[clang-format] Fix a crash in qualifier alignment

Related to llvm#54513.

Author: owenca

clang/lib/Format/QualifierAlignmentFixer.cpp

@@ -303,6 +303,8 @@ const FormatToken *LeftRightQualifierAlignmentFixer::analyzeLeft(
 
   if (LastQual && Qual != LastQual && Qual->is(QualifierType)) {
     rotateTokens(SourceMgr, Fixes, Tok, Qual, /*Left=*/true);
+    if (!Qual->Next)
+      return Tok;
     Tok = Qual->Next;
   } else if (Tok->startsSequence(tok::identifier, QualifierType)) {
     if (Tok->Next->Next && Tok->Next->Next->isOneOf(tok::identifier, tok::star,

clang/unittests/Format/QualifierFixerTest.cpp

@@ -816,6 +816,7 @@ TEST_F(QualifierFixerTest, NoOpQualifierReplacements) {
   EXPECT_EQ(ReplacementCount, 0);
   verifyFormat("static const uint32 foo[] = {0, 31};", Style);
   verifyFormat("#define MACRO static const", Style);
+  verifyFormat("using sc = static const", Style);
   EXPECT_EQ(ReplacementCount, 0);
 }