Shadowing

TIP

This can be configured. Read more about configuration.

WebAssembly allows shadowing identifiers in block labels. For example:

(module
  (func
    (block $label
      (block $label
        br $label))))

However, it's confusing that you may want to jump to the label at line 3 or line 4. (Actually it jumps to the inner block label, which is line 4 in this case.) This checks such cases when you accidentally give the same name to different block labels.

Same name but not being as inner block won't be reported, such as:

(module
  (func
    (block $label
      br $label)
    (block $label
      br $label)))