LoadModule now always returns the module

We don't need to load the configuration twice, since configload can
return the module for us.

internal/command/init.go

@@ -182,24 +182,6 @@ func (c *InitCommand) Run(args []string) int {
 		}
 	}
 
-	// Using loadSingleModule will allow us to get the sniffed required_version
-	// before trying to build the complete config.
-	rootMod, _ := c.loadSingleModule(path)
-	// We can ignore the error, since we are going to reload the full config
-	// again below once we know the root module constraints are valid.
-	if rootMod != nil {
-		rootCfg := &configs.Config{
-			Module: rootMod,
-		}
-		// If our module version constraints are not valid, then there is no
-		// need to continue processing.
-		versionDiags := terraform.CheckCoreVersionRequirements(rootCfg)
-		if versionDiags.HasErrors() {
-			c.showDiagnostics(versionDiags)
-			return 1
-		}
-	}
-
 	// With all of the modules (hopefully) installed, we can now try to load the
 	// whole configuration tree.
 	config, confDiags := c.loadConfig(path)
@@ -207,9 +189,9 @@ func (c *InitCommand) Run(args []string) int {
 	// incorrect version of terraform may be producing errors for configuration
 	// constructs added in later versions.
 
-	// Check again to make sure none of the modules in the configuration
-	// declare that they don't support this Terraform version, so we can
-	// produce a version-related error message rather than
+	// Before we go further, we'll check to make sure none of the modules in
+	// the configuration declare that they don't support this Terraform
+	// version, so we can produce a version-related error message rather than
 	// potentially-confusing downstream errors.
 	versionDiags := terraform.CheckCoreVersionRequirements(config)
 	if versionDiags.HasErrors() {

internal/command/init_test.go

@@ -1611,6 +1611,7 @@ func TestInit_checkRequiredVersion(t *testing.T) {
 // Verify that init will error out with an invalid version constraint, even if
 // there are other invalid configuration constructs.
 func TestInit_checkRequiredVersionFirst(t *testing.T) {
+	t.Run("root_module", func(t *testing.T) {
 		td := t.TempDir()
 		testCopyDir(t, testFixturePath("init-check-required-version-first"), td)
 		defer testChdir(t, td)()
@@ -1633,6 +1634,31 @@ func TestInit_checkRequiredVersionFirst(t *testing.T) {
 		if !strings.Contains(errStr, `Unsupported Terraform Core version`) {
 			t.Fatalf("output should point to unmet version constraint, but is:\n\n%s", errStr)
 		}
+	})
+	t.Run("sub_module", func(t *testing.T) {
+		td := t.TempDir()
+		testCopyDir(t, testFixturePath("init-check-required-version-first-module"), td)
+		defer testChdir(t, td)()
+
+		ui := cli.NewMockUi()
+		view, _ := testView(t)
+		c := &InitCommand{
+			Meta: Meta{
+				testingOverrides: metaOverridesForProvider(testProvider()),
+				Ui:               ui,
+				View:             view,
+			},
+		}
+
+		args := []string{}
+		if code := c.Run(args); code != 1 {
+			t.Fatalf("got exit status %d; want 1\nstderr:\n%s\n\nstdout:\n%s", code, ui.ErrorWriter.String(), ui.OutputWriter.String())
+		}
+		errStr := ui.ErrorWriter.String()
+		if !strings.Contains(errStr, `Unsupported Terraform Core version`) {
+			t.Fatalf("output should point to unmet version constraint, but is:\n\n%s", errStr)
+		}
+	})
 }
 
 func TestInit_providerLockFile(t *testing.T) {

internal/command/testdata/init-check-required-version-first-module/main.tf

@@ -0,0 +1,3 @@
+module "mod" {
+  source = "./mod"
+}

internal/command/testdata/init-check-required-version-first-module/mod/main.tf

@@ -0,0 +1,17 @@
+terraform {
+  required_version = ">200.0.0"
+
+  bad {
+    block = "false"
+  }
+
+  required_providers {
+    bang = {
+      oops = "boom"
+    }
+  }
+}
+
+nope {
+  boom {}
+}