# E4219

Compiler diagnostic name: `invalid_export_name`.

The `#export_name` attribute is invalid. Exported names must be unique valid C
symbol identifiers, and the attribute may be used only on public, non-generic
function definitions without optional arguments in a foreign-library package.

## Erroneous example

```{literalinclude} /sources/error_codes/4219_error/top.mbt
:language: moonbit
```

## Suggestion

Use a valid symbol name and declare the package as a foreign library with
`pkgtype(kind: "foreign_library")`.

```{literalinclude} /sources/error_codes/4219_fixed/top.mbt
:language: moonbit
```