Switch to go-toml v2

We have been using `go-toml` for language files only. This commit makes it the only TOML library.

It's spec compliant and very fast.

A benchark building a site with 200 pages with TOML front matter:

```bash
name                                  old time/op    new time/op    delta
SiteNew/Regular_TOML_front_matter-16    48.5ms ± 1%    47.1ms ± 1%  -2.85%  (p=0.029 n=4+4)

name                                  old alloc/op   new alloc/op   delta
SiteNew/Regular_TOML_front_matter-16    16.9MB ± 0%    16.7MB ± 0%  -1.56%  (p=0.029 n=4+4)

name                                  old allocs/op  new allocs/op  delta
SiteNew/Regular_TOML_front_matter-16      302k ± 0%      296k ± 0%  -2.20%  (p=0.029 n=4+4)
```

Note that the front matter unmarshaling is only a small part of building a site, so the above is very good.

Fixes #8801

12 files changed, 50 insertions, 40 deletions

diff --git a/commands/commands_test.go b/commands/commands_test.go
index 99ffea48c..ef61dc7a5 100644
--- a/commands/commands_test.go
+++ b/commands/commands_test.go
@@ -121,7 +121,7 @@ func TestExecute(t *testing.T) {
 		resp := Execute([]string{"new", "site", siteDir, "-e=staging"})
 		c.Assert(resp.Err, qt.IsNil)
 		config := readFileFrom(c, filepath.Join(siteDir, "config.toml"))
-		c.Assert(config, qt.Contains, "baseURL = \"http://example.org/\"")
+		c.Assert(config, qt.Contains, "baseURL = 'http://example.org/'")
 		checkNewSiteInited(c, siteDir)
 	})
 }
diff --git a/common/herrors/file_error_test.go b/common/herrors/file_error_test.go
index 4b42f8f39..675be94e8 100644
--- a/common/herrors/file_error_test.go
+++ b/common/herrors/file_error_test.go
@@ -36,7 +36,6 @@ func TestToLineNumberError(t *testing.T) {
 		{errors.New(`template: _default/single.html:4:15: executing "_default/single.html" at <.Titles>: can't evaluate field Titles in type *hugolib.PageOutput`), 0, 4, 15},
 		{errors.New("parse failed: template: _default/bundle-resource-meta.html:11: unexpected in operand"), 0, 11, 1},
 		{errors.New(`failed:: template: _default/bundle-resource-meta.html:2:7: executing "main" at <.Titles>`), 0, 2, 7},
-		{errors.New("error in front matter: Near line 32 (last key parsed 'title')"), 0, 32, 1},
 		{errors.New(`failed to load translations: (6, 7): was expecting token =, but got "g" instead`), 0, 6, 7},
 	} {
 
diff --git a/common/herrors/line_number_extractors.go b/common/herrors/line_number_extractors.go
index 13e94614d..3df62bdfe 100644
--- a/common/herrors/line_number_extractors.go
+++ b/common/herrors/line_number_extractors.go
@@ -16,6 +16,10 @@ package herrors
 import (
 	"regexp"
 	"strconv"
+
+	"github.com/pkg/errors"
+
+	"github.com/pelletier/go-toml/v2"
 )
 
 var lineNumberExtractors = []lineNumberExtractor{
@@ -24,8 +28,7 @@ var lineNumberExtractors = []lineNumberExtractor{
 	newLineNumberErrHandlerFromRegexp(".*:(\\d+):"),
 
 	// TOML parse errors
-	newLineNumberErrHandlerFromRegexp(".*Near line (\\d+)(\\s.*)"),
-
+	tomlLineNumberExtractor,
 	// YAML parse errors
 	newLineNumberErrHandlerFromRegexp("line (\\d+):"),
 
@@ -35,6 +38,14 @@ var lineNumberExtractors = []lineNumberExtractor{
 
 type lineNumberExtractor func(e error) (int, int)
 
+var tomlLineNumberExtractor = func(e error) (int, int) {
+	e = errors.Cause(e)
+	if terr, ok := e.(*toml.DecodeError); ok {
+		return terr.Position()
+	}
+	return -1, -1
+}
+
 func newLineNumberErrHandlerFromRegexp(expression string) lineNumberExtractor {
 	re := regexp.MustCompile(expression)
 	return extractLineNo(re)
diff --git a/go.mod b/go.mod
index 219e9d64d..a04655eec 100644
--- a/go.mod
+++ b/go.mod
@@ -2,7 +2,6 @@ module github.com/gohugoio/hugo
 
 require (
 	github.com/BurntSushi/locker v0.0.0-20171006230638-a6e239ea1c69
-	github.com/BurntSushi/toml v0.3.1
 	github.com/PuerkitoBio/purell v1.1.1
 	github.com/PuerkitoBio/urlesc v0.0.0-20170810143723-de5bf2ad4578 // indirect
 	github.com/alecthomas/chroma v0.9.2
@@ -44,7 +43,7 @@ require (
 	github.com/nfnt/resize v0.0.0-20180221191011-83c6a9932646 // indirect
 	github.com/niklasfasching/go-org v1.5.0
 	github.com/olekukonko/tablewriter v0.0.5
-	github.com/pelletier/go-toml v1.9.3
+	github.com/pelletier/go-toml/v2 v2.0.0-beta.3
 	github.com/pkg/errors v0.9.1
 	github.com/rogpeppe/go-internal v1.8.0
 	github.com/russross/blackfriday v1.5.3-0.20200218234912-41c5fccfd6f6
diff --git a/go.sum b/go.sum
index 3eb5bd4c3..b38926d9d 100644
--- a/go.sum
+++ b/go.sum
@@ -433,6 +433,8 @@ github.com/olekukonko/tablewriter v0.0.5/go.mod h1:hPp6KlRPjbx+hW8ykQs1w3UBbZlj6
 github.com/pascaldekloe/goe v0.0.0-20180627143212-57f6aae5913c/go.mod h1:lzWF7FIEvWOWxwDKqyGYQf6ZUaNfKdP144TG7ZOy1lc=
 github.com/pelletier/go-toml v1.9.3 h1:zeC5b1GviRUyKYd6OJPvBU/mcVDVoL1OhT17FCt5dSQ=
 github.com/pelletier/go-toml v1.9.3/go.mod h1:u1nR/EPcESfeI/szUZKdtJ0xRNbUoANCkoOuaOx1Y+c=
+github.com/pelletier/go-toml/v2 v2.0.0-beta.3 h1:PNCTU4naEJ8mKal97P3A2qDU74QRQGlv4FXiL1XDqi4=
+github.com/pelletier/go-toml/v2 v2.0.0-beta.3/go.mod h1:aNseLYu/uKskg0zpr/kbr2z8yGuWtotWf/0BpGIAL2Y=
 github.com/pkg/diff v0.0.0-20210226163009-20ebb0f2a09e/go.mod h1:pJLUxLENpZxwdsKMEsNbx1VGcRFpLqf3715MtcvvzbA=
 github.com/pkg/errors v0.8.0/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
 github.com/pkg/errors v0.8.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
@@ -490,8 +492,9 @@ github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UV
 github.com/stretchr/testify v1.4.0/go.mod h1:j7eGeouHqKxXV5pUuKE4zz7dFj8WfuZ+81PSLYec5m4=
 github.com/stretchr/testify v1.5.1/go.mod h1:5W2xD1RspED5o8YsWQXVCued0rvSQ+mT+I5cxcmMvtA=
 github.com/stretchr/testify v1.6.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
-github.com/stretchr/testify v1.7.0 h1:nwc3DEeHmmLAfoZucVR881uASk0Mfjw8xYJ99tb5CcY=
 github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
+github.com/stretchr/testify v1.7.1-0.20210427113832-6241f9ab9942 h1:t0lM6y/M5IiUZyvbBTcngso8SZEZICH7is9B6g/obVU=
+github.com/stretchr/testify v1.7.1-0.20210427113832-6241f9ab9942/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
 github.com/subosito/gotenv v1.2.0 h1:Slr1R9HxAlEKefgq5jn9U+DnETlIUa6HfgEzj0g5d7s=
 github.com/subosito/gotenv v1.2.0/go.mod h1:N0PQaV/YGNqwC0u51sEeR/aUtSLEXKX9iv69rRypqCw=
 github.com/tdewolff/minify/v2 v2.9.20 h1:Fut7w3T7nWfDOb/bOgyEvshQRRMt+xzi1T7spEEKXDw=
diff --git a/hugolib/config_test.go b/hugolib/config_test.go
index 575931975..bda1c7fb5 100644
--- a/hugolib/config_test.go
+++ b/hugolib/config_test.go
@@ -287,13 +287,13 @@ name = "menu-theme"
 					"pl1": "p1-en-main",
 				},
 				"menus": maps.Params{
-					"main": []map[string]interface{}{
-						{
+					"main": []interface{}{
+						map[string]interface{}{
 							"name": "menu-lang-en-main",
 						},
 					},
-					"theme": []map[string]interface{}{
-						{
+					"theme": []interface{}{
+						map[string]interface{}{
 							"name": "menu-lang-en-theme",
 						},
 					},
@@ -307,18 +307,18 @@ name = "menu-theme"
 					"pl2": "p2-nb-theme",
 				},
 				"menus": maps.Params{
-					"main": []map[string]interface{}{
-						{
+					"main": []interface{}{
+						map[string]interface{}{
 							"name": "menu-lang-nb-main",
 						},
 					},
-					"theme": []map[string]interface{}{
-						{
+					"theme": []interface{}{
+						map[string]interface{}{
 							"name": "menu-lang-nb-theme",
 						},
 					},
-					"top": []map[string]interface{}{
-						{
+					"top": []interface{}{
+						map[string]interface{}{
 							"name": "menu-lang-nb-top",
 						},
 					},
@@ -393,8 +393,8 @@ name   = "menu-theme"
 				"en": maps.Params{
 					"languagename": "English",
 					"menus": maps.Params{
-						"main": []map[string]interface{}{
-							{
+						"main": []interface{}{
+							map[string]interface{}{
 								"name": "menu-theme",
 							},
 						},
diff --git a/hugolib/configdir_test.go b/hugolib/configdir_test.go
index aa1013ec0..b3fc71e58 100644
--- a/hugolib/configdir_test.go
+++ b/hugolib/configdir_test.go
@@ -119,10 +119,10 @@ p3 = "p3params_no_production"
 	c.Assert(cfg.GetString("params.p3"), qt.Equals, "p3params_development")
 	c.Assert(cfg.GetString("languages.no.params.p3"), qt.Equals, "p3params_no_development")
 
-	c.Assert(len(cfg.Get("menus.docs").(([]map[string]interface{}))), qt.Equals, 2)
+	c.Assert(len(cfg.Get("menus.docs").([]interface{})), qt.Equals, 2)
 	noMenus := cfg.Get("languages.no.menus.docs")
 	c.Assert(noMenus, qt.Not(qt.IsNil))
-	c.Assert(len(noMenus.(([]map[string]interface{}))), qt.Equals, 1)
+	c.Assert(len(noMenus.([]interface{})), qt.Equals, 1)
 }
 
 func TestLoadConfigDirError(t *testing.T) {
diff --git a/langs/i18n/translationProvider.go b/langs/i18n/translationProvider.go
index c66505817..e8bfbf6f1 100644
--- a/langs/i18n/translationProvider.go
+++ b/langs/i18n/translationProvider.go
@@ -25,7 +25,7 @@ import (
 
 	"github.com/gohugoio/go-i18n/v2/i18n"
 	"github.com/gohugoio/hugo/helpers"
-	toml "github.com/pelletier/go-toml"
+	toml "github.com/pelletier/go-toml/v2"
 
 	"github.com/gohugoio/hugo/deps"
 	"github.com/gohugoio/hugo/hugofs"
diff --git a/parser/frontmatter.go b/parser/frontmatter.go
index 4965d3fe8..e7492745e 100644
--- a/parser/frontmatter.go
+++ b/parser/frontmatter.go
@@ -20,7 +20,7 @@ import (
 
 	"github.com/gohugoio/hugo/parser/metadecoders"
 
-	"github.com/BurntSushi/toml"
+	toml "github.com/pelletier/go-toml/v2"
 
 	yaml "gopkg.in/yaml.v2"
 )
diff --git a/parser/frontmatter_test.go b/parser/frontmatter_test.go
index 9d9b7c3b8..dfbc695d8 100644
--- a/parser/frontmatter_test.go
+++ b/parser/frontmatter_test.go
@@ -31,9 +31,9 @@ func TestInterfaceToConfig(t *testing.T) {
 		// TOML
 		{map[string]interface{}{}, metadecoders.TOML, nil, false},
 		{
-			map[string]interface{}{"title": "test 1"},
+			map[string]interface{}{"title": "test' 1"},
 			metadecoders.TOML,
-			[]byte("title = \"test 1\"\n"),
+			[]byte("title = \"test' 1\"\n"),
 			false,
 		},
 
diff --git a/parser/metadecoders/decoder.go b/parser/metadecoders/decoder.go
index 131d6f39b..168c130ed 100644
--- a/parser/metadecoders/decoder.go
+++ b/parser/metadecoders/decoder.go
@@ -24,7 +24,7 @@ import (
 	"github.com/gohugoio/hugo/common/herrors"
 	"github.com/niklasfasching/go-org/org"
 
-	"github.com/BurntSushi/toml"
+	toml "github.com/pelletier/go-toml/v2"
 	"github.com/pkg/errors"
 	"github.com/spf13/afero"
 	"github.com/spf13/cast"
diff --git a/tpl/transform/remarshal_test.go b/tpl/transform/remarshal_test.go
index 9f3e05e61..c34122a2a 100644
--- a/tpl/transform/remarshal_test.go
+++ b/tpl/transform/remarshal_test.go
@@ -30,20 +30,20 @@ func TestRemarshal(t *testing.T) {
 	ns := New(newDeps(v))
 	c := qt.New(t)
 
-	tomlExample := `title = "Test Metadata"
+	tomlExample := `title = 'Test Metadata'
 		
 [[resources]]
-  src = "**image-4.png"
-  title = "The Fourth Image!"
+  src = '**image-4.png'
+  title = 'The Fourth Image!'
   [resources.params]
-    byline = "picasso"
+    byline = 'picasso'
 
 [[resources]]
-  name = "my-cool-image-:counter"
-  src = "**.png"
-  title = "TOML: The Image #:counter"
+  name = 'my-cool-image-:counter'
+  src = '**.png'
+  title = 'TOML: The Image #:counter'
   [resources.params]
-    byline = "bep"
+    byline = 'bep'
 `
 
 	yamlExample := `resources:
@@ -129,11 +129,9 @@ a = "b"
 
 `
 
-	expected := `
-Hugo = "Rules"
-		
+	expected := `Hugo = 'Rules'
 [m]
-  a = "b"
+a = 'b'
 `
 
 	for _, format := range []string{"json", "yaml", "toml"} {
@@ -149,7 +147,7 @@ Hugo = "Rules"
 
 		diff := htesting.DiffStrings(expected, converted)
 		if len(diff) > 0 {
-			t.Fatalf("[%s] Expected \n%v\ngot\n%v\ndiff:\n%v\n", fromTo, expected, converted, diff)
+			t.Fatalf("[%s] Expected \n%v\ngot\n>>%v\ndiff:\n%v\n", fromTo, expected, converted, diff)
 		}
 	}
 }
@@ -182,5 +180,5 @@ func TestTestRemarshalMapInput(t *testing.T) {
 
 	output, err := ns.Remarshal("toml", input)
 	c.Assert(err, qt.IsNil)
-	c.Assert(output, qt.Equals, "hello = \"world\"\n")
+	c.Assert(output, qt.Equals, "hello = 'world'\n")
 }