Check required_version as early as possible

internal/command/init.go

@@ -150,19 +150,7 @@ func (c *InitCommand) Run(args []string) int {
 	// initialization functionality remains built around "earlyconfig" and
 	// so we need to still load the module via that mechanism anyway until we
 	// can do some more invasive refactoring here.
-	rootMod, confDiags := c.loadSingleModule(path)
 	rootModEarly, earlyConfDiags := c.loadSingleModuleEarly(path)
-	if confDiags.HasErrors() {
-		c.Ui.Error(c.Colorize().Color(strings.TrimSpace(errInitConfigError)))
-		// TODO: It would be nice to check the version constraints in
-		// rootModEarly.RequiredCore and print out a hint if the module is
-		// declaring that it's not compatible with this version of Terraform,
-		// though we're deferring that for now because we're intending to
-		// refactor our use of "earlyconfig" here anyway and so whatever we
-		// might do here right now would likely be invalidated by that.
-		c.showDiagnostics(confDiags)
-		return 1
-	}
 	// If _only_ the early loader encountered errors then that's unusual
 	// (it should generally be a superset of the normal loader) but we'll
 	// return those errors anyway since otherwise we'll probably get
@@ -172,7 +160,12 @@ func (c *InitCommand) Run(args []string) int {
 		c.Ui.Error(c.Colorize().Color(strings.TrimSpace(errInitConfigError)))
 		// Errors from the early loader are generally not as high-quality since
 		// it has less context to work with.
-		diags = diags.Append(confDiags)
+
+		// TODO: It would be nice to check the version constraints in
+		// rootModEarly.RequiredCore and print out a hint if the module is
+		// declaring that it's not compatible with this version of Terraform,
+		// and that may be what caused earlyconfig to fail.
+		diags = diags.Append(earlyConfDiags)
 		c.showDiagnostics(diags)
 		return 1
 	}
@@ -192,28 +185,31 @@ func (c *InitCommand) Run(args []string) int {
 	// With all of the modules (hopefully) installed, we can now try to load the
 	// whole configuration tree.
 	config, confDiags := c.loadConfig(path)
-	diags = diags.Append(confDiags)
-	if confDiags.HasErrors() {
-		c.Ui.Error(strings.TrimSpace(errInitConfigError))
-		c.showDiagnostics(diags)
-		return 1
-	}
+	// configDiags will be handled after the version constraint check, since an
+	// incorrect version of terraform may be producing errors for configuration
+	// constructs added in later versions.
 
-	// 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
+	// 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)
-	diags = diags.Append(versionDiags)
 	if versionDiags.HasErrors() {
+		c.showDiagnostics(versionDiags)
+		return 1
+	}
+
+	diags = diags.Append(confDiags)
+	if confDiags.HasErrors() {
+		c.Ui.Error(strings.TrimSpace(errInitConfigError))
 		c.showDiagnostics(diags)
 		return 1
 	}
 
 	var back backend.Backend
 	if flagBackend {
 
-		be, backendOutput, backendDiags := c.initBackend(rootMod, flagConfigExtra)
+		be, backendOutput, backendDiags := c.initBackend(config.Module, flagConfigExtra)
 		diags = diags.Append(backendDiags)
 		if backendDiags.HasErrors() {
 			c.showDiagnostics(diags)

internal/command/init_test.go

@@ -1608,6 +1608,59 @@ 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)()
+
+		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)
+		}
+	})
+	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) {
 	// Create a temporary working directory that is empty
 	td := tempDir(t)

internal/command/show_test.go

@@ -103,8 +103,6 @@ func TestShow_aliasedProvider(t *testing.T) {
 		},
 	}
 
-	fmt.Println(os.Getwd())
-
 	// the statefile created by testStateFile is named state.tfstate
 	args := []string{"state.tfstate"}
 	if code := c.Run(args); code != 0 {

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 {}
+}

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

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

internal/configs/configload/loader_load.go

@@ -21,7 +21,13 @@ import (
 func (l *Loader) LoadConfig(rootDir string) (*configs.Config, hcl.Diagnostics) {
 	rootMod, diags := l.parser.LoadConfigDir(rootDir)
 	if rootMod == nil || diags.HasErrors() {
-		return nil, diags
+		// Ensure we return any parsed modules here so that required_version
+		// constraints can be verified even when encountering errors.
+		cfg := &configs.Config{
+			Module: rootMod,
+		}
+
+		return cfg, diags
 	}
 
 	cfg, cDiags := configs.BuildConfig(rootMod, configs.ModuleWalkerFunc(l.moduleWalkerLoad))

internal/configs/configload/loader_load_test.go

@@ -91,8 +91,16 @@ func TestLoaderLoadConfig_loadDiags(t *testing.T) {
 		t.Fatalf("unexpected error from NewLoader: %s", err)
 	}
 
-	_, diags := loader.LoadConfig(fixtureDir)
+	cfg, diags := loader.LoadConfig(fixtureDir)
 	if !diags.HasErrors() {
-		t.Fatalf("success; want error")
+		t.Fatal("success; want error")
+	}
+
+	if cfg == nil {
+		t.Fatal("partial config not returned with diagnostics")
+	}
+
+	if cfg.Module == nil {
+		t.Fatal("expected config module")
 	}
 }