LDC-E1201 — Name already declared in this package

What it means

A package keeps a single flat namespace for the names it declares: the second declaration of an already-taken name does not shadow or merge, it collides. When a declaration reuses a name an earlier declaration owns, the compiler stops at the newcomer and points back at the first owner.

The repair is a rename of one of the two sides, or a merge into a single declaration if both meant the same thing. In a multi-file package the first owner may live in another file — the message says so.

Example

Arxo Law

language "law.core" version "0.2";
package demo.diagnostics version "0.1.0";
namespace "urn:law:demo:diagnostics";

entity Applicant;
entity Applicant;

Fix

Arxo Law

language "law.core" version "0.2";
package demo.diagnostics version "0.1.0";
namespace "urn:law:demo:diagnostics";

entity Applicant;

Engine message

The engine reports this in its own wording:

Output

example.law:6:8: error LDC-E1201: name "Applicant" is already declared in this package (§24; in a multi-file package — possibly in another file)

Related

• Vocabulary — how names are declared and which positions take them.
• LDC-E1338 — the companion collision at the identifier level.