reader.ref_des_collision

What it is ¶

reader.ref_des_collision(ref_des) yields one row per reference designator that more than one distinct part claimed. A designator names exactly one physical part (R1 is one resistor on the board), so when two placements share a designator the input is malformed. Either the reader has a gap or the source holds a duplicate, and a person did not draw the design that way. The relation is keyed by ref_des so a query joins the collision to the components and nets it tangles.

The duplicate-ref-des integrity rule fires a finding on the same condition. This relation is the rule’s query face, and it lets you interrogate the condition ad hoc.

For hardware engineers ¶

You should almost never see this. A reference designator is the one label that lets a person point at a single part across the schematic, the layout, and the BOM. Two parts both called R1 cannot be told apart, so a row means the tool’s read of the file collapsed two placements that should have been kept separate, or the source itself repeated a designator. A row never comes from the legitimate multi-unit case. A dual op-amp drawn as U1A and U1B is still one component with two sections, and it does not collide. Treat a row as “fix the read (or the source),” not “fix the board.”

For software engineers ¶

A reference designator is the instance’s variable name (see the analogy guide), so the designator set should behave like a symbol table with unique keys. This relation reports the keys that got a second binding. A linter flags the same break as a duplicate declaration when one identifier is defined twice in one scope. Rows are 1:1 with colliding designators (one row per shared name, regardless of how many placements claimed it). An empty result means every designator resolved to a single part, the normal state.

Go projector ¶

refDesCollisionFacts in stdlib/relations/facts.go iterates Model.RefDesCollisions() and emits one reader.ref_des_collision(ref_des) row per collided designator. Model.RefDesCollisions() returns the reader-emitted ir.RefDesCollision list off InputDiagnostics, and each reader decides duplicate-versus-legitimate by its own format’s rule. Every colliding instance is cited (agni issue 546). One row per shared designator; empty when the read is clean.

Datalog ¶

Every colliding designator:

reader.ref_des_collision(?r) => ?r

Join to the nets each colliding designator sits on (which nets the tangled read connected together):

reader.ref_des_collision(?r), component.net(?r, ?n) => ?n

Schematic ¶