From a443f0a1a4b79faa0b0271b72ea4a8e5f3d03ffd Mon Sep 17 00:00:00 2001
From: Ryo Nihei <nihei.dev@gmail.com>
Date: Sat, 14 May 2022 14:42:00 +0900
Subject: Prohibit applying the expansion operator to anything other than
 identifiers

---
 spec/parser.go | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

(limited to 'spec/parser.go')

diff --git a/spec/parser.go b/spec/parser.go
index 9c66bfb..efbd072 100644
--- a/spec/parser.go
+++ b/spec/parser.go
@@ -494,10 +494,14 @@ func (p *parser) parseParameter() *ParameterNode {
 			Group: g,
 			Pos:   pos,
 		}
-	default:
-		return nil
 	}
 	if p.consume(tokenKindExpantion) {
+		switch {
+		case param == nil:
+			raiseSyntaxError(p.pos.Row, synErrStrayExpOp)
+		case param.ID == "":
+			raiseSyntaxError(p.pos.Row, synErrInvalidExpOperand)
+		}
 		param.Expansion = true
 	}
 	return param
-- 
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