fix issue 6297 (#6299)

closes #6297

Author: mccanne

compiler/semantic/expr.go

@@ -885,7 +885,7 @@ func deriveNameFromExpr(e ast.Expr) string {
 			name = f.Name
 		}
 		if strings.ToLower(name) == "quiet" && len(e.Args) > 0 {
-			return deriveNameFromExpr(e)
+			return deriveNameFromExpr(e.Args[0])
 		}
 		return name
 	case *ast.BinaryExpr:

compiler/ztests/implied-quiet-assignment.yaml

@@ -1,8 +1,8 @@
-spq: cut a.b:=quiet(a.b)
+spq: cut quiet(a.b)
 
 input: |
   {a:1}
   {a:{b:1}}
 
 output: |
-  {a:{b:1}}
+  {b:1}