Deprecate EnsureNoError helper (#236)

helper/runner.go

@@ -265,6 +265,8 @@ func (r *Runner) EmitIssue(rule tflint.Rule, message string, location hcl.Range)
 }
 
 // EnsureNoError is a method that simply runs a function if there is no error.
+//
+// Deprecated: Use errors.Is() instead to determine which errors can be ignored.
 func (r *Runner) EnsureNoError(err error, proc func() error) error {
 	if err == nil {
 		return proc()

plugin/plugin2host/client.go

@@ -367,6 +367,8 @@ func (c *GRPCClient) EmitIssue(rule tflint.Rule, message string, location hcl.Ra
 
 // EnsureNoError is a helper for error handling. Depending on the type of error generated by EvaluateExpr,
 // determine whether to exit, skip, or continue. If it is continued, the passed function will be executed.
+//
+// Deprecated: Use errors.Is() instead to determine which errors can be ignored.
 func (*GRPCClient) EnsureNoError(err error, proc func() error) error {
 	if err == nil {
 		return proc()

tflint/errors.go

@@ -5,16 +5,15 @@ import (
 )
 
 // List of errors returned by TFLint.
-// It's possible to get this error from a plugin, but the error handling is hidden
-// inside the plugin system, so you usually don't have to worry about it.
 var (
-	// ErrUnknownValue is an error when an unknown value is referenced
+	// ErrUnknownValue is an error that occurs when decoding an unknown value to a Go value.
 	ErrUnknownValue = errors.New("unknown value found")
-	// ErrNullValue is an error when null value is referenced
+	// ErrNullValue is an error that occurs when decoding null to a Go value.
 	ErrNullValue = errors.New("null value found")
-	// ErrUnevaluable is an error when a received expression has unevaluable references.
+	// ErrUnevaluable is an error that occurs when decoding an unevaluable value to a Go value.
+	//
 	// Deprecated: This error is no longer returned since TFLint v0.41.
 	ErrUnevaluable = errors.New("")
-	// ErrSensitive is an error when a received expression contains a sensitive value.
+	// ErrSensitive is an error that occurs when decoding a sensitive value to a Go value.
 	ErrSensitive = errors.New("")
 )

tflint/interface.go

@@ -161,20 +161,29 @@ type Runner interface {
 
 	// EvaluateExpr evaluates the passed expression and reflects the result in the 2nd argument.
 	// In addition to the obvious errors, this function returns an error if:
-	//   - The expression contains unknown variables (e.g. variables without defaults)
-	//   - The expression contains null variables
-	//   - The expression contains unevaluable references (e.g. `aws_instance.arn`)
+	//   - The expression contains unknown values (e.g. variables without defaults, `aws_instance.foo.arn`)
+	//   - The expression contains null values
+	//   - The expression contains sensitive values (variables with `sensitive = true`)
 	//
-	// To ignore these, use EnsureNoError for the returned error:
+	// You can use `errors.Is` to ignore these errors:
 	//
 	// ```
 	// var val string
 	// err := runner.EvaluateExpr(expr, &val, nil)
-	// err = runner.EnsureNoError(err, func () error {
-	//   // Only when no error occurs
-	// })
 	// if err != nil {
-	//   // Only for obvious errors, excluding the above errors
+	//   if errors.Is(err, tflint.ErrUnknownValue) {
+	//     // Ignore unknown values
+	//	   return nil
+	//   }
+	//   if errors.Is(err, tflint.ErrNullValue) {
+	//     // Ignore null values because null means that the value is not set
+	//	   return nil
+	//   }
+	//   if errors.Is(err, tflint.ErrSensitive) {
+	//     // Ignore sensitive values
+	//     return nil
+	//   }
+	//   return err
 	// }
 	// ```
 	//
@@ -211,6 +220,8 @@ type Runner interface {
 
 	// EnsureNoError is a helper for error handling. Depending on the type of error generated by EvaluateExpr,
 	// determine whether to exit, skip, or continue. If it is continued, the passed function will be executed.
+	//
+	// Deprecated: Use errors.Is() instead to determine which errors can be ignored.
 	EnsureNoError(error, func() error) error
 }