cli: Remove dead code for output -module flag

The -module flag to terraform output has been unimplemented since 0.12.
This commit removes some dead code and the specific error message for
this flag.

The website documentation for output does not mention this flag, so it
is unchanged.

command/apply.go

@@ -6,7 +6,6 @@ import (
 	"sort"
 	"strings"
 
-	"github.com/hashicorp/terraform/addrs"
 	"github.com/hashicorp/terraform/backend"
 	"github.com/hashicorp/terraform/repl"
 	"github.com/hashicorp/terraform/states"
@@ -178,7 +177,7 @@ func (c *ApplyCommand) Run(args []string) int {
 	}
 
 	if !c.Destroy {
-		if outputs := outputsAsString(op.State, addrs.RootModuleInstance, true); outputs != "" {
+		if outputs := outputsAsString(op.State, true); outputs != "" {
 			c.Ui.Output(c.Colorize().Color(outputs))
 		}
 	}
@@ -315,16 +314,12 @@ Options:
 	return strings.TrimSpace(helpText)
 }
 
-func outputsAsString(state *states.State, modPath addrs.ModuleInstance, includeHeader bool) string {
+func outputsAsString(state *states.State, includeHeader bool) string {
 	if state == nil {
 		return ""
 	}
 
-	ms := state.Module(modPath)
-	if ms == nil {
-		return ""
-	}
-
+	ms := state.RootModule()
 	outputs := ms.OutputValues
 	outputBuf := new(bytes.Buffer)
 	if len(outputs) > 0 {

command/output.go

@@ -9,7 +9,6 @@ import (
 	"github.com/zclconf/go-cty/cty/convert"
 	ctyjson "github.com/zclconf/go-cty/cty/json"
 
-	"github.com/hashicorp/terraform/addrs"
 	"github.com/hashicorp/terraform/repl"
 	"github.com/hashicorp/terraform/states"
 	"github.com/hashicorp/terraform/tfdiags"
@@ -27,13 +26,12 @@ type OutputCommand struct {
 
 func (c *OutputCommand) Run(args []string) int {
 	args = c.Meta.process(args)
-	var module, statePath string
+	var statePath string
 	var jsonOutput, rawOutput bool
 	cmdFlags := c.Meta.defaultFlagSet("output")
 	cmdFlags.BoolVar(&jsonOutput, "json", false, "json")
 	cmdFlags.BoolVar(&rawOutput, "raw", false, "raw")
 	cmdFlags.StringVar(&statePath, "state", "", "path")
-	cmdFlags.StringVar(&module, "module", "", "module")
 	cmdFlags.Usage = func() { c.Ui.Error(c.Help()) }
 	if err := cmdFlags.Parse(args); err != nil {
 		c.Ui.Error(fmt.Sprintf("Error parsing command-line flags: %s\n", err.Error()))
@@ -101,35 +99,12 @@ func (c *OutputCommand) Run(args []string) int {
 		return 1
 	}
 
-	moduleAddr := addrs.RootModuleInstance
-	if module != "" {
-		// This option was supported prior to 0.12.0, but no longer supported
-		// because we only persist the root module outputs in state.
-		// (We could perhaps re-introduce this by doing an eval walk here to
-		// repopulate them, similar to how "terraform console" does it, but
-		// that requires more thought since it would imply this command
-		// supporting remote operations, which is a big change.)
-		diags = diags.Append(tfdiags.Sourceless(
-			tfdiags.Error,
-			"Unsupported option",
-			"The -module option is no longer supported since Terraform 0.12, because now only root outputs are persisted in the state.",
-		))
-		c.showDiagnostics(diags)
-		return 1
-	}
-
 	state := stateStore.State()
 	if state == nil {
 		state = states.NewState()
 	}
 
-	mod := state.Module(moduleAddr)
-	if mod == nil {
-		c.Ui.Error(fmt.Sprintf(
-			"The module %s could not be found. There is nothing to output.",
-			module))
-		return 1
-	}
+	mod := state.RootModule()
 
 	if !jsonOutput && (state.Empty() || len(mod.OutputValues) == 0) {
 		diags = diags.Append(tfdiags.Sourceless(
@@ -190,7 +165,7 @@ func (c *OutputCommand) Run(args []string) int {
 			c.Ui.Output(string(jsonOutputs))
 			return 0
 		} else {
-			c.Ui.Output(outputsAsString(state, moduleAddr, false))
+			c.Ui.Output(outputsAsString(state, false))
 			return 0
 		}
 	}

command/output_test.go

@@ -268,35 +268,6 @@ func TestOutput_jsonEmptyOutputs(t *testing.T) {
 	}
 }
 
-func TestMissingModuleOutput(t *testing.T) {
-	originalState := states.BuildState(func(s *states.SyncState) {
-		s.SetOutputValue(
-			addrs.OutputValue{Name: "foo"}.Absolute(addrs.RootModuleInstance),
-			cty.StringVal("bar"),
-			false,
-		)
-	})
-	statePath := testStateFile(t, originalState)
-
-	ui := new(cli.MockUi)
-	c := &OutputCommand{
-		Meta: Meta{
-			testingOverrides: metaOverridesForProvider(testProvider()),
-			Ui:               ui,
-		},
-	}
-
-	args := []string{
-		"-state", statePath,
-		"-module", "not_existing_module",
-		"blah",
-	}
-
-	if code := c.Run(args); code != 1 {
-		t.Fatalf("bad: \n%s", ui.ErrorWriter.String())
-	}
-}
-
 func TestOutput_badVar(t *testing.T) {
 	originalState := states.BuildState(func(s *states.SyncState) {
 		s.SetOutputValue(

command/refresh.go

@@ -4,7 +4,6 @@ import (
 	"fmt"
 	"strings"
 
-	"github.com/hashicorp/terraform/addrs"
 	"github.com/hashicorp/terraform/backend"
 	"github.com/hashicorp/terraform/tfdiags"
 )
@@ -96,7 +95,7 @@ func (c *RefreshCommand) Run(args []string) int {
 		return op.Result.ExitStatus()
 	}
 
-	if outputs := outputsAsString(op.State, addrs.RootModuleInstance, true); outputs != "" {
+	if outputs := outputsAsString(op.State, true); outputs != "" {
 		c.Ui.Output(c.Colorize().Color(outputs))
 	}