Use Unicode 12.0.0 grapheme cluster segmentation rules

HCL uses grapheme cluster segmentation to produce accurate "column"
indications in diagnostic messages and other human-oriented source
location information. Each new major version of Unicode introduces new
codepoints, some of which are defined to combine with other codepoints to
produce a single visible character (grapheme cluster).

We were previously using the rules from Unicode 9.0.0. This change
switches to using the segmentation rules from Unicode 12.0.0, which is
the latest version at the time of this commit and is also the version of
Unicode used for other purposes by the Go 1.14 runtime.

HCL does not use text segmentation results for any purpose that would
affect the meaning of decoded data extracted from HCL files, so this
change will only affect the human-oriented source positions generated for
files containing characters that were newly-introduced in Unicode 10, 11,
or 12. (Machine-oriented uses of source location information are based on
byte offsets and not affected by text segmentation.)

go.mod

@@ -1,9 +1,11 @@
 module github.com/hashicorp/hcl/v2
 
+go 1.12
+
 require (
 	github.com/agext/levenshtein v1.2.1
 	github.com/apparentlymart/go-dump v0.0.0-20180507223929-23540a00eaa3
-	github.com/apparentlymart/go-textseg v1.0.0
+	github.com/apparentlymart/go-textseg/v12 v12.0.0
 	github.com/davecgh/go-spew v1.1.1
 	github.com/go-test/deep v1.0.3
 	github.com/google/go-cmp v0.3.1

go.sum

@@ -4,6 +4,8 @@ github.com/apparentlymart/go-dump v0.0.0-20180507223929-23540a00eaa3 h1:ZSTrOEhi
 github.com/apparentlymart/go-dump v0.0.0-20180507223929-23540a00eaa3/go.mod h1:oL81AME2rN47vu18xqj1S1jPIPuN7afo62yKTNn3XMM=
 github.com/apparentlymart/go-textseg v1.0.0 h1:rRmlIsPEEhUTIKQb7T++Nz/A5Q6C9IuX2wFoYVvnCs0=
 github.com/apparentlymart/go-textseg v1.0.0/go.mod h1:z96Txxhf3xSFMPmb5X/1W05FF/Nj9VFpLOpjS5yuumk=
+github.com/apparentlymart/go-textseg/v12 v12.0.0 h1:bNEQyAGak9tojivJNkoqWErVCQbjdL7GzRt3F8NvfJ0=
+github.com/apparentlymart/go-textseg/v12 v12.0.0/go.mod h1:S/4uRK2UtaQttw1GenVJEynmyUenKwP++x/+DdGV/Ec=
 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/go-test/deep v1.0.3 h1:ZrJSEWsXzPOxaZnFteGEfooLba+ju3FYIbOrS+rQd68=

hclsyntax/parser.go

@@ -6,7 +6,7 @@ import (
 	"strconv"
 	"unicode/utf8"
 
-	"github.com/apparentlymart/go-textseg/textseg"
+	"github.com/apparentlymart/go-textseg/v12/textseg"
 	"github.com/hashicorp/hcl/v2"
 	"github.com/zclconf/go-cty/cty"
 )

hclsyntax/parser_template.go

@@ -5,7 +5,7 @@ import (
 	"strings"
 	"unicode"
 
-	"github.com/apparentlymart/go-textseg/textseg"
+	"github.com/apparentlymart/go-textseg/v12/textseg"
 	"github.com/hashicorp/hcl/v2"
 	"github.com/zclconf/go-cty/cty"
 )

hclsyntax/token.go

@@ -4,7 +4,7 @@ import (
 	"bytes"
 	"fmt"
 
-	"github.com/apparentlymart/go-textseg/textseg"
+	"github.com/apparentlymart/go-textseg/v12/textseg"
 	"github.com/hashicorp/hcl/v2"
 )
 

hclwrite/tokens.go

@@ -4,7 +4,7 @@ import (
 	"bytes"
 	"io"
 
-	"github.com/apparentlymart/go-textseg/textseg"
+	"github.com/apparentlymart/go-textseg/v12/textseg"
 	"github.com/hashicorp/hcl/v2"
 	"github.com/hashicorp/hcl/v2/hclsyntax"
 )

json/scanner.go

@@ -3,7 +3,7 @@ package json
 import (
 	"fmt"
 
-	"github.com/apparentlymart/go-textseg/textseg"
+	"github.com/apparentlymart/go-textseg/v12/textseg"
 	"github.com/hashicorp/hcl/v2"
 )
 

pos_scanner.go

@@ -4,7 +4,7 @@ import (
 	"bufio"
 	"bytes"
 
-	"github.com/apparentlymart/go-textseg/textseg"
+	"github.com/apparentlymart/go-textseg/v12/textseg"
 )
 
 // RangeScanner is a helper that will scan over a buffer using a bufio.SplitFunc