hcl2: handle unquoted undefined variables (#10419)

This fixes a regression in #10326, to handle unquoted unknown variables.

The HCL job may contain unquoted undefined variable references without ${...} wrapping, e.g. value = meta.node_class. In 1.0.4, this got parsed as value = "${meta.node_class}".

This code performs a scan to find the relevant ${ and }, and only tries to find the closest ones with whitespace as the only separator.

jobspec2/parse_test.go

@@ -873,6 +873,21 @@ func TestParse_UndefinedVariables(t *testing.T) {
 			require.Equal(t, c, *job.Region)
 		})
 	}
+
+	t.Run("unquoted", func(t *testing.T) {
+		hcl := `job "example" {
+  region = meta.mytest
+}`
+
+		job, err := ParseWithConfig(&ParseConfig{
+			Path: "input.hcl",
+			Body: []byte(hcl),
+		})
+		require.NoError(t, err)
+
+		require.Equal(t, "${meta.mytest}", *job.Region)
+
+	})
 }
 
 func TestParseServiceCheck(t *testing.T) {

jobspec2/types.config.go

@@ -1,7 +1,6 @@
 package jobspec2
 
 import (
-	"bytes"
 	"fmt"
 	"strings"
 
@@ -315,18 +314,32 @@ func (c *jobConfig) EvalContext() *hcl.EvalContext {
 			end := t.SourceRange().End.Byte
 
 			v := string(body[start:end])
-			if i := bytes.IndexByte(body[end:], '}'); i != -1 {
-				v += string(body[end : end+i+1])
-			} else {
-				// fallback for unexpected cases
-				v += "}"
+
+			// find the start of inclusing "${..}" if it's inclused in one; otherwise, wrap it in one
+			isBracketed := false
+			for i := start - 1; i >= 1; i-- {
+				if body[i] == '{' && body[i-1] == '$' {
+					isBracketed = true
+					v = string(body[i-1:start]) + v
+					break
+				} else if body[i] != ' ' {
+					break
+				}
 			}
 
-			if i := bytes.LastIndex(body[:start], []byte("${")); i != 0 {
-				v = string(body[i:start]) + v
+			if isBracketed {
+				for i := end + 1; i < len(body); i++ {
+					if body[i] == '}' {
+						v += string(body[end:i])
+					} else if body[i] != ' ' {
+						// unexpected!
+						v += "}"
+						break
+					}
+				}
+
 			} else {
-				// fallback for unexpected cases
-				v = "${" + v
+				v = "${" + v + "}"
 			}
 
 			return cty.StringVal(v), nil