
+
+	printTree := func(p *Parser) {
+		for p.NextExpression() {
+			e := p.Expression()
+			fmt.Println("---")
+			printGeneric(p, 0, e)
+		}
+		if err := p.Error(); err != nil {
+			panic(err)
+		}
+	}
+
+	p := &Parser{
+		KeepComments: true,
+	}
+	p.Reset([]byte(doc))
+	printTree(p)
+
+	// Output:
+	// ---
+	// 1:1->1:31 (0->30)         | Comment [# Top of the document comment.]
+	// ---
+	// 2:1->2:33 (31->63)        | Comment [# Optional, any amount of lines.]
+	// ---
+	// 4:1->4:15 (65->79)        | Comment [# Above table.]
+	// ---
+	// 1:1->1:1 (0->0)           | Table []
+	// 5:2->5:7 (81->86)         |   Key [table]
+	// 5:9->5:25 (88->104)       | Comment [# Next to table.]
+	// ---
+	// 6:1->6:22 (105->126)      | Comment [# Above simple value.]
+	// ---
+	// 1:1->1:1 (0->0)           | KeyValue []
+	// 7:7->7:14 (133->140)      |   String [value]
+	// 7:1->7:4 (127->130)       |   Key [key]
+	// 7:15->7:38 (141->164)     | Comment [# Next to simple value.]
+	// ---
+	// 8:1->8:22 (165->186)      | Comment [# Below simple value.]
+	// ---
+	// 10:1->10:22 (188->209)    | Comment [# Some comment alone.]
+	// ---
+	// 12:1->12:40 (211->250)    | Comment [# Multiple comments, on multiple lines.]
+	// ---
+	// 14:1->14:22 (252->273)    | Comment [# Above inline table.]
+	// ---
+	// 1:1->1:1 (0->0)           | KeyValue []
+	// 15:8->15:9 (281->282)     |   InlineTable []
+	// 1:1->1:1 (0->0)           |     KeyValue []
+	// 15:18->15:23 (291->296)   |       String [Tom]
+	// 15:10->15:15 (283->288)   |       Key [first]
+	// 1:1->1:1 (0->0)           |     KeyValue []
+	// 15:32->15:48 (305->321)   |       String [Preston-Werner]
+	// 15:25->15:29 (298->302)   |       Key [last]
+	// 15:1->15:5 (274->278)     |   Key [name]
+	// 15:51->15:74 (324->347)   | Comment [# Next to inline table.]
+	// ---
+	// 16:1->16:22 (348->369)    | Comment [# Below inline table.]
+	// ---
+	// 18:1->18:15 (371->385)    | Comment [# Above array.]
+	// ---
+	// 1:1->1:1 (0->0)           | KeyValue []
+	// 1:1->1:1 (0->0)           |   Array []
+	// 1:1->1:1 (0->0)           |     Integer [1]
+	// 1:1->1:1 (0->0)           |     Integer [2]
+	// 1:1->1:1 (0->0)           |     Integer [3]
+	// 19:1->19:6 (386->391)     |   Key [array]
+	// 19:21->19:46 (406->431)   | Comment [# Next to one-line array.]
+	// ---
+	// 20:1->20:15 (432->446)    | Comment [# Below array.]
+	// ---
+	// 22:1->22:26 (448->473)    | Comment [# Above multi-line array.]
+	// ---
+	// 1:1->1:1 (0->0)           | KeyValue []
+	// 1:1->1:1 (0->0)           |   Array []
+	// 23:10->23:42 (483->515)   |     Comment [# Next to start of inline array.]
+	// 24:3->24:38 (518->553)    |       Comment [# Second line before array content.]
+	// 1:1->1:1 (0->0)           |     Integer [1]
+	// 25:6->25:30 (559->583)    |     Comment [# Next to first element.]
+	// 26:3->26:25 (586->608)    |       Comment [# After first element.]
+	// 27:3->27:27 (611->635)    |       Comment [# Before second element.]
+	// 1:1->1:1 (0->0)           |     Integer [2]
+	// 1:1->1:1 (0->0)           |     Integer [3]
+	// 29:6->29:28 (646->668)    |     Comment [# Next to last element]
+	// 30:3->30:24 (671->692)    |       Comment [# After last element.]
+	// 23:1->23:5 (474->478)     |   Key [key5]
+	// 31:3->31:26 (695->718)    | Comment [# Next to end of array.]
+	// ---
+	// 32:1->32:26 (719->744)    | Comment [# Below multi-line array.]
+	// ---
+	// 34:1->34:22 (746->767)    | Comment [# Before array table.]
+	// ---
+	// 1:1->1:1 (0->0)           | ArrayTable []
+	// 35:3->35:11 (770->778)    |   Key [products]
+	// 35:14->35:36 (781->803)   | Comment [# Next to array table.]
+	// ---
+	// 36:1->36:21 (804->824)    | Comment [# After array table.]
+}
+
 func ExampleParser() {
 	doc := `
 	hello = "world"

unstable/scanner.go

@@ -151,7 +151,6 @@ func scanWhitespace(b []byte) ([]byte, []byte) {
 	return b, b[len(b):]
 }
 
-//nolint:unparam
 func scanComment(b []byte) ([]byte, []byte, error) {
 	// comment-start-symbol = %x23 ; #
 	// non-ascii = %x80-D7FF / %xE000-10FFFF