From 88f5abbe1898a4e56b9aa32088ff135e7dddce87 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E4=BA=AC=E5=9F=8E=E9=83=AD=E5=B0=91?=
 <39666162+GuoFlight@users.noreply.github.com>
Date: Tue, 12 May 2026 15:28:23 +0800
Subject: [PATCH] fix When parsing {}, the parser enters startLabelName state
 with p.currentMetric == nil, causing the crash.
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Signed-off-by: 京城郭少 <39666162+GuoFlight@users.noreply.github.com>
---
 expfmt/text_parse.go | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/expfmt/text_parse.go b/expfmt/text_parse.go
index 00c8841a..a60cf1d7 100644
--- a/expfmt/text_parse.go
+++ b/expfmt/text_parse.go
@@ -339,6 +339,11 @@ func (p *TextParser) startLabelName() stateFn {
 		return nil // Unexpected end of input.
 	}
 	if p.currentByte == '}' {
+		if p.currentMetric == nil {
+			p.parseError("unexpected '}' without metric name")
+			p.currentLabelPairs = nil
+			return nil
+		}
 		p.currentMetric.Label = append(p.currentMetric.Label, p.currentLabelPairs...)
 		p.currentLabelPairs = nil
 		if p.skipBlankTab(); p.err != nil {