Ignore invalid references in referencesInExpr

rules/terraformrules/terraform_unused_declaration.go

@@ -132,13 +132,7 @@ func (r *TerraformUnusedDeclarationsRule) declarations(runner *tflint.Runner) (*
 }
 
 func (r *TerraformUnusedDeclarationsRule) checkForRefsInExpr(expr hcl.Expression, decl *declarations) error {
-	refs, diags := referencesInExpr(expr)
-	if diags.HasErrors() {
-		log.Printf("[DEBUG] Cannot find references in expression, ignoring: %v", diags)
-		return nil
-	}
-
-	for _, ref := range refs {
+	for _, ref := range referencesInExpr(expr) {
 		switch sub := ref.subject.(type) {
 		case inputVariableReference:
 			delete(decl.Variables, sub.name)

rules/terraformrules/terraform_workspace_remote.go

@@ -92,12 +92,7 @@ func (r *TerraformWorkspaceRemoteRule) checkForTerraformWorkspaceInExpr(runner *
 		return nil
 	}
 
-	refs, diags := referencesInExpr(expr)
-	if diags.HasErrors() {
-		return diags
-	}
-
-	for _, ref := range refs {
+	for _, ref := range referencesInExpr(expr) {
 		switch sub := ref.subject.(type) {
 		case terraformReference:
 			if sub.name == "workspace" {

rules/terraformrules/terraform_workspace_remote_test.go

@@ -236,6 +236,24 @@ resource "aws_instance" "foo" {
 				},
 			},
 		},
+		{
+			Name: "with ignore_changes",
+			Content: `
+terraform {
+  backend "remote" {}
+}
+
+resource "kubernetes_secret" "my_secret" {
+  data = {}
+
+  lifecycle {
+    ignore_changes = [
+      data
+    ]
+  }
+}`,
+			Expected: tflint.Issues{},
+		},
 	}
 
 	rule := NewTerraformWorkspaceRemoteRule()

rules/terraformrules/utils.go

@@ -260,35 +260,41 @@ func (d *dataResourceReference) String() string {
 	return fmt.Sprintf("data.%s.%s", d.typeName, d.name)
 }
 
+// referencesInExpr extracts and returns references from hcl.Expression.
+// This is roughly equivalent to ReferencesInExpr in Terraform interlan API,
+// but simply ignores invalid references without returing diagnostics.
+// This is because it is not the responsibility of this method to detect invalid references.
+// Invalid references should be caught by terraform validate.
+//
 // @see https://github.com/hashicorp/terraform/blob/v1.2.5/internal/lang/references.go#L75
-func referencesInExpr(expr hcl.Expression) ([]*reference, hcl.Diagnostics) {
+func referencesInExpr(expr hcl.Expression) []*reference {
 	references := []*reference{}
-	diags := hcl.Diagnostics{}
 
 	for _, traversal := range expr.Variables() {
 		name := traversal.RootName()
 
 		switch name {
 		case "var":
-			name, parseDiags := parseSingleAttrRef(traversal)
-			diags = diags.Extend(parseDiags)
+			name, diags := parseSingleAttrRef(traversal)
+			if diags.HasErrors() {
+				continue
+			}
 			references = append(references, &reference{subject: inputVariableReference{name: name}})
 		case "local":
-			name, parseDiags := parseSingleAttrRef(traversal)
-			diags = diags.Extend(parseDiags)
+			name, diags := parseSingleAttrRef(traversal)
+			if diags.HasErrors() {
+				continue
+			}
 			references = append(references, &reference{subject: localValueReference{name: name}})
 		case "terraform":
-			name, parseDiags := parseSingleAttrRef(traversal)
-			diags = diags.Extend(parseDiags)
+			name, diags := parseSingleAttrRef(traversal)
+			if diags.HasErrors() {
+				continue
+			}
 			references = append(references, &reference{subject: terraformReference{name: name}})
 		case "data":
 			if len(traversal) < 3 {
-				diags = diags.Append(&hcl.Diagnostic{
-					Severity: hcl.DiagError,
-					Summary:  "Invalid reference",
-					Detail:   `The "data" object must be followed by two attribute names: the data source type and the resource name.`,
-					Subject:  traversal.SourceRange().Ptr(),
-				})
+				// The "data" object must be followed by two attribute names: the data source type and the resource name.
 				continue
 			}
 
@@ -299,32 +305,21 @@ func referencesInExpr(expr hcl.Expression) ([]*reference, hcl.Diagnostics) {
 			case hcl.TraverseAttr:
 				typeName = tt.Name
 			default:
-				// If it isn't a TraverseRoot then it must be a "data" reference.
-				diags = diags.Append(&hcl.Diagnostic{
-					Severity: hcl.DiagError,
-					Summary:  "Invalid reference",
-					Detail:   `The "data" object does not support this operation.`,
-					Subject:  traversal[1].SourceRange().Ptr(),
-				})
+				// The "data" object does not support this operation.
 				continue
 			}
 
 			attrTrav, ok := traversal[2].(hcl.TraverseAttr)
 			if !ok {
-				diags = diags.Append(&hcl.Diagnostic{
-					Severity: hcl.DiagError,
-					Summary:  "Invalid reference",
-					Detail:   `A reference to a data source must be followed by at least one attribute access, specifying the resource name.`,
-					Subject:  traversal[1].SourceRange().Ptr(),
-				})
+				// A reference to a data source must be followed by at least one attribute access, specifying the resource name.
 				continue
 			}
 
 			references = append(references, &reference{subject: dataResourceReference{typeName: typeName, name: attrTrav.Name}})
 		}
 	}
 
-	return references, diags
+	return references
 }
 
 // @see https://github.com/hashicorp/terraform/blob/v1.2.5/internal/addrs/parse_ref.go#L392