Decode: error on array table mismatched type (#804)

Prevent the decoder from continuing if it encounters a type it cannot decode an
array table into.

Fixes #799

.github/workflows/coverage.yml

@@ -15,6 +15,6 @@ jobs:
       - name: Setup go
         uses: actions/setup-go@master
         with:
-          go-version: 1.18
+          go-version: 1.19
       - name: Run tests with coverage
         run: ./ci.sh coverage -d "${GITHUB_BASE_REF-HEAD}"

.github/workflows/release.yml

@@ -22,7 +22,7 @@ jobs:
       - name: Set up Go
         uses: actions/setup-go@v2
         with:
-          go-version: 1.18
+          go-version: 1.19
       - 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: [ '1.17', '1.18' ]
+        go: [ '1.18', '1.19' ]
     runs-on: ${{ matrix.os }}
     name: ${{ matrix.go }}/${{ matrix.os }}
     steps:

cmd/jsontoml/main.go

@@ -1,6 +1,6 @@
 // Package jsontoml is a program that converts JSON to TOML.
 //
-// Usage
+// # Usage
 //
 // Reading from stdin:
 //
@@ -10,7 +10,7 @@
 //
 //	jsontoml file.json > file.toml
 //
-// Installation
+// # Installation
 //
 // Using Go:
 //

cmd/jsontoml/main_test.go

@@ -26,7 +26,6 @@ func TestConvert(t *testing.T) {
 }`,
 			expected: `[mytoml]
 a = 42.0
-
 `,
 		},
 		{

cmd/tomljson/main.go

@@ -1,6 +1,6 @@
 // Package tomljson is a program that converts TOML to JSON.
 //
-// Usage
+// # Usage
 //
 // Reading from stdin:
 //
@@ -10,7 +10,7 @@
 //
 //	tomljson file.toml > file.json
 //
-// Installation
+// # Installation
 //
 // Using Go:
 //

cmd/tomll/main.go

@@ -1,6 +1,6 @@
 // Package tomll is a linter program for TOML.
 //
-// Usage
+// # Usage
 //
 // Reading from stdin, writing to stdout:
 //
@@ -10,7 +10,7 @@
 //
 //	tomll a.toml b.toml c.toml
 //
-// Installation
+// # Installation
 //
 // Using Go:
 //

cmd/tomll/main_test.go

@@ -23,7 +23,6 @@ mytoml.a = 42.0
 `,
 			expected: `[mytoml]
 a = 42.0
-
 `,
 		},
 		{

errors.go

@@ -103,6 +103,7 @@ func (e *DecodeError) Key() Key {
 //
 // The function copies all bytes used in DecodeError, so that document and
 // highlight can be freely deallocated.
+//
 //nolint:funlen
 func wrapDecodeError(document []byte, de *decodeError) *DecodeError {
 	offset := danger.SubsliceOffset(document, de.highlight)

fuzz_test.go

@@ -1,5 +1,4 @@
-//go:build go1.18
-// +build go1.18
+//go:build go1.18 || go1.19
 
 package toml_test
 

go.mod

@@ -2,4 +2,4 @@ module github.com/pelletier/go-toml/v2
 
 go 1.16
 
-require github.com/stretchr/testify v1.7.2
+require github.com/stretchr/testify v1.8.0

go.sum

@@ -1,11 +1,15 @@
-github.com/davecgh/go-spew v1.1.0 h1:ZDRjVQ15GmhC3fiQ8ni8+OwkZQO4DARzQgrnXU1Liz8=
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
-github.com/stretchr/testify v1.7.2 h1:4jaiDzPyXQvSd7D0EjG45355tLlV3VOECpq10pLC+8s=
-github.com/stretchr/testify v1.7.2/go.mod h1:R6va5+xMeoiuVRoj+gSkQ7d3FALtqAAGI1FQKckRals=
+github.com/stretchr/objx v0.4.0/go.mod h1:YvHI0jy2hoMjB+UWwv71VJQ9isScKT/TqJzVSSt89Yw=
+github.com/stretchr/testify v1.7.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
+github.com/stretchr/testify v1.8.0 h1:pSgiaMZlXftHpm5L7V1+rVB+AZJydKsMxsQBIJw4PKk=
+github.com/stretchr/testify v1.8.0/go.mod h1:yNjHg4UonilssWZ8iaSj1OCr/vHnekPRkoO+kdMU+MU=
 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=
 gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
 gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

internal/imported_tests/marshal_imported_test.go

@@ -67,6 +67,7 @@ func TestDocMarshal(t *testing.T) {
 	}
 
 	marshalTestToml := `title = 'TOML Marshal Testing'
+
 [basic_lists]
 floats = [12.3, 45.6, 78.9]
 bools = [true, false, true]
@@ -89,7 +90,6 @@ name = 'Second'
 [subdoc.first]
 name = 'First'
 
-
 [basic]
 uint = 5001
 bool = true
@@ -101,9 +101,9 @@ date = 1979-05-27T07:32:00Z
 
 [[subdoclist]]
 name = 'List.First'
+
 [[subdoclist]]
 name = 'List.Second'
-
 `
 
 	result, err := toml.Marshal(docData)
@@ -117,14 +117,15 @@ func TestBasicMarshalQuotedKey(t *testing.T) {
 
 	expected := `'Z.string-àéù' = 'Hello'
 'Yfloat-𝟘' = 3.5
+
 ['Xsubdoc-àéù']
 String2 = 'One'
 
 [['W.sublist-𝟘']]
 String2 = 'Two'
+
 [['W.sublist-𝟘']]
 String2 = 'Three'
-
 `
 
 	require.Equal(t, string(expected), string(result))
@@ -159,8 +160,8 @@ bool = false
 int = 0
 string = ''
 stringlist = []
-[map]
 
+[map]
 `
 
 	require.Equal(t, string(expected), string(result))

internal/imported_tests/unmarshal_imported_test.go

@@ -151,6 +151,7 @@ type quotedKeyMarshalTestStruct struct {
 }
 
 // TODO: Remove nolint once var is used by a test
+//
 //nolint:deadcode,unused,varcheck
 var quotedKeyMarshalTestData = quotedKeyMarshalTestStruct{
 	String:  "Hello",
@@ -160,6 +161,7 @@ var quotedKeyMarshalTestData = quotedKeyMarshalTestStruct{
 }
 
 // TODO: Remove nolint once var is used by a test
+//
 //nolint:deadcode,unused,varcheck
 var quotedKeyMarshalTestToml = []byte(`"Yfloat-𝟘" = 3.5
 "Z.string-àéù" = "Hello"
@@ -272,6 +274,7 @@ var docData = testDoc{
 }
 
 // TODO: Remove nolint once var is used by a test
+//
 //nolint:deadcode,unused,varcheck
 var mapTestDoc = testMapDoc{
 	Title: "TOML Marshal Testing",
@@ -559,10 +562,12 @@ func (c customMarshaler) MarshalTOML() ([]byte, error) {
 var customMarshalerData = customMarshaler{FirstName: "Sally", LastName: "Fields"}
 
 // TODO: Remove nolint once var is used by a test
+//
 //nolint:deadcode,unused,varcheck
 var customMarshalerToml = []byte(`Sally Fields`)
 
 // TODO: Remove nolint once var is used by a test
+//
 //nolint:deadcode,unused,varcheck
 var nestedCustomMarshalerData = customMarshalerParent{
 	Self:    customMarshaler{FirstName: "Maiku", LastName: "Suteda"},
@@ -570,6 +575,7 @@ var nestedCustomMarshalerData = customMarshalerParent{
 }
 
 // TODO: Remove nolint once var is used by a test
+//
 //nolint:deadcode,unused,varcheck
 var nestedCustomMarshalerToml = []byte(`friends = ["Sally Fields"]
 me = "Maiku Suteda"
@@ -611,6 +617,7 @@ func TestUnmarshalTextMarshaler(t *testing.T) {
 }
 
 // TODO: Remove nolint once type and methods are used by a test
+//
 //nolint:unused
 type precedentMarshaler struct {
 	FirstName string
@@ -629,6 +636,7 @@ func (m precedentMarshaler) MarshalTOML() ([]byte, error) {
 }
 
 // TODO: Remove nolint once type and method are used by a test
+//
 //nolint:unused
 type customPointerMarshaler struct {
 	FirstName string
@@ -641,6 +649,7 @@ func (m *customPointerMarshaler) MarshalTOML() ([]byte, error) {
 }
 
 // TODO: Remove nolint once type and method are used by a test
+//
 //nolint:unused
 type textPointerMarshaler struct {
 	FirstName string
@@ -653,6 +662,7 @@ func (m *textPointerMarshaler) MarshalText() ([]byte, error) {
 }
 
 // TODO: Remove nolint once var is used by a test
+//
 //nolint:deadcode,unused,varcheck
 var commentTestToml = []byte(`
 # it's a comment on type
@@ -690,6 +700,7 @@ type mapsTestStruct struct {
 }
 
 // TODO: Remove nolint once var is used by a test
+//
 //nolint:deadcode,unused,varcheck
 var mapsTestData = mapsTestStruct{
 	Simple: map[string]string{
@@ -713,6 +724,7 @@ var mapsTestData = mapsTestStruct{
 }
 
 // TODO: Remove nolint once var is used by a test
+//
 //nolint:deadcode,unused,varcheck
 var mapsTestToml = []byte(`
 [Other]
@@ -735,6 +747,7 @@ var mapsTestToml = []byte(`
 `)
 
 // TODO: Remove nolint once type is used by a test
+//
 //nolint:deadcode,unused
 type structArrayNoTag struct {
 	A struct {
@@ -744,6 +757,7 @@ type structArrayNoTag struct {
 }
 
 // TODO: Remove nolint once var is used by a test
+//
 //nolint:deadcode,unused,varcheck
 var customTagTestToml = []byte(`
 [postgres]
@@ -758,6 +772,7 @@ var customTagTestToml = []byte(`
 `)
 
 // TODO: Remove nolint once var is used by a test
+//
 //nolint:deadcode,unused,varcheck
 var customCommentTagTestToml = []byte(`
 # db connection
@@ -771,6 +786,7 @@ var customCommentTagTestToml = []byte(`
 `)
 
 // TODO: Remove nolint once var is used by a test
+//
 //nolint:deadcode,unused,varcheck
 var customCommentedTagTestToml = []byte(`
 [postgres]
@@ -825,6 +841,7 @@ func TestUnmarshalTabInStringAndQuotedKey(t *testing.T) {
 }
 
 // TODO: Remove nolint once var is used by a test
+//
 //nolint:deadcode,unused,varcheck
 var customMultilineTagTestToml = []byte(`int_slice = [
   1,
@@ -834,6 +851,7 @@ var customMultilineTagTestToml = []byte(`int_slice = [
 `)
 
 // TODO: Remove nolint once var is used by a test
+//
 //nolint:deadcode,unused,varcheck
 var testDocBasicToml = []byte(`
 [document]
@@ -846,12 +864,14 @@ var testDocBasicToml = []byte(`
 `)
 
 // TODO: Remove nolint once type is used by a test
+//
 //nolint:deadcode
 type testDocCustomTag struct {
 	Doc testDocBasicsCustomTag `file:"document"`
 }
 
 // TODO: Remove nolint once type is used by a test
+//
 //nolint:deadcode
 type testDocBasicsCustomTag struct {
 	Bool       bool      `file:"bool_val"`
@@ -864,6 +884,7 @@ type testDocBasicsCustomTag struct {
 }
 
 // TODO: Remove nolint once var is used by a test
+//
 //nolint:deadcode,varcheck
 var testDocCustomTagData = testDocCustomTag{
 	Doc: testDocBasicsCustomTag{
@@ -966,6 +987,7 @@ func TestUnmarshalInvalidPointerKind(t *testing.T) {
 }
 
 // TODO: Remove nolint once var is used by a test
+//
 //nolint:deadcode,unused
 type testDuration struct {
 	Nanosec   time.Duration  `toml:"nanosec"`
@@ -980,6 +1002,7 @@ type testDuration struct {
 }
 
 // TODO: Remove nolint once var is used by a test
+//
 //nolint:deadcode,unused,varcheck
 var testDurationToml = []byte(`
 nanosec = "1ns"
@@ -994,6 +1017,7 @@ a_string = "15s"
 `)
 
 // TODO: Remove nolint once var is used by a test
+//
 //nolint:deadcode,unused,varcheck
 var testDurationToml2 = []byte(`a_string = "15s"
 hour = "1h0m0s"
@@ -1007,6 +1031,7 @@ sec = "1s"
 `)
 
 // TODO: Remove nolint once type is used by a test
+//
 //nolint:deadcode,unused
 type testBadDuration struct {
 	Val time.Duration `toml:"val"`

marshaler.go

@@ -54,7 +54,7 @@ func NewEncoder(w io.Writer) *Encoder {
 // This behavior can be controlled on an individual struct field basis with the
 // inline tag:
 //
-//   MyField `inline:"true"`
+//	MyField `toml:",inline"`
 func (enc *Encoder) SetTablesInline(inline bool) *Encoder {
 	enc.tablesInline = inline
 	return enc
@@ -89,7 +89,7 @@ func (enc *Encoder) SetIndentTables(indent bool) *Encoder {
 //
 // If v cannot be represented to TOML it returns an error.
 //
-// Encoding rules
+// # Encoding rules
 //
 // A top level slice containing only maps or structs is encoded as [[table
 // array]].
@@ -117,7 +117,20 @@ func (enc *Encoder) SetIndentTables(indent bool) *Encoder {
 // When encoding structs, fields are encoded in order of definition, with their
 // exact name.
 //
-// Struct tags
+// Tables and array tables are separated by empty lines. However, consecutive
+// subtables definitions are not. For example:
+//
+//	[top1]
+//
+//	[top2]
+//	[top2.child1]
+//
+//	[[array]]
+//
+//	[[array]]
+//	[array.child2]
+//
+// # Struct tags
 //
 // The encoding of each public struct field can be customized by the format
 // string in the "toml" key of the struct field's tag. This follows
@@ -333,13 +346,13 @@ func isNil(v reflect.Value) bool {
 	}
 }
 
+func shouldOmitEmpty(options valueOptions, v reflect.Value) bool {
+	return options.omitempty && isEmptyValue(v)
+}
+
 func (enc *Encoder) encodeKv(b []byte, ctx encoderCtx, options valueOptions, v reflect.Value) ([]byte, error) {
 	var err error
 
-	if (ctx.options.omitempty || options.omitempty) && isEmptyValue(v) {
-		return b, nil
-	}
-
 	if !ctx.inline {
 		b = enc.encodeComment(ctx.indent, options.comment, b)
 	}
@@ -365,6 +378,8 @@ func (enc *Encoder) encodeKv(b []byte, ctx encoderCtx, options valueOptions, v r
 
 func isEmptyValue(v reflect.Value) bool {
 	switch v.Kind() {
+	case reflect.Struct:
+		return isEmptyStruct(v)
 	case reflect.Array, reflect.Map, reflect.Slice, reflect.String:
 		return v.Len() == 0
 	case reflect.Bool:
@@ -381,6 +396,34 @@ func isEmptyValue(v reflect.Value) bool {
 	return false
 }
 
+func isEmptyStruct(v reflect.Value) bool {
+	// TODO: merge with walkStruct and cache.
+	typ := v.Type()
+	for i := 0; i < typ.NumField(); i++ {
+		fieldType := typ.Field(i)
+
+		// only consider exported fields
+		if fieldType.PkgPath != "" {
+			continue
+		}
+
+		tag := fieldType.Tag.Get("toml")
+
+		// special field name to skip field
+		if tag == "-" {
+			continue
+		}
+
+		f := v.Field(i)
+
+		if !isEmptyValue(f) {
+			return false
+		}
+	}
+
+	return true
+}
+
 const literalQuote = '\''
 
 func (enc *Encoder) encodeString(b []byte, v string, options valueOptions) []byte {
@@ -410,7 +453,6 @@ func (enc *Encoder) encodeLiteralString(b []byte, v string) []byte {
 	return b
 }
 
-//nolint:cyclop
 func (enc *Encoder) encodeQuotedString(multiline bool, b []byte, v string) []byte {
 	stringQuote := `"`
 
@@ -757,7 +799,13 @@ func (enc *Encoder) encodeTable(b []byte, ctx encoderCtx, t table) ([]byte, erro
 	}
 	ctx.skipTableHeader = false
 
+	hasNonEmptyKV := false
 	for _, kv := range t.kvs {
+		if shouldOmitEmpty(kv.Options, kv.Value) {
+			continue
+		}
+		hasNonEmptyKV = true
+
 		ctx.setKey(kv.Key)
 
 		b, err = enc.encodeKv(b, ctx, kv.Options, kv.Value)
@@ -768,7 +816,20 @@ func (enc *Encoder) encodeTable(b []byte, ctx encoderCtx, t table) ([]byte, erro
 		b = append(b, '\n')
 	}
 
+	first := true
 	for _, table := range t.tables {
+		if shouldOmitEmpty(table.Options, table.Value) {
+			continue
+		}
+		if first {
+			first = false
+			if hasNonEmptyKV {
+				b = append(b, '\n')
+			}
+		} else {
+			b = append(b, "\n"...)
+		}
+
 		ctx.setKey(table.Key)
 
 		ctx.options = table.Options
@@ -777,8 +838,6 @@ func (enc *Encoder) encodeTable(b []byte, ctx encoderCtx, t table) ([]byte, erro
 		if err != nil {
 			return nil, err
 		}
-
-		b = append(b, '\n')
 	}
 
 	return b, nil
@@ -791,6 +850,10 @@ func (enc *Encoder) encodeTableInline(b []byte, ctx encoderCtx, t table) ([]byte
 
 	first := true
 	for _, kv := range t.kvs {
+		if shouldOmitEmpty(kv.Options, kv.Value) {
+			continue
+		}
+
 		if first {
 			first = false
 		} else {
@@ -806,7 +869,7 @@ func (enc *Encoder) encodeTableInline(b []byte, ctx encoderCtx, t table) ([]byte
 	}
 
 	if len(t.tables) > 0 {
-		panic("inline table cannot contain nested tables, online key-values")
+		panic("inline table cannot contain nested tables, only key-values")
 	}
 
 	b = append(b, "}"...)
@@ -905,6 +968,10 @@ func (enc *Encoder) encodeSliceAsArrayTable(b []byte, ctx encoderCtx, v reflect.
 	b = enc.encodeComment(ctx.indent, ctx.options.comment, b)
 
 	for i := 0; i < v.Len(); i++ {
+		if i != 0 {
+			b = append(b, "\n"...)
+		}
+
 		b = append(b, scratch...)
 
 		var err error

marshaler_test.go

@@ -39,21 +39,21 @@ func TestMarshal(t *testing.T) {
 			v: map[string]string{
 				"hello": "world",
 			},
-			expected: "hello = 'world'",
+			expected: "hello = 'world'\n",
 		},
 		{
 			desc: "map with new line in key",
 			v: map[string]string{
 				"hel\nlo": "world",
 			},
-			expected: `"hel\nlo" = 'world'`,
+			expected: "\"hel\\nlo\" = 'world'\n",
 		},
 		{
 			desc: `map with " in key`,
 			v: map[string]string{
 				`hel"lo`: "world",
 			},
-			expected: `'hel"lo' = 'world'`,
+			expected: "'hel\"lo' = 'world'\n",
 		},
 		{
 			desc: "map in map and string",
@@ -62,9 +62,9 @@ func TestMarshal(t *testing.T) {
 					"hello": "world",
 				},
 			},
-			expected: `
-[table]
-hello = 'world'`,
+			expected: `[table]
+hello = 'world'
+`,
 		},
 		{
 			desc: "map in map in map and string",
@@ -75,10 +75,10 @@ hello = 'world'`,
 					},
 				},
 			},
-			expected: `
-[this]
+			expected: `[this]
 [this.is]
-a = 'test'`,
+a = 'test'
+`,
 		},
 		{
 			desc: "map in map in map and string with values",
@@ -90,18 +90,20 @@ a = 'test'`,
 					"also": "that",
 				},
 			},
-			expected: `
-[this]
+			expected: `[this]
 also = 'that'
+
 [this.is]
-a = 'test'`,
+a = 'test'
+`,
 		},
 		{
 			desc: "simple string array",
 			v: map[string][]string{
 				"array": {"one", "two", "three"},
 			},
-			expected: `array = ['one', 'two', 'three']`,
+			expected: `array = ['one', 'two', 'three']
+`,
 		},
 		{
 			desc:     "empty string array",
@@ -118,14 +120,16 @@ a = 'test'`,
 			v: map[string][][]string{
 				"array": {{"one", "two"}, {"three"}},
 			},
-			expected: `array = [['one', 'two'], ['three']]`,
+			expected: `array = [['one', 'two'], ['three']]
+`,
 		},
 		{
 			desc: "mixed strings and nested string arrays",
 			v: map[string][]interface{}{
 				"array": {"a string", []string{"one", "two"}, "last"},
 			},
-			expected: `array = ['a string', ['one', 'two'], 'last']`,
+			expected: `array = ['a string', ['one', 'two'], 'last']
+`,
 		},
 		{
 			desc: "array of maps",
@@ -135,9 +139,9 @@ a = 'test'`,
 					{"map2.1": "v2.1"},
 				},
 			},
-			expected: `
-[[top]]
+			expected: `[[top]]
 'map1.1' = 'v1.1'
+
 [[top]]
 'map2.1' = 'v2.1'
 `,
@@ -148,9 +152,9 @@ a = 'test'`,
 				"key1": "value1",
 				"key2": "value2",
 			},
-			expected: `
-key1 = 'value1'
-key2 = 'value2'`,
+			expected: `key1 = 'value1'
+key2 = 'value2'
+`,
 		},
 		{
 			desc: "simple struct",
@@ -159,7 +163,8 @@ key2 = 'value2'`,
 			}{
 				A: "foo",
 			},
-			expected: `A = 'foo'`,
+			expected: `A = 'foo'
+`,
 		},
 		{
 			desc: "one level of structs within structs",
@@ -174,8 +179,7 @@ key2 = 'value2'`,
 					K2: "v2",
 				},
 			},
-			expected: `
-[A]
+			expected: `[A]
 K1 = 'v1'
 K2 = 'v2'
 `,
@@ -190,10 +194,10 @@ K2 = 'v2'
 					},
 				},
 			},
-			expected: `
-[root]
+			expected: `[root]
 [[root.nested]]
 name = 'Bob'
+
 [[root.nested]]
 name = 'Alice'
 `,
@@ -203,49 +207,53 @@ name = 'Alice'
 			v: map[string]interface{}{
 				"a": "'\b\f\r\t\"\\",
 			},
-			expected: `a = "'\b\f\r\t\"\\"`,
+			expected: `a = "'\b\f\r\t\"\\"
+`,
 		},
 		{
 			desc: "string utf8 low",
 			v: map[string]interface{}{
 				"a": "'Ę",
 			},
-			expected: `a = "'Ę"`,
+			expected: `a = "'Ę"
+`,
 		},
 		{
 			desc: "string utf8 low 2",
 			v: map[string]interface{}{
 				"a": "'\u10A85",
 			},
-			expected: "a = \"'\u10A85\"",
+			expected: "a = \"'\u10A85\"\n",
 		},
 		{
 			desc: "string utf8 low 2",
 			v: map[string]interface{}{
 				"a": "'\u10A85",
 			},
-			expected: "a = \"'\u10A85\"",
+			expected: "a = \"'\u10A85\"\n",
 		},
 		{
 			desc: "emoji",
 			v: map[string]interface{}{
 				"a": "'😀",
 			},
-			expected: "a = \"'😀\"",
+			expected: "a = \"'😀\"\n",
 		},
 		{
 			desc: "control char",
 			v: map[string]interface{}{
 				"a": "'\u001A",
 			},
-			expected: `a = "'\u001A"`,
+			expected: `a = "'\u001A"
+`,
 		},
 		{
 			desc: "multi-line string",
 			v: map[string]interface{}{
 				"a": "hello\nworld",
 			},
-			expected: `a = "hello\nworld"`,
+			expected: `a = "hello\nworld"
+`,
 		},
 		{
 			desc: "multi-line forced",
@@ -256,7 +264,8 @@ name = 'Alice'
 			},
 			expected: `A = """
 hello
-world"""`,
+world"""
+`,
 		},
 		{
 			desc: "inline field",
@@ -271,8 +280,8 @@ world"""`,
 					"isinline": "no",
 				},
 			},
-			expected: `
-A = {isinline = 'yes'}
+			expected: `A = {isinline = 'yes'}
+
 [B]
 isinline = 'no'
 `,
@@ -286,8 +295,7 @@ isinline = 'no'
 				A: []int{1, 2, 3, 4},
 				B: []int{1, 2, 3, 4},
 			},
-			expected: `
-A = [
+			expected: `A = [
   1,
   2,
   3,
@@ -303,8 +311,7 @@ B = [1, 2, 3, 4]
 			}{
 				A: [][]int{{1, 2}, {3, 4}},
 			},
-			expected: `
-A = [
+			expected: `A = [
   [1, 2],
   [3, 4]
 ]
@@ -329,7 +336,8 @@ A = [
 			}{
 				A: []*int{nil},
 			},
-			expected: `A = [0]`,
+			expected: `A = [0]
+`,
 		},
 		{
 			desc: "nil pointer in slice uses zero value",
@@ -338,7 +346,8 @@ A = [
 			}{
 				A: []*int{nil},
 			},
-			expected: `A = [0]`,
+			expected: `A = [0]
+`,
 		},
 		{
 			desc: "pointer in slice",
@@ -347,7 +356,8 @@ A = [
 			}{
 				A: []*int{&someInt},
 			},
-			expected: `A = [42]`,
+			expected: `A = [42]
+`,
 		},
 		{
 			desc: "inline table in inline table",
@@ -358,23 +368,25 @@ A = [
 					},
 				},
 			},
-			expected: `A = {A = {A = 'hello'}}`,
+			expected: `A = {A = {A = 'hello'}}
+`,
 		},
 		{
 			desc: "empty slice in map",
 			v: map[string][]string{
 				"a": {},
 			},
-			expected: `a = []`,
+			expected: `a = []
+`,
 		},
 		{
 			desc: "map in slice",
 			v: map[string][]map[string]string{
 				"a": {{"hello": "world"}},
 			},
-			expected: `
-[[a]]
-hello = 'world'`,
+			expected: `[[a]]
+hello = 'world'
+`,
 		},
 		{
 			desc: "newline in map in slice",
@@ -382,7 +394,8 @@ hello = 'world'`,
 				"a\n": {{"hello": "world"}},
 			},
 			expected: `[["a\n"]]
-hello = 'world'`,
+hello = 'world'
+`,
 		},
 		{
 			desc: "newline in map in slice",
@@ -398,7 +411,8 @@ hello = 'world'`,
 			}{
 				A: []struct{}{},
 			},
-			expected: `A = []`,
+			expected: `A = []
+`,
 		},
 		{
 			desc: "nil field is ignored",
@@ -418,7 +432,8 @@ hello = 'world'`,
 				Public:  "shown",
 				private: "hidden",
 			},
-			expected: `Public = 'shown'`,
+			expected: `Public = 'shown'
+`,
 		},
 		{
 			desc: "fields tagged - are ignored",
@@ -442,7 +457,8 @@ hello = 'world'`,
 			v: map[string]interface{}{
 				"hello\nworld": 42,
 			},
-			expected: `"hello\nworld" = 42`,
+			expected: `"hello\nworld" = 42
+`,
 		},
 		{
 			desc: "new line in parent of nested table key",
@@ -452,7 +468,8 @@ hello = 'world'`,
 				},
 			},
 			expected: `["hello\nworld"]
-inner = 42`,
+inner = 42
+`,
 		},
 		{
 			desc: "new line in nested table key",
@@ -465,7 +482,8 @@ inner = 42`,
 			},
 			expected: `[parent]
 [parent."in\ner"]
-foo = 42`,
+foo = 42
+`,
 		},
 		{
 			desc: "invalid map key",
@@ -488,7 +506,8 @@ foo = 42`,
 			}{
 				T: time.Time{},
 			},
-			expected: `T = 0001-01-01T00:00:00Z`,
+			expected: `T = 0001-01-01T00:00:00Z
+`,
 		},
 		{
 			desc: "time nano",
@@ -497,7 +516,8 @@ foo = 42`,
 			}{
 				T: time.Date(1979, time.May, 27, 0, 32, 0, 999999000, time.UTC),
 			},
-			expected: `T = 1979-05-27T00:32:00.999999Z`,
+			expected: `T = 1979-05-27T00:32:00.999999Z
+`,
 		},
 		{
 			desc: "bool",
@@ -508,9 +528,9 @@ foo = 42`,
 				A: false,
 				B: true,
 			},
-			expected: `
-A = false
-B = true`,
+			expected: `A = false
+B = true
+`,
 		},
 		{
 			desc: "numbers",
@@ -541,8 +561,7 @@ B = true`,
 				K: 42,
 				L: 2.2,
 			},
-			expected: `
-A = 1.1
+			expected: `A = 1.1
 B = 42
 C = 42
 D = 42
@@ -553,7 +572,8 @@ H = 42
 I = 42
 J = 42
 K = 42
-L = 2.2`,
+L = 2.2
+`,
 		},
 		{
 			desc: "comments",
@@ -566,8 +586,7 @@ L = 2.2`,
 					Three: []int{1, 2, 3},
 				},
 			},
-			expected: `
-# Before table
+			expected: `# Before table
 [Table]
 One = 1
 # Before kv
@@ -589,7 +608,7 @@ Three = [1, 2, 3]
 			}
 
 			require.NoError(t, err)
-			equalStringsIgnoreNewlines(t, e.expected, string(b))
+			assert.Equal(t, e.expected, string(b))
 
 			// make sure the output is always valid TOML
 			defaultMap := map[string]interface{}{}
@@ -664,12 +683,6 @@ func testWithFlags(t *testing.T, flags int, setters flagsSetters, testfn func(t
 	}
 }
 
-func equalStringsIgnoreNewlines(t *testing.T, expected string, actual string) {
-	t.Helper()
-	cutset := "\n"
-	assert.Equal(t, strings.Trim(expected, cutset), strings.Trim(actual, cutset))
-}
-
 func TestMarshalFloats(t *testing.T) {
 	v := map[string]float32{
 		"nan":  float32(math.NaN()),
@@ -709,7 +722,8 @@ func TestMarshalIndentTables(t *testing.T) {
 			v: map[string]interface{}{
 				"foo": "bar",
 			},
-			expected: `foo = 'bar'`,
+			expected: `foo = 'bar'
+`,
 		},
 		{
 			desc: "one level table",
@@ -719,8 +733,7 @@ func TestMarshalIndentTables(t *testing.T) {
 					"two": "value2",
 				},
 			},
-			expected: `
-[foo]
+			expected: `[foo]
   one = 'value1'
   two = 'value2'
 `,
@@ -736,10 +749,11 @@ func TestMarshalIndentTables(t *testing.T) {
 					},
 				},
 			},
-			expected: `
-root = 'value0'
+			expected: `root = 'value0'
+
 [level1]
   one = 'value1'
+
   [level1.level2]
     two = 'value2'
 `,
@@ -754,7 +768,7 @@ root = 'value0'
 			enc.SetIndentTables(true)
 			err := enc.Encode(e.v)
 			require.NoError(t, err)
-			equalStringsIgnoreNewlines(t, e.expected, buf.String())
+			assert.Equal(t, e.expected, buf.String())
 		})
 	}
 }
@@ -799,7 +813,7 @@ func TestMarshalTextMarshaler(t *testing.T) {
 	m := map[string]interface{}{"a": &customTextMarshaler{value: 2}}
 	r, err := toml.Marshal(m)
 	require.NoError(t, err)
-	equalStringsIgnoreNewlines(t, "a = '::2'", string(r))
+	assert.Equal(t, "a = '::2'\n", string(r))
 }
 
 type brokenWriter struct{}
@@ -822,10 +836,10 @@ func TestEncoderSetIndentSymbol(t *testing.T) {
 	enc.SetIndentSymbol(">>>")
 	err := enc.Encode(map[string]map[string]string{"parent": {"hello": "world"}})
 	require.NoError(t, err)
-	expected := `
-[parent]
->>>hello = 'world'`
-	equalStringsIgnoreNewlines(t, expected, w.String())
+	expected := `[parent]
+>>>hello = 'world'
+`
+	assert.Equal(t, expected, w.String())
 }
 
 func TestEncoderOmitempty(t *testing.T) {
@@ -856,9 +870,9 @@ func TestEncoderOmitempty(t *testing.T) {
 	b, err := toml.Marshal(d)
 	require.NoError(t, err)
 
-	expected := `[Struct]`
+	expected := ``
 
-	equalStringsIgnoreNewlines(t, expected, string(b))
+	assert.Equal(t, expected, string(b))
 }
 
 func TestEncoderTagFieldName(t *testing.T) {
@@ -873,13 +887,12 @@ func TestEncoderTagFieldName(t *testing.T) {
 	b, err := toml.Marshal(d)
 	require.NoError(t, err)
 
-	expected := `
-hello = 'world'
+	expected := `hello = 'world'
 '#' = ''
 Bad = ''
 `
 
-	equalStringsIgnoreNewlines(t, expected, string(b))
+	assert.Equal(t, expected, string(b))
 }
 
 func TestIssue436(t *testing.T) {
@@ -893,12 +906,11 @@ func TestIssue436(t *testing.T) {
 	err = toml.NewEncoder(&buf).Encode(v)
 	require.NoError(t, err)
 
-	expected := `
-[[a]]
+	expected := `[[a]]
 [a.b]
 c = 'd'
 `
-	equalStringsIgnoreNewlines(t, expected, buf.String())
+	assert.Equal(t, expected, buf.String())
 }
 
 func TestIssue424(t *testing.T) {
@@ -980,7 +992,7 @@ func TestIssue678(t *testing.T) {
 
 	out, err := toml.Marshal(cfg)
 	require.NoError(t, err)
-	equalStringsIgnoreNewlines(t, "BigInt = '123'", string(out))
+	assert.Equal(t, "BigInt = '123'\n", string(out))
 
 	cfg2 := &Config{}
 	err = toml.Unmarshal(out, cfg2)
@@ -1020,6 +1032,69 @@ Name = ''
 	require.Equal(t, expected, string(out))
 }
 
+func TestIssue786(t *testing.T) {
+	type Dependencies struct {
+		Dependencies         []string `toml:"dependencies,multiline,omitempty"`
+		BuildDependencies    []string `toml:"buildDependencies,multiline,omitempty"`
+		OptionalDependencies []string `toml:"optionalDependencies,multiline,omitempty"`
+	}
+
+	type Test struct {
+		Dependencies Dependencies `toml:"dependencies,omitempty"`
+	}
+
+	x := Test{}
+	b, err := toml.Marshal(x)
+	require.NoError(t, err)
+
+	require.Equal(t, "", string(b))
+
+	type General struct {
+		From      string `toml:"from,omitempty" json:"from,omitempty" comment:"from in graphite-web format, the local TZ is used"`
+		Randomize bool   `toml:"randomize" json:"randomize" comment:"randomize starting time with [0,step)"`
+	}
+
+	type Custom struct {
+		Name string `toml:"name" json:"name,omitempty" comment:"names for generator, braces are expanded like in shell"`
+		Type string `toml:"type,omitempty" json:"type,omitempty" comment:"type of generator"`
+		General
+	}
+	type Config struct {
+		General
+		Custom []Custom `toml:"custom,omitempty" json:"custom,omitempty" comment:"generators with custom parameters can be specified separately"`
+	}
+
+	buf := new(bytes.Buffer)
+	config := &Config{General: General{From: "-2d", Randomize: true}}
+	config.Custom = []Custom{{Name: "omit", General: General{Randomize: false}}}
+	config.Custom = append(config.Custom, Custom{Name: "present", General: General{From: "-2d", Randomize: true}})
+	encoder := toml.NewEncoder(buf)
+	encoder.Encode(config)
+
+	expected := `# from in graphite-web format, the local TZ is used
+from = '-2d'
+# randomize starting time with [0,step)
+randomize = true
+
+# generators with custom parameters can be specified separately
+[[custom]]
+# names for generator, braces are expanded like in shell
+name = 'omit'
+# randomize starting time with [0,step)
+randomize = false
+
+[[custom]]
+# names for generator, braces are expanded like in shell
+name = 'present'
+# from in graphite-web format, the local TZ is used
+from = '-2d'
+# randomize starting time with [0,step)
+randomize = true
+`
+
+	require.Equal(t, expected, buf.String())
+}
+
 func TestMarshalNestedAnonymousStructs(t *testing.T) {
 	type Embedded struct {
 		Value string `toml:"value" json:"value"`
@@ -1041,6 +1116,7 @@ func TestMarshalNestedAnonymousStructs(t *testing.T) {
 	}
 
 	expected := `value = ''
+
 [top]
 value = ''
 
@@ -1049,7 +1125,6 @@ value = ''
 
 [anonymous]
 value = ''
-
 `
 
 	result, err := toml.Marshal(doc)
@@ -1073,9 +1148,9 @@ func TestMarshalNestedAnonymousStructs_DuplicateField(t *testing.T) {
 	doc.Value = "shadows"
 
 	expected := `value = 'shadows'
+
 [top]
 value = ''
-
 `
 
 	result, err := toml.Marshal(doc)
@@ -1086,7 +1161,7 @@ value = ''
 
 func TestLocalTime(t *testing.T) {
 	v := map[string]toml.LocalTime{
-		"a": toml.LocalTime{
+		"a": {
 			Hour:       1,
 			Minute:     2,
 			Second:     3,

unmarshaler.go

@@ -79,7 +79,7 @@ func (d *Decoder) DisallowUnknownFields() *Decoder {
 // strict mode and a field is missing, a `toml.StrictMissingError` is
 // returned. In any other case, this function returns a standard Go error.
 //
-// Type mapping
+// # Type mapping
 //
 // List of supported TOML types and their associated accepted Go types:
 //
@@ -344,9 +344,9 @@ func (d *decoder) handleArrayTableCollectionLast(key ast.Iterator, v reflect.Val
 		elem := v.Index(idx)
 		_, err := d.handleArrayTable(key, elem)
 		return v, err
+	default:
+		return reflect.Value{}, fmt.Errorf("toml: cannot decode array table into a %s", v.Type())
 	}
-
-	return d.handleArrayTable(key, v)
 }
 
 // When parsing an array table expression, each part of the key needs to be

unmarshaler_test.go

@@ -1735,6 +1735,28 @@ B = "data"`,
 				}
 			},
 		},
+		{
+			desc:  "kv that points to a slice",
+			input: "a.b.c = 'foo'",
+			gen: func() test {
+				doc := map[string][]string{}
+				return test{
+					target: &doc,
+					err:    true,
+				}
+			},
+		},
+		{
+			desc:  "kv that points to a pointer to a slice",
+			input: "a.b.c = 'foo'",
+			gen: func() test {
+				doc := map[string]*[]string{}
+				return test{
+					target: &doc,
+					err:    true,
+				}
+			},
+		},
 	}
 
 	for _, e := range examples {
@@ -1876,8 +1898,7 @@ key2 = "missing2"
 key3 = "missing3"
 key4 = "value4"
 `,
-			expected: `
-2| key1 = "value1"
+			expected: `2| key1 = "value1"
 3| key2 = "missing2"
  | ~~~~ missing field
 4| key3 = "missing3"
@@ -1887,8 +1908,7 @@ key4 = "value4"
 3| key2 = "missing2"
 4| key3 = "missing3"
  | ~~~~ missing field
-5| key4 = "value4"
-`,
+5| key4 = "value4"`,
 			target: &struct {
 				Key1 string
 				Key4 string
@@ -1897,10 +1917,8 @@ key4 = "value4"
 		{
 			desc:  "multi-part key",
 			input: `a.short.key="foo"`,
-			expected: `
-1| a.short.key="foo"
- | ~~~~~~~~~~~ missing field
-`,
+			expected: `1| a.short.key="foo"
+ | ~~~~~~~~~~~ missing field`,
 		},
 		{
 			desc: "missing table",
@@ -1908,24 +1926,19 @@ key4 = "value4"
 [foo]
 bar = 42
 `,
-			expected: `
-2| [foo]
+			expected: `2| [foo]
  |  ~~~ missing table
-3| bar = 42
-`,
+3| bar = 42`,
 		},
 
 		{
 			desc: "missing array table",
 			input: `
 [[foo]]
-bar = 42
-`,
-			expected: `
-2| [[foo]]
+bar = 42`,
+			expected: `2| [[foo]]
  |   ~~~ missing table
-3| bar = 42
-`,
+3| bar = 42`,
 		},
 	}
 
@@ -1944,7 +1957,7 @@ bar = 42
 
 				var tsm *toml.StrictMissingError
 				if errors.As(err, &tsm) {
-					equalStringsIgnoreNewlines(t, e.expected, tsm.String())
+					assert.Equal(t, e.expected, tsm.String())
 				} else {
 					t.Fatalf("err should have been a *toml.StrictMissingError, but got %s (%T)", err, err)
 				}
@@ -2417,12 +2430,27 @@ func TestIssue774(t *testing.T) {
 	expected := `# Array of Secure Copy Configurations
 [[scp]]
 Host = 'main.domain.com'
-
 `
 
 	require.Equal(t, expected, string(b))
 }
 
+func TestIssue799(t *testing.T) {
+	const testTOML = `
+# notice the double brackets
+[[test]]
+answer = 42
+`
+
+	var s struct {
+		// should be []map[string]int
+		Test map[string]int `toml:"test"`
+	}
+
+	err := toml.Unmarshal([]byte(testTOML), &s)
+	require.Error(t, err)
+}
+
 func TestUnmarshalDecodeErrors(t *testing.T) {
 	examples := []struct {
 		desc string
@@ -2874,6 +2902,36 @@ world'`,
 	}
 }
 
+func TestOmitEmpty(t *testing.T) {
+	type inner struct {
+		private string
+		Skip    string `toml:"-"`
+		V       string
+	}
+
+	type elem struct {
+		Foo   string `toml:",omitempty"`
+		Bar   string `toml:",omitempty"`
+		Inner inner  `toml:",omitempty"`
+	}
+
+	type doc struct {
+		X []elem `toml:",inline"`
+	}
+
+	d := doc{X: []elem{elem{
+		Foo: "test",
+		Inner: inner{
+			V: "alue",
+		},
+	}}}
+
+	b, err := toml.Marshal(d)
+	require.NoError(t, err)
+
+	require.Equal(t, "X = [{Foo = 'test', Inner = {V = 'alue'}}]\n", string(b))
+}
+
 func TestUnmarshalTags(t *testing.T) {
 	type doc struct {
 		Dash   string `toml:"-,"`