falconGitHub

no-empty-block

Same as no-empty-block in Dart Code Metrics

Path
lint/suspicious/no-empty-block
Default
Off, opt in
Origin
Dart Code Metrics
Rule
284 of 512

Flags empty blocks ({}).

An empty function, method, loop, or switch-case body is frequently an unfinished implementation or a leftover after code was deleted, and it hides whether the emptiness is deliberate. Fill in the intended behavior, or, if a no-op is genuinely correct, add a comment saying so. A block containing only a comment is treated as intentional and left alone. The report lands on the closing brace.

Invalid

example.dartdart
// Test cases for no-empty-block rule
// All violations are marked inline below.

void testEmptyCatchBlock() {
  try {
    riskyOperation();
  } catch (e) {
  }
}

void testEmptyIfBlock() {
  if (condition) {
  }
}

void testEmptyElseBlock() {
  if (condition) {
    print("yes");
  } else {
  }
}

void testEmptyMethodBody() {
  onPressed() {
  }
}

class Widget {
  void onTap() {
  }

  void onLongPress() {
  }
}

void testEmptyForLoop() {
  for (int i = 0; i < 10; i++) {
  }
}

void testEmptyWhileLoop() {
  while (condition) {
  }
}

void testEmptyFinallyBlock() {
  try {
    doSomething();
  } finally {
  }
}

void testMultipleEmptyBlocks() {
  if (a) {
  }
  if (b) {
  }
}

void testEmptyOnBlock(Future<String> future) {
  future.then((_) {
  });
}
Avoid empty blocks — add a comment explaining the intent or remove the block.
7 } catch (e) {
8 }
Avoid empty blocks — add a comment explaining the intent or remove the block.
12 if (condition) {
13 }
Avoid empty blocks — add a comment explaining the intent or remove the block.
19 } else {
20 }
Avoid empty blocks — add a comment explaining the intent or remove the block.
24 onPressed() {
25 }
Avoid empty blocks — add a comment explaining the intent or remove the block.
29 void onTap() {
30 }
Avoid empty blocks — add a comment explaining the intent or remove the block.
32 void onLongPress() {
33 }
Avoid empty blocks — add a comment explaining the intent or remove the block.
37 for (int i = 0; i < 10; i++) {
38 }
Avoid empty blocks — add a comment explaining the intent or remove the block.
42 while (condition) {
43 }
Avoid empty blocks — add a comment explaining the intent or remove the block.
49 } finally {
50 }
Avoid empty blocks — add a comment explaining the intent or remove the block.
54 if (a) {
55 }
Avoid empty blocks — add a comment explaining the intent or remove the block.
56 if (b) {
57 }
Avoid empty blocks — add a comment explaining the intent or remove the block.
61 future.then((_) {
62 });

Valid

example.dartdart
// Good cases for no-empty-block rule
// No violations expected

void testCatchBlockWithHandler() {
  try {
    riskyOperation();
  } catch (e) {
    logger.error('Operation failed: $e');
  }
}

void testCatchBlockWithRethrow() {
  try {
    riskyOperation();
  } catch (e) {
    rethrow;
  }
}

void testIfBlockWithBody() {
  if (condition) {
    print("yes");
  }
}

void testElseBlockWithBody() {
  if (condition) {
    print("yes");
  } else {
    print("no");
  }
}

void testMethodWithBody() {
  onPressed() {
    print("pressed");
  }
}

class Widget {
  void onTap() {
    handleTap();
  }

  void onLongPress() {
    // Allow long press without action for now
    handleLongPress();
  }
}

void testForLoopWithBody() {
  for (int i = 0; i < 10; i++) {
    print(i);
  }
}

void testWhileLoopWithBody() {
  while (condition) {
    process();
    condition = evaluate();
  }
}

void testFinallyBlockWithBody() {
  try {
    doSomething();
  } finally {
    cleanup();
  }
}

void testIfBlockWithComment() {
  if (impossible) {
    // This condition should never be true in practice
    throw AssertionError('Impossible state reached');
  }
}

void testCatchWithComment() {
  try {
    parse();
  } catch (e) {
    // Intentionally swallow parse errors in legacy format
  }
}

void testAsyncCallback(Future<String> future) {
  future.then((value) {
    print('Got: $value');
  });
}

void testEmptyCallbackWithComment(VoidCallback callback) {
  callback = () {
    // No-op callback for testing
  };
}

class ErrorHandler {
  void handleOptional(Error? error) {
    if (error == null) {
      // No error to handle, silent success
      return;
    }
    log(error);
  }
}

Configure no-empty-block

Set its severity in falcon.json. See the configuration guide.

falcon.jsonjson
{
  "linter": {
    "rules": {
      "suspicious": {
        "no-empty-block": "error"
      }
    }
  }
}

Or silence one occurrence with a suppression comment; the reason is required.

example.dartdart
// falcon-ignore lint/suspicious/no-empty-block: <reason>
  • no-equal-argumentsno-equal-arguments

    Flags an argument passed more than once in the same invocation.

  • no-equal-then-elseno-equal-then-elserecommended

    Flags an if/else or ternary whose two branches are identical.

  • no-magic-string

    Extract inline string literals into named variables or constants.

  • no-self-comparisonsno_self_comparisonsrecommended

    Flags proven self-comparisons of side-effect-free scalar values.

  • no-wildcard-variable-usesno_wildcard_variable_usesrecommended

    Flags references to a wildcard variable or parameter (a name made solely of underscores, such as _ or __).

  • overridden-fieldsoverridden_fieldsrecommended

    Flags instance fields that redeclare an inherited field.

  • prefer-unique-test-namestest

    Reports duplicate test descriptions within a group and constant names in loops.

  • recursive-gettersrecursive_gettersrecommended

    Flags a getter that unconditionally returns itself.