[lex.key]

The identifiers shown in Table 5 are reserved for use as keywords (that is, they are unconditionally treated as keywords in phase 7) except in an attribute-token ([dcl.attr.grammar]).

[Note 1:

The register keyword is unused but is reserved for future use.

— end note]

Table 5 — Keywords [tab:lex.key]

🔗 alignas	constinit	extern	protected	throw
🔗 alignof	const_cast	false	public	true
🔗 asm	continue	float	register	try
🔗 auto	contract_assert	for	reinterpret_cast	typedef
🔗 bool	co_await	friend	requires	typeid
🔗 break	co_return	goto	return	typename
🔗 case	co_yield	if	short	union
🔗 catch	decltype	inline	signed	unsigned
🔗 char	default	int	sizeof	using
🔗 char8_t	delete	long	static	virtual
🔗 char16_t	do	mutable	static_assert	void
🔗 char32_t	double	namespace	static_cast	volatile
🔗 class	dynamic_cast	new	struct	wchar_t
🔗 concept	else	noexcept	switch	while
🔗 const	enum	nullptr	template
🔗 consteval	explicit	operator	this
🔗 constexpr	export	private	thread_local

Furthermore, the alternative representations shown in Table 6 for certain operators and punctuators ([lex.digraph]) are reserved and shall not be used otherwise.

Table 6 — Alternative representations [tab:lex.key.digraph]

🔗 and	and_eq	bitand	bitor	compl	not
🔗 not_eq	or	or_eq	xor	xor_eq

5 Lexical conventions [lex]

5.12 Keywords [lex.key]