terraform: use the new TypeUnknown type from HIL

This makes all the computed stuff "just work" since HIL uses the same
computed sentinel value (string UUID) and the type differentiates it
from a regular string.

terraform/context_validate_test.go

@@ -87,7 +87,9 @@ func TestContext2Validate_computedVar(t *testing.T) {
 		t.Fatalf("bad: %#v", w)
 	}
 	if len(e) > 0 {
-		t.Fatalf("bad: %#v", e)
+		for _, err := range e {
+			t.Errorf("bad: %s", err)
+		}
 	}
 }
 

terraform/interpolate.go

@@ -121,7 +121,7 @@ func (i *Interpolater) valueCountVar(
 
 func unknownVariable() ast.Variable {
 	return ast.Variable{
-		Type:  ast.TypeString,
+		Type:  ast.TypeUnknown,
 		Value: config.UnknownVariableValue,
 	}
 }
@@ -215,10 +215,7 @@ func (i *Interpolater) valueResourceVar(
 	// If we're computing all dynamic fields, then module vars count
 	// and we mark it as computed.
 	if i.Operation == walkValidate {
-		result[n] = ast.Variable{
-			Value: config.UnknownVariableValue,
-			Type:  ast.TypeString,
-		}
+		result[n] = unknownVariable()
 		return nil
 	}
 
@@ -243,10 +240,7 @@ func (i *Interpolater) valueResourceVar(
 		// This applies only to graph nodes that interpolate during the
 		// config walk, e.g. providers.
 		if i.Operation == walkInput {
-			result[n] = ast.Variable{
-				Value: config.UnknownVariableValue,
-				Type:  ast.TypeString,
-			}
+			result[n] = unknownVariable()
 			return nil
 		}
 

terraform/interpolate_test.go

@@ -306,7 +306,7 @@ func TestInterpolater_resourceVariableMissingDuringInput(t *testing.T) {
 
 		testInterpolate(t, i, scope, "aws_instance.web.foo", ast.Variable{
 			Value: config.UnknownVariableValue,
-			Type:  ast.TypeString,
+			Type:  ast.TypeUnknown,
 		})
 	}
 
@@ -360,7 +360,7 @@ func TestInterpolater_resourceVariableMulti(t *testing.T) {
 
 	testInterpolate(t, i, scope, "aws_instance.web.*.foo", ast.Variable{
 		Value: config.UnknownVariableValue,
-		Type:  ast.TypeString,
+		Type:  ast.TypeUnknown,
 	})
 }
 
@@ -565,7 +565,7 @@ func TestInterpolator_resourceMultiAttributesComputed(t *testing.T) {
 
 	testInterpolate(t, i, scope, "aws_route53_zone.yada.name_servers", ast.Variable{
 		Value: config.UnknownVariableValue,
-		Type:  ast.TypeString,
+		Type:  ast.TypeUnknown,
 	})
 }
 

terraform/resource.go

@@ -209,9 +209,13 @@ func (c *ResourceConfig) GetRaw(k string) (interface{}, bool) {
 
 // IsComputed returns whether the given key is computed or not.
 func (c *ResourceConfig) IsComputed(k string) bool {
-	_, ok := c.get(k, c.Config)
+	v, ok := c.get(k, c.Config)
 	_, okRaw := c.get(k, c.Raw)
-	return !ok && okRaw
+
+	// Both tests probably aren't needed anymore since we don't remove
+	// values any longer. The latter is probably good enough since we
+	// thread through that value now.
+	return (!ok && okRaw) || v == config.UnknownVariableValue
 }
 
 // IsSet checks if the key in the configuration is set. A key is set if