terraform: Add ephemeral resources to the graph, and validate refs

This is not yet sufficient to actually open/renew/close ephemeral resource
instances, and so as of this commit a module including ephemeral resources
will misbehave. Further work in subsequent commits.

internal/providers/schemas.go

@@ -23,6 +23,9 @@ func (ss ProviderSchema) SchemaForResourceType(mode addrs.ResourceMode, typeName
 	case addrs.DataResourceMode:
 		// Data resources don't have schema versions right now, since state is discarded for each refresh
 		return ss.DataSources[typeName].Block, 0
+	case addrs.EphemeralResourceMode:
+		// Ephemeral resources don't have schema versions because their objects never outlive a single phase
+		return ss.EphemeralResourceTypes[typeName].Block, 0
 	default:
 		// Shouldn't happen, because the above cases are comprehensive.
 		return nil, 0

internal/terraform/evaluate_valid.go

@@ -197,11 +197,15 @@ func staticValidateResourceReference(modCfg *configs.Config, addr addrs.Resource
 	var diags tfdiags.Diagnostics
 
 	var modeAdjective string
+	modeArticleUpper := "A"
 	switch addr.Mode {
 	case addrs.ManagedResourceMode:
 		modeAdjective = "managed"
 	case addrs.DataResourceMode:
 		modeAdjective = "data"
+	case addrs.EphemeralResourceMode:
+		modeAdjective = "ephemeral"
+		modeArticleUpper = "An"
 	default:
 		// should never happen
 		modeAdjective = "<invalid-mode>"
@@ -223,8 +227,14 @@ func staticValidateResourceReference(modCfg *configs.Config, addr addrs.Resource
 		diags = diags.Append(&hcl.Diagnostic{
 			Severity: hcl.DiagError,
 			Summary:  `Reference to undeclared resource`,
-			Detail:   fmt.Sprintf(`A %s resource %q %q has not been declared in %s.%s`, modeAdjective, addr.Type, addr.Name, moduleConfigDisplayAddr(modCfg.Path), suggestion),
-			Subject:  rng.ToHCL().Ptr(),
+			Detail: fmt.Sprintf(
+				`%s %s resource %q %q has not been declared in %s.%s`,
+				modeArticleUpper, modeAdjective,
+				addr.Type, addr.Name,
+				moduleConfigDisplayAddr(modCfg.Path),
+				suggestion,
+			),
+			Subject: rng.ToHCL().Ptr(),
 		})
 		return diags
 	}
@@ -259,8 +269,13 @@ func staticValidateResourceReference(modCfg *configs.Config, addr addrs.Resource
 		diags = diags.Append(&hcl.Diagnostic{
 			Severity: hcl.DiagError,
 			Summary:  `Invalid resource type`,
-			Detail:   fmt.Sprintf(`A %s resource type %q is not supported by provider %q.`, modeAdjective, addr.Type, providerFqn.String()),
-			Subject:  rng.ToHCL().Ptr(),
+			Detail: fmt.Sprintf(
+				`%s %s resource type %q is not supported by provider %q.`,
+				modeArticleUpper, modeAdjective,
+				addr.Type,
+				providerFqn.String(),
+			),
+			Subject: rng.ToHCL().Ptr(),
 		})
 		return diags
 	}

internal/terraform/evaluate_valid_test.go

@@ -74,6 +74,14 @@ For example, to correlate with indices of a referring resource, use:
 			Ref:     "data.boop_data.boop_nested",
 			WantErr: `Reference to scoped resource: The referenced data resource "boop_data" "boop_nested" is not available from this context.`,
 		},
+		{
+			Ref:     "ephemeral.beep.boop",
+			WantErr: ``,
+		},
+		{
+			Ref:     "ephemeral.beep.nonexistant",
+			WantErr: `Reference to undeclared resource: An ephemeral resource "beep" "nonexistant" has not been declared in the root module.`,
+		},
 		{
 			Ref:     "data.boop_data.boop_nested",
 			WantErr: ``,
@@ -119,6 +127,11 @@ For example, to correlate with indices of a referring resource, use:
 						},
 					},
 				},
+				EphemeralResourceTypes: map[string]providers.Schema{
+					"beep": {
+						Block: &configschema.Block{},
+					},
+				},
 			},
 		}),
 	}

internal/terraform/testdata/static-validate-refs/static-validate-refs.tf

@@ -4,6 +4,10 @@ terraform {
       source = "foobar/beep" # intentional mismatch between local name and type
     }
   }
+  # TODO: Remove this if ephemeral values / resources get stabilized. If this
+  # experiment is removed without stabilization, also remove the
+  # "ephemeral" block below and the test cases it's supporting.
+  experiments = [ephemeral_values]
 }
 
 resource "aws_instance" "no_count" {
@@ -22,6 +26,10 @@ resource "boop_whatever" "nope" {
 data "beep" "boop" {
 }
 
+ephemeral "beep" "boop" {
+  provider = boop
+}
+
 check "foo" {
   data "boop_data" "boop_nested" {}
 

internal/terraform/transform_config.go

@@ -92,13 +92,16 @@ func (t *ConfigTransformer) transformSingle(g *Graph, config *configs.Config) er
 	module := config.Module
 	log.Printf("[TRACE] ConfigTransformer: Starting for path: %v", path)
 
-	allResources := make([]*configs.Resource, 0, len(module.ManagedResources)+len(module.DataResources))
+	allResources := make([]*configs.Resource, 0, len(module.ManagedResources)+len(module.DataResources)+len(module.EphemeralResources))
 	for _, r := range module.ManagedResources {
 		allResources = append(allResources, r)
 	}
 	for _, r := range module.DataResources {
 		allResources = append(allResources, r)
 	}
+	for _, r := range module.EphemeralResources {
+		allResources = append(allResources, r)
+	}
 
 	// Take a copy of the import targets, so we can edit them as we go.
 	// Only include import targets that are targeting the current module.