core: Remove module input transformer

The nodes it adds were immediately skipped by flattening and therefore
never had any effect. That makes the transformer effectively dead code
and removable. This was the only usage of FlattenSkip so we can remove
that as well.

terraform/graph_config_node_module.go

@@ -57,12 +57,6 @@ func (n *GraphNodeConfigModule) Expand(b GraphBuilder) (GraphNodeSubgraph, error
 		return nil, err
 	}
 
-	// Add the parameters node to the module
-	t := &ModuleInputTransformer{Variables: make(map[string]string)}
-	if err := t.Transform(graph); err != nil {
-		return nil, err
-	}
-
 	{
 		// Add the destroy marker to the graph
 		t := &ModuleDestroyTransformer{}
@@ -75,7 +69,7 @@ func (n *GraphNodeConfigModule) Expand(b GraphBuilder) (GraphNodeSubgraph, error
 	return &graphNodeModuleExpanded{
 		Original:  n,
 		Graph:     graph,
-		Variables: t.Variables,
+		Variables: make(map[string]string),
 	}, nil
 }
 
@@ -169,11 +163,6 @@ func (n *graphNodeModuleExpanded) FlattenGraph() *Graph {
 	// flattening. We have to skip some nodes (graphNodeModuleSkippable)
 	// as well as setup the variable values.
 	for _, v := range graph.Vertices() {
-		if sn, ok := v.(graphNodeModuleSkippable); ok && sn.FlattenSkip() {
-			graph.Remove(v)
-			continue
-		}
-
 		// If this is a variable, then look it up in the raw configuration.
 		// If it exists in the raw configuration, set the value of it.
 		if vn, ok := v.(*GraphNodeConfigVariable); ok && input != nil {
@@ -204,12 +193,6 @@ func (n *graphNodeModuleExpanded) Subgraph() *Graph {
 	return n.Graph
 }
 
-// This interface can be implemented to be skipped/ignored when
-// flattening the module graph.
-type graphNodeModuleSkippable interface {
-	FlattenSkip() bool
-}
-
 func modulePrefixStr(p []string) string {
 	parts := make([]string, 0, len(p)*2)
 	for _, p := range p[1:] {

terraform/graph_config_node_module_test.go

@@ -71,8 +71,6 @@ const testGraphNodeModuleExpandStr = `
 aws_instance.bar
   aws_instance.foo
 aws_instance.foo
-  module inputs
-module inputs
 plan-destroy
 `
 

terraform/transform_module.go

@@ -2,38 +2,10 @@ package terraform
 
 import (
 	"fmt"
+
 	"github.com/hashicorp/terraform/dag"
 )
 
-// ModuleInputTransformer is a GraphTransformer that adds a node to the
-// graph for setting the module input variables for the remainder of the
-// graph.
-type ModuleInputTransformer struct {
-	Variables map[string]string
-}
-
-func (t *ModuleInputTransformer) Transform(g *Graph) error {
-	// Create the node
-	n := &graphNodeModuleInput{Variables: t.Variables}
-
-	// Add it to the graph
-	g.Add(n)
-
-	// Connect the inputs to the bottom of the graph so that it happens
-	// first.
-	for _, v := range g.Vertices() {
-		if v == n {
-			continue
-		}
-
-		if g.DownEdges(v).Len() == 0 {
-			g.Connect(dag.BasicEdge(v, n))
-		}
-	}
-
-	return nil
-}
-
 // ModuleDestroyTransformer is a GraphTransformer that adds a node
 // to the graph that will just mark the full module for destroy in
 // the destroy scenario.
@@ -88,21 +60,3 @@ func (n *graphNodeModuleDestroyFlat) Name() string {
 func (n *graphNodeModuleDestroyFlat) Path() []string {
 	return n.PathValue
 }
-
-type graphNodeModuleInput struct {
-	Variables map[string]string
-}
-
-func (n *graphNodeModuleInput) Name() string {
-	return "module inputs"
-}
-
-// GraphNodeEvalable impl.
-func (n *graphNodeModuleInput) EvalTree() EvalNode {
-	return &EvalSetVariables{Variables: n.Variables}
-}
-
-// graphNodeModuleSkippable impl.
-func (n *graphNodeModuleInput) FlattenSkip() bool {
-	return true
-}

terraform/transform_module_test.go

@@ -1,41 +1 @@
 package terraform
-
-import (
-	"strings"
-	"testing"
-
-	"github.com/hashicorp/terraform/dag"
-)
-
-func TestModuleInputTransformer(t *testing.T) {
-	var g Graph
-	g.Add(1)
-	g.Add(2)
-	g.Add(3)
-	g.Connect(dag.BasicEdge(1, 2))
-	g.Connect(dag.BasicEdge(1, 3))
-
-	{
-		tf := &ModuleInputTransformer{}
-		if err := tf.Transform(&g); err != nil {
-			t.Fatalf("err: %s", err)
-		}
-	}
-
-	actual := strings.TrimSpace(g.String())
-	expected := strings.TrimSpace(testModuleInputTransformStr)
-	if actual != expected {
-		t.Fatalf("bad:\n\n%s", actual)
-	}
-}
-
-const testModuleInputTransformStr = `
-1
-  2
-  3
-2
-  module inputs
-3
-  module inputs
-module inputs
-`