# E4193

Compiler diagnostic name: `declare_body_not_empty`.

Declaration body is not empty.

A declaration describes an item without providing its implementation body. For
function declarations, the declaration must not contain a `{ ... }` block. For
type declarations, the declared type must be abstract rather than a concrete
struct, enum, or tuple struct definition.

## Erroneous example

```{literalinclude} /sources/error_codes/4193_error/top.mbt
:language: moonbit
```

The `#declaration_only` attribute marks `declared_answer` as a declaration, but
the function still provides an implementation body.

## Suggestion

Remove the declaration marker when the item is already implemented, or keep the
declaration body empty and provide a matching implementation elsewhere.

```{literalinclude} /sources/error_codes/4193_fixed/top.mbt
:language: moonbit
```