From 58cc58d1d347fa725f4c85688d54a5b21ab23fa1 Mon Sep 17 00:00:00 2001
From: Varun Gandhi <varun.gandhi@sourcegraph.com>
Date: Thu, 27 Jun 2024 13:24:50 +0800
Subject: [PATCH] Fix index logic in detecting descriptor kind

---
 bindings/go/scip/symbol.go | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/bindings/go/scip/symbol.go b/bindings/go/scip/symbol.go
index 4c0f7308..4b52821f 100644
--- a/bindings/go/scip/symbol.go
+++ b/bindings/go/scip/symbol.go
@@ -512,11 +512,9 @@ func (z *zeroAllocSymbolParser) Advance(nextRune rune, nextRuneByteLength int32)
 
 func (z *zeroAllocSymbolParser) parseDescriptor(out *RawDescriptorList) error {
 	start := z.byteIndex
-	nextRune, nextRuneByteLength := z.peekNext()
-	switch nextRune {
+	switch z.currentRune {
 	case '(':
-		z.Advance('(', nextRuneByteLength)
-		z.advanceRune()
+		z.advanceOneByte('(')
 		name, err := z.acceptIdentifier(parseCtxParameterName)
 		if err != nil {
 			return err
@@ -524,8 +522,7 @@ func (z *zeroAllocSymbolParser) parseDescriptor(out *RawDescriptorList) error {
 		out.pushDescriptor(name, Descriptor_Parameter)
 		return z.acceptOneByte(')', parseCtxClosingParameterName)
 	case '[':
-		z.Advance('[', nextRuneByteLength)
-		z.advanceRune()
+		z.advanceOneByte('[')
 		name, err := z.acceptIdentifier(parseCtxTypeParameterName)
 		if err != nil {
 			return err
@@ -612,12 +609,15 @@ func isIdentifierCharacter(r rune) bool {
 func (z *zeroAllocSymbolParser) advanceOneByte(_ byte) {
 	// TODO: Add build tag with asserts and check that current byte matches the passed in byte.
 	nextRune, nextRuneByteLength := z.peekNext()
-	z.Advance(nextRune, nextRuneByteLength)
+	// z.byteIndex can become equal to len(z.SymbolString) here
+	z.byteIndex += 1
+	z.currentRune = nextRune
+	z.bytesToNextRune = nextRuneByteLength
 }
 
 func (z *zeroAllocSymbolParser) advanceRune() {
 	nextRune, nextRuneByteLength := z.peekNext()
-	z.Advance(nextRune, nextRuneByteLength)
+	z.Advance(nextRune, min(nextRuneByteLength, 1))
 }
 
 func (z *zeroAllocSymbolParser) acceptOneByte(b byte, what parseCtx) error {