reorder-parameter-duplicate

Id

@azure-tools/typespec-client-generator-core/reorder-parameter-duplicate

Severity: error

This diagnostic is issued when reorderParameters lists the same parameter name more than once.

Impact

• Area: Client customization transformations. Blocks reorderParameters because a duplicated name would make the generated method parameter order ambiguous.
• Not affected: The operation’s actual parameters are unchanged.

❌ Incorrect Usage

@service
namespace MyService {
  op myOp(a: string, b: string): void;
}

alias Modified = reorderParameters(MyService.myOp, #["a", "a"]); // `a` appears twice

Diagnostic Message

TCGC reports:

Parameter "a" appears more than once in the reorder list for operation "myOp".

✅ How to Fix

Include each parameter exactly once in the reorder list.

@service
namespace MyService {
  op myOp(a: string, b: string): void;
}

alias Modified = reorderParameters(MyService.myOp, #["b", "a"]);