vendor: update github.com/hashicorp/hcl2

This includes a fix to hcl.RelTraversalForExpr where it would
inadvertantly modify the internals of a traversal AST node as part of
relativizing the traversal in order to return it.

go.mod

@@ -71,7 +71,7 @@ require (
 	github.com/hashicorp/go-version v1.0.0
 	github.com/hashicorp/golang-lru v0.5.0 // indirect
 	github.com/hashicorp/hcl v0.0.0-20170504190234-a4b07c25de5f
-	github.com/hashicorp/hcl2 v0.0.0-20181214235302-dac4796ca146
+	github.com/hashicorp/hcl2 v0.0.0-20181215005721-253da47fd604
 	github.com/hashicorp/hil v0.0.0-20170627220502-fa9f258a9250
 	github.com/hashicorp/logutils v0.0.0-20150609070431-0dc08b1671f3
 	github.com/hashicorp/memberlist v0.1.0 // indirect

go.sum

@@ -173,6 +173,8 @@ github.com/hashicorp/hcl2 v0.0.0-20181214224644-4c4fdbdcc016 h1:rWpgzURetj/et0J6
 github.com/hashicorp/hcl2 v0.0.0-20181214224644-4c4fdbdcc016/go.mod h1:ShfpTh661oAaxo7VcNxg0zcZW6jvMa7Moy2oFx7e5dE=
 github.com/hashicorp/hcl2 v0.0.0-20181214235302-dac4796ca146 h1:y2SWlAjINnc8OYpcVZ0vJDDaX++nzctjoOnB8Y+pqaI=
 github.com/hashicorp/hcl2 v0.0.0-20181214235302-dac4796ca146/go.mod h1:ShfpTh661oAaxo7VcNxg0zcZW6jvMa7Moy2oFx7e5dE=
+github.com/hashicorp/hcl2 v0.0.0-20181215005721-253da47fd604 h1:k660QMbAqhL4vxSNPmvOAjzZJ7BQiwTrT8pa8RH3OEA=
+github.com/hashicorp/hcl2 v0.0.0-20181215005721-253da47fd604/go.mod h1:ShfpTh661oAaxo7VcNxg0zcZW6jvMa7Moy2oFx7e5dE=
 github.com/hashicorp/hil v0.0.0-20170627220502-fa9f258a9250 h1:fooK5IvDL/KIsi4LxF/JH68nVdrBSiGNPhS2JAQjtjo=
 github.com/hashicorp/hil v0.0.0-20170627220502-fa9f258a9250/go.mod h1:KHvg/R2/dPtaePb16oW4qIyzkMxXOL38xjRN64adsts=
 github.com/hashicorp/logutils v0.0.0-20150609070431-0dc08b1671f3 h1:oD64EFjELI9RY9yoWlfua58r+etdnoIC871z+rr6lkA=

vendor/github.com/hashicorp/hcl2/hcl/traversal_for_expr.go

@@ -52,11 +52,14 @@ func AbsTraversalForExpr(expr Expression) (Traversal, Diagnostics) {
 func RelTraversalForExpr(expr Expression) (Traversal, Diagnostics) {
 	traversal, diags := AbsTraversalForExpr(expr)
 	if len(traversal) > 0 {
+		ret := make(Traversal, len(traversal))
+		copy(ret, traversal)
 		root := traversal[0].(TraverseRoot)
-		traversal[0] = TraverseAttr{
+		ret[0] = TraverseAttr{
 			Name:     root.Name,
 			SrcRange: root.SrcRange,
 		}
+		return ret, diags
 	}
 	return traversal, diags
 }

vendor/modules.txt

@@ -344,7 +344,7 @@ github.com/hashicorp/hcl/hcl/scanner
 github.com/hashicorp/hcl/hcl/strconv
 github.com/hashicorp/hcl/json/scanner
 github.com/hashicorp/hcl/json/token
-# github.com/hashicorp/hcl2 v0.0.0-20181214235302-dac4796ca146
+# github.com/hashicorp/hcl2 v0.0.0-20181215005721-253da47fd604
 github.com/hashicorp/hcl2/hcl
 github.com/hashicorp/hcl2/hcl/hclsyntax
 github.com/hashicorp/hcl2/hcldec