[clang-check][syntax] Crash in TraverseCXXOperatorCallExpr: Assertion `getOperatorNodeKind(*S) == syntax::NodeKind::PostfixUnaryOperatorExpression' ` ailed.

This input is generated by a fuzzer.
Seems to be valid?
```cxx
struct Loc {
int operator()(const char *f = "") const;
};

void g() {
Loc()();
}
```

```
clang-check --tokens-dump example.cpp -- -xc++ -std=c++23
```

```
clang-check: /home/ubuntu2404/llvm-project-196067/clang/lib/Tooling/Syntax/BuildTree.cpp:1253: bool {anonymous}::BuildTreeVisitor::TraverseCXXOperatorCallExpr(clang::CXXOperatorCallExpr*): Assertion `getOperatorNodeKind(*S) == syntax::NodeKind::PostfixUnaryOperatorExpression' failed.
#0 0x00006213f783a1f1 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/home/ubuntu2404/build-196067-assert/bin/clang-check+0x96d1f1)
#1 0x00006213f7836dac llvm::sys::RunSignalHandlers() (/home/ubuntu2404/build-196067-assert/bin/clang-check+0x969dac)
#2 0x00006213f7836f0c SignalHandler(int, siginfo_t*, void*) Signals.cpp:0:0
#3 0x0000707b8ae45330 (/lib/x86_64-linux-gnu/libc.so.6+0x45330)
#4 0x0000707b8ae9eb2c __pthread_kill_implementation ./nptl/pthread_kill.c:44:76
#5 0x0000707b8ae9eb2c __pthread_kill_internal ./nptl/pthread_kill.c:78:10
#6 0x0000707b8ae9eb2c pthread_kill ./nptl/pthread_kill.c:89:10
#7 0x0000707b8ae4527e raise ./signal/../sysdeps/posix/raise.c:27:6
#8 0x0000707b8ae288ff abort ./stdlib/abort.c:81:7
#9 0x0000707b8ae2881b _nl_load_domain ./intl/loadmsgcat.c:1177:9
#10 0x0000707b8ae3b517 (/lib/x86_64-linux-gnu/libc.so.6+0x3b517)
#11 0x00006213f7be0944 clang::RecursiveASTVisitor<(anonymous namespace)::BuildTreeVisitor>::dataTraverseNode(clang::Stmt*, llvm::SmallVectorImpl, llvm::PointerIntPairInfo>>>*) BuildTree.cpp:0:0
#12 0x00006213f7be19be clang::RecursiveASTVisitor<(anonymous namespace)::BuildTreeVisitor>::TraverseStmt(clang::Stmt*, llvm::SmallVectorImpl, llvm::PointerIntPairInfo>>>*) (.constprop.0) BuildTree.cpp:0:0
#13 0x00006213f7be3bfc clang::RecursiveASTVisitor<(anonymous namespace)::BuildTreeVisitor>::TraverseCompoundStmt(clang::CompoundStmt*, llvm::SmallVectorImpl, llvm::PointerIntPairInfo>>>*) BuildTree.cpp:0:0
#14 0x00006213f7be19be clang::RecursiveASTVisitor<(anonymous namespace)::BuildTreeVisitor>::TraverseStmt(clang::Stmt*, llvm::SmallVectorImpl, llvm::PointerIntPairInfo>>>*) (.constprop.0) BuildTree.cpp:0:0
#15 0x00006213f7bec740 clang::RecursiveASTVisitor<(anonymous namespace)::BuildTreeVisitor>::TraverseFunctionHelper(clang::FunctionDecl*) BuildTree.cpp:0:0
#16 0x00006213f7bd8ddc clang::RecursiveASTVisitor<(anonymous namespace)::BuildTreeVisitor>::TraverseDecl(clang::Decl*) BuildTree.cpp:0:0
#17 0x00006213f7bd9aea clang::RecursiveASTVisitor<(anonymous namespace)::BuildTreeVisitor>::TraverseDeclContextHelper(clang::DeclContext*) BuildTree.cpp:0:0
#18 0x00006213f7bf283b clang::RecursiveASTVisitor<(anonymous namespace)::BuildTreeVisitor>::TraverseTranslationUnitDecl(clang::TranslationUnitDecl*) BuildTree.cpp:0:0
#19 0x00006213f7bd9439 clang::syntax::buildSyntaxTree(clang::syntax::Arena&, clang::syntax::TokenBufferTokenManager&, clang::ASTContext&) (/home/ubuntu2404/build-196067-assert/bin/clang-check+0xd0c439)
#20 0x00006213f72cd4af (anonymous namespace)::DumpSyntaxTree::CreateASTConsumer(clang::CompilerInstance&, llvm::StringRef)::Consumer::HandleTranslationUnit(clang::ASTContext&) ClangCheck.cpp:0:0
#21 0x00006213f9103f9c clang::ParseAST(clang::Sema&, bool, bool) (/home/ubuntu2404/build-196067-assert/bin/clang-check+0x2236f9c)
#22 0x00006213f7891271 clang::FrontendAction::Execute() (/home/ubuntu2404/build-196067-assert/bin/clang-check+0x9c4271)
#23 0x00006213f78dd308 clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (/home/ubuntu2404/build-196067-assert/bin/clang-check+0xa10308)
#24 0x00006213f7bb9cb7 clang::tooling::FrontendActionFactory::runInvocation(std::shared_ptr, clang::FileManager*, std::shared_ptr, clang::DiagnosticConsumer*) (/home/ubuntu2404/build-196067-assert/bin/clang-check+0xceccb7)
#25 0x00006213f7bb3b2a clang::tooling::ToolInvocation::runInvocation(char const*, clang::driver::Compilation*, std::shared_ptr, std::shared_ptr) (/home/ubuntu2404/build-196067-assert/bin/clang-check+0xce6b2a)
#26 0x00006213f7bb61e2 clang::tooling::ToolInvocation::run() (/home/ubuntu2404/build-196067-assert/bin/clang-check+0xce91e2)
#27 0x00006213f7bb7e19 clang::tooling::ClangTool::run(clang::tooling::ToolAction*) (/home/ubuntu2404/build-196067-assert/bin/clang-check+0xceae19)
#28 0x00006213f7252405 main (/home/ubuntu2404/build-196067-assert/bin/clang-check+0x385405)
#29 0x0000707b8ae2a1ca __libc_start_call_main ./csu/../sysdeps/nptl/libc_start_call_main.h:74:3
#30 0x0000707b8ae2a28b call_init ./csu/../csu/libc-start.c:128:20
#31 0x0000707b8ae2a28b __libc_start_main ./csu/../csu/libc-start.c:347:5
#32 0x00006213f72cc045 _start (/home/ubuntu2404/build-196067-assert/bin/clang-check+0x3ff045)
Aborted (core dumped)
```

Reproduce the crash with clang-check using the C++23 input and --tokens-dump options shown in the issue. Then inspect clang/lib/Tooling/Syntax/BuildTree.cpp around TraverseCXXOperatorCallExpr at line 1253, focusing on the failing operator-node assertion. Done means the input is processed without an assertion failure and the regression is covered by an appropriate test.

Written by the indexing model from the issue text.