From 6a6546db8d3d481cfaf5adcb71c2329d1284cbd3 Mon Sep 17 00:00:00 2001
From: James Shubin <james@shubin.ca>
Date: Sat, 16 Dec 2023 14:25:41 -0500
Subject: [PATCH] lang: ast: Save the non-polyfunc args

We probably want to save these args too in case.
---
 lang/ast/structs.go | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/lang/ast/structs.go b/lang/ast/structs.go
index b5181d13bf..c0775eb3be 100644
--- a/lang/ast/structs.go
+++ b/lang/ast/structs.go
@@ -6984,6 +6984,16 @@ func (obj *ExprFunc) SetType(typ *types.Type) error {
 			}
 			// Cmp doesn't compare arg names.
 			typ = newTyp // check it's compatible down below...
+		} else {
+			// Even if it's not polymorphic, we'd like to use the
+			// real arg names of that function, in case they don't
+			// get passed through type unification somehow...
+			// (There can be an AST bug that this would prevent.)
+			sig := obj.function.Info().Sig
+			if sig == nil {
+				return fmt.Errorf("could not read nil expr func sig")
+			}
+			typ = sig // check it's compatible down below...
 		}
 	}